以結構可靠度為基準之橋梁耐震能力評估及最佳化設計

台灣位處地震頻繁地帶，使得橋梁常因地震而造成損毀，此種情況與自然界所發生之隨機現象有著密切之關係，本身即具不確定性之特徵，致使橋梁分析時必須考量許多不確定性。爰此，可靠度分析對橋梁可能產生失效機率做量化之分析，使工程師能較精確掌握橋梁之失效機率或風險。本研究蒐集國內外學者所進行之鋼筋混凝土柱試體側推實驗，根據SERCB for Bridge2012程式計算各塑鉸特性，並藉由SAP2000內建之側推分析(Pushover Analysis)功能求得該單柱試體之容量曲線(Capacity Curve)及容量震譜(Capacity Spectrum)，且假設單柱試體工址，進而推估該單柱試體之耐震性能。為瞭解耐震性能於理論分析與實驗之準確性，以分析為基準求得與實驗之比值，進行統計分析，獲取結構容量(Structural Capacity)之標準差。此外，並以地震危害度分析資料，求取各回歸期所對應之最大地表加速度(PGA)，進而統計分析地震需求(Seismic Demand)之標準差。進而利用橋梁側推分析所得之耐震性能曲線，透過前述結構容量統計分析求得平均值進行轉換，採為結構容量之平均值。藉由上述成果，本研究進行以可靠度為基準的兩大議題：(1)以三座既有橋梁為對象，分析其可靠度指標；(2)研擬一套以遺傳演算法結合SERCB程式及可靠度指標應用於橋梁斷面最佳化分析，以求得新設橋梁既具有經濟性兼安全之斷面配筋。本研究所得成果冀能供為工程師之參考。

關鍵字

可靠度分析；最佳化；側推分析

並列摘要

The existing bridges in Taiwan are inevitably threatened by earthquake shock. How to study failure probability of the bridges is important. Conventional seismic design of bridge by deterministic analysis is unable to consider the uncertainties in both seismic demand and structural capacity. Developing the reliability-based seismic assessment and design of bridges revealing the failure probability corresponding to various earthquake level is the core of this thesis. Twenty-seven experimental results of cyclic loading test of reinforced concrete column were served as the statistical study of pushover analysis conducted by software of SERCB for Bridge 2012 associated with SAP2000. Accordingly, the variance of structural capacity determined by analysis is able to be calculated. On the other hand, statistical analyses of seismic hazard curves at different sites were performed to find variance of seismic demands with respect to different earthquake levels. According to the above study, this thesis carried out two main reliability-based applications to bridges. The first one is to propose a realistic approach to evaluate the reliability indices as well as failure probabilities of the existing bridges corresponding to three earthquake levels. The second one is to develop an GA-based optimal design method of the bridge pier with the reliability index prescribed. The results obtained show that the proposed method can fulfill the reliability-based seismic assessment and optimum design of bridges.

並列關鍵字

Structural reliability ； Optimization ； Pushover Analysis

參考文獻

34. 蘇進國，模糊遺傳演算法在橋梁耐震性能設計之應用與耐震維修補強生命週期成本最小化之研究，國立台北科技大學工程科技研究所博士論文，2008。

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2. Lindt, J. W., Goh, G. H.,“Effect of earthquake duration on structural reliability,”Journal of Structural Engineering, Vol.26, 2004, pp.1585-1597.

3. Moustafa, A., Mahadevan, S.,“Reliability analysis of uncertain structures using earthquake response spectra,”Earthquakes and Structures , Vol.2, No.3, 2011, pp.279-295.

4. Monti, G., Nistico`, N.,“Simple Probability-Based Assessment of Bridges under Scenario Earthquakes,”Journal of Bridge Engineering, Vol.7, No.2, 2002, pp.104-114.

國際替代計量

以結構可靠度為基準之橋梁耐震能力評估及最佳化設計

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