Static and dynamic experimental validations of a frictional isolator with improved internal lateral impact behavior

Abstract

Under extreme seismic conditions, large displacements in frictional isolators may trigger internal impacts between sliders and restraining rims, jeopardizing the effectiveness of using seismic isolation interfaces. These impacts may produce the failure of the bearing or a dramatic increase in the displacement demand of the superstructure. A novel configuration of a frictional device has been suggested to improve the seismic performance of base-isolated structures. The Lateral Impact Resilient Double Concave Frictional Pendulum (LIR-DCFP) bearing has an enhanced inner slider with a plane high-friction interface and an internal gap. The internal lateral impact causes a high-friction slide that limits the magnitude of the impact force and dissipates an additional amount of energy. This work presents and discusses the main results of static and dynamics tests concerning the LIR-DCFP bearing ‘ s lateral behavior. The data obtained was employed to calibrate a numerical modal aiming to represent the response of a timber structure equipped with LIR-DCFP bearings. Static tests were conducted to confirm the expected lateral behavior of the novel device. Special attention was paid to constructing a proper slider with a high-friction interface, the main feature of the isolator. The results of the static tests indicate that the construction of this improved slider, which exhibits a high-friction phase only when the impact is produced, is feasible. Finally, dynamic tests of a timber superstructure equipped with four LIR-DCFP bearings subjected to unidirectional inputs were conducted. A proper response of the isolation system was obtained, even when internal lateral impacts were observed. The results of these experimental tests suggest that using LIR-DCFP isolators represents an excellent alternative to mitigate the adverse effects of lateral internal impacts.