ibc software
DESCRIPTION
IBC 2000TRANSCRIPT
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LATERAL FORCE DESIGN
SOFTWARE FOR WIND AND SEISMIC LOADS PER IBC 2003 AND ASCE 7-02
by
Xin Wang
A Thesis Presented to the FACULTY OF THE SCHOOL OF ARCHITECTURE
UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the
Requirements for the Degree MASTER OF BUILDING SCIENCE
May 2004
Copyright 2004 Xin Wang
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CHAPTER 5
SOFTWARE DESIGN FOR WIND AND SEISMIC LOADS
5.1. Scope of the Software
Since building codes have evolved from simple to very complex, computers
are broadly used by designers in practice. Quite a few software packages have been
developed to help structural engineers design for wind and seismic forces.
Code Search Excel Spreadsheet (Fig. 5.1) was developed by Struware. This
software can calculate lateral loads based on several building codes including IBC
(2000 or 2003) and ASCE 7 (1998 or 2002). It utilizes Excel spreadsheet and the
information for generating lateral loads can be input or selected. Another software,
Wind Load on Structures 2002, was designed by Standards Design Group. It can
generate wind loads based on ASCE 7-98 or ASCE 7-02.
More applications can be found for determining wind and seismic loads based
on building codes. They are designed for structural engineers and require that users
be familiar with building codes. Because building code theory is not consistently
taught in architectural schools, they are not easy to use for students of architecture.
This thesis presents a software, LATERAL FORCE DESIGN (LFD), designed
to teach students of architecture building code theory of determining wind and
seismic loads. The software is based on IBC 2003 and ASCE 7-02. While teaching
the main concepts and procedures of determining wind and seismic loads, the
software can compute: wind base shear, distribution per level of wind pressure,
force, shear and overturning moment on main wind-force resisting systems of
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enclosed and partially enclosed rigid buildings of all heights, seismic base shear,
distribution per level of seismic force, shear and overturning moment.
Fig. 5.1 A screenshot of input module of Code Search Excel Spreadsheet developed by Struware (no date)
There are two main goals in the design software. First, the application is a
teaching tool. It should lead users through the whole application and provide brief
and clear descriptions for all the input, output and intermediate entities.
Wherever possible, images shall be used to convey the idea in visual format. One
picture is worth a thousand words.
The application is also a computing tool. It should allow users to input
relevant parameters in determining wind and seismic forces for common structures,
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and then give the output in an easy-to-understand way. The application is not meant
to have industrial strength but more for teaching purpose, thus it should streamline
some complex formula and conditions into simple ways for users to understand
computing procedures.
5.2. Software Structure
Window-based C# is chosen as the computer programming language. Because
the design software is quite complex by considering its scope, divide and conquer
strategy is used in designing the whole application. In computer terms, it is called
object oriented programming paradigm. Basically what it does is to separate the
functionalities of an application into small parts, each part can do a particular job
well, then connect them together whenever it is needed. In this way, most parts can
be reused in different other parts of the system.
The software can run in Windows. It consists of 4 components, help, input,
computation and output. Fig. 5.2 shows the software structure and flow sequence.
The design of help is to demonstrate the software as a teaching tool. It
includes tutorial and input instructions. Tutorial gives users the information
including the scope of the software, the instructions how to use the software, and
building code theory used in the software. Tutorial can be entered at the beginning
of the software or from Tutorial menu in the software design screen. It can run
independently from the main application.
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Input is to collect information to generate wind or seismic loads. It is
divided into 4 parts including building information, dimension, wind-related
information, and seismic-related information.
LFD - Introduction
LFD - Main screen
LFD - Tutorial
LFD Input Output
Building info
Dimension
Wind info
Occupancy category
LFRS
Number of levels
Exposure category
Fundamental period
Wind speed
Seismic info
S1, Ss
Site Class
R value
Wind outputSeismic output
Wind pressure
Wind force
Wind shear
Wind overturn moment
Seismic overturn moment
Seismic force
Seismic shear
Exit LFD
Note: Red arrows show LFD flow sequence.
Fig. 5.2 Software structure and flow sequence
Each part of input is represented with a tab page. On each tab, the input is
given step by step. The input is on the left, and its explanations are in the textbox to
the right. After finishing input, the user can proceed by clicking next button or go
back by clicking back button whenever any change needs to be made.
The tab of Building Info (Fig. 5.3) is collecting the building information for
generating wind or seismic loads. There are 3 entries in the order of occupancy
category, lateral-force resisting systems and the number of levels.
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The tab of Dimension (Fig. 5.4) is also to collect the building information. It
allows users to draw diaphragm geometry, input height and dead load at each level.
The input instructions are provided for each entry. The building summary gives the
user a report of all the entries so far and let the users check the correctness of the
input information.
Fig. 5.3 A sample of Building Info input
The tab of Wind Info (Fig. 5.5) includes the information only for generating
wind loads. There are 3 entries including rigidity, wind speed and exposure
category. The tab of Seismic Info (Fig. 5.6) is used to generate seismic loads only.
There are 3 entries including S1 and SS, site class and response modification
coefficient R.
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Input flexibility is provided to the user. Input menu lists all the entries
associated with each tab. In this way, the user can easily access one particular entry.
It is designed for advanced users or saved projects when some changes are needed.
Fig. 5.4 A sample of Dimension input
Fig. 5.5 A sample of Wind Info input
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Input is in the layer of User Interface (UI). All the UI related functionalities of
LFD are implemented in Windows Forms, the standard Windows application
interface. The images or text in color are used to make the UI more interactive and
clear to the user. Default values are given and also warnings when input is out of the
range of the application capacity.
Fig. 5.6 A sample of Seismic Info input
The users input through the UI layer, then the values for each entry are
recorded in the application. The computing logic is based on the theory in Chapter 3
and 4. The flow of data follows input -> process (either wind or seismic processing)
-> output paths.
The output of wind or seismic loads is displayed on separate tabs. The
computation is executed by clicking computation button on each tab. The wind
loads on each orthogonal direction are listed in the separate Table (Fig. 5.7).
Because the seismic loads at each orthogonal direction are equal, they are listed in
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one Table. Wind and seismic loads can be display graphically by right clicking in
the Output Table to select the output values.
Fig. 5.7 A sample of Wind Output
If shear wall systems are selected as lateral-force resisting systems, overall
length per level of shear walls can be displayed by clicking shear wall generation
button on the tab of wind or seismic output. The values of shear wall length at each
level are listed in the output Table (Fig. 5.8). If the user does not specify the
allowable shear stress, default values will be used for the computation.
The computing theory of determining wind and seismic loads can be accessed
by clicking each data in the output Tables. If the data is clicked, a new form appears
to provide the information such as the formula, factors in the formula and their
explanations. The question marks are used to explain some factors when more
computations are involved.
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The software has the menus including file, input, tutorial, print and help. File
menu includes the common functions for managing the file, such as new, open, save,
save as, and exit. Input menu provides the entries associated with each input tab.
Tutorial menu allows the user to access Tutorial while the design screen is in use.
This software can not send data to the printer. Print menu suggests the user to use
print screen button on the keyboard, then paste the screen into another application
such as Microsoft Word or Adobe Photoshop to print. Help menu includes about and
flow chart. Flow chart provides the software flow sequence that helps the user
navigate in the software.
Fig.5.8 A sample of shear wall output form
5.3. Sample Structures
This section includes the general procedure of using this software, sample
structures and their brief explanations.
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Since the software is implemented in C#, which is one programming language
in the Microsoft .Net Framework programming language family. To run .Net
applications, .Net framework is required. The framework is installed on Windows
XP by default. To run in other operating systems such as Windows 2000, it is
required to install the .Net framework first. The .Net framework can be downloaded
from www.microsoft.com for free.
The software, LATERAL FORCE DESIGN, does not need complicated
installation. To run it, just copy and paste the whole folder to a location on the hard
disk, then double click the executable in Windows Explorer.
The first page (Fig. 5.9) of the application appears including the software title,
general scope of the software, the information of the author, the advisors and school.
The user can click continue button to go to the next page.
The next screen (Fig 5.10) displays the scope of the software, computing
theory and the selections to read Tutorial or start to use the software.
If the user clicks Tutorial, the main menu of Tutorial provides several
selections for the user to proceed. The user can click each selection to read through
the whole content by clicking back or next button or clicking main menu button to go
back to the main menu of Tutorial. The user can click exit button to exit Tutorial.
Its sample structures are listed from Fig. 5.11 to Fig. 5.13.
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Fig. 5.9 A sample of the software open page
Fig. 5.10 A sample of the software introduction page
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Fig. 5.11 A sample of the tutorial main menu
Fig. 5.12 A sample of the software scope in the tutorial
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Fig. 5.13 A sample of how to use the tutorial in the tutorial
If the user clicks design button, the main screen of the application appears. On
each tab, the step-by-step input is provided to the left and its instruction is to the
right. The sample structures of the input tabs are listed below.
Fig. 5.14 A sample of the first input in Building Info tab
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Fig. 5.15 A sample of the second input in Building Info tab
Fig. 5.16 A sample of the third input in Building Info tab
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Fig. 5.17 A sample of an input in Wind Info tab
Fig. 5.18 A sample of an input in Seismic Info tab
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After the user inputs all the information for generating wind or seismic loads,
the user can click wind or seismic output tab, then click computation button on each
tab. Its sample structures are listed from Fig. 5.19 to Fig. 5.22.
Fig. 5.19 A sample of wind output
Fig. 5.20 A sample of graphic wind overturn moment
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Fig. 5.21 A sample of seismic output
Fig. 5.22 A sample of a pop-up form by clicking the data in the seismic output Table
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BIBLIOGRAPHY
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