橋墩式碼頭之易損性分析

Fragility Analysis of Pier-Supported Wharf

游家銘(Jia-Ming You)

指導教授 ： 王淑娟

朝陽科技大學/理工學院/營建工程系/碩士(2013年)

摘要

臺灣位於多地震的西環太平洋地震帶，在地體構造上位在歐亞大陸板塊與菲律賓板塊的複雜交界面上，地震的發生尤其頻繁，所以地震工程研究與地震災害防制顯得格外重要。然而現今仍無法精確預測地震的發生，故須探討結構物在工址相關區域內之地震危險度分析，作為耐震設計之參考及地震風險評估與管理之基礎。
本文首先使用ATC-40發展出來的容量震譜法(Capacity Spectrum)來評估橋墩式碼頭之耐震能力。主要是利用SAP 2000分析程式求得橋墩式碼頭之容量曲線(Capacity Curve)，再依據設計地震及最大考量地震之需求反應譜並考慮非線性效應求得性能點，評估橋墩
式碼頭之耐震能力是否足夠。
接著利用橋墩式碼頭容量震譜與對應不同地震強度之需求反應譜相交求得之性能點，依據損壞狀態門檻值判別各性能點之損壞狀態，再配合最大概率法建立易損性曲線。假設易損性曲線型式符合對數常態之累積分佈型式，對應設定之易損性曲線函數型式的中值及對數標準偏差係採用推廣式基因演算法搜尋使概率函數為最大之參數值。本文在建立易損性曲線時考慮地震隨機特性、材料性質變異性及損壞狀態門檻值不確定性等因素組合之影響，建立三個層次之易損性曲線，並討論這三種之易損性曲線差異性。

關鍵字

易損性分析 ； 橋墩式碼頭

並列摘要

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.

並列關鍵字

Pier-Supported Wharf ； Fragility Analysis

參考文獻

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