Seismic behavior and restoring force model of precast beam-column connections with locally reactive powder concrete

Abstract

In this study, an innovative approach to enhance the seismic performance of prefabricated concrete frame beam-column joints, incorporating high-strength steel bars and reactive powder concrete (RPC), was developed. The research involved the construction of four prefabricated joints and one cast-in-place node, subjecting them to low-cycle reverse load tests. The findings indicate that the inclusion of high-strength steel bars in the node core area led to a notable increase in load-bearing capacity, ranging from 9.5 % to 9.7 %. Moreover, when RPC and high-strength steel bars were simultaneously used in the node core area, the load-bearing capacity improved even further, with an increase of 19.1 %–20.8 %. Additionally, RPC was found to enhance crack resistance in columns and beams, reducing the severity of node failures. Comparing specimens with different spacing of hoops in the core area, it was observed that RPC not only ensured the seismic performance of the nodes but also addressed the issue of excessive hoop density in the core area. Through experimental data, a restoring force model for prefabricated RPC/RC composite frame beam-column joints was established using theoretical analysis. This model exhibited strong agreement with experimental results and effectively depicted the stress distribution within the proposed joints at various stages.