ABSTRACT

Multi-span simply supported (MSSS) highway bridges are one of the most common bridge types across the world and have several vulnerable components, including bearings, piers, and abutments. Although several past studies have evaluated the seismic response and fragility of common multi-span simply supported bridges, there is negligible research that explores the influence of bearing types, and non-ductile failure modes of bridge piers on the performance of older non-seismically designed simply supported bridges. Additionally, a better understanding of seismic risk to highway transportation systems necessitates the exploration of design code advances and subsequent impact on the seismic vulnerability of MSSS highway bridges. Consequently, this study also focuses on developing and comparing fragility curves for the older design era non-seismically designed, and modern era seismically designed MSSS bridges. High-fidelity three-dimensional (3-D) analytical models, which account for the nonlinear behavior of different components, including non-ductile failure modes of bridge piers, are developed. Deterministic seismic response assessment reveals a higher seismic demand on bridge pier for MSSS bridges with steel bearings as compared to those with elastomeric bearings. The bridge component and system fragility curves are developed with a suite of ground motions representative of the seismic hazard of the case-study region. Results reveal the significant vulnerability of older non-seismically designed MSSS bridge with steel bearings due to the non-ductile failure of the bridge pier. The vulnerability of the bridge is significantly reduced with the adoption of modern seismic design and detailing practices.

摘要

多跨简支 (MSSS) 公路桥梁是世界上最常见的桥梁类型之一，并且有几个易受攻击的部件，包括支座、桥墩和桥台。尽管过去的几项研究已经评估了普通多跨简支桥梁的地震响应和脆弱性，但很少有研究探讨支座类型和桥墩的非延性破坏模式对老式非抗震设计的性能的影响简支桥梁。此外，为了更好地了解公路交通系统的地震风险，需要探索设计规范的进步以及随后对 MSSS 公路桥梁地震脆弱性的影响。最后，本研究还侧重于开发和比较旧设计时代的非抗震设计和现代抗震设计的 MSSS 桥梁的脆弱性曲线。开发了高保真三维 (3-D) 分析模型，该模型解释了不同组件的非线性行为，包括桥墩的非延性破坏模式。确定性地震响应评估表明，与具有弹性体支座的 MSSS 桥梁相比，钢支座对桥墩的抗震要求更高。桥梁构件和系统的脆弱性曲线是通过一套代表案例研究区域地震危险性的地面运动来开发的。结果表明，由于桥墩的非延性破坏，旧的非抗震设计的带钢支座的 MSSS 桥的显着脆弱性。