Abstract

In this study, seismic fragility analysis of multi-span steel truss bridges still giving service in railway network of Turkey was aimed. For this purpose, two representative multi-span steel truss bridges were selected in Turkish railway lines. A detailed three-dimensional inelastic finite element (FE) model for each bridge was created using commercial FE software. These models were used to perform non-linear time history analyses for each of the selected 30 ground motions scaled to 10 different peak ground acceleration (PGA) values to assess seismic demands of the bridges. To develop fragility curves, probabilistic seismic demand models (PSDMs) were defined. The most appropriate ground motion intensity measure (IM) for PSDMs of both bridges was determined among 11 IMs and the PGA was found as the optimal IM. Finally, the fragility curves for both the components and structural systems of the bridges were developed. The results clearly showed that the multi-span continuous (MSC) steel truss bridge is more vulnerable than the multi-span simply supported (MSSS) steel truss bridge, and for both bridge types, steel bearings are the most vulnerable components. Additionally, top wind braces for the MSC bridge as well as transverse beams and truss vertical members for the MSSS bridge were found as the most vulnerable superstructure members.

摘要

在这项研究中，目标是对仍在土耳其铁路网中服役的多跨钢桁架桥进行抗震脆弱性分析。为此，在土耳其铁路线上选择了两座具有代表性的多跨钢桁架桥。使用商业有限元软件为每座桥梁创建详细的三维非弹性有限元 (FE) 模型。这些模型用于对选定的 30 个地面运动中的每一个进行非线性时间历史分析，这些地面运动被缩放到 10 个不同的峰值地面加速度 (PGA) 值，以评估桥梁的抗震需求。为了开发脆弱性曲线，定义了概率地震需求模型 (PSDM)。在 11 个 IM 中确定了两座桥梁的 PSDM 最合适的地面运动强度测量 (IM)，并且发现 PGA 是最佳 IM。最后，开发了桥梁组件和结构系统的脆弱性曲线。结果清楚地表明，多跨连续 (MSC) 钢桁架桥比多跨简支 (MSSS) 钢桁架桥更易损坏，对于这两种桥梁类型，钢支座是最易损坏的部件。此外，MSC 桥的顶部风力支撑以及 MSSS 桥的横梁和桁架垂直构件被发现是最脆弱的上部结构构件。