Stability Analysis and Design of Steel-Concrete Composite Columns

This paper investigates the use of the Direct Analysis method, established within the AISC Specification for Structural Steel Buildings, for steel-concrete composite beam-columns, including both concrete-filled steel tube and steel reinforced concrete members. In addition, the paper outlines recommendations for equivalent flexural rigidity to be used in elastic analyses for composite columns. Both the Direct Analysis recommendations and equivalent rigidity values were developed based on computational results from a comprehensive suite of analyses of benchmark frames. The validity of the elastic analysis and design approach is confirmed though comparisons to results of fully nonlinear analyses using distributed plasticity finite elements that explicitly model the key phenomena that affect system response, including member inelasticity (e.g., concrete cracking and steel residual stresses) and initial geometric imperfections.

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