Enhancing Pounding Hazard Assessment: Investigating Rubber Bumper Behavior in Base Isolation Systems during Earthquakes

Seismic vibrations naturally induce significant horizontal displacements, resulting in collisions between neighboring buildings when there is insufficient spacing. Pounding, which occurs primarily in tall buildings, leads to severe damage due to these impacts. To mitigate structure collisions and reduce the risk of pounding, several approaches have been proposed. These include maintaining adequate separation distances, enhancing structural stiffness, employing supplementary elements, incorporating different dampers, and implementing bumpers. These measures aim to regulate lateral displacement and dissipate energy within the contact zones during impacts. This research paper aims to examine the impact of rubber bumpers in enhancing energy dissipation during collisions. Through experimental testing and numerical simulations, an impact scenario is recreated, and the damping ratio is calculated based on energy dissipation. The study proposes a novel formula for determining the damping ratio specifically tailored for bumpers attached at the base level of structures. This study focuses on defining a new equation to determine the damping ratio of bumpers used in impact scenarios. An iterative procedure is employed, considering parameters such as bumper dimensions, stiffness, and coefficient of restitution. The equation is solved to calculate impact force and energy dissipation. Numerical analysis results are validated against experimental data. Parametric studies are conducted to evaluate the formula's accuracy by analyzing hysteresis loops obtained from impact tests. The research aims to provide a reliable and effective equation for accurately determining the damping ratio of bumpers in real-world impact situations. The study concludes by selecting the best calibration of hysteresis loops from numerical analyses and experimental tests as the optimal parameter values for demonstrating the equation. To investigate the equation's impact, two 5-story buildings are modeled, with one of them equipped with a base isolation system and rubber bumpers to assess the influence of the bumpers during earthquakes. The research findings indicated that reducing the number of bumpers and increasing their thickness leads to decreased energy dissipation. Therefore, the suggestion is to increase the number of rubber bumpers and decrease their thickness for improved performance.