Stability of Elastomeric and Lead-Rubber Seismic Isolation Bearings Under Extreme Earthquake Loading

本计画的研究目的是发展改良的弹性体与铅芯橡胶隔震支座稳定极限的模拟与预测方法。弹性体隔震支座和铅芯橡胶隔震支座用于建筑和桥梁结构的隔震，以减小强震的破坏作用。弹性支座由粘结在中间钢垫板上的交替橡胶层组成，铅橡胶支座有一个插入中心孔的附加铅塞。在强烈的地震地面震动，这些隔震支座可能会受到同时大的横向位移和轴向压缩载荷，可能会导致轴承不稳定。本研究将通过详细的非线性有限元分析和组件级测试来确定导致轴承不稳定的根本机制。这些研究将有助于开发一个改进的宏观模型，能够捕捉轴承的不稳定性和推导出一个基于力学的封闭形式的表达式，用于预测轴承的稳定性极限状态，本研究的结果将提供工具，以提高评估的轴承安全性的隔震系统的设计组成的弹性体或铅芯橡胶支座。本研究还将开发用于快速数值地震模拟的改进的宏观模型，这将为极端地震荷载下隔震结构的性能提供新的知识。这一新知识将导致创新的解决方案，以修改和提高个别轴承的响应，以实现所需的系统性能。研究结果将通过期刊出版物、研讨会、会议和设计建议广泛传播给研究和设计界。该项目将为研究生提供高级培训，并提供专业发展机会，在技术会议和大会上介绍他们的工作。该项目还将招募来自不同背景的本科生参加结构工程研究，并通过宾夕法尼亚州立大学工程多样性办公室的夏季研究计划（SROP）计划进行土木工程研究生教育。

The research objective of this project is to develop improved methods for modeling and predicting the stability limit of elastomeric and lead rubber seismic isolation bearings. Elastomeric and lead-rubber isolation bearings are used for seismic isolation of building and bridge structures to reduce the damaging effects of strong ground shaking. The Elastomeric bearings consist of alternating layers of rubber bonded to intermediate steel shim plates and the lead-rubber bearings have an additional lead plug inserted into a central hole. During severe earthquake ground shaking, these isolation bearings are likely to be subjected to simultaneous large lateral displacements and axial compressive loads that could cause bearing instability. This research will identify the fundamental mechanism(s) causing bearing instability through detailed nonlinear finite element analysis and component level testing. These studies will aid in the development of an improved macro-model capable of capturing bearing instability and the derivation of a mechanics-based closed-form expression for predicting the bearing stability limit state.The results of this research will provide tools to improve the assessment of bearing safety for the design of isolation systems composed of elastomeric or lead-rubber bearings. This research will also develop improved macro-models for rapid numerical earthquake simulation that will provide new knowledge about the performance of isolated structures under extreme earthquake loads. This new knowledge would lead to innovative solutions to modify and enhance the response of individual bearings to achieve a desired system performance. The results will be disseminated broadly to the research and design communities through journal publications, seminars, conference sessions and design recommendations. The project will provide advanced training to graduate students with professional development opportunities of presenting their work at technical meetings and conferences. This project will also recruit undergraduate students from diverse backgrounds to participate in structural engineering research and to pursue a graduate education in civil engineering through Penn State's Office of Engineering Diversity's Summer Research Program (SROP) program.