tutorial - flat slab
Post on 24-Nov-2014
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Tutorial 1. Flat Slab
ContentsSummary Working Environment Setting Enter Material and Section Properties Import a CAD DXF File Define Elastic Support Conditions Enter Column Support Conditions Generate Area Objects Assign Members Enter Wall Support Conditions Enter Punching Check Sizes Enter Loading Data Set Static Load Cases Enter Floor Loads Perform Structural Analysis Verify and Review Analysis Results Load Combinations Verify Reactions Check Reaction Table Verify Deformations Verify Member Forces Check Mesh Line Output Design Enter Design Parameters Shear Check Result Design Floor Slab 1 3 4 8 9 13 14 17 21 22 23 23 24 28 30 30 31 32 33 34 37 39 39 40 42
Tutorial 1. Flat SlabMIDAS/SDS Version 3.1.0
SummaryIn this example, we will construct a Flat Slab model and perform analysis and design. We will generate a Flat Slab model by importing a DXF file.
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Set a unit system. Enter material and section properties. Import a CAD DXF file. Define support type. Generate area objects. Assign members. Enter elastic support conditions. Enter static loads. Check and review analysis results. Design
Analysis ModelUnit: mm
Model DescriptionAnalysis Model Story Height Support Condition Slab Size Flat Slab for office use 4.0 m (both above and below the slab) Column Support, Wall Support 56.4 m20 m
Structural MaterialsConcrete Reinforcing Bar ASTM, Grade C4000 Grade 60
Section Data() Slab Drop Panel Column Core Wall Thickness = 200 Thickness = 350 700700 (rectangular shape) Thickness = 200
Applied Load1) Floor Load (kN/) Use Office Corridor Dead Load Finish 1.00 1.00 Slab 4.70 4.70 Total 5.70 5.70 Live Load 2.40 3.93
Building Code Requirements for Structural Concrete and Commentary (ACI318-02, 2002)
Working Environment SettingUnit SystemDouble click the MIDAS/SDS icon system. to execute SDS.exe. Open a new file and set a unit
1. New 2. Save> Select a folder.> File Name> Flat Slab 3. 4. Main Menu> Tools> Unit System 5. Length> mm ; Force (Mass)> kN 6.
Unit System Assignment
Enter Material and Section PropertiesBefore generating a model, enter the material properties of the elements, which will be used as structural members. 1. 2. 3. 4. 5. 6. 7. 8. Main Menu> Model> Properties> Material Name> Slab Type> Concrete Concrete>Standard> ASTM(RC) DB> Grade C4000 Apply Confirm the generated material data. Assign the material data for Drop Panel and Wall similarly (Refer to Figure 3).
Enter material properties
Enter the section dimensions of a wall beam, which is an equivalent beam substituted for a core wall.
1. 2. 3. 4. 5. 6. 7.
Properties> Section Name> Wall Solid Rectangle> User (on) H> 8000 ; B> 200 Check the auto-calculated stiffness data at the bottom of the dialog box (Refer to Figure 4-).
Enter section properties 5
Enter the thickness data of the floor slab.
1. 2. 3. 4. 5. 6.
Properties> Thickness ID> 1 Name> Slab Thickness> In-plane & Out-of-plane> 200
Enter slab thickness data
Enter the thickness data of the drop panel.
1. ID> 2 2. Name> Drop 3. Thickness> In-plane & Out-of-plane> 350 4. 5.
Enter drop panel thickness data
Import a CAD DXF FileTo generate a Flat Slab, import a DXF file, which will be the basis for generating slabs, drop panels and core walls.
1. Main Menu> File> Import> AutoCAD DXF File 2. > Flat Slab.dxf 3. Option> Insertion Position> 0, 0 ; Rotate Angle> 0 4.
CAD DXF File Import
Define Elastic Support ConditionsDefine boundary conditions. MIDAS/SDS automatically calculates the elastic support stiffness of columns or walls supporting a floor slab by using the main dimensions such as section sizes, story heights, etc and the material properties such as modulus of elasticity. First, we define the elastic support stiffness of column supports, which will be assigned by using the Column Supports.
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Main Menu> Model> Boundaries> Column Support Type Name> C Support Type> Solid Rectangle Mesh and Link at Column Boundary (on) Material> Standard> ASTM(RC) ; DB> Grade C4000 Material> Modulus of Elasticity> 25.1255 ; Poissons Ratio> 0.2 Thickness> Above> Depth(D)> 700 ; Width(B)> 700 ; Height(H)> 4000 Bending Stiffness Scale Factor> 4.0 > Check the auto-calculated stiffness data.
TipThe program will automatically calculate the rotational stiffness of column support based on the Bending Stiffness Scale Factor entered here. The boundary conditions of the model used for the determination of the bending stiffness factor for the columns, , are shown below.
AE, I H
Let the columns above and below have the same story height, H, modulus of elasticity, E and moment of inertia, I. Then the rotational stiffness of column support equals 2 Where, E: Modulus of elasticity of the columns I: Moment of inertia of the columns H: Story height of the columns : Bending stiffness factor for the columns Rotational stiffness of column support at A is found to be is taken as 4.
EI . H
8EI . Therefore, H
Define Column Support Types
Define Wall Support Types for the core walls. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. Supports > Wall Name> Wall Support Type> Thickness Material> Standard> ASTM(RC) ; DB> Grade C4000 Material> Modulus of Elasticity> 25.1255 ; Poissons Ratio> 0.2 Thickness> Above> Thickness(T)> 200 ; Height(H)> 4000 Bending Stiffness Scale Factor> 4.0 > Check the auto-calculated stiffness data.
Define a Wall Support Type
Enter Column Support ConditionsAssign column support conditions.
1. Point Object Snap (on), Line Object Snap (on) 2. Main Menu> Model> Boundaries> Column Supports 3. Column Support Type> C 4. Select Single> Select the point objects to enter column supports. 5. 6.
Assign column supports
Generate Area ObjectsCreate area objects at the locations of slab, drop panels and openings by referring to Figure 1 (plan). First generate three area objects for slab. The slab needs to be divided into three area objects in order to enter different area loads for different floor uses.
1. Main Menu> Model> Objects> Create 2. Object Type> Area 3. Rectangle> Pick the upper left corner and the lower right corner of the bright green rectangle (See Figure 11- 1 ). 4. Polygon> Pick each corner of the red polygon (See Figure 11- 2 ). 5. Polygon> Pick each corner of the turquoise polygon (See Figure 11- 3 ).
2 3 Corridor Office
Create area objects for slab
Based on the DXF underdrawing, generate area objects at the locations of drop panels.
6. Main Menu> Model> Objects> Create 7. Object Type> Area 8. Rectangle> Pick the upper left and lower right corners of each drop panel (See Figure 12).
Create area objects for drop panels
Generate area objects at the locations of openings by referring to the DXF underdrawing.
9. Object Type> Area 10. Rectangle> Create area objects at the opening locations (Openings are shown enclosed by blue lines in Figure 13).
Create area objects for openings
Assign MembersAssign wall beams to the line objects corresponding to the core walls.
1. 2. 3. 4. 5. 6. 7. 8.
Main Menu> Model> Member> Beam Zoom Window> Magnify the core at the lower left (Figure 14- 1 ). Select Single> Select the line objects corresponding to the core walls. Type> Wall Beam Material Name> 2:Wall Section Name> 1:Wall
Zoom Fit> Zoom Window> Magnify the core at the upper right (Figure 142 ). 9. In a similar manner, assign the Wall Beams.
Assign Wall Beam Members 17
Assign Slab Members.
1. Zoom Fit 2. Member> Slab (Refer to Figure 15-). 3. Select Single> Select three area objects corresponding to the slab (Refer to Figure 11- 1 , 2 and 3 ). 4. Option> Add/Replace 5. Type> Slab 6. Material> 1: Slab 7. Thickness> 1: Slab 8.
Assign Slab Members
Assign Drop Panel members.
9. Member> Slab 10. Select Single> Select area objects corresponding to the drop panels (Refer to Figure 16). 11. Option> Add/Replace 12. Type> Drop Panel 13. Material> 2: Drop 14. Thickness> 2: Drop 15.
Assign Drop Panel Members
Assign Opening Members to the openings.
16. Member> Opening (Refer to Figure 17-). 17. Select Single> Select area objects corresponding to the openings (Refer to Figure 17). 18. Option> Add/Replace 19. 20.
Assign Opening Members
Enter Wall Support ConditionsWe have already assigned column supports. Assigning wall supports corresponding to the core walls is now remaining. Assign the previously defined Wall Support Type to the core wall locations by Drag & Drop.
1. Works Tree> Section> 1:Wall> Line objects