Experimental investigation on seismic performance of self-centering frictional cast-in-situ beam-column joints

Abstract

Excessive residual deformation makes it difficult to repair reinforced concrete frame after earthquakes, and self-centering techniques have been widely adopted to mitigate residual displacement of structures. Therefore, a self-centering frictional cast-in-situ beam-column joint (SCFJ) is developed. This SCFJ mitigates damage and residual displacement via reduced beam section and self-centering frictional connectors (SFCs). The construction and working mechanism of the SCFJ are first studied, after which cyclic loading tests of SFCs, SCFJs and an ordinary reinforced concrete joint (ORCJ) are carried out. The damage evolution process, strength, hysteresis characteristics, and residual displacement of these joints are systematically discussed. The results indicate that the proposed SCFJ exhibits excellent self-centering characteristics with limited damage, while having comparable energy dissipation with ORCJ. Specifically, the damage of the SCFJ mainly occurs in the reduced beam section, and the reinforcement in the intact beam section and column is always elastic. The number and width of cracks in the SCFJ are significantly less than those of the ORCJ under the same displacements. Even if the drift ratio of the SCFJ reaches 2.5%, its residual drift ratio remains less than 0.5%, which is only 40% of the residual drift ratio of the ORCJ, thus facilitating rapid post-earthquake repair.