Seismic behaviour of through-beam connection between square CFST columns and RC beams

This paper investigates the seismic behaviour of a new type of through-beam connection between a square concrete-filled steel tubular (CFST) column and a reinforced concrete (RC) beam. In this new connection system, the steel stub is completely interrupted in the connection zone, with longitudinal steel bars of the frame beam being continuous through this zone. The connection incorporates a strengthening joint system with a steel cage consisting of multi-layer steel meshes and radial pattern stirrups to compensate the possible decrease of strength of connection due to the interruption of the steel tube. The connection is rigid with the integrity and continuity of the columns and beams. Cyclic loading tests on five beam-column specimens are conducted to evaluate this new connection. The hysteretic response, the skeletal and load-deflection curves, the strain, ductility, strength and the stiffness degradation and energy dissipation are obtained. Experimental results demonstrate the favourable seismic performance of the connection including their superior ductility and energy dissipation capacity. A sophisticated solid finite element model is developed and verified by comparing with the experimental results, and being applied for further parametric studies. A simple fibre finite model using OpenSEES is also proposed and the efficiency and accuracy of the model are illustrated.