During a mainshock‐aftershock (MSAS) sequence, there is no time to retrofit structures that are damaged by a mainshock; therefore, aftershocks could cause additional damage. This study proposes a new approach to develop state‐dependent fragility curves using real MSAS records. Specifically, structural responses before and after each event of MSAS sequences are used to obtain statistical relationships among the engineering demand parameter prior to the seismic event (pre‐EDP), the intensity measure of the seismic event (IM), and the engineering demand parameter after the seismic event (post‐EDP). The developed fragility curves account for damage accumulation, providing the exceeding probability of damage state (DS) given the IM of the event and the DS of the structure prior to the seismic excitation. The UBC‐SAWS model, which was developed for wood‐frame houses in British Columbia, Canada, is considered as a case study application. Results indicate that for the examined structural typology, state‐dependent fragility curves based on residual interstorey drift ratio (pre‐EDP), peak ground velocity (IM), and maximum inter‐storey drift ratio (post‐EDP) are the best choice to characterise the cumulative damage effect. An illustration of the developed fragility curves is provided by considering a hypothetical MSAS scenario of a M_w 9.0 Cascadia mainshock triggering a M_w 6.0 crustal event in the Leech River fault, affecting wooden houses in Victoria, Canada. The MSAS scenario increases Yellow tags (restricted access) by 12.3% and Red tags (no access) by 4.8%.

中文翻译：

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主震-余震状态相关的脆性曲线：以加拿大不列颠哥伦比亚省的木结构房屋为例

在主震-余震（MSAS）序列中，没有时间来改造受主震破坏的结构。因此，余震可能会造成其他损坏。这项研究提出了一种使用真实的MSAS记录来开发状态相关的脆性曲线的新方法。具体来说，使用MSAS序列的每个事件之前和之后的结构响应来获得地震事件之前的工程需求参数（pre-EDP），地震事件的强度度量（IM）和工程需求参数之间的统计关系。地震事件发生后（EDP之后）。所开发的脆性曲线说明了损伤累积，在给定IM的情况下提供了超过损伤状态（DS）的可能性地震激发之前的事件和结构的DS。为加拿大不列颠哥伦比亚省的木结构房屋开发的UBC‐SAWS模型被视为案例研究应用程序。结果表明，对于所检查的结构类型，基于残余层间漂移比（EDP​​之前），峰值地面速度（IM）和最大层间漂移比（EDP​​之后）的状态相关的脆性曲线是最佳选择。描述累积损伤效应。发达脆弱曲线的图示通过考虑的假定情景MSAS提供中号_瓦特9.0卡斯卡迪亚主震触发中号_瓦特水Lee河断层的6.0地壳事件影响了加拿大维多利亚州的木屋。MSAS方案将黄色标签（访问受限）增加了12.3％，将红色标签（没有访问权限）增加了4.8％。