Session Dates
09 Nov 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
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
Recommended Citation
Rendall, Morgan A.; Hancock, Gregory J.; and Rasmussen, Kim J. R., "Identifying Shear Buckling Coefficients for Channels with Rectangular Web Stiffeners using the Generalised cFSM" (2016). CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018). 3.
https://scholarsmine.mst.edu/isccss/23iccfss/session4/3
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.
