MBMAAISC Design Guide Frame Design Using WebTapered Members

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MBMAAISC Design Guide Frame Design Using WebTapered Members

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... Guide. Frame Design Using Web-Tapered Members. Richard Kaehler, P.E. ... Presented in detail in Timoshenko and Gere - Theory of Elastic Stability, Section 2.15 ... – PowerPoint PPT presentation

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Title: MBMAAISC Design Guide Frame Design Using WebTapered Members

1
MBMA/AISC Design Guide Frame Design Using
Web-Tapered Members

Richard Kaehler, P.E.
Computerized Structural Design, S.C.

2
Steel Design Guide Series Frame Design
Using Web-Tapered Members RICHARD C.
KAEHLER Computerized Structural Design,
S.C. Milwaukee, Wisconsin DONALD W.
WHITE Georgia Institute of Technology Atlanta,
Georgia YOON DUK KIM Georgia Institute of
Technology Atlanta, Georgia METAL BUILDING
MANUFACTURERS ASSOCIATION AMERICAN INSTITUTE
OF STEEL CONSTRUCTION, INC.
3
Document Goals

Present a methodology for the design of frames
with web-tapered members
Practical
Rational
Comprehensive
Programmable
In accordance with 2005 AISC Specification

4
Document Emphasis

Necessary but Minimal Theoretical Background
Design Procedures
Example Problems
Practical Advice
Extensive References to Other Work

5
Table of Contents

1. Introduction
2. Web Tapered Member Behavior
3. Design Basis
4. Stability Analysis-and-Design Requirements
5. Member Design
6. Frame Design
7. Annotated Bibliography
Appendices

6
1. Introduction

Scope and Applicability
Basis for Recommendations
Limitations
Benefits of Web-Tapered Members
Fabrication of Web-Tapered Members

7
2. Web-Tapered Member Behavior

Previous Research
Overview of tapered member research
Relationship to Prior Provisions
Overview of major differences with 1989 and
earlier ASD Specs

8
3. Design Basis

New AISC Terminology
Required Strength
Nominal Strength
Available Strength
Allowable Strength
Design Strength
Limit State Design

9
4. Stability Analysis-and-Design Requirements

Key Terminology
P-D P-d
ASCE7-IBC Seismic Stability Requirements
2005 AISC Stability Requirements
2005 AISC Analysis-and-Design Methods
Common Analysis Parameters
aPr PeL or geLPr
Requirements for 2005 AISC Methods

10
5. Member Design

Key Terminology
ge
Axial Tension
Axial Compression
Flexure
Combined Flexure and Axial Force
Shear
Flanges and Webs with Concentrated Forces

11
6. Frame Design

First-Order Analysis of Frames
Second-Order Analysis of Frames
Analysis of Gabled Frames
Serviceability Considerations

12
7. Annotated BibliographyReferences
13
Appendices

A. Calculating ?eL or PeL for Tapered Members
For both DM and ELM
B. Calculating In-Plane ?e Factors for the ELM
C. Benchmark Problems
First-Order Accuracy
Second-Order Accuracy
In-Plane Flexural Buckling Accuracy

14
Beam Design

LTB Strength
One LTB Strength Ratio Calculated per Unbraced
Length
Cb based on Flexural Stress, not Moment
AASHTO Cb
Calculate Critical Stress, FeLTB, using Midspan
Properties
Find Controlling Ratio of Mr/Mn

15
Column Design

In-Plane Strength
One In-Plane Strength Ratio Calculated per Member
For DM, Calculated from PeL
For ELM, Calculated from Pcr
Find Controlling Ratio of Pr/Pn

16
How do I Calculate K?

You Dont - Use alternate expressions for Fe

17
Method of Successive Approximations

Practical method to determine elastic in-plane
buckling load (or multiplier) of tapered column
with any loading pattern
Presented in detail in Timoshenko and Gere -
Theory of Elastic Stability, Section 2.15
Adaptable to Spreadsheet and/or Procedural
Programming

18
Column Design