A Beginner's Guide to the Steel Construction Manual, 14th ed.

Chapter 8 - Bending Members

2006, 2007, 2008, 2011 T. Bartlett Quimby

Introduction


Flexure


Shear


Deflection


Misc. Limit States


Beam Design

Chapter Summary

Example Problems

Homework Problems

References


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Section 8.2.2

Determining Applicable Flexural Limit States

Last Revised: 07/30/2011

The selection of the appropriate limit states, in the appropriate form, can be a bit confusing since the 13th edition of the SCM.  To help the process, Table User Note F1.1 has been provided (see SCM page 16.1-45).  This table, however, does not preclude reading of the criteria statements at the beginning of each section of chapter F.  It has been found that beginning students are often times confused when selecting the appropriate SCM criteria. To aid the beginning student, additional tables are provided here as another view of the selection for I shaped members.

The choice of Chapter F section depends on the shape of the section and the slenderness of the cross sectional plate elements.  While the sections address many of the same limit states, they do so slightly different in each case.  The following tables may help to select the correct limit states in the correct sections.

Table 8.2.2.1
Limit States and Applicable Chapter F Sections
For Doubly Symmetric I-Shapes (W, M, S, HP and built-up Sections)
Bent About Their Major Axis

Flange Web Limit State
Y CFY LTB FLB TFY
Compact Compact F2.1 ---- F2.2 ---- ----
Compact Non-Compact ---- F4.1 F4.2 F4.3a F4.4
Compact Slender ---- F5.1 F5.2 F5.3a F5.4
Non-Compact Compact ---- ---- F3.1 F3.2a ----
Non-Compact Non-Compact ---- F4.1 F4.2 F4.3b F4.4
Non-Compact Slender ---- F5.1 F5.2 F5.3b F5.4
Slender Compact ---- ---- F3.1 F3.2b ----
Slender Non-Compact ---- F4.1 F4.2 F4.3c F4.4
Slender Slender ---- F5.1 F5.2 F5.3c F5.4

Table 8.2.2.2
Limit States and Applicable Chapter F Sections
For Singly Symmetric I-Shapes with Web Attached at Mid Flange
Bent About Their Major Axis

Flange Web Limit State
CFY LTB FLB TFY
Compact Compact F4.1 F4.2 F4.3a F4.4
Compact Non-Compact F4.1 F4.2 F4.3a F4.4
Compact Slender F5.1 F5.2 F5.3a F5.4
Non-Compact Compact F4.1 F4.2 F4.3b F4.4
Non-Compact Non-Compact F4.1 F4.2 F4.3b F4.4
Non-Compact Slender F5.1 F5.2 F5.3b F5.4
Slender Compact F4.1 F4.2 F4.3c F4.4
Slender Non-Compact F4.1 F4.2 F4.3c F4.4
Slender Slender F5.1 F5.2 F5.3c F5.4

Table 8.2.2.3
Limit States and Applicable Chapter F Sections
For Channels Bent About Their Major Axis

Flange Web Limit State
Y LTB
Compact Compact F2.1 F2.2
Compact Non-Compact SCM Chapter F makes no provisions for these conditions.  There is some vague reference in F12 to using principles of mechanics to determine the critical stresses.   The goal is to keep the actual stress below the critical stresses determined by principles of mechanics.
Compact Slender
Non-Compact Compact
Non-Compact Non-Compact
Non-Compact Slender
Slender Compact
Slender Non-Compact
Slender Slender

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