Seismic performance of PC beam-to-CECFST column joints with novel wet connections

Precast concrete (PC) construction, featuring efficiency and reduced labour costs, has attracted increasing attention for connecting concrete beams and concrete-encased concrete-filled steel tube (CECFST) columns. To further improve constructability and overall seismic performance, this study proposed a novel connection detail for PC beam-to-CECFST column joints. A total of 4 specimens, including 2 interior and 2 exterior PC joints with proposed novel wet connections, were tested under lateral cyclic loading. Besides, the influence of substituting normal-strength concrete with high-strength steel fibre-reinforced concrete at structural topping of PC beams and joint region was also investigated. During the tests, crack evolution and failure mode for each joint specimen were recorded and analysed. To further study the seismic performance of joints with the proposed connection detail, several critical indices, including ductility coefficient, energy dissipation capability and rigidity degradation, were obtained through the analysis of load−displacement hysteretic curves. Thereafter, a component-based model (CBM) was proposed to simulate the joint behaviour incorporating bond-slip relationship of lapping reinforcing bars and shear behaviour of composite joints. The proposed CBM was then verified against the four experimental results and could accurately predict the load-carrying capacity, yield displacement, peak displacement, ultimate displacement, ductility and energy dissipation capability. Parametric studies were subsequently conducted to investigate the effects of cast-in-place (CIP) concrete strength and concrete encasement strength on the failure mode and seismic performance. It reveals that an increase in both CIP concrete strength and concrete encasement strength could influence the load-carrying capacity, ductility and energy dissipation capability to various degrees.