Seismic fragility assessment using structural dynamic analysis remains challenging for complex systems due to the high computational demand, such as the sea-crossing cable-stayed bridges. The paper aims to overcome this difficulty by developing an efficient seismic fragility analysis framework based on endurance time method (ETM). To demonstrate the framework for developing fragility curves, an example sea-crossing cable-stayed bridge is used as a case study. The ETM framework is validated by comparing the calculated fragility curves with those calculated by IDA framework. It is shown that the ETM is capable of significantly reducing computational effort without compromising the accuracy of fragility analysis results. The validated framework is then used to discuss the seismic fragility of sea-crossing cable-stayed bridges under scour and earthquakes. The influence of the time duration of endurance time acceleration functions (ETAFs) on the structural fragility is discussed. The influence of the time duration of ETAFs on the component fragility varies across different components, but the system fragility increases with the increasing time duration on the whole. Scour can produce either beneficial or adverse effects on the component and system seismic fragilities depending on the scour depth.

由于复杂的系统（例如跨海斜拉桥）的高计算需求，使用结构动力分析进行地震脆性评估仍然具有挑战性。本文旨在通过开发一种基于耐久时间方法（ETM）的有效地震脆性分析框架来克服这一难题。为了演示开发脆性曲线的框架，以一个跨海斜拉桥为例进行了研究。通过将计算出的脆弱性曲线与IDA框架计算出的脆弱性曲线进行比较，可以验证ETM框架的有效性。结果表明，ETM能够显着减少计算工作量，而不会影响脆弱性分析结果的准确性。然后使用经过验证的框架讨论冲刷和地震作用下的跨海斜拉桥的地震易损性。讨论了耐力时间加速函数（ETAF）的持续时间对结构脆性的影响。ETAF的持续时间对组件脆弱性的影响在不同组件之间有所不同，但是系统脆弱性总体上随着持续时间的增加而增加。根据冲刷深度，冲刷会对组件和系统的地震脆弱性产生有利或不利影响。但是系统的脆弱性总体上随着持续时间的增加而增加。根据冲刷深度，冲刷会对组件和系统的地震脆弱性产生有利或不利影响。但是系统的脆弱性总体上随着持续时间的增加而增加。根据冲刷深度，冲刷会对组件和系统的地震脆弱性产生有利或不利影响。