Development of Fragility Curves for Problems in Geotechnical Earthquake Engineering

本研究项目的目的是为岩土地震工程中广泛的问题建立易损性曲线；特别是地基、斜坡和挡土墙。易损性曲线作为地震事件严重程度的函数，提供了某种类型结构超过规定损伤等级（如轻微、中等、严重、完全）的概率。从工程应用的角度来看，脆弱性曲线是非常重要的，因为执业工程师可以直接使用它们，而无需进行任何复杂的计算，因为它们构成了土木基础设施系统所有风险分析/损失估计/风险降低的基础。虽然已经建立了建筑物和桥梁等结构的易损性曲线，但还没有任何系统的努力来开发岩土结构（如地基、斜坡、挡土墙）的易损性曲线。这样的任务尤其重要，因为这些结构在大地震中受到的破坏相当广泛。经验脆弱性曲线将使用来自最近地震事件的可用损害数据进行计算，这些地震事件包括：洛马普里塔地震、北岭地震、日本神户地震、土耳其伊兹米特地震和台湾齐齐地震。在建立经验脆弱性曲线的同时，将使用蒙特卡罗模拟技术计算分析性脆弱性曲线。其中一个重要的任务是比较“经验”和“分析”的脆弱性曲线，以提高其准确性和可靠性。与建立这类土工结构的易损性曲线有关的几个问题将被讨论，包括每种结构的不同破坏状态的定义和地震事件强度的测量。不同的机制将被考虑对所考虑的土工结构造成破坏。将特别强调土壤液化，由于超过抗剪强度造成的边坡破坏，以及基础和基础系统的倾斜。建立一系列土工结构的易损性曲线，将构成这些结构在遭受地震时的风险分析/损失估计/风险降低的基础。这些脆弱性曲线将允许公共和私人组织做出合理的评估：1)地震对民用基础设施系统的潜在损害；2)改造策略；3)保险费；4)指导应急管理团队识别高风险系统。该项目涉及普林斯顿大学和纽约州立大学布法罗分校的研究人员之间的合作。

The objective of this research project is to develop fragility curves for a wide range of problems in geotechnical earthquake engineering; specifically, for foundations, slopes, and retaining walls.Fragility curves provide the probability of exceeding a prescribed damage level (e.g. minor, moderate, major, complete) for a certain type of structure, as a function of the severity of the seismic event. Fragility curves are extremely significant from the engineering applications point of view as practicing engineers can use them directly without having to perform any complex computations, and because they form the basis for all risk analysis/loss estimation/risk reduction of civil infrastructure systems. Although fragility curves have been established for structures such as buildings and bridges, there hasn't been any systematic effort to develop such curves for geotechnical structures (e.g. foundations, slopes, retaining walls). Such a task is particularly important, as damage to these structures is quite extensive during major earthquake events.Empirical fragility curves will be computed using available damage data from recent seismic events such as: the Loma Prieta, the Northridge, the Kobe, Japan, the Izmit, Turkey and the Chi-Chi, Taiwan earthquakes. In parallel with the task of establishing the empirical fragility curves, analytical fragility curves will be computed using Monte Carlo simulation techniques. One of the important tasks is to compare the "empirical" and "analytical" fragility curves so as to improve their accuracy and reliability. Several issues related to the establishment of fragility curves for such geotechnical structures will be addressed, including the definition of the different damage states for each type of structure and the measure of the intensity of the earthquake event. Different mechanisms will be considered to cause damage to the geotechnical structures considered. Particular emphasis will be given to soil liquefaction, to slope failure due to exceeding the shear strength, and to tilting of foundations and foundation systems.The establishment of fragility curves for a range of geotechnical structures will form the basis for the risk analysis/loss estimation/risk reduction of such structures, when subjected to earthquakes. These fragility curves will allow public and private organizations to make rational assessment of 1) the potential damage to civil infrastructure systems from earthquakes, 2) retrofitting strategies, 3) insurance premiums, and 4) guide emergency management teams to identify high-risk systems.This project involves a collaboration between researchers at Princeton University and the State University of New York at Buffalo.