Seismic performance assessment of a precast concrete-encased CFST composite wall with twin steel tube connections

Abstract

A new type of Precast Concrete-encased high-strength Concrete-filled Steel tube (PCCS) composite shear wall with twin steel tube connections is proposed. Six two-storey PCCS wall specimens were prepared and tested under reversed quasi-static cyclic loading. The axial load ratio, the out-of-plane load eccentricity and the connection of the outer steel tubes are considered in this investigation of the assembly integrity and seismic performance of the PCCS walls. The experimental results show that the PCCS walls exhibit good assembly integrity and satisfactory seismic performance in terms of hysteresis behaviour, ductility, stiffness degradation and energy dissipation capacity. The use of bolts to radially fasten the inner and outer steel tubes can constrain the twin steel tubes. The out-of-plane load eccentricity significantly influences the cyclic behaviour. The specimens with large load eccentricity still have good deformation and ductility capabilities, which can be attributed to the ability of the embedded high-strength concrete-filled steel tube columns to improve the out-of-plane flexural capacity of a PCCS wall. Finally, the PCCS walls are compared with other typical precast concrete walls and cast-in-place concrete-encased concrete-filled steel tube composite walls in terms of ductility capacity, and a calculation model for shear bearing capacity is proposed and evaluated.