Location

Saint Louis, Missouri

Session Start Date

10-20-1992

Abstract

The American Iron and Steel Institute's Specification for the Design of Cold-Formed Steel Structural Members (1) presently requires that channel and zee flexural members, when not attached to sheathing, be braced against twist and lateral translation at the quarter-points of the span (Section D3.2.2). This provision first appeared in the Second Edition of the Specification in 1956, and has been there through all succeeding editions up through the 1989 Addendum. The newest formula for lateral buckling (part (a) of C3.1.2) is a more exact procedure for calculating lateral torsional buckling of a doubly, singly, or point symmetrical section than was the earlier one (now part (b)). It is fair to ask, then, whether the requirement for quarter-point bracing is still needed. If a user wishes to space lateral braces at greater distances and accept a reduced bending capacity, why should quarter-point braces be mandated? Was the original reason for including this provision in the 1956 Specification more a serviceability consideration than strength? The purpose of this research was to find answers to these questions.

Department(s)

Civil, Architectural and Environmental Engineering

Research Center/Lab(s)

Wei-Wen Yu Center for Cold-Formed Steel Structures

Meeting Name

11th International Specialty Conference on Cold-Formed Steel Structures

Publisher

University of Missouri--Rolla

Publication Date

10-20-1992

Document Version

Final Version

Rights

© 1992 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Oct 20th, 12:00 AM

Flexural Capacity of Discretely Braced C's and Z's

Saint Louis, Missouri

The American Iron and Steel Institute's Specification for the Design of Cold-Formed Steel Structural Members (1) presently requires that channel and zee flexural members, when not attached to sheathing, be braced against twist and lateral translation at the quarter-points of the span (Section D3.2.2). This provision first appeared in the Second Edition of the Specification in 1956, and has been there through all succeeding editions up through the 1989 Addendum. The newest formula for lateral buckling (part (a) of C3.1.2) is a more exact procedure for calculating lateral torsional buckling of a doubly, singly, or point symmetrical section than was the earlier one (now part (b)). It is fair to ask, then, whether the requirement for quarter-point bracing is still needed. If a user wishes to space lateral braces at greater distances and accept a reduced bending capacity, why should quarter-point braces be mandated? Was the original reason for including this provision in the 1956 Specification more a serviceability consideration than strength? The purpose of this research was to find answers to these questions.