Session Start Date

11-7-2018

Session End Date

11-8-2018

Abstract

This paper presents a proposal for the codification of an efficient design approach, based on the Direct Strength Method (DSM), for cold-formed steel equal-leg angle columns with short-to-intermediate lengths, i.e., those buckling in flexural-torsional modes. Initially, the available experimental failure load data, comprising fixed-ended and pin-ended (“cylindrical hinges”) columns with several geometries (cross-section dimensions and lengths) and tested by various researchers, are collected and used to show that the currently codified DSM design provisions are not able to handle adequately short-to- intermediate angle columns and that a specific DSM-based design approach is needed to estimate the failure loads of such columns. Then, the paper presents a brief overview of the structural reasoning behind the DSM-based design approach proposed by Dinis & Camotim (2015, 2016). Next, the quality (accuracy and reliability) of the failure load estimates obtained with this design approach is assessed through the comparison with the above experimental failure load data and also a fairly large number of numerical failure loads. This merit assessment includes the determination of the LRFD resistance factors concerning the failure-to-predicted load ratios -- it is shown that the value recommended, for compression members, by the North American Specification (AISI 2016), Φc=0.85, can also be adopted for short-to-intermediate angle columns designed with this DSM-based approach. Finally, the paper presents and discusses a few numerical examples, which illustrate the application of the proposed design approach and provide evidence of its advantages and benefits, when compared with the currently codified one.

Department(s)

Civil, Architectural and Environmental Engineering

Meeting Name

Wei-Wen Yu International Specialty Conference on Cold-Formed Steel Structures 2018

Publisher

Missouri University of Science and Technology

Publication Date

11-7-2018

Document Version

Final Version

Rights

© 2018 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Proposal to Improve the DSM Design of Cold-Formed Steel Angle Columns: Need, Background, Quality Assessment and Illustration

This paper presents a proposal for the codification of an efficient design approach, based on the Direct Strength Method (DSM), for cold-formed steel equal-leg angle columns with short-to-intermediate lengths, i.e., those buckling in flexural-torsional modes. Initially, the available experimental failure load data, comprising fixed-ended and pin-ended (“cylindrical hinges”) columns with several geometries (cross-section dimensions and lengths) and tested by various researchers, are collected and used to show that the currently codified DSM design provisions are not able to handle adequately short-to- intermediate angle columns and that a specific DSM-based design approach is needed to estimate the failure loads of such columns. Then, the paper presents a brief overview of the structural reasoning behind the DSM-based design approach proposed by Dinis & Camotim (2015, 2016). Next, the quality (accuracy and reliability) of the failure load estimates obtained with this design approach is assessed through the comparison with the above experimental failure load data and also a fairly large number of numerical failure loads. This merit assessment includes the determination of the LRFD resistance factors concerning the failure-to-predicted load ratios -- it is shown that the value recommended, for compression members, by the North American Specification (AISI 2016), Φc=0.85, can also be adopted for short-to-intermediate angle columns designed with this DSM-based approach. Finally, the paper presents and discusses a few numerical examples, which illustrate the application of the proposed design approach and provide evidence of its advantages and benefits, when compared with the currently codified one.