Experimental study on seismic behaviour of the outrigger truss-core wall spatial joints with peripheral CFST columns

To understand the feasibility and seismic behaviour of the outrigger truss-core wall joints with peripheral concrete-filled steel tubular (CFST) columns, this paper presented an experimental study on outrigger trussconcrete shear wall joints under quasi-static cyclic loading. Two joint specimens with various details, namely, the length of the shear wall, were tested and intensively compared. The failure mode, load versus displacement hysteretic curve, strain distribution, failure mechanism and the key indexes reflecting the seismic behaviours, i. e., strength degradation, stiffness degradation, ductility and energy dissipation capacity of joints were analysed, respectively. The results show that the failure process of joints can be divided into three stages, namely, stress stages of shear wall and outrigger truss, outrigger truss and concealed column system, and failure stage of truss system, and the energy consumption of joints mainly occurs in the second stage. The failure of the two joints are located at the connection of outrigger truss and concealed column in shear wall. The length of wall has limited influence on the peak bearing capacity of joints, and the concentrated load of chord and web members of outrigger truss is transferred to shear wall through concealed column connection. The reasonable transition of stiffness of the connection between the shear wall and the outrigger truss should be adopted in the joint design, and the increase of the distance from the concealed column to the edge of the shear wall is beneficial to improve the mechanical performance and ductility of joints. The average ductility factor of two tested joints under the positive and negative loading is 1.67. The average value of the equivalent viscous damping coefficient of tested joints is 0.23, which is 130% higher than that of reinforced concrete joints of 0.1. These indicate that the tested joint exhibits a superior seismic performance and energy dissipation capacity.