A precast beam-column joint using an innovative friction damper as a connector: Experimental and numerical study. (January 2022) - Qi, Ai
Abstract: The beam-column connection is the weakest link of the precast concrete (PC) frame in earthquakes. An innovative friction damper (FD) as connector is proposed in this paper to improve the quality of beam-column connection. To promote the use of FD in PC frames, corresponding research was conducted in this paper. Firstly, hysteretic behaviors of three FDs were investigated using cyclic tests, test variables including the bolt hole pattern (circular or slotted) and materials that form the friction interface (steel-steel or steel-brass interface). Then, a cyclic test was conducted on a PC beam-column joint equipped with an optimized FD (PCJ-FD) to compare its failure pattern and hysteretic behavior with that of a PC joint (PCJ) from a previous literature. Finally, a parametric study using ABAQUS was conducted. The parameters include the bolt preload and the bolt hole diameter. Results showed that the bolt hole pattern has little effect on FD's hysteretic behavior, while the steel-brass interface could achieve a more stable hysteretic behavior than the steel-steel case. Under hysteretic loads, large concrete spalled at beam compressive zone near the joint core in PCJ, but only several slight cracks generated at the beam and near the joint core in PCJ-FD. FD can effectively protect the PC joint from damage caused by earthquakes. The hysteretic curve of PCJ-FD was very plump, while that of PCJ experienced a severe pinching, indicating FD's excellent ability to dissipate energy. Numerical study showed that increasing the bolt preload increases the accumulated dissipated energy of FD, while decreasing the bolt hole diameter to some extent restrains the friction plates from sliding against each other, which is not beneficial to dissipating energy.