ABSTRACT

The main objective of this study is to assess the accuracy and suitability of Nonlinear Static Procedures (NSPs) in the development of analytical damage fragility curves for seismic risk assessment of large portfolios of Reinforced Concrete (RC) bridges. Seven NSP approaches, from widely used single-mode conventional pushover-based approaches to the more rigorous multi-mode conventional or adaptive pushover-based procedures are implemented. By systematically comparing fragility curve estimations in terms of shape and accuracy in predicting mean annual rates of exceeding predefined damage limit states, results indicate that when bridges can be classified as higher mode sensitive, multi-mode-based approaches offer a powerful alternative to rigorous time history analysis. In particular, Generalized Pushover Analysis and Adaptive Capacity Spectrum methods offer a better performance with respect to other multi-mode alternatives. For first mode dominated bridges, with a classical first mode shape, the performance of all methods is similar. Single-mode based procedures present an acceptable alternative only in such particular cases, for which the N2 method represents a viable approach when compared to other single-mode or multi-mode procedures.

摘要

本研究的主要目的是评估非线性静态程序 (NSP) 在为大型钢筋混凝土 (RC) 桥梁组合的地震风险评估开发分析损伤脆性曲线时的准确性和适用性。实施了七种 NSP 方法，从广泛使用的单模传统 Pushover 方法到更严格的多模传统或自适应 Pushover 程序。通过系统地比较脆弱性曲线估计的形状和预测超过预定义损伤极限状态的平均年率的准确性，结果表明，当桥梁可以被归类为更高的模式敏感度时，基于多模式的方法提供了一个强大的替代严格时间的方法历史分析。特别是，广义 Pushover 分析和自适应容量谱方法相对于其他多模式替代方案提供了更好的性能。对于第一模式主导的桥梁，具有经典的第一模式形状，所有方法的性能是相似的。仅在这种特殊情况下，基于单模的程序才是可接受的替代方案，与其他单模或多模程序相比，N2 方法代表了一种可行的方法。