Refined Numerical Modeling of a Bidirectional Rotational Friction Damper for Seismic Retrofitting

Over the past few decades, numerous precast reinforced concrete (RC) structures designed under outdated seismic codes have exhibited critical vulnerabilities. To enhance their seismic performance, this study examines a novel retrofit solution: The bidirectional rotational friction damper (BRFD). This passive energy dissipation device can function as both a connection and a damper in two orthogonal directions. The objective is to develop and validate a refined numerical model (BRFD-RNM) that accurately simulates the device's bidirectional rotational friction behavior. The BRFD-RNM was implemented in OpenSees using flat slider bearing and elastic beam column elements, adopting a corotational transformation to reproduce circular motion. Experimental monodirectional and bidirectional tests conducted at the University of Bristol were used to calibrate and validate the model. The BRFD-RNM was then applied in a case study and compared with a simplified analytical model (BRFD-SAM) to assess the importance of modeling fidelity in capturing device-structure interaction. Results show that the BRFD-RNM effectively replicates experimental hysteresis behavior, especially when a velocity-dependent friction model is used. The inclusion of BRFDs in the frame significantly improves seismic performance, reducing interstory drifts by up to 64% and base shear by 25% without appreciably altering the structural configuration. While global structural performance is similar between the BRFD-SAM and BRFD-RNM, only the refined model captures critical local effects. These findings confirm the BRFD-RNM as a reliable and efficient tool for seismic assessment and retrofit design of precast RC structures and support its use in future blind predictions and shaking table validations.