A novel bidirectional friction damper for retrofitting of RC precast structures: Experimental and numerical assessment

Precast RC structures, commonly used since the '60 s for industrial and commercial buildings, often feature poor connections among the main structural elements and between structural and non-structural components due to sub-standard old building codes. Such a high vulnerability, in combination with the considerable exposed value, leads to a disproportionate seismic risk. To address this, a novel Bidirectional Rotation Friction Damper (BRFD) for RC precast structures is introduced. This easy-to-install, low-cost, and reusable damper simultaneously behaves as a beam-to-column joint and a damper with bidirectional dissipative capacity, improving seismic performance and preventing brittle failures. The BRFD's bidirectional capacity requires a unique testing methodology, validated through experimental and numerical analysis. An ad hoc setup with two orthogonal actuators was used to test the damper's behavior, measuring forces, displacements, and temperatures at varying levels. The experimental results are validated with FEM analysis in the Opensees environment by developing a refined numerical model that reproduces the behaviour of all the BRFD elements. Results show the promising bidirectional behaviour of the BRFD, both in terms of hysteresis steadiness and good damping capacity.