Experimental database, analysis and design of noncompact and slender concrete-filled steel tube (CFT) members

Concrete-filled steel tube beam-columns are categorized as compact, noncompact or slender depending on the governing tube slenderness ratio. AISC 360-10 specifies the provisions for designing noncompact and slender rectangular and circular CFT members under axial compression, flexure, and combined axial and flexural loading. This research presents the development and evaluation of these design provisions. Available experimental databases of CFT members are reviewed, and a new experimental database of tests conducted on noncompact and slender CFT members is compiled. Detailed 3D finite element method (FEM) models are developed for noncompact and slender CFT members, and benchmarked using experimental results. The AISC 360-10 design provisions for noncompact and slender CFT members are then evaluated by both the experimental test results and additional FEM analysis that address the gaps in the experimental database. The current AISC 360-10 P-M interaction equations are updated using the results from comprehensive parametric studies (conducted using the benchmarked FEM model). Effective stress-strain curves for the steel tube and concrete infill are also developed. The validation of these effective stress-strain curves are confirmed by implementing them in a benchmarked nonlinear fiber analysis based macro model