Experimental study of precast self-centering concrete shear walls with external friction dampers

Self-centering walls perform relatively well in reducing structural damage and residual defor-mation owing to the joint rocking mechanism. Nevertheless, drawbacks of the self-centering walls were limited robustness and redundancy, thus sufficient dissipating capacity is essential for improving stiffness, reducing seismic response, and controlling structural collapse. Among all these dampers used in self-centering systems in previous studies, slip-friction dampers are highly preferred because of their simplicity, perfect rigid-plastic hysteresis characteristic, large stroke, and stable dissipating capacity. After the earthquake ceases, friction force can be eliminated by loosening the tightening bolts to help facilitate post-earthquake recovery, and it is convenient to be replaced or repaired. In the present study, experiments of asymmetric friction dampers with brass-steel interfaces were conducted. To obtain the optimal characteristics for stable dissipating, different configurations of slip-friction dampers were designed and tested. The friction dampers were further installed vertically at the base rocking joint of the self -centering shear walls, and the performance of the walls was studied under horizontal quasi-static cyclic loading. Application of the friction dampers significantly increases the energy dissipating capacity and the post-yield stiffness. The energy dissipating ratio improved up to 81.2% compared to rocking walls with no additional damping. Damage was limited to the brass shims in friction dampers, while wall specimens were able to exhibit up to 3.0% horizontal drift without cracks, degradation, and significant concrete damage at the boundary elements. An average maximum residual drift of both positive and negative directions observed at the end of the test was 0.415% at 3.0% horizontal drift, that major structural realignment is not required, and repair of the structure is practically feasible.