Optimum design parameters for double concave friction pendulum system considering ground motion characteristics and friction heating

Double concave friction pendulum system (DCFPS) performs well in the vibration control of building structures, while its effectiveness is limited due to the absence of considering the interrelation between design parameters, ground motion (GM) characteristics, friction heating and seismic responses. By systematically evaluating the optimum design parameters for DCFPS under different strong GM classifications and taking into account the effect of friction heating, this paper contributes a comprehensive understanding of the optimum design solutions for DCFPS. To provide a precise characterization of the effect of friction heating and loading conditions on the responses, an analytical model for DCFPS in the SDOF structure is established, and its accuracy in characterizing the friction heating effect is validated by full-scale bearings under different dynamic loading conditions. Based on this, the friction coefficient considering the influence of friction heating under strong GMs is applied in the seismic design. Subsequently, from the perspective of GM generation, strong GM records are categorized based on earthquake magnitude, distance-to-fault and soil conditions to indicate their magnitudes and spectral attributes. Then, the optimal design parameters are investigated for different GM classifications considering the effect of friction heating and response restrictions using response magnitude as criterion, and the effect of GM characteristics on the response and design parameters of DCFPS is investigated. It was found that, the consideration of residual displacement restriction and friction heating shows critical influence on the optimum selection of design parameters. Furthermore, the optimum friction coefficient is highly related to distance-to-fault, while the optimum range of isolation period is minimally influenced by GM characteristics. On top of these, a performance-based design method of FPS considering three performance criteria corresponding to three GM intensity levels is proposed, providing an effective method for mitigating the vibration of FPS under GMs.