Development of the Probabilistic Evaluation System of Seismic Damage States for Bridge Structures

阪神大地震对阪神地区多座公路桥造成严重影响。通过对公路桥梁在强震作用下的破坏机理的大量研究发现，将公路桥梁视为由桩、基座、桥墩、支座、约束、上部结构等多种结构组成的体系，对于改进实际设计程序具有重要意义。首先，对钢筋混凝土桥墩体系进行了非线性动力响应分析，并计算了响应值。应用随机振动理论中的门限越界法，计算了每个响应值对应于多个损伤状态的门限首次漂移的概率。然后，根据第一次偏移的概率构造损伤转移概率矩阵。然后，利用损伤转移概率矩阵建立了考虑单元间损伤相互作用的损伤转移模型。最后，基于结构单元多种损伤状态的概率结果，对桥梁结构在地震作用下的功能损伤状态和社会损伤状态进行了评估。此外，通过图形用户界面可视化损伤随时间变化的程序的开发，使得在地震期间整个桥梁结构的行为中容易地检查结构损伤的转变成为可能。然后通过对比抗震加固前后的算例，评价了不同抗震加固措施对抗震性能的影响。

The Great Hanshin Earthquake had affected seriously on many highway bridges in Hanshin area. From a lot of investigations about the failure mechanisms on the highway bridges during strong earthquake, it was found that the consideration as a highway bridge system which consists of many structural elements such as piles, footings, piers, bearings, restrainers, super structures, etc. is very important to improve of the practical design procedure.This study attempted to develop a newly developed probabilistic evaluation system of seismic damage states for bridge structures. At first, non-linear dynamic response analyses for the reinforced concrete bridge pier system were performed and the response values were calculated. And also, the probability of the first excursion for the threshold that corresponds to multiple damage states was calculated for each response value by the application of threshold-crossing in random vibration theory. Next, the damage transition probability matrix was constructed on the basis of probability of the first excursion. Then, the damage transition probability matrix conducted the damage transition model that included the damage interaction between elements. Finally, based on resulting probabilities of multiple damage states of structure elements, both functional and social damage states of the bridge structures damaged by earthquakes were evaluated. In addition, the development of a program for visualizing damage transition over time with graphical user interface made it possible to check the transition of structural damage easily in the behavior of the entire bridge structure during an earthquake. Then, by comparing cases with and without seismic retrofits, the effects of different seismic retrofit measures on seismic performance were evaluated.