Nonlinear analysis of member sections play an important role in structural seismic investigation.Based on the triaxial-force feature of the steel, a constitutive model of steel suitable for concrete-filled square steel tubular beam-column was proposed for establishing moment-curvature envelop curve, meanwhile hoop tension stress was considered in this model;a fiber-based numerical model program for beam-columns subjected to bending and axial load was developed with the proposed steel constitutive model and the existing confined concrete constitutive model.The influence on moment-curvature envelop curve of concrete-filled square steel tubular beam-column from those parameters, including steel ratio, steel yield strength, concrete strength and axial compression ratio, was studied respectively.The trilinear envelop curve model of concrete-filled square steel tubular beam-column was proposed by the analysis of yield moment and ultimate bending moment, and this model could be used for the structural dynamic analysis of projects.
[6] Sakino K,Sun Y. Stress-Strain Curve of Concrete Confined by?Rectilinear Hoop[J]. Journal of Structural Construction?Engineering of AIJ,1994,461(7):95-104.
[7] Shams M,Saadeghvaziri M A. Nonlinear Response of ConcreteFilled Steel Tubular Columns Under Axial Loading [ J]. ACI?Structural Journal,1999,96(6):1009-1017.