Investigation on seismic behavior of a new beam-column joint for precast concrete structures under reversed cyclic loading

A new type of precast concrete beam-column connection based on partial steel-concrete composite structure is proposed to improve the seismic behavior and assembly efficiency of precast concrete structures. Quasi-static tests on half-scale models were initially conducted to assess the seismic behavior of the joint and the effect of the axial compression ratio. A refined finite element model of the joint was then created to explore the influence of various factors such as reinforcement ratio, strength of post-poured concrete, and yield force of the connecting plate on the seismic behavior. The experimental and analytical results show that including a steel joint connector in the core area creates local composite structures. These structures successfully redirect plastic hinges from the beam end towards a location closer to the mid-span, protecting the integrity of the core area concrete. As a result, the seismic behavior of the proposed joint exceeds that of traditional cast-in-place joints. Additionally, a higher axial compression ratio results in a fuller hysteresis curve for the assembled specimen, suggesting increased loadbearing capacity but reduced deformation capacity. Furthermore, increasing the beam reinforcement ratio or the strength of post-poured concrete improves the seismic behavior of the joint. The connection plate also plays a role in energy dissipation, and when its yield strength is about 1.2 times that of longitudinal reinforcement, the total hysteresis energy dissipation of the new joint increases by approximately 6.4 %. It crucial to ensure a highquality connection between longitudinal reinforcements at beam ends and maintain proper pouring quality in practical engineering.