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Global buckling strength of discretely fastened back-to-back built-up cold-formed steel columns
Abstract This study proposes a design equation for built-up cold-formed steel (CFS) columns to eliminate the inconsistencies present in Section I1.2 of AISI S100 specification. The proposed equation was developed by using the results from the authors' compound spline finite strip-based numerical framework and 228 experimental and numerical results from literature on built-up CFS columns, failing by minor axis buckling. Investigations were conducted using numerical models with mode-specific deformations incorporated in compound spline finite strip framework. The shear slip behaviour between the individual columns, characterised by (i) fastener spacing and (ii) slenderness ratio of fully-composite cross-section, was investigated using parametric variations. The study shows that the modified slenderness ratio (MSR) in Section I1.2 of AISI S100 yields conservative strength predictions with increased fastener spacing. This is possibly because the MSR considers the effect of fastener spacing and overall slenderness ratio as disjoint and treat them as additive components. In reality, they interact, and hence a compound slenderness ratio (CSR) is proposed with a term that captures the interaction of these two entities. The prediction of strength by the proposed CSR and direct strength method (DSM) is in good agreement with the results of experimental and numerical studies, with the mean close to one. When incorporated in the DSM design equations, the proposed CSR yields matching reliability with AISI S100.
Graphical abstract Display Omitted
Highlights Investigated the global buckling behaviour and design of back-to-back connected built-up columns. Used the buckling stress results of mode specific model in compound spline finite strip method as the basis. 228 experimental and numerical results from literature were investigated and used. Highlighted the shortcomings of modified slenderness ratio for high fastener spacings. Proposed a compound slenderness ratio for improved strength predictions.
Global buckling strength of discretely fastened back-to-back built-up cold-formed steel columns
Abstract This study proposes a design equation for built-up cold-formed steel (CFS) columns to eliminate the inconsistencies present in Section I1.2 of AISI S100 specification. The proposed equation was developed by using the results from the authors' compound spline finite strip-based numerical framework and 228 experimental and numerical results from literature on built-up CFS columns, failing by minor axis buckling. Investigations were conducted using numerical models with mode-specific deformations incorporated in compound spline finite strip framework. The shear slip behaviour between the individual columns, characterised by (i) fastener spacing and (ii) slenderness ratio of fully-composite cross-section, was investigated using parametric variations. The study shows that the modified slenderness ratio (MSR) in Section I1.2 of AISI S100 yields conservative strength predictions with increased fastener spacing. This is possibly because the MSR considers the effect of fastener spacing and overall slenderness ratio as disjoint and treat them as additive components. In reality, they interact, and hence a compound slenderness ratio (CSR) is proposed with a term that captures the interaction of these two entities. The prediction of strength by the proposed CSR and direct strength method (DSM) is in good agreement with the results of experimental and numerical studies, with the mean close to one. When incorporated in the DSM design equations, the proposed CSR yields matching reliability with AISI S100.
Graphical abstract Display Omitted
Highlights Investigated the global buckling behaviour and design of back-to-back connected built-up columns. Used the buckling stress results of mode specific model in compound spline finite strip method as the basis. 228 experimental and numerical results from literature were investigated and used. Highlighted the shortcomings of modified slenderness ratio for high fastener spacings. Proposed a compound slenderness ratio for improved strength predictions.
Global buckling strength of discretely fastened back-to-back built-up cold-formed steel columns
Mahar, Akshay Mangal (author) / Jayachandran, S. Arul (author) / Mahendran, Mahen (author)
2021-10-11
Article (Journal)
Electronic Resource
English
Strength buckling predictions of cold-formed steel built-up columns
| British Library Online Contents | 2008