staadpro knowledge base

Curso “Análisis Estructural con el

Uso del Programa StaadPro”

Material de Apoyo

StaadPro Knowledge Base

Ing. José Gerardo Castillo

Print this Page Close Window

STAAD.Pro Knowledge Base

Issue #: SP-8866 Date Posted: 3/16/2006

Description: Is it possible to quickly find out the total number of nodes & beams in a model?

Version: Build No:

Solution: Yes. On the left side of the screen, click on the Setup page. On the right side of the screen, click on the button called "More". Another place to get this from is the button that looks like a question mark. It is called Info. See the figure below.

Page 1 of 2Research Engineers International

31/05/2006http://www.reiworld.com/support/kb/FaqDet1.asp?id=9092


To send this page to a friend or colleague, please use the following URL: http://www.reiworld.com/Search.asp?id=SP-2629



Description: What are the meanings of the different parameters used in the STAAD.Pro UBC analysis and how do we use them in a practical situation ?How is the base shear calculated and applied? Is the UBC load applied as a joint load ?

Version: ALL Build No: ALL

Solution: The base shear calculated in STAAD from a properly defined UBC 97 loading is redistributed at each floor using the rules laid down in clause 1630.5 of the subject code. In STAAD, the UBC load is not interpreted as joint loads. The method of calculation, in brief, can be explained as follows: a) While defining the UBC load, the user specifies the the different co-efficients to calculate the base shear. The total inertia of the structure due to its selfweight and external loading on the joints & members are lumped at the joints. It is used to calculate the factor W required to arrive at the value of the base shear. b)The time period of the structure is calculated based on clause 1630.2.2.1(Method A) and 1630.2.2.2(Method B). The user may optionally provide a value of CT to calculate the time period by method A. The user may also override the period calculated by the progrom via Method B by specifying a value for PX or PZ depending on the direction of the UBC load. c) The governing time period of the structure is chosen from the two periods (calculated in (b) above) on the basis of the guidance provided in clause 1630.2.2.2. d) The numerical coefficient for lateral load (R) should be selected properly by the user to account for the effect of the contribution of panel zone deformations to over all story drift for steel moment frame systems (UBC-97, Volume #2: Section:1630.1.2(2)) . e) In table 16-I the seismic zone factor is tabulated.The importance factor is provided by Table 16-K. In STAAD, the STYP values 1 to 5 refer to the soil profile types Sa to Se as given in Table 16-J. Soil profile type Sf is not supported by STAAD.The seismic source type is tabulated in the Table 16-U.The factors Na & Nv are tabulated in Tables 16-S and 16-T. The zone factor, importance factor,soil profile type,Na and Nv must be input by the user as the UBC-97 parameters. Based on the above parameters(except the importance factor, which is directly used) the coefficients Ca and Cv are found out by STAAD from Tables 16-Q and 16-R . f) The design base shear is then calculated by equation 30-4 of clause 1630.2.1 and it is checked with equations 30-5,30-6 and, if applicable, with equation 30-7. g) If the ACCIDENTAL option is specified, the program calculates the additional torsional moments where the lever arm for calculation is 5% of the building dimension at each floor level perpendicular to the direction of the UBC load(clause 1630.6). h) The design base shear is distributed at each floor via clause 1630.5. The average lateral displacement of all joints at each vertical level of the structure can be printed through the command PRINT STORY DRIFT. i) The nodal displacements are then calculated. The forces/moments are then subsequently calculated.







Description: What is the difference between a JOINT WEIGHT and a JOINT LOAD?


Solution: The JOINT WEIGHT option is specified under the DEFINE UBC LOAD command and is used merely to assemble the weight values which make up the value of "W" in the UBC equations. In other words, it is the amount of lumped weight at the joint and a fraction of this weight eventually makes up the total base shear for the structure. A JOINT LOAD on the other hand is an actual force which is acting at the joint, and is defined through the means of an actual load case.







Description: I am trying to model a beam connecting to the flange of a column instead of at the center. How is this modeled?


Solution: You have to use a facility called member offsets. You "offset" the face of the beam by a distance equal to half the depth of the column cross-section. An example of this can be found in Example # 7 in the STAADPro Examples Manual.







Description: When assigning loads using the cursor, I clicked on the wrong node, and hence the load ended up being assigned to a node that wasn't supposed to receive it. How can I graphically remove the load from this node ?


Solution: On the right side of the screen, where the facility for assigning various types of loads is available, you will see a check box called Toggle Load. Switch on the Toggle Load option. Then assign the load to the same node once again. You will see that the load gets de-assigned. Then un-check the Toggle Load check box.







Description: When does one use FLOOR LOAD and when does one use ELEMENT LOAD?


Solution: When modelling a grid system made up of horziontal beams and the slabs which span between the beams, we have found that there are 2 approaches that users take : 1) They model the beams only, and do not include the slabs in the model. However, they take into account the large inplane stiffness of the slab by using the master-slave relationship to tie together the nodes of the deck so that a rigid diaphragm effect is simulated for the horizontal plane at the slab level. 2) They model the slabs along with the beams. The slabs are modelled using plate elements. The question that arises is, how does one account for the distributed loading (load per area of floor) which is present on top of the slab? If you model the structure using method (1), the load can be assumed to be transferred directly on to the beams. The slab-beam grillage is assumed to be made up of a number of panels, similar to the squares of a chess board. The load on each panel is then tranferred to beams surrounding the panel, using a triangular or trapezoidal load distribution method. You can do this in STAAD by defining the load intensity in the FLOOR LOAD command. In other words, the pressure load on the slabs (which are not included in the model) are converted to individual beam loads by utilizing the FLOOR LOAD facility. In method (2), the fact that the slab is part of the model makes it very easy to handle the load. The load can be applied on individual elements using the ELEMENT LOAD facility. The connectivity between the beams and elements ensures that the load will flow from the plates to the beams through the columns to the supports.







Description: I am modelling a steel building consisting of columns and beams. The floor slab is a non-structural entity which, though capable of carrying the loads acting on itself, is not meant to be an integral part of the framing system. It merely transmits the load to the beam-column grid. There are uniform area loads on the floor (think of the load as wooden pallets supporting boxes of paper). Since the slab is not part of the structural model, is there a way to tell the program to transmit the load to the beams without manually figuring out the beam loads on my own?


Solution: STAAD's FLOOR LOAD option is ideally suited for such cases. This is a facility where you specify the load as a pressure, and the program converts the pressure to individual beam loads. Thus, the input required from the user is very simple - load intensity in the form of pressure, and the region of the structure in terms of X, Y and Z coordinates in space, of the area over which the pressure acts. In the process of converting the pressure to beam loads, STAAD will consider the empty space between criss-crossing beams (in plan view) to be panels, similar to the squares of a chess board. The load on each panel is then tranferred to beams surrounding the panel, using a triangular or trapezoidal load distribution method. Additional information on this facility is available in example problem 15 in the examples manual, and section 5.32.4 in the STAAD.Pro Technical Reference manual.







Description: I am trying to analyse a structure which consists of a large dia pipe supported at discrete points. I am unableto get STAAD to analyse this for UBC loads.


Solution: When the UBC committee came up with the recommendations for analysing structures subjected to earthquakes, the type of structures they had in mind were conventional style buildings where the base of the model, namely, the points where the supports are located is at the lowest elevation with respect to the rest of the model. If you look at the UBC procedure, it involves computation of the base shear, which then has to be distributed over the height of the building, so that one can then calculate the inter-story shears. A certain amount of the weight gets lumped at the highest point of the building, and the rest gets distributed along the height. In other words, the principle is that a mass at any height of the building is subjected to an acceleration and the force caused by the acceleration is represented by a concentrated force where the mass is located. The summation of all such forces at a given floor cause the columns beneath that floor to be subjected to a shear force. When you talk of a model like a pipe which is defined as line members attached to several collinear nodes, all of which are at the same elevation, the UBC rules become impossible to apply. The fact is, to analyse your structure for seismic effects, you do not even need the elaborate procedure of the UBC code. You can take the selfweight, and any imposed loads on the pipe, and apply them along a horizontal direction like X or Z with a factor, and you will get what is normally expected in a seismic analysis. So, you just have to have LOAD 2 SELF X n where n is a number like 1.5, which represents that there is a net force of 1.5 times the weight of the structure acting along the X direction due to an earthquake. For better handling of the distributed loads, you might want to consider defining several nodes along the length of the pipe, between supports.







Description: While the analysis and design takes place, STAAD generates a results file. This file can be viewed using the STAAD Output Viewer. I want to send this file electronically (email, on a disk, etc.) to somebody who does not have STAAD on their computer. How can they view these results?


Solution: The STAAD output file is the one which has the extension .anl. For example, if the input file is called mast34.std, the output file is called mast34.anl. For the most part, the output file is a text file, and can hence be viewed using an text editor, such as Windows NotePad. However, there are some special characters in the file which enables the STAAD output viewer to present the information in a more organized format, such as with a table of contents. If you are willing to accept a lesser quality presentation style for viewing, you can use a text editor to view the .anl file. You can request your colleague to rename the file from .anl to .txt, or specify the extension .anl in the File - Open dialog box of the text editor.







Description: I am currently working on a seismic model which requires a response spectrum input. What I am finding is that regardless of the value I specify for damping, the displacements and forces appear the same. Is this right?


Solution: The damping factor that one specifies in the input has no effect at all if the combination method is SRSS. For the SRSS scheme, the effect of damping is built into the spectrum values (period vs. acceleration or period vs. displacement) that the user specifies. In other words, if the damping factor is f1, the acceleration that the user should provide ought to be A1 corresponding to period T1. If the damping factor is f2, the acceleration ought to be A2 for the same period T1. In other words, for the SRSS method, the effect of damping has to be reflected on the spectral acceleration or spectral displacement that is being input. The damping coefficient by itself does not have a direct impact on the results. It's effect is indirect. With the CQC method, it is a different story. Damping will generally have an impact on the results, because, the damping factor is an explicit term in the equation used in CQC.







Description: I want to calculate and display the vertical deflection along the span length of a beam. Could you please tell me what would be the commands required to obtain these values?


Solution: You can obtain displacements at intermediate points along the member span by specifying two commands in your input : 1) The SECTION command This is the one with which you specify the location where you want the displacement. The location is specified with the help of a number between 0 and 1, and that number represents the distance from the start node, as a fraction of the member length. Upto 3 locations can be specified per one instance of the command. 2) The PRINT SECTION FORCES command This is the command whose output will consist of the displacements in global X, Y and Z directions at the locations listed in the SECTION command explained above. For example SECTION 0.1 0.2 0.3 ALL PRINT SECTION FORCES SECTION 0.4 0.5 0.6 ALL PRINT SECTION FORCES SECTION 0.7 0.8 0.8 ALL PRINT SECTION FORCES SECTION 0.25 0.65 0.86 ALL PRINT SECTION FORCES You can also obtain the section displacement values using the Member Query option of the Tools menu, or by double clicking on the member. The Query dialog box has a Displacement tab in which displacements at any point within the member span can be obtained for any load case.







Description: How do you assign properties to solids?


Solution: You do not have to assign any properties for solid elements. For solids, the only information required is their geometry (node numbers and their coordinates), and material constants (E, Poisson, etc.). You may refer to example problem 24 in the examples manual if you want details.







Description: I have modeled a 40" x 40" column base plate with (4) 12" dia. pipe columns on it (equally spaced in both directions). How do I tell STAAD that the base plate will be on a concrete pedestal (f'c = 4.0 ksi)? My first guess is to assign supports at the mesh intersections: SUPPORTS 1 TO 529 ELASTIC MAT DIRECT Y SUBGRADE 4 Any suggestions?


Solution: Your guess is a good one. You can model the support as an elastic mat foundation. To do that, you first need to know the subgrade modulus of concrete. One of the methods by which the modulus can be computed is using the following equation: Ks = Es / B ( 1 - PoissonRation * PoissonRatio ) ( Reference: Foundation Analysis and Design ( Fifth Edition ) by Joseph E. Bowels Page 503 , Equation 9-6a ) In addition, if you want to make sure the concrete pedestal takes only compressive force, then specify the SPRING COMPRESSION command for those joints in the direction KFY. An example of this is SUPPORTS 1 TO 529 ELASTIC MAT YONLY SUBGRADE 987 SPRING COMPRESSION 1 TO 529 KFY If you have any anchor bolts attached to the baseplate, they can be modeled as spring supports (tension only). An example of this is SUPPORTS 1000 TO 1004 FIXED BUT MX MY MZ KFY 5467 SPRING TENSION 1000 TO 1004 KFY







Description: I am not sure how STAAD deals with the specifications of the unsupported length for top flange compression. For example, if I have a truss whose top chord is laterally supported at every other node (i.e. two member lengths being unsupported), then should I highlight every two members (of the top chord) seperately and then tell the program to take their combined length as being unsupported, or should I highlight the entire top chord and then specify the correct unsupported length.


Solution: The value you specify for UNL is what STAAD uses for the expression Lb which you will find in Chapter F of the AISC ASD & LRFD codes. Starting from Version 2001, UNL has been replaced with UNT and UNB for these codes. If the Lb value for the top flange is different from that for the bottom flange, you have to specify the corresponding values for UNT & UNB. So if the bracing points are at every alternate node, first determine the distance between the alternate nodes. Then assign that value for both beams which exist between those nodes. For example, if you have Member 5 connected between nodes 10 and 11, and is 6.5 ft long Member 6 connected between nodes 11 and 12, and is 7.3 ft long and both the top and bottom flanges are braced at nodes 10 & 12, you can assign UNIT FEET PARAMETER CODE AISC UNT 13.8 MEMB 5 6 UNB 13.8 MEMB 5 6 To assign these parameters using the GUI, while in the Modelling mode, select the Design page from the left side of the screen. Make sure the focus is on the Steel sub-page. On the right side, select the proper code name from the list box on the top. Click on the Define Parameters button along the bottom right side. In the dialog box which comes up, select the tab for UNT and UNB, specify the value, and assign it to the appropriate members.







Description: I am performing concrete design for a beam per the ACI code and I encounter an error message : "LOCATION FOR DESIGN FOR SHEAR AT START OF MEMBER 2 IS BEYOND THE MIDPOINT OF MEMBER. DESIGN FOR SHEAR AND TORSION NOT PERFORMED." How can I get around this situation?


Solution: STAAD performs concrete design for shear and torsion at locations defined by (d + SFACE) from the start of the member and (d+EFACE) from the end of the member respectively. The basis for this assumption can be found in Section 11.1.3.1 of ACI 318-99. If these locations are beyond the mid-point of the member, that triggers the error message you encountered. In case you are not familiar with the parameters SFACE and EFACE, you will see in Chapter 3 of the Technical Reference Manual in Table 3.1 that these are values which the user may specify to convey to STAAD how far the face of the member is from the nodal point of the member. The default value for SFACE and EFACE is 0.0. "d" is the effective depth of the member. So, this is what you can do. You can set the values for SFACE and EFACE to be negative quantities equal in magnitude to "d". That will result in (d+SFACE) and (d+EFACE) becoming zero, which means that the design will be performed at the nodal points of the member, thereby avoiding the situation of the design point being beyond the mid-point of the member. So, in your input file, under the START CONCRETE DESIGN command, specify these parameters along the following lines : START CONCRETE DESIGN CODE ACI SFACE -d MEMB 110 EFACE -d MEMB 110 DESIGN BEAM 110 END CONCRETE DESIGN where "d" is the effective depth of the member.





Description: Can you please explain the concept behind member offsets?


Solution: When creating a model consisting of beams and columns, generally, the START or END face of the member is assumed to be located at the nodal point. In other words, the distance from the respective node to the start or end face of the member is treated as zero. Thus, for example, if member 47 is defined as being connected between nodes 12 and 13, then, the start face of the member is located at node 12, and the end face at node 13.

This assumption may not always reflect the true physical condition on the structure. For example, when a beam meets a column, the common node between the beam and column is usually defined as being at the shear center (centerline for symmetrically shaped) of the column.



But, physically, the start face of the beam is not at that node, but at half the column depth away from the node. One may choose to ignore this "shift" if the column depth is negligible in comparison to the span of the beam. However, if one wishes to take advantage of the high stiffness that the half-depth region of the column offers, he/she may consider this using the member offset command. The member offset is a way of declaring that the region, whose length is defined by the offset, is a rigid zone. Hence, if the offset values in X, Y and Z coordinates are a, b and c, the length of that region is d=sqrt(a*a + b*b + c*c). The face of the member is then assumed to be "d" away from the node.





The member end forces that STAAD reports are at the face of the member, not at the node, when an offset is specified. If the offset is applied at the base of a column, then the member end force may not be equal in magnitude to the corresponding support reaction terms. If one is interested in checking static equilibrium based on the free body diagram at that support, the member end forces must be transferred from the member face to the support node taking into consideration the rigid link defined by the offset.







Description: I have a model consisting of several members. I would like to find the moments and axial forces at node 182?


Solution: Forces and moments are currently reported only at member ends, plate corners and as reactions at supports. The first of these is reported in the individual member local axis system, while the other two are in the global axis system. If you are asking about a way to gather up the forces from all members connected to node 182, resolve them so that they are all along the same axis system - say the global axis system, algebraically add them up along that axis system along with the applied loads at that location, and then report that result, there is presently no automated way of doing this. We will consider implementing this in a future version of STAAD. So, you will have to do this using a manual procedure. There is a little tool in STAAD.Pro 2002 which can reduce the amount of effort it takes to obtain this. From the Select menu, choose "Entity at Node - Beams". Specify the node number as 182. The beams at node 182 will be highlighted. Close the dialog box. Click the right mouse button, and choose New View - Create a new window for the view. The selected beams will now be independently displayed in a new window, to an enlarged scale. You can now double click on the beams to view the forces at node 182 on the individual beams for any load case. You can switch on the load display, and use the load edit cursor to obtain the values of those loads, etc.







Description: Can the spring constant values for a nodal support be a negative number? For example, if I wanted my spring to act in one direction only, such as the negative Y direction, would you use the syntax KFY -5000?


Solution: Use the SPRING COMPRESSION command. Tension-only springs are capable of carrying tensile forces only. Thus, they are automatically inactivated for load cases that create compression in them. Compression-only springs are capable of carrying compressive forces only. Thus, they are automatically inactivated for load cases that create tension in them. If no spring spec is entered then all translational springs at that joint will be tension (or compression) only. This input command does not create a spring, only that if a support spring exists at the joint in the specified direction then it will also be tension (or compression) only. The procedure for analysis of Tension-only or Compression-only springs requires iterations for every load case and therefore may be quite involved. It is very important to recognize that the input data must be provided in such a way that only one primary load case is provided for each PERFORM ANALYSIS command. Also, the SET NL and CHANGE commands must be used to convey to STAAD that multiple analyses and multiple structural conditions are involved. SPRING TENSION 12 17 19 TO 37 65 SPRING COMPRESSION 5 13 46 TO 53 87 KFY







Description: Is there any command in STAAD.Pro to change the number of decimal places upto which the results are displayed in the output. (In Output File or Report or for values displayed on pictures using Result>View Values).


Solution: To set the number of decimal places for the information presented in tables or annotated diagrams, click on the View - Options menu. Then, select Section Units, Force Units, or Structure Units, depending on the type of result whose display you wish to modify. All of them have an edit box called "Show" alongside the individual result items. The number of decimal places is set over here. However, the maximum that you can go upto is 3. The other suggestion we can offer is that you may change the basic unit in which the particular value is being displayed. For example, a force which you wish to display in upto 6 decimal places in kip unit can be just as effectively displayed in 3 decimal places if you use pound units, or to a greater sensitivity using Newton units. You can change the basic unit in which results are displayed by going through the View - Options dialog box mentioned above, or by selecting the Set Current Display Unit option from the Tools menu, and selecting the appropriate tab of the ensuing dialog box. As far as the STAAD output file is concerned, there isn't any method available to control the number of decimal places to which values are displayed. You can only change the units in which the values are reported. Just specify a UNIT command prior to the PRINT command. For example, UNIT KNS METER PRINT MEMBER FORCES







Description: How can I copy and paste an entire structure from one STAAD file to another without losing the properties, loading, etc. during the process? I assembled my structure as separate components in separate STAAD models, and now I want to put them together.


Solution: A problem with simply copying and pasting the members from one STAAD file to another is that the properties can be lost. STAAD uses reference numbers to identify the properties. You see those in the Properties dialog box as R1, R2, R3, etc. Suppose you have two models you want to merge. Model 1 has members designated R1 and so does Model 2, but in Model 1, R1 is a wide flange whereas in Model 2, R1 is a single angle. If you paste members with properties designated R1 from Model 2 to Model 1, the program will assign the R1 members from Model 2 with the R1 properties the way they are defined in Model 1. Under this scenario, members you had intended to be single angles will thus end up as wide flange sections. One approach you can use that may help resolve this problem involves the use of your input files (i.e. *.STD files). You cancopy and paste your member incidences and properties from your STAAD input file. If you have two STAAD models, you can open both of them and use the copy and paste commands in the editor to copy the joint coordinates, member incidences, member properties, constants, etc. to merge the two smaller files into a single input file. You will need to exercise a certain amount of care in doing this. In particular, there are two items of concern you should be careful to consider. 1. The copy/paste will not work correctly if you have duplicate entity members, plates, solids and/or nodes) numbers. To prevent conflicts from duplicate numbers in the input file, you should check that each STAAD model you intend to merge has completely unique entity numbers. If there are duplicate numbers in the models you wish to merge, you can use STAAD's RENUMBER command from the Geometry menu to renumber the entities in your model before you begin editing the input files. 2. Be careful to copy and paste the various items from you models in the correct order. For example, the member incidences and joint coordinates must precede the properties, constants, etc. for the members and joints. You cannot tell the program that Member 35 is a W18x35 without first specifying the member incidences and joint coordinates for member 35.







Description: My model is a simple rectangular beam fixed at both ends, with an applied torsional moment at the mid-span point of the beam. Results shows zero moment at one end. At the other end, the value equals the full amount of the applied torsional moment. The results are unchanged even in the case of uniform torsional moment applied throughout the span.


Solution: If you defined the beam as a single member, with fixed supports at both ends, it becomes a model with zero degrees of freedom. Under those conditions, there are no displacements to solve for. For such a case, STAAD by default releases the torsional degree of freedom at one end, and a message to this effect will appear in your output file. So, look at the output file and see if the following message is present ***STAAD.Pro WARNING - ALL DEGREES OF FREEDOM FIXED. STAAD WILL RELEASE MOMENT-X AT FIRST JOINT ENTERED. If you see such a message, go back to your model, and change the support at one of the nodes from FIXED to FIXED BUT MY. Alternatively, break up the beam into 2 members, so that a node is create at the mid-span point. This will change the model from a zero d.o.f system to a 6 d.o.f system, which hence wouldn't require STAAD to release anything on its own. Then change the applied load from a concentrated moment to a joint load MX at the middle joint. You will get the answers you expect.







Description: What is the difference between a partial moment release and providing a spring with a stiffness as a release?


Solution: Both of these types of releases accomplish the same thing. They provide a connection where the transfer of force or moment is somewhere between 0 and 100%. The difference is that when a spring constant (stiffness) has to be defined, it is sometimes rather difficult to determine what that spring constant should be. A value like 1200 kip/in can be somewhat esoteric when describing the percentage of fixity of a connection. Partial moment releases allow you to describe the amount of force or moment to be transferred as a percentage rather than a stiffness (i.e. 0.75 or 0.50). This makes modeling a connection much easier. Mathematically, the stiffnesses corresponding to the DOFs from the connection are not fully statically condensed out, but instead, at the percentage specified.





Description: I have a one member structure. The coordinates of its 2 ends are : Node 1 : (0,0,12) Node 2 : (10,0,12) It has been assigned a single angle L50356 from the AISC table, using the "ST" specification (not "RA"). What do I have to do to orient it so that its longer leg is parallel to the global XY plane as shown?


Solution: By default, STAAD orients the above member in such a way that its local Y axis is parallel to the global Y axis. In othe coordinate location (-5,0,12) and look along the positive direction of the global X axis, he/she would see the following :



There are two simple methods you can adopt to orient it in the way you desire. 1) Take a look at the figures on page 1-12 and 1-13 of the STAAD.Pro 2002 Technical Reference manual. It shows a total ofcases, the beta angle is very easily computed as N - Alpha where N is an integer multiple of 90 Alpha is the "inclination angle" in degrees between the geometric axis and the principal axis. Alpha is readily obtained from t For our specific case, Tan(Alpha) is listed in the code as 0.486. Hence, Alpha is 25.92 degrees. Referring to case 14 on page 1-12 of the STAAD.Pro 2002 Technical Reference manual, the beta angle hence is 90 - 25.92 = 64.08 degrees



Hence, we just have to apply a beta angle of 64.08 degrees. 2) As is explained in Section 5.26.2 of the STAAD.Pro 2002 Technical Reference manual, there are 3 possible values one cannumeric value, which we saw in the previous method. The other two are the expressions "ANGLE" and "RANGLE". These expcalculate the BETA value on its own. There is a figure on page 5-108 of the STAAD.Pro 2002 Technical Reference manual wh In other words, we can specify the following set of commands in the STAAD input file CONSTANT BETA ANGLE MEMBER 1 If we were to specify the command PRINT MEMBER INFORMATION in the file, and run the analysis engine, the output file will contain a report consisting of the beta angle value among other th

As seen from the point (-5,0,12), the orientation of the member after the beta angle is applied will be







Description: What's the difference between ELASTIC MAT and PLATE MAT for spring support generation?


Solution: With the ELASTIC MAT you enter a list of joints from which STAAD will attempt to form a perimeter which encloses an overall area. This is done with a convex hull algorithm. Lastly, areas are assigned to each joint. If the convex hull rules are met, the algorithm works well. However for mats with irregular edges or holes, the algorithm may not do what the user expects and one may end up with springs with unreasonable spring constant values. Since many mat foundation problems have plates defining the entire mat, we have added the PLATE MAT option where you enter a list of plates that entirely define the mat. Roughly 1/4th of the area of each plate is assigned to each joint in the plate in the same manner as uniform pressure or self weight is distributed. So if you have the foundation support entirely defined by plates, then use the PLATE MAT option. Otherwise use the ELASTIC MAT option. With this option please observe the rules listed in the Tech Ref Manual. Avoid convex angles. You may have to subdivide the region into several sub-regions with several ELASTIC MAT commands. Add "PRINT" to the end of the command to see the areas assigned to each joint where a support is generated.







Description: This is a question dealing with response spectrum analysis. I know that if a force is applied in the response spectrum load case, it will be converted to a mass that will in turn affect the modal response. My question is, will that input force still be applied as a static force in the analysis? Or, would I have to apply the force in a different load case to account for it?


Solution: Response spectrum analysis is a dynamic analysis based on ground motion spectral acceleration. The acceleration usually varies with the period. Since there is no direct input for masses, what you are entering as forces are weights, and STAAD extracts masses from those weights. Hence, the same weight value should be entered in all 3 global directions for general space structures in order to get the natural modes and frequencies correctly. The response spectrum result will be an absolute unsigned value for each output quantity which represents the maximum value for that quantity. Because of this, the 6 force/moments at each end of a beam will all be positive. Also given the member forces/moments on one end, you cannot compute those results on the other end because the values are considered independent much the same as if these were peak values in time history that all occurred at different times. If you want static loading results combined with spectrum results, then use load combinations, possibly with the SRSS option.







Description: In the output file of a response spectrum analysis, there is the section that shows the mass participation factors in the x, y, and z directions. Then it shows the 'base shear' in all 3 directions. What is the reference point for this? I mean, does Staad select a 'base' or is the value just the sum of all forces in that particular direction?


Solution: Each mode has a base shear that comes from the modal displacement at each joint with mass in the direction being excited by the base acceleration and the input spectral acceleration and the modal frequency. These modal base shears are combined by SRSS or any other method in STAAD that you select. In effect, all supported joint directions form the base where the displacement of every mode is zero.







Description: In my model, there are several pairs of nodes which are separated by a very small distance. For example, node 43 has the coordinates (17.25, 12, 0) while node 57 is at (17.26, 12, 0). Some members are connected to node 43, while others end at node 57. I want all those members attached to node 43, and not to 57. So, what I am asking for is, I want to merge such pairs so that the program treats the 2 points of each pair as a "single" joint and not 2 separate joints. Is there a quick way to do this, or must I change the points one by one in the incidences table? In the example I explained above, how do I merge node 57 with node 43?


Solution: Under the Tools menu, you will find a facility called Check Duplicate Nodes. Click on that, and the ensuing dialog box will ask for a tolerance, which represents the distance by which the "duplicate" nodes are separated. The default value is 0.0, which indicates that 2 points have the same coordinate, but different node numbers. You can set it to a non-zero value if you want, thus expanding the definition of duplicate nodes to include points which are physically separated due to the manner in which the model was generated. So, set the tolerance to the desired value. The program will then bring up a list of all such points in the structure which are separated by that distance. You can then selectively merge them in such a way that the 2 separate node numbers will be replaced by a single one, and you have the freedom to decide which number to keep.





Issue: Analysing box culverts

Description: How can I use STAADPro to analyse a multi-cell box culvert?

Version: Build No:

Solution: For box culverts, STAADPro may be used in the following manner : a) Use the program's 3 and 4-noded plate element capability for modelling the structure. The program's mesh generation facreduce the work involved in creating multi-cell boxes. Alternatively, create the model in AutoCAD using the 3DFACE entity, simport the model into STAADPro. b) Specify the material attributes, such as Modulus of elasticty, Poisson's ratio, Density, coefficient of thermal expansion, etc c) Specify the subgrade modulus of soil beneath the culvert, and have the program automatically generate the spring constathe element nodes. A similar approach may be used for soil which abuts the side walls. Alternatively, use PINNED, FIXED or types the program offers. d) If the base slab or side walls are likely to undergo uplift or loss of contact with the soil, specify the supports as unidirectio e) Specify the dead weight of the structure using the program's selfweight load generation capability. f) Apply the weight of soil resting on top of the box, as uniform pressure on the elements which make up the upper slab of tloads such as weight of vehicles on roadways above the culvert may be applied as concentrated or patch loads on elements, g) Apply the lateral earth pressure and water pressure using trapezoidal/uniform pressure loading on the elements which maThe built-in hydrostatic loading facility can simplify the task to some degree. h) Perform the analysis to obtain displacements, support reactions, plate element stresses and moments. i) Use the program's concrete design facility to obtain the reinforcement requirements on an element-by-element basis, for tsurfaces of slabs, and inside and outside surfaces of side walls. Limitations : The concrete design facility can currently provide the area of steel required only, and that on an individual element basis. It of providing a bar arrangement. You will have to take the area of steel required from the program's output, and based on tharrangement on your own. Some of this limitation is expected to be addressed in version 2003 of the program, which is duefirst half of 2003.





Description: In the post-processing mode, the title row of the Beam Stresses table contains the headings Corner 1, Corner Corner 4. What are these 4 corners?

Version: Build No:

Solution: Please see the diagram below. This diagram is applicable for models where Y is the global vertical direction.







Description: What is the difference between a LOAD COMBINATION and a REPEAT LOAD?

Version: 2002 Build No: 1005

Solution: The difference lies in the way STAAD goes about calculating the results - joint displacements, member forces and support reactions. For a load combination case, STAAD simply ALGEBRAICALLY COMBINES THE RESULTS of the component cases after factoring them. In other words, for example, in order to obtain the results of load 10, it has no needto know what exactly constitutes load cases 3, 4 and 5. It just needs to know what the results of those cases are. Thus, the structure is NOT actually analysed for a combination load case. With a REPEAT LOAD case however, the procedure followed is that which occurs for any other primary load case. A load vector {P} is first created, and later, that load vector gets pre-multiplied by the inverted stiffness matrix. [Kinv] {P} to obtain the joint displacements. Those displacements are then used to calculate the member forces and support reactions. Thus, the structure IS analysed for that load case {P}.







Description: I want STAAD.Pro to perform a steel design based on the LRFD 3rd Ed rather than the 2nd Edition. The output always says "LRFD 1994". How do I tell it what code to use?

Version: 2002 Build No: ALL

Solution: If you wish to use LRFD 3rd Edition Code, you can write CODE LRFD3 when providing the design parameters. The 3rd edition of the American LRFD steel code has been implemented along with the 2nd edition. In general, the principles outlined in the code for design for axial tension, compression, flexure, shear etc., are quite similar to those in earlier versions of the code. The major differences are in the form of incorporation of the Young’s modulus of steel in the various equations for determining various limits like slenderness and capacities. Consequently, the general procedure used in STAAD for design of steel members per the AISC-LRFD code has not changed significantly. Users may refer to Section 2 of the STAAD.Pro Technical Reference manual for these procedures. Those who wish to use the 1994 edition of the code can still do so by specifying the code name as: CODE LRFD2 An example of commands used for performing design based on the new and old codes are as shown. Example for the LRFD-2001 code (3rd Ed) UNIT KIP INCH PARAMETER CODE LRFD or CODE LRFD3 FYLD 50 ALL UNT 72 MEMBER 1 TO 10 UNB 72 MEMB 1 TO 10 MAIN 1.0 MEMB 17 20 SELECT MEMB 30 TO 40 CHECK CODE MEMB 1 TO 30 Example for the LRFD-1994 code (2nd Ed) UNIT KIP INCH PARAMETER CODE LRFD2 FYLD 50 ALL UNT 72 MEMBER 1 TO 10 UNB 72 MEMB 1 TO 10 MAIN 1.0 MEMB 17 20 SELECT MEMB 30 TO 40 CHECK CODE MEMB 1 TO 30







Description: I am using STAAD.Pro 2003 and I want to use physical members to do a steel design. I know how to manually create physical members by selecting the individual members, right-clicking the mouse and choosing Form Member. But if I have hundreds of these members, can I do it faster?


Solution: In STAAD.Pro 2003, you can use the Auto-Form member option to let the program automatically create physical members for you. From the Member Design page in the Steel Design Mode, go to Member Design | Physical Members | Auto Form Members. The rules it uses to create physical members are as follows: 1) All elements must form a single continuous line. But they do not have to form a straight line. Thus curved members may be formed. 2) There must be a free end. Whilst curved members are allowed, they cannot form a closed loop. 3) All elements should have the same beta angle. 4) All elements must point in the same direction. Check with the orientation labels if necessary. Use the reverse element command on elements that point the wrong way. 5) None of the elements can be part of another member. 6) The section properties must be consistent at each element end. Elements can taper along their length, but where one element ends and the next starts, they must have the same section reference. 7) All elements must be made from the same material. 8) Vertical segments are converted into columns first.







Description: How does the sign convention (positive or negative) of bending moments work in STAAD.Pro?


Solution: Given a simply supported, statically determinate beam of length L, with a midspan concentrated load P:

The support reactions are both P/2 and the shear diagram in STAAD is as follows:

However, some people draw the bending moment diagram using the convention that a positive moment produces compressive stress in the “top” of a beam. STAAD plots bending moments on the tension side of the member. The side on which the plot appears is the side where the extreme fiber is in tension due to bending. For this example, the bending moment would look like this:







Description: I usually include the STAAD Output file (*.anl) in my documentation for projects. But the printed pages are too light. Is there an easy way to change the print style in STAAD to bold for this output?


Solution: First, go into the STAAD output file viewer. This is available under File | View | Output File | STAAD Output. Once the viewer window comes up, go to the File menu (of the viewer), and choose Font Setup. Change the Font style from Regular to Bold.





Issue: Modelling walls and slabs

Description: I have a structure consisting of a wall and a slab. How do I model this structure using finite elements in an efficient way using available STAAD.Pro 2002 or 2003 tools?

Version: Build No:

Solution: The mesh generation tools available in STAAD can be quite useful in modeling this structure so that the wall and slab are properly connected along their common boundary. You can use the following steps to accomplish this. Step 1 : Mesh the slab To do this, switch on the Generate Surface Meshing cursor.



Alternatively, you can go to the Select menu, and choose Mesh Generation Cursor.

Or, select the element (by using the Plate Cursor), click the right mouse button, and select Generate Mesh.



If you choose the mesh generation cursor approach (figures 2 or 3), click on the nodes that comprise the outer boundary of the slab in the following order : 1-2-3-4-1 STAAD's mesh generation cursor can handle any shaped polygon (even with holes or cutouts). When you finally click on node 1 the second time, you will see the following dialog box:

If you choose the Polygonal Meshing option, you will get triangular elements. You will also be presented with the option of adding holes or cutouts. If you choose Quadrilateral Meshing, you will get 4-sided elements. For either one, you have to specify the number of divisions along each of the 4 sides.



If you choose the figure 4 approach, the following dialog box will appear.

Specify the number of divisions along each edge. You will have to remember the incidence order of the slab plate to understand the layout of the 4 edges. Step 2 : Mesh the wall Repeat the above steps with the wall plate. Make sure that the number of divisions you specify for the wall along the side 2-3 is the same as that you specified for the slab along that side. The perimieter beams will automatically be broken up for continuity purposes. The end result will be something like that shown in the following diagram:







Description: I am using the Add Beam cursor to create a beam or column between two existing members. Sometimes, I wish to create a beam from an existing node to a point within the beam span that is not defined by a node. Is there a quickway of doing this?


Solution: When the Add Beam cursor is on, simply click on any point along the beam. The Insert Node dialog box will popup requesting you to specify where along the beam a node is to be created. STAAD.Pro will split the beam if necessary.







Description: How can I change the axis or point of rotation from the current point which is always at the center of the structure?


Solution: In STAAD.Pro 2003, there is new feature called "Select Node to Set Center of Rotation". The icon is shown below. Click on the icon to activate the Rotation cursor. Select an exisiting node where you would like the new center of rotation to be. The structure will now rotate about the new point.







Issue: Max Absolute Stresses in plates

Description: In the post processing mode, if you select the Plate page along the left side of the screen, it brings up a dialog box called Diagrams. In the Plate Stress Contour tab of this box, there is a stress type listed by the name Max Absolute. What does it represent?

Version: Build No:

Solution: The membrane stresses and bending stresses can be combined to form the principal stresses on the top and bottom surfaces of plate elements. The procedure for obtaining these is explained in example problem 18 of the examples manual. Thus, for each load case, there is an SMAX and an SMIN on each of the 2 surfaces of each element. The absolute maximum from among these 4 numbers is the quantity termed as "Max Absolute" under the Plate Stress Contour facility.







Description: I have two separate STAAD models that I wish to merge into a single structure. Any suggestions on how this can be done?


Solution: Please go through the document available at the link below for a detailed procedure.

combineModels.chm







Description: How does Staad "direct" a spring to determine if it is in compression or tension? In view of the above, how should one specified radially directed springs located around a circular tunnel or pipe and designate them as "compression" only in the physical sense of the term?


Solution: For the purpose of defining the sense of the force in the SPRING TENSION/SPRING COMPRESSION facility, the following rules are adopted in STAAD : A support reaction force is considered TENSILE if it is opposite to the positive direction of the axis under consideration. Another way of putting it is that, for this condition, the displacement along that axis of the support node is in the same direction as the positive direction of that axis. A support reaction force is considered COMPRESSIVE if it is along the positive direction of the axis under consideration. Another way of putting it is that, for this condition, the displacement along that axis of the support node is in the direction opposite to the positive direction of that axis. These rules are applicable for global axis supports, as well as inclined axis supports. Hence, use the center of the circular pipe as the REFERENCE POINT for the INCLINED supports. The local X axis for the inclined supports will then point from the perimeter towards the center of the circle. The supports around the circumference can then be assigned COMPRESSION only springs.







Issue: Preserving empty load cases

Description: Is there anyway to prevent STAAD 2002 Build 1006 US from deleting load cases with no loads specified in them? Currently, if I have a load case that has no loads, this case gets deleted when I save the file from the GUI. This is troublesome as we have template STAAD text files (which include all load cases). When we save, STAAD truncates the file and deletes all empty load cases.

Version: Build No:

Solution: Please note that the solution provided below will work only with STAAD.Pro 2002 Build 1006 and later. The steps are : 1) Exit STAAD.pro. 2) Using Windows Explorer, go to the WINDOWS or WINNT folder. Locate a file called staadpro20020.ini (or in the case of STAAD.Pro 2003, it is called staadpro20030.ini). Open that file. It is a simple text file, and can hence be opened using NotePad. 3) Locate a line called Delete Orphan Titles=1 Change the value from 1 to a zero, so that is should read Delete Orphan Titles=0 Save and exit that INI file. Start running STAAD.pro again. Orphan or empty load cases will no longer be deleted.







Issue: Importing data from Microsoft Excel

Description: I am curious if there is a way to import or copy load information from an Excel spreadsheet into STAAD. I have done this by the copy paste method for beams and nodes, but the paste option is not available for loads. Any other suggestions on how I could get loads from an Excel table into Staad?

Version: Build No:

Solution: You cannot paste them into the loads table. However, there is an alternative but just as easy a method. That is to paste them directly into the STAAD input file. In case you are not aware, the STAAD input file is a simple command file accessible from the Edit menu. Look for the option Edit Input Command File. It opens up a simple editor with the data displayed in various colors. If you understand the command syntax, you can create new load cases and paste the data into those load cases. Or, you can append the information to existing load cases too. If you go through any of the example and verification problems described in the examples manual, you will find that the syntax of the commands is explained and quite easy to understand. If you do not have a physical copy of the manual, the electronic version can be accessed from Help - Contents in the main screen of the program.







Issue: Specifying a moving load

Description: I am looking for some assistance in using the graphical method for specifying a moving load. Can you help?

Version: Build No:

Solution: Please go to http://www.reiworld.com/Product/AllDemo.asp and click on the link titled Moving Load generation on a bridge deck model using STAAD.Pro under the STAAD.Pro Tutorials. This will play a short movie explaining how to use this feature on the bridge deck model used in example problem 12 in the Examples manual. Other tutorials are also listed there.







Issue: Ignore Inplane Rotation for Plate Elements

Description: What is the application of the IGNORE INPLANE ROTATION specification for plate elements?

Version: Build No:

Solution: Imagine that you have a wall upon which you apply a concentrated force at the top along the plane of the element (see figure).

STAAD normally takes into consideration in-plane rotation action. In other words, STAAD normally assumes that the wall has some inherent flexibility, which means that the distance between two points that are at the far corners of the wall would change as force is applied to the wall. If the wall was a rigid body, however, the distance between the two points would remain the same. If you wanted the plate to behave as a rigid body, you would add this Ignore Inplane Rotation specification and assign it to the plate. This feature is not used very often. It is available in case you wish to compare STAAD’s analysis results with those of another structural analysis program that ignores in-plane rotation by default.







Issue: Material factor for design

Description: If using an American code for code check, is there any parameter to define the material factor or is it already included?

Version: Build No:

Solution: The American codes do not have explicit material factors. Instead, they use "strength reduction factors". These strength reduction factors account for unavoidable variations in material strength, design equations, fabrication and erection. For example, in the American steel code LRFD 2001, these factors are : 0.90 for limit states involving yielding 0.75 for limit states involving rupture 0.85 for limit states involving compression buckling For the American concrete code ACI 318-02, some of the values used are Tension-controlled sections - 0.9 Compression controlled sections, members with spiral reinforcement - 0.7 Shear and Torsion - 0.75 Bearing on concrete - 0.65 etc. These are requirements placed by the code. So, we do not have parameters for altering these.







Issue: Terms in AISC LRFD design output

Description: I am running STAAD.Pro 2003. In the TRACK 2 output for the American LRFD code, I find some terms that I am not familiar with. Can you tell me what those are?

Version: Build No:

Solution: The terms reported in the TRACK 2 output for American LRFD are : AX = Cross section Area. AY : Area used in computing shear stresses along local Y axis. AZ : Area used in computing shear stresses along local Z axis. PY : Plastic Section modulus about local Y axis. PZ : Plastic Section modulus about local Z axis. RY : Radius of gyration about local Y axis. RZ : Radius of gyration about local Z axis. PNC : Axial compression capacity. pnc : Axial compressive force used in critical condition. PNT : Axial tensile capacity. pnt : Axial tensile force used in critical condition. MNZ : Nominal bending capacity about local Z axis. mnz : Bending moment about local Z axis, used in critical condition. MNY : Nominal bending capacity about local Y axis. mny : Bending moment about local Y axis, used in critical condition. VN : Shear capacity. vn : Shear force associated with critical load case and section location. DFF : Permissible limit for checking length to deflection ratio. dff : Actual length to deflection ratio.







Issue: STAAD input and result data files

Description: Is there a document (or something in the STAAD.Pro manual) that describes the "file extension names"? For example, *.std is the STAAD Input file and *.bmd is the bending-moment diagram file. What do the other extensions represent such as *.cod, *.scn, etc.

Version: Build No:

Solution: There are only two files you need to worry about: the STD file and the ANL file. As you already know, the STD file is the input file. The ANL file is the output file, a.k.a. the Analysis file. Both these files are in ASCII format. You can open them with any text editor. Occasionally people want to save the ANL file under a different name or in a different folder so that they can preserve the results of an analysis, make some changes to the input, then produce another ANL file and compare the results. As you might know, if you run the analysis and then make some changes to the input file and try to save the changes, STAAD deletes the existing output file. People also might like to open the ANL file in a word processing program in order to edit it and format it for printing. All the remaining files produced by STAAD are for the program's internal use only. The program uses these files to display results. There is no need to keep backup copies of any of these files. The only exceptions might be the files BK1, BK2 and BK3. These files are backup files of the input file. They might be useful if your original input file became corrupted due to some system failure.







Issue: Snapshot and brief description of model

Description: When opening an existing file, we used to get a preview graphic image and a 5 line description for each file. How do we get this feature back?

Version: Build No:

Solution: The preview image and the Job Info that appear in the lower half of the File > Open dialog box are stored in a file with an EMF extension. This *.EMF file is created when you save your input file inside STAAD.Pro. I believe the extension name stands for Extended Metafile. The fact that you are not seeing this preview leads me to suspect that perhaps you have archived only the input (*.STD) files. If this is the case, you can get the program to recreate the EMF files for you. To do this, run STAAD.Pro and open the existing file, then go to the STAAD.Pro editor, make some inconsequential change, save the input file and close it. Now you can close the project file. The next time you open it, you should see the preview image. If you also had entered anything in the Job, Client, Job No., Part or Ref edit boxes in the Job Info dialog box, you should also see that information displayed in the Preview Pane of the File > Open dialog box. There are a couple of ways you can make insignificant changes in the Input File: 1. Open your existing file, then go to the Input File Editor. Place your cursor at the beginning of the input file, type a space, then backspace over the space you just typed. Save the file and close it. 2. Open your existing file, then go to the Setup page in the Page Control, enter something in one or more fields in the Job Info dialog box in the data area, then select the Save command, either from the File menu or using the Save button on the File toolbar. This action will add a START JOB INFORMATION command to your input file, and the program will create an EMF file. Please keep in mind that in order to recreate the EMF file, you have to use STAAD's GUI (Graphical User Interface) to modify and save the input file. Modifying and saving the input file in Notepad, for example, will not generate a new EMF file. You can go to Windows Explorer and verify that the EMF file is present after you modify and save the input file. I realize that the purpose of the preview is to save you the trouble of actually opening each file to look at it when you are searching for a particular project. Still, it shouldn't take too long to open your existing files and make some insignificant change to the input file and save them, so that the preview feature will work the next time you open any of those files. In future, you can just keep in mind to archive the EMF files along with your STD files. I can understand that you might also wonder why we save the preview in some peripheral file. After all, many other programs save everything in a single, large file. Such an approach, however, requires that the file be in a proprietary (i.e. "black box") format not directly accessible to the users. STAAD's text-based input exposes the internal workings of the program to the users, and provides a means of auditing the design process that is very important in a civil engineering software application. Many experienced users find it much easier to do parts of their modeling and make changes to their projects by editing the input file, rather than using the GUI. We feel that the consequent need to generate various peripheral files for the program to use internally in displaying results is a relatively minor inconvenience compared to the benefits of our users being able to openly access the input file.







Issue: Why Member Releases

Description: What is the purpose of the "member release" command? What is the basis for the terms MX, MY and MZ in this command?

Version: Build No:

Solution: By default, STAAD assumes the connection between any 2 members to be fully capable of transmitting all 3 forces and all 3 moments from one member to the other. This is usually achieved in practice by moment resistant connections, such as between a concrete beam and a concrete column which are monolithically cast. If you want the connection to be of the type which does not permit one or more forces/moments to be transmitted, use member releases. A shear connection is such an example. The degrees of freedom FX through MZ that you release are based on the local axis of the member at whose end the release is specified. See section 5.22.1 and the figures in Section 1.19 of the STAAD.Pro Technical Reference manual for additional information.







Issue: OpenSTAAD Macro for calculating K factors

Description: I am using the Staad Pro 2003 build 1003 program on a computer running Windows XP. I am trying to calculate the effective length factors for steel design. Within the help menu, I printed out the instructions to use the VBA macro. I made it through the beginning steps and located the macro, but when I got to the screen titled "Calculate K Factors" as shown on page 2, figure 36 of the help menu, and clicked the Load Selected Members it kept giving me an error, saying "Internal Appication Error". I tried several times, reselecting the members and all, and still got the same error message. Any advice?

Version: Build No:

Solution: This problem may arise if you have not purchased the OpenSTAAD Professional version for STAAD.Pro 2003. The professional version of OpenSTAAD allows you to run VBA macros within STAAD itself. The normal version of OpenSTAAD (which is free) simply allows you to run VBA scripts data mining STAAD's results database or controlling its GUI from outside STAAD (like in Excel, Word, etc.). In the Release Report for STAAD.Pro 2003 2nd Edition, it says: AD.2003.28.13 Calculation of Effective Length Factors (K Factors) for Steel Design Purpose This feature is only available for users who have purchased the OpenSTAAD Professional Edition which enables users to run VBA macros within STAAD.Pro using the new embedded STAAD VBA Editor. The automatic calculation of the K factor in steel design has been added based on the nomograph method presented in the AISC ASD manual in Chapter 5 Section C-C2.2. If you want to purchase this, you can contact our sales department at 1-800-FOR-RESE. This will allow you to have access to other VBA macros REI writes in the future as well as VBA macros other people write and post on the REIWORLD site.





Issue: Bending moments in a slab

Description: Shown below is a STAAD model for a simple plate fixed at bottom. The problem is this: when I apply any in-plmoments can not be zero.

Version: Build No:

Solution: In plate results, MX & MY are moments which cause the plate to bend out of plane. For this particular model, in-pactions such as SX, SY and SXY.





Issue: Orienting unequal leg single angles along global directions

Description: I am trying to model a box type structure which has an unequal leg single angle at its ridges (see figure below



I want to orient the angles in the manner shown in the figure below. The long leg has to be vertical, the short leg horizontal,from the center of the box. How do I model this?



Version: Build No:

Solution: The critical issue in modelling this is choosing the right beta angle for the angles. Below are two suggestions, oneusing the "RA" type of angle. Solution 1 using the "ST" type angle specification.



Solution 2 using the "RA" type angle specification.







Issue: Applying selfweight selectively

Description: I was wondering if the option of "Selfweight" loading generates the selfweight for all of the members and elements of any model? Can I specify that the weight should be calculated for only some members and elements and not all?

Version: Build No:

Solution: The selfweight command takes into consideration the weight of all beams, plates and solids in the model. No entity is left out. So, if you wish to have the selfweight calculation excluded for some entities, you will have to assign a Density of 0.0, or a very small value for those entities.







Issue: Moments in a slab modelled with plate elements

Description: I am modelling a concrete slab using plate elements. I am looking for the moments in the slab at the center of each element. I noticed that the output gives the bending moments per unit width. What is the per unit width? Would that be the thickness of the plate element?

Version: Build No:

Solution: For Mx, the unit width is a unit distance at the center of the element, parallel to the local Y axis. For My, the unit width is a unit distance at the center of the element, parallel to the local X axis. Attached is a diagram to clarify this. It is taken from section 1.6.1 of the Technical Reference manual.

Mx_and_My_in_plates.pdf







Issue: Connecting nodes by creating beams and columns

Description: STAAD-III used to have features called "Connect Beam Along" and "Connect Column". I do not find those features in STAAD.Pro. Have they been eliminated?

Version: Build No:

Solution: No. The "Connect Beam Along" option is available under the same name from within the Geometry menu. The "Connect Column" feature is also available in the Geometry menu, under the name "Create Colinear Beams". For both these options, the nodes between which the members are to be created must be selected first using the Nodes cursor. Once the nodes are selected, these options can be activated.







Issue: Combining lateral seismic loads with gravity loads

Description: After determining the lateral loads using Staad UBC seismic analysis in a first file, I note down the lateral loads computed at each joint. In a second separate file with the same frame model, I apply the lateral loads from the first file combining them with the gravity loads and perform the analysis. I consider this procedure of mine very tedious in case of a 3D high rise building most specifically in view of the first file. Is there any shorter procedure for this? Please take note that I am using the Command File Editor.

Version: Build No:

Solution: There is absolutely no need for you to take the lateral load data from the output of the first file, and insert it as input into the second file. In STAAD, once the lateral loads due to UBC or IBC are generated, they are automatically available for combining with gravity loads, or any other loads for that matter. Consequently, there are 2 ways in which this combination can be achieved, and each is demonstrated below : Method 1 : Generate the lateral load in one load case. Specify the gravity load in another load case. Then, combine the two in a load combination case. LOAD 1 - GENERATE LATERAL LOADS DUE TO UBC ALONG X UBC X 1.0 LOAD 2 - SPECIFY GRAVITY LOADS SELFWEIGHT Y -1.0 MEMBER LOAD 1 TO 25 UNI GY -1.2 JOINT LOAD 10 39 FY -10.0 LOAD COMBINATION 3 - COMBINE THE LATERAL AND GRAVITY LOADS IN ONE CASE 1 1.0 2 1.0 Method 2 : Create a single load case in which the lateral forces are generated, and gravity loads are specified. LOAD 1 - LATERAL LOADS + GRAVITY LOADS UBC X 1.0 SELFWEIGHT Y -1.0 MEMBER LOAD 1 TO 25 UNI GY -1.2 JOINT LOAD 10 39 FY -10.0







Issue: Member properties for analysis of a plane frame

Description: I am analysing a plane frame. I specify a prismatic section with IX. The analysis stops with the error message that I need to specify IZ. What is the need to specify IZ?

Version: Build No:

Solution: For plane frames with no beta angle, what is needed is IZ, not IX. IX is the torsion constant. IZ is the moment of inertia about the Z axis. Members of a plane frame with a beta angle of zero will bend about the Z axis, which explains the need for IZ. They are not prone to twisting, and that is why IX is not needed. Table 1.1 from the Technical Reference manual, which shows the properties required for various types of structures, is reproduced below.







Issue: Repeating REPEAT LOADS

Description: I would like to create a REPEAT LOAD case whose constituent load cases are themselves REPEAT LOAD cases. Is this allowed?

Version: Build No:

Solution: You can do this if you have STAAD.Pro version 2002 or later. An example of this is shown below. LOADING 1 SELFWEIGHT Y -1.0 LOAD 2 REPEAT LOAD 1 1.0 JOINT LOAD 4 5 FY -15. ; 11 FY -35. LOAD 3 REPEAT LOAD 2 1.0 MEMB LOAD 8 TO 13 UNI Y -0.9 ; 6 UNI GY -1.2 LOAD 4 SELFWEIGHT Y -1.0 JOINT LOAD 4 5 FY -15. ; 11 FY -35. MEMB LOAD 8 TO 13 UNI Y -0.9 ; 6 UNI GY -1.2 PERF ANALY LOAD LIST 3 4 PRINT ANAL RES FINISH In the above example, load case 3 repeats load case 2, which in turn repeats load case 1.







Issue: Material properties for Timber

Description: In STAAD.Pro, you are providing Steel, Concrete and Aluminum as standard materials with built-in default values. Why isn't timber included? I am looking for the Modulus of Elasticity and Density of Douglas Fir.

Version: Build No:

Solution: Unlike the 3 materials mentioned in your question, timber comes in several varieties, with each variety having its own unique set of material properties. Douglas Fir alone comes in several varieties, as explained below. The American Wood Council and the American Forest & Paper Association publish a document called the "Supplement NDS for Wood Construction", 1997 edition. It provides design values for structural sawn lumber and glued laminated timber. There is also a category called Visually Graded Decking. Under each category, Douglas Fir comes in various species or combination of species. Under each species, there are various commercial grades. Each of those grades have a unique value of E, ranging from 1000 ksi to 1900 ksi. If the category, species, and commercial grade is known, the E value can be read from the tables in this document. The American Wood Council and the American Forest & Paper Association also publish a document called the "ASD Manual for Engineered Wood Construction". In the 1999 edition of this document, Table 8A, page 15 contains the specific gravity of Douglas Fir as ranging from 0.46 to 0.5.







Issue: Mat foundation spring supports and instability conditions

Description: When we generate the spring supports for a raft foundation using the command "list-of-joints Elastic mat Dir YONLY SUB 10000" we get instability warnings in FX, FZ and MY directions at certain joints. Why?

Version: Build No:

Solution: The Elastic Mat instability messages have to do with the Y option versus the YONLY option. The Y option automatically fixes the FX and FZ directions at all mat joints whereas the YONLY option does not. Without any support in the FX and FZ directions, your structure is unstable in these directions and MY as well. You could switch to the Y option or perhaps fix FX, FZ and MY at one joint near the center. Since STAAD automatically applies very small springs at one joint to stabilize an unstable structure, you could ignore the messages if there are no FX, FZ, or MY loadings and if the displacements are small in those directions.







Issue: Working in cylindrical coordinates

Description: I have a model of a circular tank containing joint coordinates in the cylindrical reverse system (JOINT COORDINATES CYLINDRICAL REVERSE commands). I would like to copy the data from this input file to another file and modify the input. But if I do this using STAAD's File-Save As, all joints are listed in the new file in the cartesian coordinate system. How can I copy the data and preserve the coordinates in the cylindrical reverse system?

Version: Build No:

Solution: Unfortunately, STAAD's graphical environment is based entirely on the cartesian coordinate system, and cannot preserve the data like you seek. You will have to do the copying from outside the STAAD environment. Exit STAAD.Pro. In Windows Explorer, go to the folder where the file is located. Select the file by single-clicking on it. From the Edit menu of Explorer, select Copy followed by Paste. A file by the name "Copy of .. " will appear. (For example, if you copy portal.std and then Paste, it will create "Copy of Portal.std". Rename the copy. In our example, select "Copy of portal.std", click the right mouse button, and choose Rename, and provide the new name. You can now open the new file in STAAD.







Issue: Units for displaying load values

Description: My current input units are Feet and Kips. However, when I display the load values on the screen, they shown up as "Kn/m". Why?

Version: Build No:

Solution: The unit system in which data is displayed in the tables and on the drawing is set using the facilities available under the View - Options menu. These are known as display units. To set the display units for uniformly distributed loads, please do the following : In the View menu, select Options - Force units. In the category called "Distr. Force", select the units you desire and click on OK.







Issue: Missing input for Na and Nv for UBC analysis

Description: I am applying a UBC seismic load on a bridge. The analysis engine reports an error message which says that EITHER NA OR NV FACTOR HAS NOT BEEN SPECIFIED WHILE SEISMIC ZONE HAS BEEN SPECIFIED AS 4.

Version: Build No:

Solution: This is due to the fact that, for your model, STAAD looks at the data under the DEFINE UBC LOAD command and concludes that you intend to analyse the structure per the UBC 1997 code. It then checks whether all the required parameters have been specified for that code, and detects that NA and NV are missing. You perhaps have an input similar to the one below : DEFINE UBC LOAD ZONE 0.4 I 1 RWX 12 RWZ 12 STYP 1.2 PX 0.2626 PZ 0.2626 For Zone 4, Na and Nv are two of the fundamental parameters necessary to calculate the base shear. If you look at Tables 16-Q and 16-R on pages 2-34 & 2-35 of the UBC 1997 code, you will find that for Zone 4, the coefficients Ca and Cv are dependent on Na and Nv. So, specify the NA and NV parameters, so that the commands look similar to the one below : DEFINE UBC LOAD ZONE 0.4 I 1 RWX 12 RWZ 12 STYP 1.2 NA 1.6 NV 1.6 PX 0.2626 PZ 0.2626







Issue: Material values in Report

Description: All the members in my model have been assigned Concrete as the material. I have added the item Materials to the Report Setup. But, the printed report shows the density as 0.0.

Version: Build No:

Solution: This is very likely due to your units being in kip/in^3. The default value in STAAD for density of concrete is 0.0000868 kip/cu.in. Since the values are printed to 3 decimal places, it will come out in your printed report as 0.000. If you change the display unit for Density to lb/cu.ft, you should be able to see the right value. To do this, go to Tools - Set Current Display Unit - Section Units and change the units for density to lb/ft3. If you then print the report again, the density value should be in accordance with this new unit.







Description: In STAAD.Pro, I create a report and export it to a Microsoft Word document. When I open that document in Word, I find that it is filled with smiling-faces, symbols and assembly language characters. How do I get around the problem?


Solution: This is most likely caused by a feature called "Script stopper" in your virus-scan program. It prevents the export process from taking place properly. Disable that feature before you export to Word, and re-start it after the exporting is complete.







Issue: Viewing members which fail the steel design checks

Description: I have a large model with several hundred members which have been assigned steel sections. I am doing a code check and I want to find out which of those members have failed. Can I get a list of just those members without having to scroll through hundreds of pages of steel design output?

Version: Build No:

Solution: There are 2 methods for finding just those members which have failed the steel design checks. 1) From the Select menu, choose By Specification - All Failed beams. The members which fail the check will be highlighted. You can then isolate them into a New View to examine them in greater detail. Double click on those members or use Tools - Query - Member to access a dialog box with tabs called Steel Design and Design Property to see the cause of the failure along with allowable and actual stresses and critical conditions. 2) In the Post processing mode, go to the Beam page along the left side of the screen. One of the sub-pages will be Unity Check. A table will appear along the right side of the screen. One of the tabs of that table is Failed Members. Select this tab, and click on each row of the table to look at each such member individually.







Issue: Viewing the output file

Description: I ran the analysis earlier today. The message came up that the output file has been successfully created. I close the file and re-open it a little later. I notice that the icon for viewing the output file is greyed out.

Version: Build No:

Solution: One possible cause is that the output file (the one which has the extension .ANL) simply does not exist. You can verify this by going to the folder where the input file (the one which has the extension .std) is located, and check to see if the output file is present. Another probable cause is that the input file is more recent in terms of date and time than the output file. This too can be verified by using Windows Explorer to examine the date and time of the individual files. If STAAD finds the input file to be newer than the output file, it interprets it as a sign that the file was modified since the last run which could mean the input data is no longer in sync with the output. The output file is made inaccesible in such an event. If this is the case, open the input file using Notepad, make an inconsequential change, such as introduce an additional blank space on any line, and save the file. The file will then have the date and time of your computer clock. Run the file through STAAD's analysis engine once again, and the output file will then be newer than the input file, enabling you to open it using the icon. If you are wondering how such a thing may happen, it could be that the file was created on one computer and moved to another. The first computer may have a date and time setting newer than the latter. Or, your colleague in the east coast may have created the file, and emailed it to you who is sitting in the West coast, resulting in a 3hour difference between your respective times. If none of the above is true, go to STAAD.Pro's File menu. Go to View - Output file - STAAD output. If the file is present, it should come up in the Viewer window. The fourth option is use Windows Explorer to go to the folder where the output file resides. Double click on the .ANL file. Explorer should automatically open it using SproView. If it doesn't, it will open a dialog box asking you to select a program using which to open it. Choose \spro200X\staad\sproview.exe where spro200X is the folder where the program is installed. Substitute X with the numbers 0, 1, 2, 3, 4, etc.







Issue: WARNING - SOFT MATERIAL

Description: In the output file, I see the following message ** WARNING ** A SOFT MATERIAL WITH (1.0 / 1.750E+01) TIMES THE STIFFNESS OF CONCRETE ENTERED. PLEASE CHECK. Please explain to me in plain English what StaadPro is trying to tell me.

Version: Build No:

Solution: STAAD checks to see if the E (Modulus of Elasticity) assigned to members and elements is comparable to the values of steel, aluminum, concrete or timber. If it falls below or above the range of these materials, warning messages similar to the one you encountered are displayed. This is done to notify the user in case he/she is not aware of this fact, or if he/she may have specified the value in an incorrect unit system. If you believe that your E is specified correctly, you may ignore the message. Else, correct the number.





Issue: Order of member lists for output

Description: I could use a little help with a truly aggravating condition which I will explain by way of an example. Command: PRINT MEMBER STRESSES LIST 72 14 122 45 I would like the STAADPro output to give me the member stresses in the following order: 72 14 122 45 Instead I get the output results in an ascending sequence, which is not what I want, as follows: 14 45 72 122 What can I do to get the output in the order I have specified?

Version: Build No:

Solution: When you assign a command using the graphical screens, the lists associated with those commands are saved in the ascending order. For example, if we were to add the command PRINT MEMBER STRESSES, and using the option "Assign to Edit List", assign it to members in the following order 14 2 16 4 18 7 and save the file from the graphical screen, the command gets written into the input file as PRINT MEMBER STRESSES LIST 2 4 7 14 16 18 This happens with any file saved from the graphical modeling mode. Unfortunately, there is no way currently available to change the order of these lists.

You can do the following to get around that problem. After the file has been saved from the graphical screen, go to the editor. (From the Edit menu, choose Edit Input CommandFile). Scroll down till you come to the desired command which currently has its list in the ascending order. You can make changes to any line of the file using the editor. So, change the list of the commands you are interested in so that they are in the order you want. For the command in the earlier example, change it to PRINT MEMBER STRESSES LIST 14 2 16 4 18 7 Save the file from within the Editor.

If you were to now run the analysis, the output of member stresses will be in the order you seek. But please understand that if subsequently, you make any changes to the file using the graphical modelling mode, and save it from the graphical modelling mode, the list is going to be re-arranged once again into the ascending order. This also happens if you use the File-Save As option of the graphical modelling mode to save an existing file into one with another name.





So, after you arrange the lists using the editor in the order you want, close the file, and make a backup of it using Windows Explorer.







Issue: What is the TRESCA Stress

Description: In the plate element stress results, what do the terms TRESCAT and TRESTAB stand for? How are they calculated?

Version: Build No:

Solution: TRESCA is 2.0 times TMAX. TMAX is the maximum inplane shear stress on a plate element. TMAX = 0.5 * max[abs((s1 – s2)) , abs((s2 – s3)) , abs((s3 – s1))] where s1 and s2 are the inplane principal stresses and the 3rd principal stress, s3, is zero at the surface. TRESCAT is the value for the top surface of the element. TRESCAB is on the bottom. Top and bottom are in accordance with the direction of the local Z axis. See the link http://www.reiworld.com/Search.asp?id=SP-1549 for more information on the meaning of TOP and BOTTOM surfaces for plates. Example problem 18 in the examples manual shows the calculation of TMAX






Issue #: SP-7924 Known Bug Date Posted: 5/18/2004

Date Discovered: 5/18/2004 Classification: Conservative Version(s) Affected: All versions of STAAD.Pro including and prior to 2003 Build 1004.US

Issue: Steel design ratios and ASCE 52 and ASCE 72 codes

Description: If design is done per the ASCE 52 or ASCE 72 codes, the following error exists : 1) For tapered poles designed per ASCE 72, the Ratio value is not displayed in the Beam - Unity Check page. 2) For design per ASCE 52, if a members (like single angles) fail the slenderness check, the Ratio value is not displayed in the Beam - Unity Check page. However, this is only a failure to display the value on the members. The program does indeed design the section per the code correctly. You can go to the output file using File - View - Output File - STAAD Output to see the details of the design.

Causes of Error(s): Programming oversight

Affected Area(s): Display of interaction ratio values in the Beam Unity Check page of the post-processing mode

Workaround (if any): Values may be obtained in the design output section of the output file.

Solution: The correction will be available in a later build of STAAD.Pro 2004.







Issue: Crash while starting the analysis in STAAD.Pro 2002

Description: We are using STAAD.Pro 2002 Build 1006. When we run the analysis with any model, the following error mess

This happens on some computers. On others, it runs fine. Please advise as to the solution to fix the problem.

Version: Build No:

Solution: Please try the following. Exit the program. Log into the computer as the administrator. Go to Start - Programs - STAAD.Pro 2002 - License Administrator. From the Uninstall menu, choose Uninstall License system. A message should be displayed in the right pane of the window that the license system has been successfully uninstalled. Next, from the install menu, choose Install License system. The message in the right pane should now indicate that the license system has been successfully installed. Exit that program. Then try running STAAD.Pro again. If you still encounter a problem, please contact the technical support department of the osend your problem report to [email protected].







Issue: Naming convention for American steel tubes

Description: STAAD lists American Tube sections using names like TUB80604. This is not the way the names are listed in the LRFD manual. How does one relate the STAAD name with that in that manual?

Version: Build No:

Solution: The STAAD naming convention for Tubes is derived in the following manner. Let us consider the tube section 8X6X1/4 listed in the LRFD manual. Take the first dimension, which is the nominal depth, and multiply it by 10. Take the second dimension, which is the nominal width, and multiply it by 10. Multiply the thickness by 16. Concatenate the numbers into a string whose first 3 characters are TUB. You get TUB80604

Related topics : http://www.reiworld.com/Search.asp?id=SP-7981 http://www.reiworld.com/Search.asp?id=SP-8031







Issue: Naming convention for American steel pipes

Description: STAAD lists American Pipe sections using names like PIPX25. This is not the way the names are listed in the LRFD manual. How does one relate the STAAD name with that in that manual?

Version: Build No:

Solution: These are the pipe sections listed in page 1-121 of the LRFD 2nd edition manual. The names of Standard Weight pipes start with the word PIPS. Extra Strong pipes start with the name PIPX, and Double-Extra Strong pipes are named with PIPD. Take the nominal diameter, multiply it by 10, and append the resulting integer value with the corresponding 4-letter word. So, an Extra Strong 2 1/2 in pipe gets the name PIPX25.

Related topics : http://www.reiworld.com/Search.asp?id=SP-7980 http://www.reiworld.com/Search.asp?id=SP-8031







Issue: Printing the drawing with forces annotated

Description: I want to print out a picture which consists of a truss I have modeled with the STAAD. I want the output forces labeled right on each member. This is very similar to what would be put on to a plan sheet. Can STAAD do this or must I print out a report to get these forces?

Version: Build No:

Solution: First, you have to ask STAAD to Annotate the drawing with the axial forces. For this, please go to the post processing mode after you have analyzed the structure. Click on the “Beam” tab on the left side and then click on the sub-tab labeled “Forces.” Click the right mouse button on the screen and select “Structure Diagrams.” From the “Loads and Results” tab, click on “Axial” under the “Beam Forces” heading. Uncheck the “bending zz” box and click “Apply” followed by “OK.” Maximize the screen and then go to the “Results” pull down menu and select “View Value…” Click on the “Beam Results” tab and then check the box under the “Axial” heading labeled “Ends.” Click “Annotate” and then “Close.” The axial loading values should be displayed on your screen. There are three methods to print this screen. These three methods are described at the following link: http://www.reiworld.com/Search.asp?id=SP-1552







Issue: Warning stating "more than 12 DOF with zero stiffness"

Description: I tried to model a concrete foundation using solid elements, basically following the approach described in example 24 of the examples manual. However, I got this warning stating "more than 12 DOF with zero stiffness". Can anyone please advise me what are the technical reasons for this and how I can possibly handle this warning?

Version: Build No:

Solution: A solid element by its basic nature does not have rotational degrees of freedom at its nodes. So, at all points on the structure where the only entities connected are solid elements, there is no rotational stiffness. There is an explanation on the reasons behind zero stiffness messages at http://www.reiworld.com/Search.asp?id=SP-1496 If you are using STAAD.Pro 2003 Build 1003.US or later, and the only entities in your structure are solids (no plates or beams), the program automatically applies restraints along those rotational degrees of freedom and the messages will hence not appear. However, if beams or plates are present in the structure in addition to solids, those messages will be present. If you do not encounter instability warning messages in your output, and the applied loads are in equilibrium with support reactions, you may consider the zero stiffness warning messages harmless, and ignore them.







Issue: Applying a moment at the node of a solid element

Description: How do I apply a moment load at the joint of a solid element?

Version: Build No:

Solution: You can directly apply a moment at the node of a solid element only if there is a beam or a plate attached to that node. If there isn't any beam or plate element attached to that node, create a fictitious beam which protrudes out of that joint, similar to that which is shown at the following link : http://www.reiworld.com/Search.asp?id=SP-3228 Then, apply the moment at the desired node, or an equivalent force at the free end of the beam.







Issue: KL/r for single angles per the AISC ASD code

Description: The KL/r value that STAAD reports for the Y axis for a single angle does not match what I get from my hand calculation. Can you explain why?

Version: Build No:

Solution: For single angles, the local Y and Z axes are the principal axes as shown below:

The KL/r value is computed using ry and rz which are based on the principal axis system. Chances are that your handculation uses the geometric axes.







Date Discovered: 2/4/2005 Classification: Version(s) Affected: STAAD.Pro 2004 Build 1004.US

Description: I am using STAAD.Pro 2004 Build 1004.US also known as the second edition. When I try to add plates using the new feature in the Geometry menu called "Create infill plates", I encounter the message "No closed polygon found to fill in with plates, please check beam selection"

What am I doing wrong?

Causes of Error(s): Programming error

Affected Area(s): Assigning plate elements to the model

Workaround (if any):

Solution: This error will be rectified in the US Build 1005. In the meantime, you can use the same facility from its icon which is shown below.







Description: Is it possible to specify a displacement and then have STAAD analyze a frame to give me a corresponding load (the load that would have been required to produce that displacement)?


Solution: You first need to know the pattern or arrangement of the loading which will eventually cause the displacement you wish to see. This is because, there can be millions of loading arrangements which cause that amount of displacement at that node, so one needs to have an idea of which of those patterns is the one that one wants. By pattern, we are talking of details like, is the load going to consist of concentrated forces at nodes, or distributed and trapezoidal loads on members, or pressures on plates, etc. For example, any of these loads will cause a certain amount of displacement at a node along a certain direction. So, a unit load analysis would be the best approach for solving this kind of a problem. That means, all the components of the loading pattern would be represented by unit loads. Let us say that by applying a member load of 100 pounds/ft, you get 0.4 inches of displacement along global X at node 43. So, if the final desired displacement at node 43 along X is say, 1.2 inches, the applied load should be simply (1.2/0.4)*100 = 300 pounds/ft.







Description: We have successfully imported an Autocad model into Staad.Pro. Since the import, the original drawing has been changed (beam spacings, etc.). Is it possible to "re-import" the revised CAD drawing into the existing Staad.Pro model? Will Staad.Pro pick up the revisions, or do we have to start over?


Solution: If the only changes are in beam spacings, that is, the actual number of beams and nodes has not changed, you can import the new geometry into a new STAAD file. Then, using the STAAD editor, you can copy all of the data which comes after the geometry from the old STAAD file to your new STAAD file.







Description: I am trying to model loads from a conical section at the bottom of a product support tower. When I check the sum of support reactions, I discovered that this sum does not equal the load of the product in the silos. I then realized that a trapezoidal load does not accurately reflect the mass distribution of a tapering cyliner or cone. Is there a feature to assign a member load based on a second order curve instead of a linearly varying function so that I can more accurately represent the vertical distribution of product in the silo?


Solution: The type of load you ask for is not currently available in STAAD. One solution is to write a little macro in Excel which converts the load into a series of concentrated loads at discrete points along the member span and apply them on the member using the MEMBER LOAD option. You could write the macro in sucha way that the data is saved into a text file and you copy and paste the contents of that file into the STAAD input file. If you are familiar with the feature called OpenSTAAD, its load creation functions may also be used in conjunction with your macro to directly input those concentrated loads into the STAAD input file.





Description: I am using the wind load generation feature. On some parts of the structure, the load generation is not being done correctly. Can you explain why?

Version: Build No:

Solution: In order to generate loads due to wind pressure, STAAD attempts to identify panels on the exposed faces of the structure. A panel is defined as an area bounded by members (beams and columns) on all sides, or supports and the ground along the lowest level and members on the remaining sides of the panel.



However, under some circumstances, the panel identification may fail. One of the reasons for this failure is when bracing members are part of the exposed face. In the next figure, the bracing members cross each other, but do not have an intersection point.



This is because, by traversing the path along the member X-axis, the program finds overlap of various panels. Loads are not generated when panels overlap. To get around this problem, there are 2 options : a) Split the bracing members at their point of intersection. In the above case, this will result in 4 distinct panels with no overlap. b) Provide a list of members in the WIND LOAD command, and exclude the bracing members from the list. In the above case, that list would comprise of just members 2,3,4 and 5. WIND LOAD Z 1 TYPE 1 LIST 2 3 4 5







Description: When using the foundation support, I am required to give the subgrade modulus and supply a direction. I have always used Y as the direction. However, I am interested in knowing what would occur if I choose Y-only. Is there some type of weak spring placed in X & Z directions, is it completely restrained, or is it somewhere in between?


Solution: If X or Y or Z is specified for direction, then, a) a spring support is generated in that direction b) the other two translational directions are fully restrained c) the associated rotational degre of freedom is fully restrained d) the other 2 rotational degrees of freedom are treated as unrestrained Example : plate-list PLATE MAT DIR Y SUBGRADE 0.4 FX is fixed FY gets a spring FZ is fixed MX is free MY is fixed MZ is free If XONLY or YONLY or ZONLY is specified, then, a spring support is generated in that direction. All the remaining 5 degrees of freedom are treated as unrestrained. Example : plate-list PLATE MAT DIR YONLY SUBGRADE 0.4 FX is free FY gets a spring FZ is free MX is free MY is free MZ is free







Date Discovered: 11/1/2005 Classification: Version(s) Affected: STAAD.Pro 2005 Build 1002

Issue: Viewing Selected Objects Only

Description: In the View menu, the option called "View Selected Objects Only" does not work in STAAD.Pro 2005 Build 1002

Causes of Error(s): Programming Error

Affected Area(s): Graphical Viewing Facility

Workaround (if any): After you select the entities you want to view exclusively, click the right mouse button. The menu that comes up will contain an option called "New View". Select that. A box will appear offering 2 choices - Create a new window for the view. If you choose this, a new window will be created displaying the selected items Display the view in the active window. If you choose this, the current window will be refreshed to display only the selected items If you choose the first option, you can simply close that window when you no longer need that view. If you choose the latter, you can restore the full structure into view by going to the top of the screen and selecting an icon called "Display Whole Structure". A picture indicating that icon is shown below.

Solution: This will be corrected in STAAD.Pro 2005 Build 1003







Issue: Sort Disaster

Description: While building a model, I keep encountering a message called Sort Disaster. What does it mean and how do I remove it?

Version: Build No:

Solution: Sort Disaster is an internal message that is generated to indicate that something has gone wrong when STAAD.Pro performs the operations required to ensure that there is no duplication of nodes, members, plates, etc., while it manages the structure geometry data. If you are using STAAD.Pro 2003 or a more recent version, this message should not appear. That is because, a procedure for self-correction has been built into the recent versions of the program if it encounters such a condition. If you are encountering the problem in STAAD.Pro Release 2002 or older, close that message box, save the file, close it and re-open it. You can find the Release number by clicking on Help - About STAAD.Pro.





Issue: THE VALUE OF E FOR MEMBER NNN DOES NOT SEEM RIGHT

Description: The steel design output for several members is accompanied by the following warning message : WARNING : THE VALUE OF E FOR MEMBER 21 DOES NOT SEEM RIGHT. WARNING : THE VALUE OF E FOR MEMBER 22 DOES NOT SEEM RIGHT. WARNING : THE VALUE OF E FOR MEMBER 23 DOES NOT SEEM RIGHT. What is the reason this message appears?

Version: Build No:

Solution: During steel design, there is a check for ensuring that the Modulus of Elasticity (E) specified for the member is within the range that is normal for steel. This is because, E is a crucial term that appears in many equations for calculating section capacities and the program wants you to know if the value appears to be abnormal. In STAAD, you specify E either explicitly under the CONSTANTS command block or through the DEFINE MATERIAL block, asin the examples below. Example 1 : UNIT KIP INCH CONSTANTS E 29000 ALL DENSITY 0.283E-3 ALL Example 2 : UNIT METER KNS DEFINE MATERIAL START ISOTROPIC STEEL E 2.05e+008 POISSON 0.3 DENSITY 76.8195 ALPHA 1.2e-005 DAMP 0.03 END DEFINE MATERIAL CONSTANTS MATERIAL STEEL MEMBER 101 TO 121 So, if you are specifying an E value which is significantly different from that for steel, such as say, Aluminum, and then later asking the member to be designed according to a steel code, as in the following example, the above-mentioned warning message will appear. UNIT FEET POUND DEFINE MATERIAL START ISOTROPIC ALUMINUM E 1.44e+009 POISSON 0.33 DENSITY 169.344 ALPHA 1.28e-005 DAMP 0.03 END DEFINE MATERIAL CONSTANTS MATERIAL ALUMINUM MEMBER 21 TO 30





..

.. PARAMETER CODE AISC CHECK CODE MEMBER 21 TO 30







Date Discovered: 1/5/2006 Classification: Severe Version(s) Affected: STAAD.Pro 2005 Builds 1001 and 1002, some builds of STAAD.Pro 2004

Issue: Crash when modifying a pre-assigned T section property

Description: For a member which has been assigned a T section property, such as in the following example, MEMBER PROPERTY AMERICAN 1 TABLE T W10X12 the following operation will cause a crash. Double click on the member. Go to the Property tab. Select Assign/Change Property.


Affected Area(s): Model generation

Workaround (if any): Change the section by going to the General-Property page, select the T section name from the displayed list, and click on Edit.

Solution: The error will be corrected in STAAD.Pro 2005 Build 1003







Issue: Where to place section database files

Description: My colleague added a few channel sections to the US coldformed section database. We both work on the same project and so I too need to use that updated database. Since we have each installed STAAD on our individual computers, and are not running it from a network installation, what file do I take from his machine, and where do I put it?

Version: Build No:

Solution: The US coldformed section database is contained in the file called uscoldformedsections.mdb Similarly, other section databases are US AISC : AISCSections.mdb British : Britishsections.mdb European : Europeansections.mdb Japan : Japanesesections.mdb etc. When you add sections to these databases from within STAAD.Pro's GUI, that information goes into one of those files, as applicable for that country. When you installed STAAD on your computer, if you chose the default folder that the STAAD.Pro installation program recommends, these files are typically located in X:\spro200n\staad\sections where X stands for the drive letter and "200n" in spro200n stands for the version number like 2003, 2004, 2005, etc. So, take uscoldformedsections.mdb from your colleague's computer and put that in the corresponding location on yours. Since your machine already contains a file by that name (which was put there during the installation), make a backup of it before you place the updated file.







Description: Several beams in my model have been defined with multiple intermediate nodes. So, a beam which is say, 45 feet long, is defined as three segments of 15 feet each. Please tell me what I should do to perform the deflection check for the 45 feet span, instead of the individual 15 ft spans. The allowable deflection is based on the length of the sum of the segments expressed in inches divided by 500.

Version: Build No:

Solution: The article below explains the procedure. The STAAD input file used in the article is also attached. Deflection Check for multi-segmented Beams Sample STAAD Input file





Description: I'm having a tough time editing member loads. What I am managing to do is remove or edit the loading from beams without deleting it entirely?

Version: Build No:

Solution: If you edit the load item from the General - Load page, all the members to which the load item is applied will rece

Since you want to change it for a specific member only, there are two methods for doing that. 1) Use the options of the Load Items page of Member Query. The article below is an extract from the software release reportintroduced.





Editing Loads using Member Query 2) Use the Load Edit cursor. The article below describes the procedure. Editing Loads using the Load Edit Cursor







Date Discovered: 12/5/2005 Classification: Severe Version(s) Affected: STAAD.Pro 2005 Builds 1001 and 1002

Issue: Error in renumbering plate elements

Description: For models containing plate elements in which some or all of those elements have been assigned element loads, the following error occurs. If the elements are renumbered using Geometry - Renumber - Plates, some places in the input data where the elements are referred to, such as the element load data, are not updated to reflect the new plate numbers. Hence, as a result of the renumbering, some of those elements could end up not having any loads, or the loads could end up being applied on non-existent or wrong elements.


Affected Area(s): Model generation when plate elements are involved.

Workaround (if any): One workaround, although an inconvenient one, is to renumber the plates before the loads are applied.

Solution: The error will be fixed in STAAD.Pro 2005 Build 1003







Issue: Graphically removing loads from members

Description: How do I remove a load from a member without removing the load from the load case?

Version: Build No:

Solution: Please go through the document below. How do I remove a load from a member.pdf







Issue: Adding Members to a Saved View

Description: I have created and saved a View to which I want to add some more members. I noticed that STAAD has an Add to View function but I am not sure how it works. Tell me how I can update an existing view.

Version: Build No:

Solution: Please see the article below for the procedure.

Adding members to a Saved View







Date Discovered: 2/14/2006 Classification: Version(s) Affected: STAAD.Pro 2005 Builds 1002 and 1001, and some of the builds of STAAD.Pro 2004

Issue: Assigning Materials

Description: When material data is assigned through the Graphical modeling mode, it fails to get applied to some members, plates, surfaces and solids in some situations. This problem occurs when the material is assigned along with the property or thickness from the General-Property page, or when it is assigned explicitly from the General-Material page.


Affected Area(s): Model generation

Workaround (if any): Assign the material data through the editor. It involves two steps : a) specifying the material data under the DEFINE MATERIAL block b) assigning it to the members, plates and solids under the CONSTANTS command.

Solution: The error will be fixed in STAAD.Pro 2005 Build 1003







Description: I have created my own set of "Auto Load Rules". Is there a way to send that data to someone else so that they don't have to create it all over again on their machine?


Solution: The "Auto Load Rules" you created are saved in an .INI file by that name. For example, if you created one for Belgium, a file called BelgiumLoad.ini is created. So, send them the following 2 files : 1) The INI file which contains the Auto Load Rules you created. In this example, it would be the file called BelgiumLoad.ini 2) Codes.ini Both these files can be found in the folder X:\spro2005\staad Your colleague too should place them in the same folder on his/her machine. Since the Codes.ini will be present on his/her machine by default, he/she needs to replace that one with the one received from you.







Description: One issue that I have encountered is that if I go into the load function and realize that I have the wrong units specified, I cannot change the units by going back to the geometry menus and selecting the correct units to use. When I enter the loading menus again, the units have not changed. Is there another way to change the units once you enter the loading functions?

Version: Build No:

Solution: From the Edit menu, choose Edit Input Command File. Scroll down till you see commands like LOAD 1 or LOAD 2 Prior to the load case which has the units error, add the appropriate unit as shown UNIT POUND FEET For example UNIT KIP FEET LOAD 1 SELF Y -1.0 MEMBER LOAD 1 TO 25 UNI GY -0.2 UNIT POUND LOAD 2 JOINT LOAD 33 FX 400 UNIT KNS METER LOAD 3 MEMBER LOAD 45 UNI GY -3.0







Description: I am trying to cut a rectangular hole in an arbitrary triangular region in space which has been meshed with plates. Is there a way to orient the construction grid (for the "snap node/plate" feature) to align with three pre-defined nodes (i.e. the corners of the triangle) to simplify removal of the rectangular feature inside? The angle of the triangle is very odd and I am concerned about the nodes defining the rectangle being slightly out of plane if I try to set the construction grid manually based on the coordinates and angle of the triangle.

Version: Build No:

Solution: Using STAAD's graphical tools, it is quite difficult to insert an opening after the plate has been meshed, unless your plate elements are aligned in a manner that exactly matches the boundary of the opening. The process is far less painful if the hole is specified before the meshing process commences. Please have a look at the solution described at the following link Meshing an Irregular Slab It deals with the meshing of a plate which has a circular opening. The similar procedure should work for your model with a rectangular opening. Alternatively, read the description of the parametric mesh generator. It is explained in the section called AD.2004.5 Enhanced Mesh Generator in the software release report for STAAD.Pro 2004's first edition.







Description: How do I stop the Auto Save screen from appearing over and over again in Staad.Pro?

Version: Build No:

Solution: From the File menu of the main program screen, select "Open Backup Manager". The dialog box that comes up has a facility to turn off the Autosave feature. See the attached figure.







Issue: How to change the orientation of the local Z axis so that it points to the opposite direction

Description: I would like to change the direction of the local Z axis of an element so that it points in the opposite direction. How do I do it?

Version: Build No:

Solution: From the Select menu at the top, select the Plates Cursor. Then select the element for which you want the Z axis direction changed. From the Commands menu, select Geometric Constants followed by Plate Reference Point and give the coordinates of this point. Choose the Local Axis direction to point towards or away from the Reference Point. The Assign option should be set to "To Selection". Click on OK.







Issue: What is the difference between the normal contour method and the enhanced contour method for Plate Elements ?

Description: In STAADPRO, for plate elements, what is the difference between the normal contour method and the enhanced contour method?

Version: Build No:

Solution: The normal contour method uses stress points at each corner of the plate along with the center stress to calculate contours. The contour regions are located along the edges of the plate & the diagonal between each node & the center point. The enhanced contour method uses the same points as the normal contour method plus an additional mid point stress along each edge of the plate. This additional mid point stress is calculated using the interpolation of all the plate center stresses associated with that edge. This method will take longer to complete as twice as many data points are calculated when compared to the normal contour method.






Description: Can you provide me with some help on how I can include deflection check as one of the criteria in steel design?


Solution: Deflection of a beam or a column can be included as one of the criteria during code checking or member selection with most steel design codes in STAAD. The ratio of length to maximum deflection of a beam (L/d ratio) will be calculated by STAAD. STAAD will then check that quantity against the allowable limit which the user specifies under the PARAMETERS option.

What are the design parameters which control deflection check ?

1. DFF : This is the value which indicates the allowable limit for L/d ratio. For example, if a user wishes to instruct the

program that L/d cannot be smaller than 900, the DFF value should be specified as 900. The default value for DFF is 0. In other words, if this parameter is not specified as an input, a deflection check will not be performed.

2. DJ1 and DJ2 : These 2 quantities affect the "L" as well as the "d" in the calculated L/d ratio. They represent node numbers that form the basis for determining L and d.

By default, DJ1 and DJ2 are the start and end nodes of the member for which the design is being performed, and "L" is the length of the member, namely, the distance between DJ1 and DJ2. However, if that member is a component segment of a larger beam, and the user wishes to instruct STAAD that the end nodes of the larger beam are to be used in the evaluation of L/d, then he/she may input DJ1 and DJ2 as the end nodes of the larger beam. Also, the "d" in L/d is calculated as the maximum local displacement of the member between the points DJ1 and DJ2. The definition of local displacement is available in Section 5.42 of the STAADPro Technical Reference Manual, as well as in Example problem # 13 in the STAADPro Examples Manual.

A pictorial representation of DJ1 and DJ2, as well additional information on these topics is available under the "Notes" section following Table 2.1 in Section 2.8 of the STAADPro Technical Reference Manual.

What are the results one gets from STAAD for the deflection check?

If the steel design parameter called TRACK is set to 2.0, the L/d ratio calculated for the member can be obtained in the STAAD output file. The value is reported against the term "dff". Notice that the expression is in lower-case letters as opposed to the upper-case "DFF" which stands for the allowable L/d.

If "dff" is smaller than "DFF", that means that the displacements exceeds the allowable limit, and that leads to the unity check exceeding 1.0. This is usually a cause for failure, unless the RATIO parameter is set to a value higher than 1.0. If "DFF" divided by "dff" exceeds the value of the parameter RATIO, the member is assumed to have failed the deflection check.

What are the limitations of this check?

Since the "d" in L/d is the local deflection, this approach is not applicable in the case of a member which deflects like a cantilever beam. That is because, the maximum deflection in a cantilever beam is the absolute quantity at the free end, rather than the localdeflection.

Since the deflection which is checked is a span deflection and not a node displacement, the check is also not useful if the user wishes to limit story drift on a structure.







Description: In the member end forces output, why are two values being reported for axial forces? Also, why is it that sometimes the numerical values of these two are the same and sometimes they are not?


Solution: There are two values because member end force output consists of the forces and moments at the start node as well as at the end node of the member.

At the start node, a positive value of the axial force indicates axial compression, and a negative value indicates axial tension. At the end node, a positive value indicates axial tension, and a negative value indicates axial compression.

Generally, if the values at the start and at the end are not the same in magnitude, it is due to a load acting along the local X axis of the member. A typical example of this is a column (vertical member) subjected to selfweight loading. The difference in magnitude of the axial forces at start and end should be equal to the load acting along the local X axis of the member.





Description: What does a zero stiffness warning message in the STAAD output file mean?

Version: Build No:

Solution: Definition of a zero stiffness condition :

The procedure used by STAAD in calculating displacements and forces in a structure is the stiffness method. One of the steps involved in this method is the assembly of the global stiffness matrix. During this process, STAAD verifies that no active degree of freedom (d.o.f) has a zero value, because a zero value could be a potential cause of instability in the model along that d.o.f. It means that the structural conditions which exist at that node and degree of freedom result in the structure having no ability to resist a load acting along that d.o.f.

A warning message is printed in the STAAD output file highlighting the node number and the d.o.f at which the zero stiffness condition exists.

Examples of cases which give rise to these conditions :

Consider a frame structure where some of the members are defined to be trusses. On this model, if a joint exists where the only structural components connected at that node are truss members, there is no rotational stiffness at that node along any of the global d.o.f. If the structure is defined as STAAD PLANE, it will result in a warning along the MZ d.o.f at that node. If it were declared as STAAD SPACE, there will be at least 3 warnings, one for each of MX, MY and MZ, and perhaps additional warnings for the translational d.o.f.

These warnings can also appear when other structural conditions such as member releases and element releases deprive the structure of stiffness at the associated nodes along the global translational or rotational directions. A tower held down by cables, defined as a PLANE or SPACE frame, where cable members are pinned supported at their base will also generate these warnings for the rotational d.o.f. at the supported nodes of the cables.

Solid elements have no rotational stiffness at their nodes. So, at all nodes where you have only solids, these zero stiffness warning messages will appear.

These are warnings and not errors because :

The reason why these conditions are reported as warnings and not errors is due to the fact that they may not necessarily be detrimental to the proper transfer of loads from the structure to the supports. If no load acts at and along the d.o.f where the stiffness is zero, that point may not be a trouble-spot.

What is the usefulness of these messages :

A zero stiffness message can be a tool for investigating the cause of instabilities in the model. An instability is a condition where a load applied on the structure is not able to make its way into the supports because no paths exist for the load to flow through, and may result in a lack of equilibrium between the applied load and the support reaction. A zero stiffness message can tell us whether any of those d.o.f are obstacles to the flow of the load.







Description: Can I carryout a machine foundation analysis using STAAD PRO (Embedded Block foundation and Pile foundation)?


Solution: The answer is Yes. The piles have to be modelled as columns. If the machinery sits on a slab, that will be modelled using plate elements. The supports for the model are going to be the resistance (based on subgrade modulus) offered by the soil, which may be modelled as springs. The dynamic loads due to the machinery will be modelled as forcing function loading, either as discrete time-force pairs as shown in example 16, or as a sinusoidal loading as shown in example 22.





Description: Some of the beams in my model are built-up steel sections comprised of a channel on top of a wide flange as shown below.

How do I assign a cross section of this type to a member?

Version: Build No:

Solution: The steel section databases available in STAAD contain most of the standard section types available in the market. However, the sections available through this facility are stand-alone sections, not built-up sections.

Consequently, there is presently no direct facility for defining built-up sections like the one above.

A way around this limitation is to use one of the methods explained below:

Method 1:

A user table GENERAL section: The user provided table (UPT) is a facility by which one can define non-standard standalone sections, as well as arbitrary shaped sections. A built-up section can be classified as an arbitrary shaped section. Arbitrary shaped sections will have to be defined through either the user table PRISMATIC type, or the user table GENERAL type. However, one would have to first calculate the basic properties such as Area, Moments of Inertia, Torsion Constant, etc., (one may use the Section Wizard program to simplify the task of calculating these values) before one can assign them. Details of this facility are available in sections 5.19 and 5.20 of the STAAD.Pro Technical Reference Manual. An example that shows the usage of UPT sections is available in problem 17 of the STAAD.Pro Examples manual. An example that illustrates the graphical method of creating and assigning these sections is available at

http://www.reiworld.com/Support/Pro/SearchSolution.asp?pid=136

Method 2:

An ordinary prismatic section type: If one wants to avoid the tedium of creating a user provided table, the basic property values of the section can be assigned through the simple PRISMATIC property type (See sections 5.20 and 5.20.2 of the





STAAD.Pro Technical Reference manual). An example that shows this is available in problem 8 of the STAAD.Pro Examples manual. Again, one would have to first calculate the basic properties such as Area, Moments of Inertia, Torsion Constant, etc., (one may use the Section Wizard program to simplify the task) before one can assign them. Graphically, this type is created through the dialog boxes shown below.

Related topics : http://www.reiworld.com/Search.asp?id=SP-1488







Description: I would like to obtain the support reactions of my model in a Microsoft Excel friendly format. Can you tell me how?


Solution:

Run the Analysis. From the Mode menu, select Post Processing. From the Select menu, choose "By Specification | All Supports". From the Report menu, select Support Reactions. In the dialog box which appears, there are 3 tabs. In the Sorting tab, select the criteria for sorting. If you do not want any sorting performed, leave the option "List with no sort done" unchanged. In the Loading tab, select the load cases for which you wish to see the results. Click on OK. The reaction values will be displayed in a table. Click on the cell called Node. The entire table will be selected (highlighted in black). To copy the contents of the table, click the right mouse button and choose Copy or simply type Ctrl-C. Start Microsoft Excel and open a new document. Click on the cell A-1 and select Paste. The support reaction table should now appear in the Excel sheet.







Description: What is the LX parameter used for?


Solution: The LX is the parameter used in calculating the axial compression capacity forflexural torsional buckling







Description: For an existing concrete member, I need to compute the capacity of the section. How do I do this?


Solution: You can do the following to compute the capacity of the concrete section: Model the strucuture. Specify the existing profile to the member properties Specify all the required member specification and Support condition Specify the load on the strucutre Specify the Concrete design parameters Specify the parameter MinMain and Maxmain to the provided bar size Do the design Check the results. Adjust the load and redo the design until the reinforcement matches with the provided steel.







Description: Can I take files from Frameworks to STAAD.Pro and then export them back to Frameworks when I am done analysing them?


Solution: To use Frameworks with STAAD Pro, please do the following: Step 1: Copy Posta.exe and Posta.Ini files in directory where FrameWorks PLUS executable is located. Step 2: Modify "ExeName" entry in the Posta.ini file so that it points to appropriate STAAD executable. You must have STAAD/Pro already installed on your system. The following is the list of STAAD executable names for different design codes. Design Codes STAAD Executable Name ------------ ---------------------- British SProStaadBr.exe Canadian SProStaadCn.exe German SProStaadGer.exe Indian SProStaadInd.exe Indian SProStaadJp.exe US SProStaadUS.exe US + TT Codes SProStaadTT.exe US + Aluminum + TT SProStaadUSAlTT.exe The STAAD executables will be in the /STAAD/SProStaad directory. For example, if you have installed STAAD/Pro Rel 2.0 in C:\SPRO2_0 directory, then for US codes the Posta.ini file should look like [StaadExe] ExeName=C:\SPRO2_0\Staad\SProStaad\SProStaadUS.exe







Description: Can you please tell me how to transfer data from EXCEL to STAAD-PRO?


Solution: The only data which can presently be transferred from Excel to STAAD is the geometry information, namely, joint coordinates, member incidences, plate element incidences, and solid element incidences. To do this, first select the cells in Excel where you have the numbers, and choose Copy from Excel's edit menu. Next, come into the STAAD program. The data may be brought into a new STAAD file or an existing STAAD file. Accordingly, open a new file or an existing file. Select the Geometry page from the left side of the screen, and choose the Beam, Plate or Solid sub-page depending upon the type of information you wish to bring in. If you are looking to bring it into a New file, close the Snap/Node dialog box which is open on the right hand side of the screen. For copying the joint coordinate data, click on the appropriate starting cell in the Node Tables grid on the right side, and type Ctrl+V or select paste from the Edit menu. For beam incidence, plate incidence or solid incidence data, click on the appropriate starting cell in the Beam Tables, Plate Tables or Solid Tables grids on the right side, and type Ctrl+V or select paste from the Edit menu. You should see the numbers you copied from Excel appear in those cells.







Description: After running the analysis, I go to the View menu, select Tables | Node Displacements, and select the load cases for which I want to see the values. The values are displayed in inch units. I want them in "cms" units. Changing the units using Tools | Set Current Unit doesn't seem to make a difference.


Solution: The unit system in which results are displayed on the tables is set using the facilities available under the View - Options menu. These are known as the display units. To set the display units for the node displacements, please do the following : In the View menu, select Options - Structure units. In the category called Displacement, select the units you desire and click on OK.







Description: What are the sign conventions for moments in a 3-D structure?

Version: Build No:

Solution: The sign conventions are as follows: Axial (FX) : Positive = Along local X axis, Negative = Opposite to local X axis Shear-Y (FY) : Positive = Along local Y axis, Negative = Opposite to local Y axis Shear-Z (FZ) : Positive = Along local Z axis, Negative = Opposite to local Z axis Torsion (MX) : Positive = Along local X axis, Negative = Opposite to local X axis Moment-Y (MY) : Positive = Along local Y axis, Negative = Opposite to local Y axis Moment-Z (MZ) : Positive = Along local Z axis, Negative = Opposite to local Z axis For axial forces, Positive at the start node indicates compression at the start node. Positive at the end node indicates tension at the end node. Negative at the start node indicates tension at the start node. Negative at the end node indicates compression at the end node.







Description: How can I remove the REI logo from my report?


Solution: Go to the StaadPro ini file (i.e. STAADPRO20000.ini, STAADPRO20010.ini). It should be in your Windows folder. Change "QL" from 1 to 0.







Description: How can I merge 2 models together?


Solution: 1) Open up the first std file- the one with the model to copy from 2) Select the appropriate cursor (beam, plate, etc.) depending on what you are trying to copy. You can do this by going "Select\ ..." (Appropriate cursor) 3) Select all or whatever part of the model you want to copy. This can be done by creating a window, inside of which everything will be highlighted. To create the window go to one endpoint, press down the left mouse button and release it when you reach another endpoint such that everything inside is what you want to select. 4) Go to Edit \ Copy 5) Open up the second std file- the one you want to paste onto 6) Go to Edit \ (Beam, Plate, etc. ) Paste. A dialog box comes up- "Paste with Move" 7) If you want the copied model to be pasted starting from the origin, press the "OK" button. a) If you want the model pasted somewhere else, select the "Reference Pt" button. b) In the "Specify reference point" window specify the reference point by clicking on that point c) Click the "OK" button. A cursor with circles on either side should now appear. d) Reselect the reference point e) The "Paste with Move" dialog box comes up. Press OK The model has now been copied/merged to the new file.







Description: I am using STAAD to perform steel design on a member per the AISC ASD code. I want the column to be designed based on an unbraced length of 20 ft. I have set the UNT and UNB values to 20 ft, but STAAD appears to consider only a 10 feet length in its KL/r calculations. How do I correct this problem?


Solution: The parameters UNT and UNB are for specifying the unsupported length of the compression flange for the purpose of computing allowable stresses in bending compression. If you want to specify the unbraced length for the purpose of computing allowable stresses in axial compression, use the parameters LY and LZ. See Table 2.1 of the STAAD.Pro Technical Reference Manual for details.







Description: I'm trying to modeling lateral supports in the roof members. Nodes 3 9 to 16 and 4 17 to 24 are zee purlins on the roof. Beam members are tapered sections. Using the support command, how do I modeling the zee purlins as lateral stability?


Solution: The lateral support information is generally not specified through supports because it typically acts only as a mechanism for preventing lateral torsional buckling (LTB) of the flange it is connected to. It does not necessarily prevent a physical displacement at that point on the roof member whose flange is being restrained. Instead, you provide the information by specifying the distance between points where the roof members are restrained against LTB. The values you may wish to specify are the terms LY, LZ, UNT and UNB. You will find an explanation of these in Table 2.1 of Section 2 of the STAAD.Pro Technical Reference Manual. You may also wish to refer to example problem 1 of the examples manual under the command PARAMETERS, as in the example below : PERFORM ANALYSIS PARAMETER CODE AISC NSF 0.85 ALL BEAM 1.0 ALL KY 1.2 MEMB 3 4 LY 25 MEMB 3 4 LZ 20 MEMB 5 6 UNT 15 MEMB 8 TO 15 RATIO 0.9 ALL CHECK CODE ALL







Description: When I perform concrete design on an element, the output reports reinforcement in terms of "SQ.MM/MM".Can you please explain why?


Solution: When you ask for an element design or a slab design using the commands DESIGN ELEMENT .. or DESIGN SLAB .. STAAD designs the element for the moments MX and MY at the centroid of the element. By definition, MX and MY are termed as Moments per Unit width, since that is what they are. They have units of Force-length/length, as in 43.5 KN-mm/mm, or 43.5 KN-m/m. In other words, if you take a one metre width of the slab at the centroid of the element in question, the moment over that one metre width on that element is equal to 43.5 KN-m. The design of that element hence has to be done on the basis of a unit width. Thus, in order to design an element for a 43.5 KN-m/m moment, one needs to use a one metre width of slab. The reinforcement required for that element is thus reported in terms of unit width of the element. The results are hence in the form Area of steel/unit-width of element, as in, "SQ.MM/MM".







Description: When I perform concrete design on an element, the output contains expressions such as "LONG. REINF.", "TRANS. REINF.", "TOP", "BOTT.", etc. Can you explain what these terms mean?


Solution: The design of an element involves determination of the reinforcement for moments Mx and My at the centroid of the element. The reinforcement calculated to resist Mx is called longitudinal reinforcement, and is denoted in the output by the expression "LONG. REINF.". The reinforcement calculated to resist My is called transverse reinforcement, and is denoted in the output by the expression "TRANS. REINF.". The sign of Mx and My will determine which face of the element the steel has to be provided on. Every element has a "top" face, and a "bottom" face, as defined by the direction of the local Z axis of the elements. Mx will cause tension on one of those faces, and compression on the other. A similar effect will be caused by My. The output report of reinforcement provided on those faces contains the terms "TOP" for top face, and "BOTT" for the bottom face. The procedure used by the program to arrive at these quantities is as follows : For each element, the program first scans through all the active load cases, to find the following maxima : Maximum positive Mx Maximum negative Mx Maximum positive My Maximum negative My The element is then designed for all those four quantities. If any of these moments happen to be zero, or if the reinforcement required to resist that moment is less than the capacity of the element with minimum reinforcement, only minimum reinforcement is provided. For the ACI code, the rules governing provision of reinforcement for shrinkage and temperature are used in calculating minimum reinforcement. The rules applicable for design of a beam for flexure are used in calculating the steel areas. The width used in this calculation is a unit width of the element. For determination of the effective depth, the steel for longitudinal moment is assumed to be the outer layer, and the steel for transverse moment is the inner layer. The output will consist of the steel area required for all of four maximas. As described earlier, they will be reported using the terms LONG, TRANSVERSE, TOP and BOTT.





Description: Is there a way to obtain a report of the moment Mz at the beam ends for load combination cases, sorted from high to low, for some of the beams in the model?


Solution: From the top of the screen, select Mode | Post Processing. In the Results Setup dialog box, select only those load cases that are the combination cases.

From the left side of the screen, go to the Beam | Forces page.

Using one of the standard selection methods, select the beams for which you want the results.

From the top of the screen, select Report | Beam End Forces.

The Beam End Force dialog box will appear. Select Moment-Z as the degree of freedom to be used as the basis for sorting. Keep the sorting order as “List from High to Low”. If you want sorting to be done on the basis of absolute values and not algebraic values, switch on the “Absolute Values” option.





Click on OK. The values will be displayed in a tabular form.







Description: I am performing concrete design for a beam per the ACI code. At the start as well as the end nodes of the member, the value "Vu" which is reported in the shear design output does not match the shear force Fy from the member end force output. Why is that?


Solution: STAAD performs concrete design for shear and torsion at locations defined by (d + SFACE) from the start of the member and (d+EFACE) from the end of the member respectively. In case you are not familiar with the parameters SFACE and EFACE, you will see in Chapter 3 of the STAAD.Pro Technical Reference Manual in Table 3.1 that these are values which the user may specify to convey to STAAD how far the face of the member is from the nodes of the member. The default value for SFACE and EFACE is 0.0. "d" is the effective depth of the member. The basis for this assumption can be found in Section 11.1.3.1 of ACI 318-95. If you want the shear & torsion design to be performed using the member end forces (the nodal values) and not those at the location mentioned in the previous paragraph, you can set the values for SFACE and EFACE to be negative quantities equal in magnitude to "d". That will result in (d+SFACE) and (d+EFACE) becoming zero, which means that the design will be performed at the nodal points of the member. So, in your input file, under the START CONCRETE DESIGN command, specify these parameters along the following lines : START CONCRETE DESIGN CODE ACI SFACE -d MEMB 110 EFACE -d MEMB 110 DESIGN BEAM 110 END CONCRETE DESIGN where "d" is the effective depth of the member.





Description: Do you have any information I can use in understanding instability messages?


Solution: Three questions and their answers are provided below to help explain this issue. Question : I have analyzed a structure and find that there are instability messages in the .anl (output) file, as follows : ***WARNING - INSTABILITY AT JOINT 26 DIRECTION = FX PROBABLE CAUSE SINGULAR-ADDING WEAK SPRING K-MATRIX DIAG= 5.3274384E+03 L-MATRIX DIAG= 0.0000000E+00 EQN NO 127 ***NOTE - VERY WEAK SPRING ADDED FOR STABILITY **NOTE** STAAD DETECTS INSTABILITIES AS EXCESSIVE LOSS OF SIGNIFICANT DIGITS DURING DECOMPOSITION. WHEN A DECOMPOSED DIAGONAL IS LESS THAN THE BUILT-IN REDUCTION FACTOR TIMES THE ORIGINAL STIFFNESS MATRIX DIAGONAL, STAAD PRINTS A SINGULARITY NOTICE. THE BUILT-IN REDUCTION FACTOR IS 1.000E-09 THE ABOVE CONDITIONS COULD ALSO BE CAUSED BY VERY STIFF OR VERY WEAK ELEMENTS AS WELL AS TRUE SINGULARITIES. What is the significance of such messages? Answer : An instability is a condition where a load applied on the structure is not able to make its way into the supports because no paths exist for the load to flow through, and may result in a lack of equilibrium between the applied load and the support reaction. There is some explanation available in Section 1.18.1 of the STAAD.Pro Technical Reference Manual for the typical cause of instabilities. You will find it under the heading "Modeling and Numerical Instability Problems". ______________________________________________________________________________ Question : If there are instability messages, does it mean my analysis results may be unsatisfactory? Answer : There are many situations where instabilities are unimportant and the STAAD approach of adding a weak spring is an ideal solution to the problem. For example, sometimes an engineer will release the MX torsion in a single beam or at the ends of a series of members such that technically the members are unstable in torsion. If there is no torque applied, this singularity can safely be "fixed" by STAAD with a weak torsional spring. Similarly a column that is at a pinned support will sometimes be connected to members that all have releases such that they cannot transmit moments that cause torsion in the column. This column will be unstable in torsion but can be safely "fixed" by STAAD with a weak torsional spring. Sometimes however, a section of a structure has members that are overly released to the point where that section can rotate with respect to the rest of the structure. In this case, if STAAD adds a weak spring, there may be large displacements because there are loads in the section that are in the direction of the extremely weak spring. Another way of saying it is, an applied load acts along an unstable degree of freedom, and causes excessive displacements at that degree of freedom. _______________________________________________________________________________ Question : If there are instability messages, are there any simple checks to verify whether my analysis results are satisfactory? Answer :





There are 2 important checks that should be carried out if instability messages are present. a) A static equilibrium check. This check will tell us whether all the applied loading flowed through the model into the supports. A satisfactory result would require that the applied loading be in equilibrium with the support reactions. b) The joint displacement check. This check will tell us whether the displacements in the model are within reasonable limits. If a load passes through a corresponding unstable degree of freedom, the structure will undergo excessive deflections at that degree of freedom. One may use the PRINT STATICS CHECK option in conjunction with the PERFORM ANALYSIS command to obtain a report of both the results mentioned in the above checks. The STAAD output file will contain a report similar to the following, for every primary load case that has been solved for : ***TOTAL APPLIED LOAD ( KG METE ) SUMMARY (LOADING 1 ) SUMMATION FORCE-X = 0.00 SUMMATION FORCE-Y = -817.84 SUMMATION FORCE-Z = 0.00 SUMMATION OF MOMENTS AROUND THE ORIGIN- MX= 291.23 MY= 0.00 MZ= -3598.50 ***TOTAL REACTION LOAD( KG METE ) SUMMARY (LOADING 1 ) SUMMATION FORCE-X = 0.00 SUMMATION FORCE-Y = 817.84 SUMMATION FORCE-Z = 0.00 SUMMATION OF MOMENTS AROUND THE ORIGIN- MX= -291.23 MY= 0.00 MZ= 3598.50 MAXIMUM DISPLACEMENTS ( CM /RADIANS) (LOADING 1) MAXIMUMS AT NODE X = 1.00499E-04 25 Y = -3.18980E-01 12 Z = 1.18670E-02 23 RX= 1.52966E-04 5 RY= 1.22373E-04 23 RZ= 1.07535E-03 8 Go through these numbers to ensure that i) The "TOTAL APPLIED LOAD" values and "TOTAL REACTION LOAD" values are equal and opposite. ii) The "MAXIMUM DISPLACEMENTS" are within reasonable limits.







Description: When one does the AISC code check or member selection, what are the calculations the program is performing?


Solution: The checks done as per the AISC ASD 9th edition code are : 1) Slenderness - Checks for KL/r limits per Chapter B 2) Local Buckling per Chapter B 3) Axial Compression + Bending per Section H 4) Axial Tension + Bending per Section H 5) Shear per Section F







Description: How do I use the CUT OFF MODE command?


Solution: Please ensure that the CUT OFF MODE command is before the first load case and do not enter it after the PERFORM ANALYSIS command. For example, CUT OFF Mode 7 LOAD 1 MODAL RESPONSE IN X SELFWEIGHT X 1 *SELFWEIGHT Y 1 *SELFWEIGHT Z 1 MODAL CALCULATION REQUESTED PERFORM ANALYSIS *CUT OFF Mode 7 FINISH In this example, without a CUT OFF MODE command before the PERFORM ANALYSIS, STAAD defaults to 6 modes. At the end STAAD is attempting to output the number of modes listed on the last CUT OFF MODE command.







Description: I have a model where supports are defined at the nodes of some of the plate elements in the structure. If I divide the support reaction values by the thickness, length etc., of the side of the elements adjacent to the support, shouldn't the values match the ELEMENT NODAL STRESSES? I am aware of the fact that element stresses are in the local axis system of the element, and support reactions are in the global axis system, and am making the required transformations before making the comparison.


Solution: The element nodal stresses are obtained as the value of the stress polynomial at the coordinates of those joints. Stresses in an element are most accurately determined only at the center of the element (in the middle of the joint displacement locations used in calculating that stress). The stress values calculated at the nodes will only be approximate (only the displacements of the joints from this one element are used in calculating the stress). Stresses at a joint would be improved if the stresses from the other elements at the joint (on the same surface) were averaged. Consequently, the comparison you suggest is not feasible. A better alternative would be to compare the forces at the node rather than the stresses at the node. However, to do so, you will require version 2001 of STAAD.Pro. In STAAD.Pro 2001, the output for the command PRINT ELEMENT FORCES consists of the 3 forces and 3 moments at each of the nodes of the elements, reported in the global axis system. Thus, the output will consist of FX,FY,FZ,MX,MY,MZ with the 3 forces having units of force (not stress) and the 3 moments have units of moment (not moment per unit width). If you add up the values at the nodes of those elements which are connected to the support, those values must be equal to the support reaction. Another consideration is the way in which element loads are evaluated and used. Staad computes the equivalent forces at the corner joints (same total force, center of force, and direction). The remainder of the analysis and results are as if you had applied the loads as joint loads rather than as element loads. Two exceptions, temperature loads are applied internally to the element and plate releases will affect the load distribution to the joints. Say you have a wall with uniform pressure. Half of the load on the elements along the base will be applied directly to the base, the other half is applied to the line of joints at the top of these elements. So the internal transverse shears are too high at the top of the element. The transverse shears are OK at the center and too small at the base. The same will be true for the element force output of transverse forces. However, the reactions will have the entire force. A finer mesh in general, and near the base in particular, will improve the element stress and load distribution.







Description: When performing steel design per the AISC 9th edition ASD code, does STAAD take into consideration the effect of L/rt while calculating the allowable bending stress?


Solution: The effect of L/rt is indeed being taken into consideration while calculating the allowable bending stress, as per Section F of the specifications of the code. The L used for this purpose is the value specified for the unsupported length of the compression flange through the input parameters UNT and UNB.







Description: I am looking at Section 5.20.1 of the STAAD.Pro Technical Reference Manual. If I want to assign a single anglemy model, I have 2 options to choose from - the “ST” option and the “RA” option. What is the difference between these optio


Solution: The difference has to do with the way in which the local Y and Z axes of the angle are defined. In general, when yis the major axis, and the local Z is the minor axis. For the “RA” option, the local Z is the major axis, and the local Y is the mbe observed in Figure 1.6 in Section 1.5.2 of the STAAD.Pro Technical Reference Manual. An extract from that figure is show






Issue #: SP-1510 Date Posted: 2/1/2002 8:45:05 AM

Description: When I save a file from the STAAD.Pro GUI, the joint coordinate data and member incidence data are written into the .std file in such a manner that there are several entries per line, separated by semi-colons. I would like it to be written in a way that the joint coordinate data is written as one joint per line and the member incidence data is written as one member per line. Is there some setting in the program to facilitate this?


Solution: Close all input files.

From the File menu, select Configure - Input File Format. Switch on the items for which you wish to have the single line format. Click on Accept.

Then, choose File - Open - open the input file. Click on Save. This setting will ensure that all desired data will henceforth besaved in the single line format.







Description: Why do tension-only members fail when kl/r is less than 300?


Solution: It is probably due to the fact that, the end of the beam is so close to compression that, the dead weight puts it into compression. To alleviate this you can turn off the slenderness test by setting the MAIN parameter to 1.0.





Issue: MEMBER TENSION and combination load cases

Description: I understand that one should use the REPEAT LOAD command and not the LOAD COMBINATION command when analysing a model for cases where the MEMBER TENSION or MEMBER COMPRESSION command has been used. Talking about load combinations, in Section 5.35 of the STAAD Technical Reference Manual, notes Item (2) mentions that the LOAD COMBINATION command is inappropriate for a PDELTA analysis, and that one should use REPEAT LOADs instead.This appears to be true for NON-LINEAR analysis also. Why?

Version: Build No:

Solution: Before we can explain why, we first need to understand a few facts about loads in STAAD. There are two types of load cases in STAAD : Primary load cases, and Combination load cases.

Primary load cases A primary load case is one where the load data is directly specified by the user in the form of member loads, joint loads, temperature loads, element pressure loads, etc. It is characterized by the fact that the data generally follow a title which has the syntax

LOAD n where "n" is the load case number. For example, LOAD 3 MEMBER LOAD 2 UNI GY -3.4 JOINT LOAD 10 FX 12.5 LOAD 4 ELEMENT LOAD 23 PR GY -1.2 LOAD 5 TEMPERATURE LOAD 15 17 TEMP 40.0 -25.0

Combination load case Here, the user does not directly specify the load data, but instead asks the program to add up the results of the componentcases - which are defined prior to the combination case - after factoring them by the user specified factors. It is characterized by the title which has the syntax

LOAD COMBINATION n where "n" is the case number of the combination load case.



LOAD COMBINATION 40 3 1.2 4 1.6 5 1.3

What is a REPEAT LOAD type, and Which category does is belong to? A Repeat Load type is a Primary load case. That is because, when the program runs into this command, it physically creates the load data for this case by assembling together the load information from all the component load cases (after factoring them by the respective load factors) which the user wants to "REPEAT". Thus, when you specify

LOAD 10 REPEAT LOAD 4 1.4 5 1.7

STAAD creates a physical load case called 10 whose contents will include all of the data of load case 4 factored by 1.4, and all of the data of load case 5 factored by 1.7. If we use the same data used in the definition of the primary load case above, STAAD internally converts the REPEAT LOAD case 10 to the following :

LOAD 10 ELEMENT LOAD 23 PR GY -1.68 TEMPERATURE LOAD 15 17 TEMP 68.0 -42.5

What is the difference between a REPEAT LOAD case and LOAD COMBINATION? The difference lies in the way STAAD goes about calculating the results - joint displacements, member forces and support reactions. For a load combination case, STAAD simply ALGEBRAICALLY COMBINES THE RESULTS of the component cases after factoring them. In the example shown above, it

gathers the results of load case 3, factors them by 1.2, gathers the results of load case 4, factors them by 1.6, gathers the results of load case 5, factors them by 1.3,

and adds them all together. In other words, in order to obtain the results of load 10, it has no need to know what exactly isit that constitues load cases 3, 4 and 5. It just needs to know what the results of those cases are. Thus, the structure is NOT actually analysed for a combination load case. With a REPEAT LOAD case however, the procedure followed is that which occurs for any other primary load case. A load vector {P} is first created, and later, that load vector gets pre-multiplied by the inverted stiffness matrix.

[Kinv] {P}

to obtain the joint displacements. Those displacements are then used to calculate the member forces and support reactions. Thus, the structure IS analysed for that load case {P}.

Why should the difference in the way STAAD treats a REPEAT LOAD case vs. a COMBINATION LOAD case





matter? Normally, if you are doing a linear static analysis - which is what a PERFORM ANALYSIS command does - it should make no difference whether you specify REPEAT or COMBINATION. However, if you are doing a PDELTA analysis, or a NONLINEAR analysis, or cases involving MEMBER TENSION and MEMBER COMPRESSION, etc., it matters. That is because, in those situations, the results of those individual cases acting simultaneously IS NOT the same as the summation of the results of those individual cases acting alone. In other words,

(Results of Load A) + (Results of Load B) is not equal to (Results of Load (A+B))

Take the case of a PDelta analysis. The P-Delta effect comes about from the interaction of the vertical load and the horizontal load. If they do not act simultaneously, there is no P-Delta effect. And the only way to make them act simultaneously is to get the program to compute the displacement with both loads being present in a single load case. A REPEAT LOAD case achieves that. A COMBINATION load case does not.







Issue: Proper usage of the MEMBER TENSION command

Description: What are some guidelines for using the MEMBER TENSION command properly?

Version: Build No:

Solution: To use the MEMBER TENSION command properly, please note the following: 1. A member declared as a MEMBER TENSION carries axial force only and thus the MEMBER RELEASE command should not be used with it. 2. The total number of primary load cases being solved for, if more than 1, must be declared at the begining using the SET NL f1 command. f1 will be an integer equal to the number of the primary load cases one intends to include in the analysis. 3. If multiple primary load cases are present, each primary load case should be followed by 'CHANGE ' & 'PERFORM ANALYSIS' commands. 4. If the results from individual load cases are to be combined, then the use of the LOAD COMBINATION command will be inappropriate. The REPEAT LOAD command should be used instead.







Description: For moving load generation, does STAAD provide the location of all the moving point loads in terms of member number and distance from the start of the member?


Solution: Yes. Please use the PRINT LOAD DATA option with your PERFORM ANALYSIS command and you will get the information in your output file.







Description: I want to use a regular text editor, such as WordPad, to create my input (std) files. How can I do that?


Solution: To use a text editor besides STAAD-Edit to create input (std) files, you need to save the document from that editor as a text file with an "std" extension. Please do the following when you want to save your work: Go to File | Save As For "File Type", select Text Document For file name, type in "filename.std". Note the double quotes. They MUST be in the File Name box. If you go filename.std (no quotes) it will be saved as filename.std.txt, but with the quotes it will be filename.std instead. To open a file in Staad Pro, the name must be of the form filename.std not filename.std.txt.







Description: What are the differences between the full and limited versions of STAAD.Pro?


Solution: The limited version has everything the full version has except: 1) Concrete Design (using concrete sections and materials are accepted) 2) Non-Linear Analysis 3) Time History Analysis 4) Response Spectrum 5) 3D Solid (Brick) Elements It has no restrictions on the size of the model.







Description: I am using STAAD to do steel design per the AISC code. For 2 members with similar cross sections, one passes, the other fails. Fact is, the one which fails has almost no load on it. The other is significantly more stressed but still passes. Is something wrong in the steel design calculations that STAAD is doing?


Solution: You will notice that, for the member which failed, the cause of the failure is reported using the phrase "L/R-EXCEEDS". This means that the member has failed the slenderness check. When STAAD performs steel design on a member per the AISC code, it adopts the following sequence : It first sets the allowable KL/r in compression to 200 and the allowable KL/r in tension to 300. For the member being designed, it goes through all the active load cases to see if the member is subjected to axial compression and/or axial tension. Next, it compares the actual KL/r against the allowable KL/r. If this check results in a FAILure, the member is declared as FAILed, and design for that member is immediately terminated. The requirement to check this condition is in Section B of the AISC specifications. If the member passes the KL/r check, only then does the program go on to do the remainder of the checks such as axial compression + bending, shear, etc. It must be noted that failure to satisfy the KL/r check is a reflection of the slenderness of the member, not the capacity of the section to carry the loads which act on it. Even if the axial load or bending moment acting on the member is a negligible quantity, the fact is, failure to satisfy KL/r will result in the member being declared as unsafe as per the code requirement. If you do not want the KL/r condition to be checked, you can switch off that check using a parameter called MAIN. Set MAIN to 1.0 for a specific member and it won't be checked for slenderness. See Table 2.1 of the STAAD.Pro Technical Reference Manual for details.





Description: The Software Release Report that accompanied the StaadPro 2001 release, Section AD.2001.4 (line 19) statesshear reported for spectrum analysis now includes direction factors (which it did not previously)" In the old StaadPro 2000, the attached file resulted in base shears in each X, Y, and Z directions even considering the fact thdynamic load is only applied in the X direction, the total base shear for X = 8505.44 kips, for Y = 5700.2 kips, and for Z = 6This should be compared to the output file for the attached input file and noted not only a change in the actual numerical vano shears in the Y and Z directions. It should also be noted that the values of base shear in the old StaaPro 2000 were completely independent of the acceleratiocoefficient and seemed to be only a function of the structure itself. However, in StaadPro 2001, the numerical values vary prwith the input acceleration scale. What do these numbers now represent and how I can verify these numbers?


Solution:

In past versions the base shear results were not multiplied by the direction factor (as if the factors were all 1.0). So a shock in the X-direction would list base shear values in the Y and Z directions as well as if the spectra curve applied to those directions as well. Also, if diresay (x=.707, z=.707, y=1.0) would be calculated as if all 3 were 1.0. Now, to get all 3 in one table as in past, you need to enter a factor of 1.0 for all 3 directions. Otherwise you would enter 3 load cases, one for each direction. The SCALE factor has not changed; it simply multiplies the spectra curve to convert it to the current units if necessary. The old base shear total combined the individual modal base shears by SRSS even if CQC were chosen. Now the CQC result chosen as well as the results from several other combination methods. If you have chosen SRSS and find that the 10PCT mesignificantly different, then I would suggest that you switch to CQC. The reason is that CQC (and 10PCT) consider the interacspaced modal frequencies. The total potential amount of base shear as computed in STAAD will not include masses at support directions or lumped frommember/element attached to a supported direction. The dynamic weight line below contains the total potential weight for bacalculations. Missing Weight is the amount of weight missing in the modes; Modal weight is the total weight in the modes. Foacceleration spectra excitation curve and the ABSOLUTE summation method of combining modes, this would also be the bas

SRSS MODAL COMBINATION METHOD USED. DYNAMIC WEIGHT X Y Z 8.165253E+02 8.165294E+02 8.165276E+02 POUN MISSING WEIGHT X Y Z -4.118054E+01 -3.292104E+02 -4.840284E+02 POUN MODAL WEIGHT X Y Z 7.753447E+02 4.873190E+02 3.324991E+02 POUN

For the following input

2681. SPECTRUM SRSS X 1 Y 1 Z 1 ACC SCALE 32.2





2682. 0.05 5; 0.1 10; 0.15 15; 0.2 20

we got the following output. The Acceleration-G column indicates the spectra acceleration that STAAD interpolated from the input SCALE and spectra curve.

MODE FACTOR ACCELERATION-G DAMPING ---- ------------- -------------- ------- 1 -4.247175E-02 5.56480 0.05000 2 3.155636E-01 5.43263 0.05000 3 2.559065E-02 2.84369 0.05000 4 2.524380E-03 2.27839 0.05000 5 1.495291E-03 2.07394 0.05000 6 1.779840E-03 1.61674 0.05000

Note that you can divide the base shears by the above accelerations and get the modal weight which will sum the previous modal weight line.

MASS PARTICIPATION FACTORS IN PERCENT BASE SHEAR IN PO ---------------------------------------- ------------------- MODE X Y Z SUMM-X SUMM-Y SUMM-Z X Y 1 24.31 3.44 1.80 24.313 3.438 1.798 1104.74 156.23 8 2 1.62 53.07 28.12 25.934 56.507 29.918 71.90 2354.08 124 3 61.92 0.00 0.00 87.858 56.507 29.919 1437.85 0.00 4 0.12 0.70 3.96 87.980 57.208 33.882 2.28 13.04 7 5 2.83 0.19 0.87 90.812 57.393 34.752 47.96 3.14 1 6 4.14 2.29 5.97 94.957 59.682 40.721 54.71 30.21 7 --------------------- TOTAL SRSS SHEAR 1816.13 2359.49 125 TOTAL 10PCT SHEAR 1859.41 2510.55 133 TOTAL ABS SHEAR 2719.43 2556.70 149







Issue: How does STAAD's Moving Load Generator convert the truck load to beam loads ?

Description: I am using the moving load generation. The truck that I am specifying is so wide (dimension perpendicular todirection of traffic) that within the width of one lane of traffic, there are 3 or more parallel beams along the direction of traffic. How does STAAD determine how the truck load should be converted to beam loads?

Version: Build No:

Solution: Based on the data you provide under the DEFINE MOVING LOAD command, each truck is treated as a set of axles. If the WIDTH option is NOT specified, each axle is assumed to be comprised of 1 tire. If the WIDTH option is specified, each axle is assumed to be comprised of 2 tires.

The program looks at each tire independently. For any given tire, it looks for one longitudinal beam to the left of the tire, and another longitudinal beam to the right of the tire. Then it distributes the tire weight on those 2 beams as though the tire is located on a simply supported cross beam that spans the two longitudinal members on either side.

Thus, even if a lane spans across 3 longitudinal beams or for that matter several beams, the above approach ensures that the tire weights get properly applied on the correct set of beams as concentrated member loads.

You can get a listing of these concentrated member loads by using the command

PERFORM ANALYSIS PRINT LOAD DATA







Description: As I understand The Rayleigh method is used for natural Frequency calculations (first mode only) in the command CALCULATE NATURAL FREQUENCY & also in the command DEFINE UBC LOAD or 1893 load. Whereas the matrix method of iteration (like Staddola method) is used in the Response Specterum method of analysis . Does this mean the values which we got by define 1893 load or Calculate natural frequency are wrong?


Solution: It is not true that the lowest frequency is the one which is associated with significant amount of participation of the masses of the model. That may be true of structures which look like a cantilever. But if the spatial distribution of masses is extensive, there is no guarantee that the fundamental mode is the most critical mode. The statement that the Rayleigh frequency is associated with the first mode of the structure too is not correct. A structure has several modes of vibration. If the structure were free to vibrate, the modes of vibration will follow the ascending order of strain energy. Consequently, if Y is the weakest direction of the structure, a Y direction mode will be the first mode. If the next weakest direction is Z, then the second mode will be a Z direction mode. Structures have local modes, where a small region within the model vibrates while the rest of the model remains stationary. It is entirely possible that a local mode is the lowest energy mode. In many cases, torsional modes happen to be the lowest modes. Local and torsional modes are associated with negligible mass participation. You should look at the mode shapes of all the modes to get a sense of all the major vibration modes. Since when using the Rayleigh method, one tends to load the structure in a manner which generally resembles a large mass participation mode, there is no sense in comparing the Rayleigh frequency with the lowest frequency from the eigensolution. Instead, you have to try to compare the displaced shape of the model used in the Rayleigh calculations with the various modes from eigensolution until you find a mode shape which resembles the displaced shape. When you do find a match, you will find that the Rayleigh frequency will be similar in value to the frequency of the matching mode. If you do not like the frequency being used in the IS 1893 load generation, which is Rayleigh based, there is an option in STAAD for the user to provide his/her own value of the frequency. This is done using the PX and PZ options, as in the following example. ZONE 0.05 K 1.0 I 1.0 B 1.0 PX 0.4 PZ 0.8 The values you provide for PX and PZ will be used in place of the one calculated by the Rayleigh method.







Description: Can I do a Pdelta analysis using STAAD for Response Spectrum load cases?


Solution: A response spectrum analysis by definition provides the user with joint displacements which are the absolute maximum displacements which can occur at the joint when the structure is subjected to dynamic loads represented by the spectrum. This also means that these displacements do not necessarily occur at all joints at the same instant of time. In other words, the absolute maximum at joint 1 and that at joint 2 are most probably occurring at different instances of time. Another fact to be considered is that the response of the individual modes is combined using either the SRSS or the CQC methods depending on the input provided by the user. Both of these are approximate methods. The result is that the joint displacements and consequently, the member forces cannot be used as a basis for obtaining the secondary forces on the structure. Hence, doing a P-Delta Analysis under such conditions does not make any sense.






Issue #: SP-1624 Date Posted: 2/10/2002 2:55:05 PM

Description: To limit the deflection in the local Z direction I plan to add lateral support(s). Can I model these as 'FIXED BUT' supports released in FX and FY, or is there a better method?


Solution: If these are physical restraints which prevent the member from undergoing a certain deformation at a specific point, declaring a support is certainly the right method. But, to do so, you have to divide the beam into sub-segments so that nodes are created where you wish to define these intermediate supports. However, if the only purpose of these is to provide lateral bracing against buckling, and if they do not necessarily behave as support points which restrain certain types of deformation, you can declare the unsupported length in buckling by using steel design parameters such as LY, LZ, UNT, UNB, etc.







Description: What are the design parameters which control deflection check?


Solution: 1) DFF : This is the value which indicates the allowable limit for L/d ratio. For example, if a user wishes to instruct the program that L/d cannot be smaller than 900, the DFF value should be specified as 900. The default value for DFF is 0. In other words, if this parameter is not specified as an input, a deflection check will not be performed. 2) DJ1 and DJ2 : These 2 quantities affect the "L" as well as the "d" in the calculated L/d ratio. They represent node numbers that form the basis for determining L and d. By default, DJ1 and DJ2 are the start and end nodes of the member for which the design is being performed, and "L" is the length of the member, namely, the distance between DJ1 and DJ2. However, if that member is a component segment of a larger beam, and the user wishes to instruct STAAD that the end nodes of the larger beam are to be used in the evaluation of L/d, then he/she may input DJ1 and DJ2 as the end nodes of the larger beam. Also, the "d" in L/d is calculated as the maximum local displacement of the member between the points DJ1 and DJ2. The definition of local displacement is available in Section 5.42 of the STAADPro Technical Reference Manual, as well as in Example problem # 13 in the STAADPro Examples Manual. A pictorial representation of DJ1 and DJ2, as well additional information on these topics is available under the "Notes" section following Table 2.1 in Section 2.8 of the STAADPro Technical Reference Manual. If you use the design parameter TRACK 2.0, you will see a term called "dff" in the STAAD output file. This terms stands for the actual length to deflection ratio computed by STAAD. If "dff" is smaller than "DFF", it means the member has violated the safety requirement for deflection, and will be treated as having failed.







Description: Will STAAD explicitly state that the beam has passed the deflection criteria?


Solution: When STAAD performs steel design (code checking as well as member selection), it checks several conditions required by the code. The one which gives rise to the highest unity check is the one determined as critical. If the deflection criteria ends up being the worst condition, you will see it being reported as the critical condition. You can verify whether a member has passed the deflection check by looking at the terms "DFF" and "dff" in the steel design output. "DFF" is the value you input. "dff" is the value the program calculates as the actual "L/d" ratio. If "dff" is larger than "DFF", the member is deemed safe for deflection.







Description: Can I get STAAD to check deflection in both axes?


Solution: Yes. However, rather than check the deflection for each axis independently, STAAD finds the resultant deflection "d" and compares the "L/d" (length to deflection ratio) against the allowable limit specified by you through the DFF parameter.







Description: If I understand correctly, utilizing DFF in STAAD only helps one check the local deflection. What if I want to check the drift of a column / beam frame? If my joint displacement printout says that joint of a column/beam joint has moved 1.42 inch in the global X, then my drift ratio is 18x12/1.42 = 152.11, but the "dff" says 1072 for the same column, then where is the dff being measured?


Solution: When the DFF parameter is specified, the deflection checks during steel design are performed on the basis of so called "local axis deflection", not the nodal displacements in the global axis. For this reason, it is not possible to include storey drift checks into the steel design calculations at present. If you want additional information on local axis deflection, please refer to example # 13, and Section 5.42 of the STAAD Technical Reference Manual. If you want some general information on obtaining storey drift values, and checking them to determine the serviceability/safety of the structure, a solution is available at : http://www.reiworld.com/Search.asp?id=SP-1894





Description: How is the wind load calculated/generated for a structure in STAAD.Pro ? What is the exposure factor calculated and how is it calculated? In 2002, I hear you can now define your own "panels"? What does this mean?


Solution: The DEFINE WIND LOAD command may be used to define the parameters for automatic generation of wind loads on the structure. The user needs to define the intensity and corresponding heights along with the exposure factors. If the exposure factor is not defined, the program takes the default value as 1.0. A value of 1.0 means that the wind force may be applied on the full influence area associated with the joints if they are also exposed to the wind load direction. All loads and heights are in the current unit system. In the list of intensities, the first value of intensity (p1) acts from the ground level up to the first height. The second intensity (p2) acts in the global vertical direction between the first two heights (h1 and h2) and so on. The program assumes that the ground level has the lowest global vertical coordinate of any joint entered for the structure. The exposure factor (e) is the fraction of the influence area associated with the joint(s) on which the load may act if it is also exposed to the wind load. Total load on a particular joint is calculated as follows. JOINT LOAD = (Exposure Factor) x (Influence Area) x (Wind Intensity). Exposure factor (User specified) = (Fraction of Influence Area) x (influence width for joint). In STAAD.Pro 2002, the built-in wind load generation facility has been enhanced to allow the user to specify the actual panels of the building which are exposed to the wind. This user-level control will now allow the user to obtain a more accurate distribution of wind forces, especially when the exposed surface of the building lies in several vertical zones, each reset from the one below or the one above, in terms of the direction of wind force. Further, the basic algorithm for detecting the shape of the panels and the amount of load which should be calculated for the panel corners too has undergone significant improvements. The parameters for definition of the wind load types are described in Section 5.31.3 of the STAAD.PRO Technical Reference Manual. The relevant extracts from Section 5.32.12 of the STAAD.Pro Technical Reference Manual, where the method for applying wind loading in the form of a data in load cases has been explained, is provided below. Note that areas bounded by beam members (and ground), and exposed to the wind, are used to define loaded areas (plates and solids are ignored). The loads generated are applied only at the joints at vertices of the bounded areas. For example, in the following set of commands: DEFINE WIND LOAD TYPE 1 INTENSITY 0.1 0.12 HEIGHT 100 200 EXP 0.6 JOI 1 TO 25 BY 7 29 TO 37 BY 4 22 23 TYPE 2 INT 0.1 0.12 HEIGHT 100 900 EXP 0.3 YR 0 500 LOAD 1 SELF Y -1.0 LOAD 2 WIND LOAD Z 1.2 TYPE 2 ZR 10 11 LOAD 3 WIND LOAD X TYPE 1 XR 7 8 A minus sign indicates that suction occurs on the other side of the selected structure. If all of the members are selected and X (or Z) is used and the factor is positive, then the exposed surfaces facing in the -x (or -z) direction will be loaded in the positive x (or z) direction (normal wind in positive direction). If X and a negative factor is used, then the exposed surfaces facing in the +x direction will be loaded in the negative x direction (normal wind in negative direction). [If -X is entered and a negative factor, then the exposed surfaces facing in the -x direction will be loaded in the negative x direction (suction). If -X is entered and a positive factor, then the exposed surfaces facing in the +x direction will be loaded in the positive x direction (suction).] A member list or a range of coordinate values (in global system) may be used. All members which have both end coordinates within the range are assumed to be candidates for defining a surface which may be loaded if the surface is exposed to the wind. The loading will be in the form of joint loads (not member loads). 1, 2 or 3 ranges can be entered to form a "layer", "tube" or "box" for selecting members in the combined ranges. Use ranges to speed up the calculations on larger models. It is advisable not to use the SET Z UP command in a model with wind load. A closed surface is generated by the program





based on the members in the ranges above and their end joints. The area within this closed surface is determined and the share of this area (influence area) for each node in the list is then calculated. The individual bounded areas must be planar surfaces, to a close tolerance, or they will not be loaded. Hence, one should make sure that the members/joints that are exposed to the wind make up a closed surface (ground may form an edge of the closed surface). Without a proper closed surface, the area calculated for the region may be indeterminate and the joint force values may be erroneous. Consequently, the number of exposed joints should be at least 3.







Description: What is the significance of the Rw Value in the UBC code?


Solution: The UBC 1997 code defines Rw as a Numerical Coefficient representative of the inherent overstrength and global

ductility capacity of lateral-force resisting systems. It is to be used in the equation for computing base shear. Its values are dependent on the type of lateral-force resisting system in the building, such as whether the system is a Light-framed wall with shear panels or Shear wall made of concrete or a special moment resisting frame, etc. Values of Rw are listed in Tables 16-N and 16-P of the UBC 1994 and 1997 codes.







Description: The STAAD graphical interface is showing a steel column in my model in an incorrect orientation. I have checked my input file (and also by double clicking on the actual member) and all of my columns consistently start at the lower node and go in the +y direction, all have a beta of 0, and all have the same member property. I have the exact same data for this graphically-incorrect column as the one below it that shows up the correct orientation. Yet another column shows a slightly skewed column orientation as if I had assigned it something other than 0 or 90 degrees, and I know for a fact that I haven't done this. a - Is the graphical interface a reliable representation of my input? b - If yes, can you think of some other possible sources of this particular error?


Solution: If you look at the coordinates of the columns which appear to be oriented in the wrong way, chances are that you will find the Z coordinate of the 2 ends to be different by a very minute value, such as 0.001. For example, one end may have a Z value of 5.999 while the other end may be at 6.000. If so, you could do the following to correct it. Select the Geometry-Beam page along the left side of the screen, and it will display the node coordinates in the tables on the right hand side. In those tables, make the necessary correction so both ends of the column have the same Z coordinate. The potential cause of this difference in coordinates is the following. The program has something called a Base Unit system. You can find this by starting the program, and before opening any file, go to the File menu, select Configure, and see if it says "English" or "Metric". If the model you are going to create is in Metres and KNs, you ought to have the base units in Metric. If the model you are going to create is in Feet and Kips, you ought to have the base units in English. Mixing unit systems causes the program to perform internal unit conversions which can result in loss of digits because the built-in conversion factors have only upto 8 digits of accuracy. In fututure versions of STAAD, there will be a feature which will enable you to select the "offending" column and make the Z coordinate of its 2 ends to be equal so it becomes truly vertical.







Description: How do you a create a user-defined or user-provided table? I want to add sections that are not part of the standard STAAD section library.


Solution: To create a user-defined Go to "Tools | Create User Table". If you have already created a User Provided Table, you may select it from the drop-down list box labeled "Select Existing Table" for further editing. If you click on the New Table button, the Select Section Type dialog box appears for inputting the Section Type for the new User Provided Table (UPT). If the sections are saved in an external file, check the External Table check box and provide the filename in which the section database will be stored. Select the Section Type from the drop down list and click OK. After creating a new table or selecting an existing table, click the Add New Property button to specify a customized UPT section. A dialog box appears for inputting property values applicable to the section type chosen for the current table. Refer to Section 5.19 User Steel Table Specification of the Technical Reference Manual for details on the property value requirements for various section types.







Description: How do I create tabularized results for a few selected members?


Solution: First you will need to classify the selected members using Group names. This can be done by selecting the appropriate members, then going to Tools | Create New Group, creating a group name, and assigning that name to the selected members. Once you have done this, analyze the structure by going Analyze | Run Analysis and pressing the "Run Analysis" button. After the analysis is successfully completed, go into the Post Processing Mode. This can be done by selecting Mode | Post Processing. When the "Results Setup" box comes up, select the desired load cases. Next, go to the "Range" tab. Click on the "Group" button and select the group name which contains just those members for which you want to view the results. Press the "OK" button. Now, the tables along the right side of the screen in the Beam Forces page will contain the results for only those members.







Description: In STAAD/Pro 2000 and STAAD.Pro, I no longer see the UNL parameter for the AISC ASD and LRFD codes. Instead, I see the parameters UNT and UNB. Can someone please explain how these should be used?


Solution: In versions of STAAD prior to STAAD/Pro 2000, the mechanism for specifying the unsupported length of the compression flange was through the means of the UNL parameter. However, the drawback of this command is that if the value for the top flange is different from that of the bottom flange, there wasn't any means to communicate that information to STAAD. Consequently, 2 new commands were introduced, namely, UNT and UNB. UNT stands for the unsupported length of the TOP flange of the member for calculating the capacity in bending compression and bending tension. UNB stands for the unsupported length of the BOTTOM flange for calculating the capacity in bending compression and bending tension. To avoid the confusion that may arise from having 3 separate parameters to specify 2 items of input, we no longer mentionthe UNL parameter. However, to enable the current versions of STAAD to analyze input files created using the older versions of STAAD, the UNL parameter continues to work the way it did. These 2 new parameters are to be used in place of UNL. If UNT/UNB is specified in addition to UNL, UNL will be ignored. If neither UNT nor UNB are specified, but UNL is specified, the value of UNL will be used for both top and bottom flange.







Description: How can I edit a Group? I want to add members to a group that has already been created.


Solution: First, find the member number of the member that you want to add to the existing group. Then, Method 1 : From the Tools menu, select Create New Group. Click on the group name you are interested in. The list of members currently in that group will be displayed in the list box. Type in the member number at the end of the list, and click on the Associate button. Method 2 : From the Edit menu, select Edit Input Command file. The data will be displayed in the STAAD editor. Go down to the region containing the commands START GROUP DEFINITION ... .. END GROUP DEFINITION Within that block, you will find the group name and associated member list. To this list, add (type in) the member number that you want included in this group. Save the file and exit the editor.







Description: I would like to adopt a numbering scheme for the beams in my model based on the floor they are located in. For example, I want the beams of the first storey level to be numbered from 1001, those of the second storey level to be numbered from 2001, etc. How can I do this?


Solution: Select the members of the first floor level. From the Geometry menu, select Renumber | Members. Provide the starting number for the series. In version 2002, specify whether you want the numbering to be performed in Ascending or Descending order. Click on OK.







Description: When modelling plate elements, should the individual elements satisfy any minimum requirements for the ratio of the length of their side to their thickness?


Solution: No, they do not have to. However, for the overall slab or wall, if the span in either direction is less than 10 times its thickness, then the slab or wall becomes more like a solid than like a plate; and thick plate theory may not be adequate. In that case, 8-noded solid elements may be necessary.







Description: Can STAAD be used in designing a mat foundation?


Solution: The answer to the question is Yes. The following are the major steps involved in the modelling and design of mat foundations using STAAD. 1) The mat foundation has to be modelled using finite elements. If the length and width of the mat are atleast 10 times larger than its thickness, plate elements can be used. If not, one may use 8 noded solid elements. The remainder of the structure involving the beams, columns and slabs also has to be modelled along with the mat. If beams share a common boundary with the mat and slabs, to ensure the proper transfer of load between the beams and the mat & slabs, the mat & slabs have to be divided into several elements, the beams have to be divided into several members, and the elements and members must share common nodes. 2) Generally, the supports for the mat are derived from the subgrade reaction of the soil. Using this attribute, and the influence area of each node of the mat, the spring constant for the supports may be derived. STAAD contains an automatic spring support generation facility for mat foundations. One may refer to Section 5.27.3 of the STAAD.Pro Technical Reference Manual for details on this type of support generation. 3) Soil spring supports generally tend to be effective against resisting compressive forces only. They are ineffective in resisting uplift. This type of a unidirectional support requires those springs to be assigned an attribute call SPRING COMPRESSION. 4) The loads on the mat and the rest of the model have to be specified. Then, the structure has to be analysed. This will generate the plate stresses and corner forces needed to design the mat. 5) You can then use the program's concrete design ability to design the individual elements which make up the mat. The only tedious aspect of this is that the program can presently design individual elements only. The task of taking the reinforcement values from each element and assembling the reinforcement picture of the overall mat has to be done by you manually. You may wish to look the information posted at the following links for details on the issues involved in designing individual elements. http://www.reiworld.com/Search.asp?id=SP-1549 http://www.reiworld.com/Search.asp?id=SP-1791 http://www.reiworld.com/Search.asp?id=SP-1792 We suggest you take a look at example problem number 27 in the STAAD.Pro examples manual for guidance on analysing mat foundations. In that example, the aspects explained in steps 1,2, 3 and 4 above are illustrated. Example problems 9 and 10 discuss concrete design of individual plate elements.







Description: Is there a way to convert the output reaction files to an Excel-friendly format?


Solution: You may follow these steps below : Run the Analysis. From the Mode menu, select Post Processing. From the Select menu, choose "By Specification | All Supports". From the Report menu, select Support Reactions. In the dialog box which appears, there are 3 tabs. In the Sorting tab, select the criteria for sorting. If you do not want any sorting performed, leave the option "List with no sort done" unchanged. In the Loading tab, select the load cases for which you wish to see the results. Click on OK. The reaction values will be displayed in a table. Click on the cell called Node. The entire table will be selected (highlighted in black). To copy the contents of the table, click the right mouse button and choose Copy or simply type Ctrl+C. Start Microsoft Excel and open a new document. Click on the cell A1 (or the cell from which you want to begin copying the values) and select Paste. The support reaction table should now appear in the Excel sheet.







Description: Is there any facility in STAAD to design buildings for blast loading?


Solution: The analysis for blast loading is done using the facilities of time history analysis. The blast load has to be defined as discrete time-force pairs, with the force changing from a very small value to a large value, and then back to a small value over a very small time interval. Please refer to example 16 for help in specifying an arbitrary time-force function. STAAD can perform design for the maximum forces resulting from the time history analysis. The examples manual containsexamples on steel and concrete design illustrating the commands and parameters required to do this.







Description: I am using the composite beam design capabilities. But the output does not show any evidence of this design. Can you help me please?


Solution: There are 2 sets of data associated with analysing and designing a composite beam. Step 1 : Define the member properties as a composite beam. To do this, one has to use the "TA CM" option as explained in Section 5.20.1 of the STAAD.Pro Technical reference Manual. For example, if member 1 is a composite beam made up of a 3.0 inch thick slab on top of a W18X35, and the grade of concrete is 4.0ksi, one would have to specify UNIT INCH KIP MEMBER PROPERTIES 1 TA CM W18X35 CT 3.0 FC 4.0 Step 2 : Parameters for steel design. This is what you find in Section 2.9 of the STAAD.Pro Technical reference Manual. These are the attributes which are to be used in the actual design equations, using the expression PARAMETER, as in, PARAMETER CODE AISC BEAM 1 ALL TRACK 2 ALL FYLD 50 ALL CMP 1 ALL DR1 0.3 ALL WID 60 ALL FPC 4 ALL THK 4 ALL SHR 0 ALL DIA 0.75 ALL HGT 4 ALL RBH 2 ALL CHECK CODE ALL The most important thing to note here is the usage of the parameter CMP. Unless it is set to 1.0, STAAD does not design the beam as a composite section. The beam will be designed as a pure steel beam section in the absence of the "CMP 1" parameter.







Description: I need to analyze a frame whose members have been rotated about the local z axis. Is there anyway to model this situation using STAAD? Can you input a point and define the orientation of the local axis of that point? Or is there some other way to model this situation?


Solution: We presume you mean that the member is rotated about the local "X" axis and not the local "Z" axis. When you use STAAD's default coordinate system, the local "X" is the longitudinal axis of the member, and local Z is generally the major axis of the member. So, changing the orientation of a member involves rotation about the local "X" axis, and not the local "Y" or local "Z" axes. There are a couple of ways to change the orientation. a) By specifying an angle using the BETA command. This is explained in Sections 1.5.2, 1.5.3 and 5.26.2 of the Technical Reference Manual. You may also refer to example 1 of the Examples manual for a sample problem which shows the usage of the command. b) Using the REFERENCE POINT method. This too is explained in Sections 1.5.2, 1.5.3 and 5.26.2 of the Technical Reference Manual. In the STAAD.Pro GUI, you may click the right mouse button, select Labels, and switch on Beam Orientation to get a visual representation of the directions the local X and Y axes point to. Graphically, you can specify the BETA angle from 2 places : If you go to the General - Property page on the left side of the screen, you will find the Properties dialog box on the right side and it contains a tab called Beta Angle through which the value can be specified. If you go to the Commands menu on top of the screen, choose Geometric Constants - Beta Angle. Graphically, you can specify the REFERENCE POINT by going to the Commands menu on top of the screen, and choosing Geometric Constants - Member Reference Point.







Description: In the post processing mode - Results menu - Plate Stress Contour, there are two options called Max Top and Max Bottom. Are these direct stresses or flexural stresses?


Solution: These are the principal stresses SMAX and SMIN. Principal stresses are a blend of axial stresses (also known as membrane stresses SX and SY), bending stresses (caused by MX and MY) and inplane shear stresses (SXY). Since the bending stresses have distinct signs for the top and bottom surfaces of the element, the principal stresses too are distinct for top and bottom. The derivation for principal stresses is shown in example 18 of the STAAD Examples manual.







Description: I am modelling an elevated silo which will be used for storing grain. The columns which support the structure are modelled as members and the walls of the silo (containment part of the structure) are modelled using plate elements. The silo has vertical and sloping walls. The loads on the structure consist of the weight of the grain contained in the silo. What is the best method for applying the load when the silo is full of grain? As pressure loads on the inside? How should the load be applied on the sloping walls?


Solution: There are 2 segments of the tank which have to be individually considered for application of the load. The vertical walls ------------------ The material in the tank, especially if it is a fluid, will exert a lateral pressure on the vertical walls of the tank. This pressure load can be applied on the tank using the ELEMENT PRESSURE load facility. You can use one of 2 options to do this. a) A uniform pressure. If you take any individual element on the wall, if you know the pressure intensity at the top edge, and the pressure intensity at the bottom edge, the average of these 2 intensities can be applied as a constant pressure on the entire surface of the element, as in the following example : 45 PRESSURE -3.5 Since the load is along the local Z axis of the element, you do not have to specify the axis name in the above command since local Z is the default for the axis. The load value must be accompanied by the proper sign (positive or negative) which accounts for whether the load acts along or opposite to the direction of the local Z axis. b) A trapezoidally varying pressure. In case (a) above, we decided to take the average of the pressures at the top and bottom edges, and thus obtain a uniform pressure. However, this is not absolutely necessary. The load can be applied as a trapezoidal load, in which case, the TRAP option is used and the intensities at the top and bottom edges must be specified. An example of that is 45 PRESSURE TRAP Y -4.5 -2.5 In this example, it is assumed that the local Y axis of element 45 is along the vertical direction, and thus the trapezoidal variation is along the local Y. The load itself acts perpendicular to the surface of the element, and hence along local Z. If local Y is in the same sense as global Y, -4.5 indicates the intensity at the lower edge, and -2.5 indicates the intensity at the upper edge. If the vertical wall has many divisions along the vertical direction, there will be several "horizontal rings" of elements. Every element contained in a ring has the same intensity at its top and bottom edge. That means, the top & bottom intensity for each of those rings will have to be manually calculated. There is a facility in the STAAD.Pro GUI to simplify this task. From the top of the screen, select Commands - Loading - Load Commands - Element - Hydrostatic Trapezoidal, and provide the intensities at the top and bottom edges of the vertical wall. The program will use the linear interpolation method to find the intensity at each intermediate division, and then create the individual element TRAPEZOIDAL loads. The sloping walls ----------------- The load on the elements which make up these walls is derived from the weight of the column of material directly above these elements, and acts along the global vertical downward direction. Since the element TRAP load facility that is availablein STAAD allows a load to be applied only along the local Z axis, and since local Z is not parallel to any of the global directions, the TRAP load option cannot be used here. Hence, one will have to apply these as uniform pressure loads, the value of which has to be calculated for each sloping element as the average of the intensities at the 4 nodes of that element. There is no generation facility currently available in the program to automate this task.







Description: How can I find the maximum shear stress on my plate element model ?


Solution: Since there are several types of shear stress results we can get from STAAD, the expression "maximum shear stress" needs to be clarified. So, let us first see what the choices are : SXY - For any given element, this is the in-plane shear stress on the element and acts along the plate local X-Y axes directions. TMAX - This is the maximum inplane shear stress on the element and is a composite of SXY and the stress resulting from torsion MXY. SQX - This is the out-of-plane shear stress on the X face at the centroid of the element. SQY - This is the out-of-plane shear stress on the Y face at the centroid of the element. All of these results can be obtained in a report form, with additional options like sorting done in ascending or descending order for a user-defined set of elements and a user-defined set of load cases. As an example, do the following for getting a report of TMAX sorted in the order from maximum to minimum for all plates for load cases 4 and 5. Go to the post-processing mode. Select all plates. From the Report menu, select Plate Results - Principal stresses. Select TMAX, and set the sorting order from High to Low. Switch on "Absolute values" also to perform sorting based on Absolute values. Click on the Loading tab, and select just cases 4 and 5. Click on OK. A report will be displayed. Click the right mouse button inside the table, and select Print.







Description: What is the difference between importing an AutoCAD DXF file and using Frameworks to create my model?


Solution: When a model is imported as a DXF file (whether from AutoCAD or some other CAD package), only the geometry (joint coordinates and member incidences) are imported. Frameworks (a CAD package from Intergraph) has the ability to generate an entire STAAD file (.std) including loads, supports and member specifications. Frameworks provides the facility to input these structural attributes in its environment and the, generates a STD file which can be opened directly with STAAD.







Description: Is it possible to apply a concentrated force on the surface of an element? The point where the load acts is not one of the nodes of the element, as a result of which I cannot use the JOINT LOAD option.


Solution: Yes, it is possible to do this. In Section 5.32.3 of the STAAD.Pro Technical Reference Manual, if you look at the syntax of the element pressure loading, you will find the following : element-list PRESSURE direction x1 y1 x2 y2 In this syntax, (x1,y1) and (x2,y2) represent the corners of the region (on the element) over which the PRESSURE load is applied. However, if you omit the terms (x2,y2), the load will be treated as a concentrated force acting at the point (x1,y1), where x1 and y1 are measured as distances, from the centroid of the element, along the local X and Y axes, of thepoint of action of the load. Thus, if you want to apply a 580 pound force along the negative global Z direction at a distance away from the centroid of (1.3,2.5)feet along the local X & Y axes of element 73, you can specify the following commands UNIT POUND FEET LOAD 1 CONCENTRATED LOAD ON WALL ELEMENT LOAD 73 PR GZ -580.0 1.3 2.5







Description: I am doing a footing design in STAAD.Pro 2002. I am unfamiliar with the term "dowel reinforcement". I am guessing that this is a term used by American engineers. Could you explain what that is?


Solution: The longitudinal reinforcement in the column must be extended into the footing so that the forces and moments at the base of the column can be properly transferred into the footing. However, since the construction sequence requires the footings to be constructed before the columns, reinforcement is placed in the footing and extends upwards. So when the column is constructed, it becomes part of the column bars. This reinforcement which comes up from the footing into the column is called the dowel reinforcement.







Description: What is the difference between the LOAD COMB & REPEAT LOAD commands?


Solution: The difference lies in the way STAAD goes about calculating the results - joint displacements, member forces and support reactions. For a load combination case, STAAD simply ALGEBRAICALLY COMBINES THE RESULTS of the component cases after factoring them. In other words, for example, in order to obtain the results of load 10, it has no needto know what exactly is it that constitutes load cases 3, 4 and 5. It just needs to know what the results of those cases are. Thus, the structure is NOT actually analysed for a combination load case. With a REPEAT LOAD case however, the procedure followed is that which occurs for any other primary load case. A load vector {P} is first created, and later, that load vector gets pre-multiplied by the inverted stiffness matrix. [Kinv] {P} to obtain the joint displacements. Those displacements are then used to calculate the member forces and support reactions. Thus, the structure IS analysed for that load case {P}.







Description: How to model Pile cap attached to batter and vertical piles in STAAD.Pro?

Version: Build No:

Solution: 1) The pile cap can be modelled using either plate elements or solid elements. If the thickness of the cap is comparable to its plan dimensions, a solid element model is preferable. If the plan dimensions are much larger than its thickess, plate elements should be a better choice. One drawback of using solid elements is that, by their very nature, they lack rotational degrees of freedom. Consequently, for a monolithic structure such as a concrete pile cap with concrete piles, the rigid connection between piles and the pile cap cannot be properly accounted for, if the cap is modelled using solids. 2) The piles themselves can be modelled using frame members. The supports for the pile come in 2 varieties - skin friction and end bearing. Skin friction action can be accounted for by modelling each pile as several collinear members and specifying a support at each of those common nodes. End bearing action can be modelled using fixed or pinned supports. The support spring stiffness is obtained by multiplying the soil subgrade reaction by the influence area of the associated support node. A standard text book on pile analysis should be a great source of information on obtaining the spring constant of the supports.







Description: For elastic mat spring support generation, how do I find out the influence area computed by STAAD for each of the nodes where a support is generated?


Solution: If you have STAAD.Pro 2001 Build 1005 and later, use the word PRINT at the end of the line where the ELASTIC MAT command has been specified. For example, 1 TO 126 ELASTIC MAT DIRECTION Y SUBGRADE 10.0 PRINT You will get an output which looks like the following : JOINT INFLUENCE AREA ----- -------------- 1 8.500000 2 25.145125 3 33.292374







Issue: How to graphically view the response spectrum in STAAD.Pro

Description: How does one view the plot of the response spectrum in the STAAD.Pro GUI?

Version: Build No:

Solution: To view the plot of the spectrum,

Select General - Load page from the left. Select the Spectrum button on the right. In the dialog box, select the "Define forcing function" page. The plot should be displayed.



Question : How do I remove a load from a member without removing it from the load case?

Answer :

To demonstrate this, let us open EXAMP_01 located in the UK examples folder: X:\SPRO2005\STAAD\EXAMPLES\UK where

"X:" is the drive, and "SPRO2005" is the name of the installation folder.

The following picture will appear on the screen. We will explore two different ways of removing a load from a specific member. The load will continue to be present on the other members on which it was originally applied..

1

Say that we want to remove the load from member 10. To identify the member, let us first switch the beam numbers on. To do this, we can either press Shift + B on the key board or go to View | Structure Diagrams from the main menu and then switch on the beam numbers on from the Labels tab.

2

Next, go to the Load Page from the left side of the screen.

3

On the right side of the screen, there is a dialog box titled Load. Here, expand Load Cases Details.

4

Under load 1, highlight the expression UNI Y -13.5 kN/m. We will notice that this load is currently assigned to members 8, 9, 10, 11, 12, and 13.

Our goal is to remove the load from member 10. Here are the two methods: Method 1 � using the Toggle Load button The Toggle Load button is a switch setting which turns on what is called the toggle mode.

5

In this mode, when an attribute is selected and assigned using the "Use Cursor to Assign" method, the following happens.

• Click on the entity once - the attribute gets assigned. • Click on the same entity a second time - the attribute gets de-assigned. • Click on the same entity again, - the attribute gets re-assigned.

Thus each click will result in an assign if the attribute was un-assigned, and a de-assign if the attribute was assigned.

Let us use this Toggle Load option to remove the load from member 10. First, switch the Toggle Load box on. Then, after making sure that the �Use Cursor To Assign� method is selected, click on the Assign button.

The cursor will change as shown below.

6

Using this cursor, click on member 10. You will see that the load applied on member 10 has been removed.

To stop the process of removing loads, either hit the �Esc� key or go back and click on the Assign button again.

7

Method 2 � using the Edit button In this method, we will use the Edit button in the Load dialog box.

First, make sure that the load item is selected. Then, click on the Edit button. (You may also double-click on the expression UNI Y -13.5 kN/m. This will also bring up the Edit dialog box shown in the next page).

8

The following Edit dialog box will appear. Here, notice that the members on which the uniform force has been applied are listed.

Let us uncheck the box next to Member 10. Then, click on the Change button.

Once that is done, close the Edit dialog box.

9

You will see that the load has been removed from member 10.

10

Editing Loads on a specific member using the Load Edit Cursor To test this feature, you may use any model which has more than 2 members. Both members must have the same loading intensity. One such simple model is a 2-span beam shown below. STAAD SPACE UNIT METER KN JOINT COORDINATES 1 0 0 0; 2 5 0 0; 3 10 0 0; MEMBER INCIDENCES 321 1 2; 352 2 3; LOAD 1 MEMBER LOAD 321 352 UNI GY -10 FINISH Click the right mouse button, and from the pop-up menu, select Labels. The following dialog box comes up. Turn on Load Values.

Click on the Loads and Results tab. Turn on Loads. Select the desired load case number. Click on OK.The dialog box disappears and the load diagram must appear on the members.

Let us say that we wish to change the intensity of the load on member 321 from 10 kN/m to 15 kN/m. From the Select menu, choose the Load Edit cursor. The cursor changes to the one shown below.

Double click on the distributed load lines on member 321. The following dialog box comes up.

Change the value of W1 from -10 to -15. Also, since the load is to be changed for member 321 only, uncheck member 352.

Click on the Change button. The diagram should now indicate the new load on member 321.

Hit the Esc key on your keyboard to go back to the regular cursor. Or simply select the Beams Cursor from the Select menu.

STAAD.Pro 2004 – Software Release Report

128

AD.2004.14 Adding, modifying and deleting loads using Member Query

New load items can now be added to existing load cases, and, existing load items edited or deleted using the Member Query window. To access the member query facility, select the Beams cursor, and double-click on the member, or, go to Tools – Query – Member.

Figure 132

STAAD.Pro 2004 – Software Release Report 129

In the dialog box which comes up, one of the tabs will be Loading.

Figure 133

From the Select Load Case drop-down list, choose the load case to which you want to add new load data for the selected member, or remove pre-assigned load data from that member. This list will be empty if no primary load cases have been defined in the model.

STAAD.Pro 2004 – Software Release Report

130 Clicking on Add new Load Item brings up the following dialog box for assigning new load items.

Figure 134

In the above box, choose the type of load from the list along the left side and follow the prompts. To remove an existing load item, highlight the item and click on Remove Selected Load Item.

Figure 135

STAAD.Pro 2004 – Software Release Report 131

To change the details of a pre-assigned load item, choose Edit Selected Load item. See the following figure for the steps.

Figure 136

Deflection check of a beam modelled as multiple segments Question : Several beams in my model have been defined with multiple intermediate nodes. So, a beam which is say, 45 feet long, is defined as three segments of 15 feet each. Please tell me what I should do to perform the deflection check for the 45 feet span, instead of the individual 15 ft spans. The allowable deflection is based on the length of the sum of the segments expressed in inches divided by 500. Answer : Let us look at the figure below which has 3 horizontal members. Together, they form a single beam that stretches from node 201 to 204. We call this single beam, a physical beam or a physical member.

The deflection check on this physical beam is achieved by doing two things : 1) The start and end nodes of the physical beam have to be conveyed to the program using the steel design parameters DJ1 and DJ2. DJ1 is assigned the node number 201, and DJ2 is set to node number 204. These two parameters are assigned to the 3 segments - 2001, 2002 and 2003. 2) The 3 segments are assigned the DFF parameter. This parameter stands for the permissible limit of length divided by maximum allowable deflection. If we do not want that limit to be less than 500, set DFF to be 500 for the 3 members.

The above two steps are represented using the following commands in the STAAD input file: PARAMETER CODE AISC TRACK 2 ALL DJ1 201 MEMB 2001 TO 2003 DJ2 204 MEMB 2001 TO 2003 DFF 500 MEMB 2001 TO 2003 CHECK CODE MEMB 2001 TO 2003

Q: I want to know how to use the View > View Management > Add to View option. I have a saved view to which I want to add some members.

Answer: To demonstrate this facility, let us open any example file, such as say, EXAMP01.std that is located in the following folder: X:\Spro2005\STAAD\EXAMP\US The model will appear on the screen as shown below.

We will do the following to demonstrate the Add to View feature. Step 1 � create a new view. Then, save that view. Step 2 � modify the saved view using the �Add to View� facility.

Step � 1 Let us create a new view displaying the truss members only. To do that, highlight those members. Then, right click and select the New View option.

The following dialog box will appear. The radio buttons determine whether the selected view would be opened in a new ("child") window or whether it would replace the current ("parent") view window. In the first case, the "parent" view window highlights the members in the "child" window, whenever the "child" window becomes active.

Let us go with the first option. So, select that and click on OK.

The highlighted portion of the model will be displayed in a new window.

Let us save this view by going to View > View Management > Save View.

The following dialog box will be displayed. Provide a name for the new view and click on OK. Let us also close the new view window.

Step - 2 Next, we want to add the top chords also to our saved view. First, go to View > Open View to open the previously saved view.

The following dialog box comes up. Select the view titled �a� and click on OK. (The radio buttons determine whether the selected view would be opened in a new window or whether it would replace the current view.)

Next, highlight the top chords.

Then, go to View > View Management > Add to View.

The following dialog box will be displayed. Confirm the view to be modified (in our example, we have created only one view � �a�), and click on OK.

Notice that the title of the newly modified view window says a*.

Once we are satisfied with the modifications, we have to save this view again. Make sure the New window is the one with the focus (title bar should be blue) and then, go to View > View Management > Save View. If the wrong window is in focus, the contents of that window will be the one which the view will be updated with.

In the dialog box that comes up, there are two ways to save the new view. We may provide a new name for the modified view and click on OK. When a new name is given, there will be two saved views � the original view showing the truss members only and the modified view showing the truss members along with the top chords.

The other option is to use the original title by selecting it from the dialog box. In that case, the following message box will appear. Choose �Yes� to overwrite the old view. This way, the original view will be modified to include the top chords as well.

If we wish to rename our saved view, first open the view by going to View > Open View. Next, go to View > View Management > Rename View. The following dialog box will appear where the view can be renamed.

1

Mesh Generation of a mat with openings

In this example, our goal is to create a plate element model of a mat foundation with a polygonal hole and a circular hole.

A (0,0,0) B (20,0,0)

D (24,0,18)E (0,0,18)

F (4,0,6)G (8,0,6)

H (8,0,10)Ι (4,0,10)

K (18,0,14)

Z

C (28,0,10)

X

Radius = 3 ft.

Our slab will be modeled with a series of finite elements. Such a series or matrix of coplanar finite elements is often referred to as a mesh, and the process of creating a series or matrix of elements is known as mesh generation. STAAD offers four alternative methods to do this.

• Structure Wizard method • Super-element method • Mesh Generator method • STAAD.Pro Input Editor method

In this example, we will be exploring the Mesh Generator method.

2

The number of divisions along each side of the slab will be as shown in the table below.

SIDE NUMBER OF DIVISIONS

AB 10

BC 4

CD 5

DE 12

EA 9

FG 2

GH 2

HI 2

IF 2

Circle 9 divisions around the circumference

3

To start STAAD.Pro, go to the Windows Start menu, select the Programs option, click on the STAAD.Pro program group, then click on the STAAD.Pro icon.

4

When STAAD.Pro starts up, the following screen is displayed.

If you recall, one of the choices made at the time of installing STAAD.Pro is this base unit system setting. That choice will serve as the default until we specifically change it. If you need to change the default units, the place from where we can do that is under the File | Configure menu. To get to that option, first close down the dialog box shown in the earlier figure by clicking on Cancel.

5

Then, click on the File | Configure menu option (see next figure).

In the ensuing dialog box, choose the appropriate units and click on Accept. For this tutorial, let us choose the English units (Kip, Feet, etc.). Next, pull down the File menu and select the New command. A dialog box with title New will open.

6

In this dialog box,

• Select a Space type project.

• Enter a project name in the File Name edit box provided for that purpose.

• Select Foot for Length Units and KiloPound for Force Units.

• Click the Next button. A dialog box with title Where do you want to go will be displayed.

• Toggle on the Add Plate check box, then click the Finish

button. The STAAD.Pro graphic environment now appears, and a grid will be displayed.

7

We are now in the Geometry-Plate page.

Even though we chose Add Plate on the previous screen, we really are not going to be drawing a plate on the grid. Our slab is 5-sided, and the grid allows us to draw either a 3 noded or a 4 noded element. Instead, we will create the corner nodes of our slab by keeping the ‘Ctrl’ key pressed and clicking on the appropriate grid intersection point. To enable us to correctly locate the slab corners, we need to set the grid dimensions accordingly.

8

In the Snap Node/Plate dialog box, change the plane to X-Z. Set the number of lines along X to 7 with a 4 ft spacing. This will allow us to see the X = 20, X = 28 and X = 24 ft lines. For the Z direction, we will have 9 lines at 2 ft spacing, thus giving us easy access to the Z = 10 and Z = 18 ft lines.

After activating the Snap Node/Plate button, hold down the ‘Ctrl’ key and click on the grid in the following 5 points. (It is very important to hold down the ‘Ctrl’ key. Keeping the ‘Ctrl’ key pressed and clicking at points on the grid successively is a way of creating new nodes without connecting those nodes with beams or plates. If the ‘Ctrl’ key weren’t kept pressed, the nodes would become connected.)

(0, 0, 0) (20, 0, 0) (28, 0 10) (24, 0, 18) and (0, 0, 18)

9

The purpose of these steps was to merely create the five nodes. Consequently, any of the several methods available in the program could have been used to create those nodes. We could have typed the data into the editor, or in the grid tables of the Geometry-Plate page control area, or even used the Snap Grid/Node – Beam option of the Geometry menu from the top of the screen to graphically create the points. After clicking on the points, close the Snap Node/Plate dialog box by clicking on the Close button at the bottom of that dialog box. The screen should now look as shown below.

10

If you are unable to see the points, right-click anywhere on your screen and select Labels. In the ensuing dialog box, toggle on the Node Points check box and click the OK button. You can also display the Node Points by pressing the K key while holding down the Shift key.

Next, select the Mesh Generation Cursor from the Geometry toolbar.

Another way to activate this same cursor is to pull down the Geometry menu and click on the Surface Mesh Generator command. Either way, the Mesh Generation Cursor will be activated.

11

We now have to select the points which form the boundary of the superelement from which the individual elements will be created. The five points we just created are those points. We will worry about the holes later. So, let us click at the five node points in succession as shown below. Click the cursor on the first node ((0, 0, 0). You can designate any node as your first node. Then, click on successive nodes around the perimeter of your slab. Remember to go in either clockwise or counterclockwise order. The order will have a bearing on the direction of the local axes of the elements, but that should not have any adverse impact on the analysis results. Close the loop by clicking at the start node (or the first clicked point) again.

When you click again on your starting node, the program understands that you have fully defined a closed figure designating the boundary of your mesh.

12

A dialog box labeled Define Mesh Region will be displayed.

The Boundary tab shows the corner nodes and associated XYZ coordinates of the superelement. It also shows the number of divisions, that is, the number of elements to be created along each side of the polygon. These numbers can be changed if desired. Let us set the Divisions for the boundaries of the polygon as shown in the figure below. Leave the Bias at 1. Bias is a factor using which we can specify the ratio of the length of the side of the last element to first element for the edge under consideration. A value of 1 means all elements along that edge will have equal lengths.

13

DO NOT CLICK ON THE OK BUTTON JUST YET. WE HAVE NOT YET ADDED THE OPENINGS. (If you do not want to add openings, you may click on OK in the above dialog box. The Define Mesh Region dialog box will be dismissed and the program will create a mesh and display the elements in the main view.)

But in our exercise, we do want to insert two openings within the slab.

14

To insert holes, first, click on the expression Holes to highlight it. You will see 2 new icons appear just above the tabs.

If you click on the icon called Add New Hole, additional tabs for each hole will appear as shown in the next figure. For this exercise, we are going to create 2 new holes. So, highlight HOLES and click on the Add New Hole icon. Repeat this until you have two new sub-tabs titled Hole 1 and Hole 2.

15

Feel free to rename the holes.

Next, click on the cell titled “Polygon”. A drop-down list will appear that lets you set the shape of the hole. Choose the Polygon shape for the first hole. For doing that, highlight Hole 1 and select Polygon from the drop-down list.

16

Next, highlight Hole 1, and specify the corner points of that hole as shown in the following figure. You may have to click on the Add New Row icon to add new rows and specify the various corners of the Hole. Notice that the coordinates shown in the first row and the last row are the same. This is because, while specifying the corner points of the polygon, we ought to close the loop by specifying the coordinates of the first point again. If you don’t, the program will remind us of the same with an error message.

DO NOT CLICK ON OK YET. WE NEED TO SPECIFY THE DETAILS FOR THE CIRCULAR HOLE.

17

After specifying the corners for the first hole, highlight the second tab – Hole 2. Click on the cell titled “Polygon”. In the drop-down list that comes up, choose the Circle shape for the second hole.

Here, let us specify the following parameters. Coordinates of the Origin – (18, 0, 14) Radius – 3ft Divisions Along Periphery - 9

18

Now that we have specified the boundaries of the Polygonal plate and the parameters for the two openings, all the data is complete. So, click on OK. The Define Mesh Region dialog box will be dismissed and the program will create a mesh with a polygonal and a circular opening and display the elements in the main view.

Hit the ‘Esc’ key to deactivate the Mesh Generation Cursor.

19

Notice that the plates are drawn in green color. You can change the color of the plates by going to View | Set Structure Colors menu option. In the ensuing dialog box, click on the Entities button. Another dialog box titled Define Colors will appear. Here, select Plate from the drop-down list against Select Structural Entity. Click on the color palette against Default Plate Color and choose a color.

Also, notice in the above dialog box a color button alongside Default Plate Back Color. It is set to black. If you go to View | Structure Diagrams and choose Fill Plates, our elements will appear in black.

20

It shows that the back of the elements is on the upper surface of the slab – a result of the order in which we went about selecting the nodes of our superelement. If you want to change this so that the back is at the under side of the slab, do the following. Turn off the Fill Plates option from View | Structure Diagrams menu. Switch on the Plates Cursor and select all the elements (by rubber-banding around them). Go to the Commands menu on the top of the screen and choose Geometric Constants – Plate Reference Point.

21

In the dialog box that comes up, set Y = 100 for the Reference Point and keep the button on Local Z Axis Towards Ref. Point. Then, click on OK.

Your screen will now look as shown below.

22

To confirm that the local Z axis points upwards, click the right mouse button in the drawing area and choose Labels. In the dialog box that comes up, switch on Plate Orientation.

staadpro knowledge base

Documents