Enhanced Seismic Resiliency for Buildings via Base Isolation
Base isolation is an effective technology for reducing seismic damage to both structural and nonstructural components, as well as to building contents, allowing buildings to remain functional during and in the aftermath of a rare and strong intensity earthquake. This makes it an ideal seismic response modification system for hospitals and buildings of high importance. Despite the enhanced seismic resiliency of buildings incorporating base isolation, many countries have been slow to adopt it in building designs prior to experiencing the devastating effects of a major earthquake, often embracing the technology as an outcome. The goal of the research in this dissertation is to advance the understanding of base isolation, in order to diminish some of the barriers that impede its widespread use.
This dissertation uses data collected from a shake table experiment of a full-scale five-story building outfitted with nonstructural components and systems to analyze the structural response of the building in both base isolated and fixed base configurations. By simulating a realistic environment, this project documents the destructive effects of an earthquake with and without base isolation, ultimately demonstrating the technology’s effectiveness in minimizing structural demands.
Another test that was conducted addressed the specific response of an isolator in realistic earthquake conditions. One of the barriers that prevents the use of base isolation in certain scenarios is because of gaps in knowledge due to lack of testing. To address this, a comprehensive multiaxial testing program of a high damping rubber bearing was performed, fully characterizing the bearing in six degrees of freedom, to understand the impact of realistic loading conditions on the isolator response.
Finally, base isolation is often implemented in buildings specifically to protect nonstructural components and ensure functionality of the building after an earthquake. Despite this, current design codes do not specifically address nonstructural components within base isolated buildings. This dissertation proposes a framework for designing inertia-sensitive nonstructural components within base isolated buildings. The framework is demonstrated through a case study using experimental structural response data in conjunction with simulated nonstructural responses generated by relative displacement floor response spectra for inelastic response.