Nonlinear inelastic behaviors of concrete-filled steel tubular framed structures using semi-rigid connections

Abstract

A new advanced method combining the fiber beam-column model and semi-rigid beam-to-column connections has been developed using the Fortran programming language to study the nonlinear inelastic dynamic and static behavior of concrete-filled steel tubular (CFST) frames. This method improves analysis time by accurately simulating nonlinear behavior with only a few beam-column elements instead of using traditional solid and shell elements. Additionally, the effect of semi-rigid beam-to-column connections on the overall behavior of CFST frames will also be considered. For static analysis, the GDC algorithm with post-peak analysis capability will be used to solve the nonlinear equilibrium equations instead of the traditional Newton-Raphson algorithm. For dynamic analysis, a nonlinear algorithm based on the Newmark-β direct integration method and the Newton-Raphson iterative method has been developed to solve the governing differential equations of motion due to its numerical stability and simplicity. The reliability and accuracy of the proposed method were verified by comparing the analysis results with those from Abaqus. The results show that when using the fiber beam-column element for simulation, the proposed method provides accurate results and significantly reduces computational resources. Additionally, the behavior of CFST frames with semi-rigid connections was observed in detail.