TY - JOUR
T1 - Design of cold-formed steel built-up columns subjected to local-global interactive buckling using direct strength method
AU - Selvaraj, Sivaganesh
AU - Madhavan, Mahendrakumar
N1 - Funding Information:
The investigation reported in this paper was funded by the Science Engineering and Research Board (SERB) Research Grant ( SB/S3/CEE/046/2014 ) from the Department of Science and Technology (DST) , Government of India. The first author would like to acknowledge the financial assistance received from this project. The authors would like to gratefully acknowledge Pennar Engineered Building Systems Ltd., Hyderabad for their help in fabricating the required test specimens.
Funding Information:
The investigation reported in this paper was funded by the Science Engineering and Research Board (SERB) Research Grant (SB/S3/CEE/046/2014) from the Department of Science and Technology (DST), Government of India. The first author would like to acknowledge the financial assistance received from this project. The authors would like to gratefully acknowledge Pennar Engineered Building Systems Ltd. Hyderabad for their help in fabricating the required test specimens.
Publisher Copyright:
© 2020 Elsevier Ltd
PY - 2021/2
Y1 - 2021/2
N2 - This paper presents the structural behavior of doubly-symmetric built-up cold-formed steel (CFS) columns that fail in local-global (flexural-torsional) interactive buckling modes. The built-up column investigated in this study is formed (back-to-back) by connecting two identical unlipped channel sections with the use of self-drilling screws. A total of 45 column tests were carried out, with various parameters such as slenderness of the section, length and intermediate spacing between self-drilling screws. The test results indicate that the axial ultimate strengths of the built-up columns are governed by buckling of the individual channel section and an unstiffened flange element due to higher local buckling stress (λl > 1.5) resulting in an interactive buckling. The test results also indicate that the effect of intermediate spacing depends on the failure mode of the CFS built-up cross-sections. The various options available to predict the elastic critical buckling stress for global flexural buckling and design strength is presented. The design strengths predicted by the current direct strength method (DSM) is unconservative when compared with the axial compressive strength of the CFS built-up column with local-global interactive buckling. Therefore, suggestions to prevent the incorrect application of the DSM method are elucidated.
AB - This paper presents the structural behavior of doubly-symmetric built-up cold-formed steel (CFS) columns that fail in local-global (flexural-torsional) interactive buckling modes. The built-up column investigated in this study is formed (back-to-back) by connecting two identical unlipped channel sections with the use of self-drilling screws. A total of 45 column tests were carried out, with various parameters such as slenderness of the section, length and intermediate spacing between self-drilling screws. The test results indicate that the axial ultimate strengths of the built-up columns are governed by buckling of the individual channel section and an unstiffened flange element due to higher local buckling stress (λl > 1.5) resulting in an interactive buckling. The test results also indicate that the effect of intermediate spacing depends on the failure mode of the CFS built-up cross-sections. The various options available to predict the elastic critical buckling stress for global flexural buckling and design strength is presented. The design strengths predicted by the current direct strength method (DSM) is unconservative when compared with the axial compressive strength of the CFS built-up column with local-global interactive buckling. Therefore, suggestions to prevent the incorrect application of the DSM method are elucidated.
KW - Cold-formed steel built-up columns
KW - Direct strength method
KW - Doubly-symmetric back-to-back connected cross-section
KW - Flexural torsional buckling
KW - Interactive buckling
UR - http://www.scopus.com/inward/record.url?scp=85098872933&partnerID=8YFLogxK
U2 - 10.1016/j.tws.2020.107305
DO - 10.1016/j.tws.2020.107305
M3 - Journal article
AN - SCOPUS:85098872933
SN - 0263-8231
VL - 159
JO - Thin-Walled Structures
JF - Thin-Walled Structures
M1 - 107305
ER -