Session Start Date

11-9-2016

Session End Date

11-9-2016

Abstract

The Direct Strength Method (DSM) of design for cold-formed sections was recently extended in the North American Specification for Cold-Formed Steel Structural Members (NAS S100:2012) to include members in shear. The method has largely been developed on the basis of work done on lipped channel sections. To utilise the method requires the critical shear buckling load of the section, which may be determined from a minimum point on the signature curve for the section in pure shear. However when longitudinal web stiffeners are added to the channel a minimum may not exist, or may occur at half-wavelengths where the critical buckling mode is localised in the individual vertical portions of the web rather than involving the full web as an essentially continuous element, as occurs for a plain lipped channel in local shear buckling.

This paper explores the application of the recently-developed generalised constrained finite strip method (cFSM) to determine critical shear buckling loads for lipped channels with rectangular web stiffeners, from which shear buckling coefficients may be back-calculated. The addition of the stiffener leads to new distortional modes, deemed web-distortional modes, that play an important role in the buckling behaviour of web-stiffened channels at half-wavelengths where buckling involves deformations of the web as a continuous element. Using the cFSM, combinations of pure local modes and the web-distortional modes are considered to produce modal solutions. These modal solutions always give a minimum regardless of section and these minima are used to identify critical buckling half-wavelengths. The critical shear buckling loads are then taken as those at the same half-wavelengths on the corresponding traditional FSM signature curves for the sections. The proposed method is appropriate for sections with small stiffeners, as are used in practice.

Department(s)

Civil, Architectural and Environmental Engineering

Research Center/Lab(s)

Wei-Wen Yu Center for Cold-Formed Steel Structures

Meeting Name

International Specialty Conference on Cold-Formed Steel Structures 2016

Publisher

Missouri University of Science and Technology

Publication Date

11-9-2016

Document Version

Final Version

Rights

© 2016 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

Available for download on Thursday, November 01, 2018

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Identifying Shear Buckling Coefficients for Channels with Rectangular Web Stiffeners using the Generalised cFSM

The Direct Strength Method (DSM) of design for cold-formed sections was recently extended in the North American Specification for Cold-Formed Steel Structural Members (NAS S100:2012) to include members in shear. The method has largely been developed on the basis of work done on lipped channel sections. To utilise the method requires the critical shear buckling load of the section, which may be determined from a minimum point on the signature curve for the section in pure shear. However when longitudinal web stiffeners are added to the channel a minimum may not exist, or may occur at half-wavelengths where the critical buckling mode is localised in the individual vertical portions of the web rather than involving the full web as an essentially continuous element, as occurs for a plain lipped channel in local shear buckling.

This paper explores the application of the recently-developed generalised constrained finite strip method (cFSM) to determine critical shear buckling loads for lipped channels with rectangular web stiffeners, from which shear buckling coefficients may be back-calculated. The addition of the stiffener leads to new distortional modes, deemed web-distortional modes, that play an important role in the buckling behaviour of web-stiffened channels at half-wavelengths where buckling involves deformations of the web as a continuous element. Using the cFSM, combinations of pure local modes and the web-distortional modes are considered to produce modal solutions. These modal solutions always give a minimum regardless of section and these minima are used to identify critical buckling half-wavelengths. The critical shear buckling loads are then taken as those at the same half-wavelengths on the corresponding traditional FSM signature curves for the sections. The proposed method is appropriate for sections with small stiffeners, as are used in practice.