Fragility Analysis of Pier-Supported Wharf

• Main Authors: Jia-Ming You, 游家銘
• Other Authors: Grace S. Wang
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/76691365637553452353

碩士 === 朝陽科技大學 === 營建工程系碩士班 === 101 === Located at the active western circum-Pacific seismic belt where the Luzon arc of the Philippine Sea plate and the Eurasian plate collides with each other, Taiwan is subjected to frequent earthquakes. Because of their devastating potential, there is a growing research interest in areas of earthquake engineering and seismic hazard mitigation. Although a great deal is known about where earthquakes are likely to occur, there is currently no reliable way to predict the time when an event will occur in any specific location. In this regard, seismic fragilities play an important role in performance-based design engineering and seismic risk analysis in region of high seismic activities as in Taiwan. In this study, the capacity spectrum method is employed to assess the seismic capacity of a pier-supported wharf. Implementing the SAP 2000 analysis program, the capacity curve of the target structure can be obtained by the push over analysis. The response spectra can then be scaled by considering the PGA values associated with the design earthquake and maximum possible earthquake. The performance points under earthquake intensity of the above two levels can be yielded by using the intersection point of capacity spectrum and demand spectrum considering nonlinear response effect. The states of these performance points can then be used to assess the seismic capacity of structure. An approach to estimate seismic fragility without the need to perform the nonlinear dynamic analysis for determining the damage state of the structure as well as the need to perform the Monte Carlo simulation for calculating the damage probability with respect to ground motion of different intensities is developed here. The capacity spectrum method employed is again adopted to determine the damage state of the target wharf structure. Fragility curves in this study are assumed to be lognormal distribution described by two parameters and the estimation of these two parameters is done by the maximum likelihood method treating each event of damage as a realization from a Bernoulli experiment. The uncertainty associated with the ground motion is simulated by analyzing the statistical characteristics of the records of ground motion collected near the site and the uncertainties associated with the capacity spectrum and the thresholds of different damage states are also analyzed. Finally, fragility curves considering different level of uncertainties are constructed and compared for target pier-supported wharves.