Damage assessment of precast reinforced concrete beam-column connections using AE technology

The beam-column connection is both the critical area and the weak part for the prefabricated reinforced concrete (PC) frame structure. The ductile connection with a U-shaped shell has been well-developed for the PC cross-shaped connection. In this paper, two optimizing reinforcement methods in the U-shell were proposed to improve the seismic performance of the PC beam-column connection. Three full-scale PC beam-column connections were designed and produced. Then, reversed cyclic loading was applied to the connections with acoustic emission (AE) technology as the measuring method to investigate the failure modes and damage mechanisms under seismic actions. The results show that increasing the connecting reinforcement area can effectively promote the bearing capacity of components while setting stirrups enables improving energy-dissipating capacity. Based on the variation of AE hits, the loading process can be divided into three stages, and the optimization effects of two measures were reflected at the different loading stages. According to the Ib-value analysis, it can be seen that the cyclic development of microcrack propagation and macrocrack penetration was the main failure mode of components. Besides, the k-means algorithm was used to classify the AE signals into four clusters with different crack patterns. In addition, based on AE energy calculation, the damage prediction model was constructed for the three full-scale specimens.