Seismic performance of concrete-encased CFST column to RC beam joints: A practical model

Abstract

This study proposed a practical model of the concrete-encased concrete-filled steel tubular (CFST) column to reinforced concrete (RC) beam joints based on the experimental and analytical investigations in companion publications. The analytical work was conducted to figure out the load transfer mechanism in the panel zone with considerations of the geometric features, material strengths and the axial load level. The strength calculation method was proposed according to the mechanical principle and parametric study for the beam, column and panel zone, respectively. The strength calculation method was proved to be consistent with the measured results and could reflect the actual failure mode. Then, a hysteretic model for the panel zone was developed that considered the stiffness degradation, which was verified by test results and FEA simulations. Finally, the practical model was proposed, which could simulate the failure mode, the strength and the cyclic behaviour of the composite joint. The predicted results of the proposed practical model coincided nicely with the test results of both composite members and joints, which indicated that the practical model could be used in the seismic analysis of the specified frame structures.