Experimental and numerical investigation on seismic performance of a composite wide beam-column interior joint

Abstract

This paper aims to scrutinize the behavior of a typical composite wide beam-column interior joint under lateral cyclic load. The investigated composite structure consists of a precast U beam with rooted A-trusses and U bars, precast columns, and cast-in-situ concrete poured over the precast U beam and in the joint region with post-tensioning. In this study, a half-scale specimen of the post-tensioned precast wide U beam-column interior joint was tested under an incremental displacement controlled lateral cyclic load. A 3D comprehensive numerical model of the tested specimen was developed in LS-DYNA finite element (FE) code, and validated with experimental results. Based on the experimental and numerical results, hysteresis behavior, failure mode, strain distribution in rebars, energy dissipation and interface interaction between the precast and cast-in-situ concrete were investigated. In addition, force transfer mechanism from the composite wide beam to the column core was elucidated with the validated numerical model. The precast wide U beam column interior joint exhibited an equivalent load-displacement behavior with the monolithic joint having the same beam-column width ratio and reinforcement detailing. Cracks and damages were found to be prevalent on the composite wide beam whilst only a few flexural cracks were observed in the precast column. The transverse flexural cracks across the wide beam, diagonal shear cracks on the beam originating at the column corner, and torsional cracks were the major crack types observed on the tested specimen. Furthermore, the interface of precast and cast-in-situ concrete remained intact until the ultimate state.