應用容量位移雙反應譜於鋼筋混凝土橋梁之耐震性能評估

SEISMIC EVALUATION OF REINFORCED CONCRETE BRIDGES USING CAPACITY-BASED INELASTIC DISPLACEMENT SPECTRA

王柄雄(Ping-Hsiung Wang) ； 張國鎮(Kuo-Chun Chang) ； 曾榮川(Dzong-Chwang Dzeng) ； 林子剛(Tzu-Kang Lin) ； 洪曉慧(Hsiao-Hui Hung) ； 鄭維中(Wei-Chung Cheng)

《中國土木水利工程學刊》 32卷8期 (2020/12) Pp. 767-776

https://doi.org/10.6652/JoCICHE.202012_32(8).0010

摘要

本研究提出一套適用於鋼筋混凝土橋梁之簡化耐震能力評估方法，該方法透過容量位移雙反應譜之應用，不僅可求得橋梁之最大非彈性位移反應，更可識別出不同橋柱間之損傷狀態。考量Park and Ang之損傷指標可適切的反應橋柱之強度容量狀態，並提供與實際破壞影像之連結對應關係，本研究以此做為評估橋梁性能狀態的重要指標。為了檢驗所提方法之準確性及可靠性，本研究建構一座假想之案例橋梁，並採用不同之結構分析軟體及國內外相關技術規範之耐震評估方法進行綜合分析比較。研究結果顯示，所提出之評估方法可準確地評估遠域及近斷層地震下之橋梁非彈性位移反應與損傷狀態。相較之下，現行國內之評估法及美國AASHTO與Caltrans的方法皆無法反應近斷層地震之頻率內涵特性所造成之結構反應效大效應，進而嚴重低估橋梁之非彈性受震反應。此外，若依AASHTO之規則性橋梁條件（三跨橋梁之橋柱最大勁度比不得大於4）將案例橋梁設定為具有高矮橋柱之情況，則評估結果顯示矮柱的損傷指標平均約略為高柱之3.5倍，以致橋梁之損壞嚴重集中在矮柱上，進而大幅降低整體橋之側向變形容量與耐震能力。

關鍵字

鋼筋混凝土 ； 橋梁 ； 地震評估方法 ； 損傷指數 ； 近斷層地震 ； 非彈性位移譜

並列摘要

A simplified seismic evaluation method using capacity-based inelastic displacement spectra is proposed for reinforced concrete (RC) bridges. The proposed method can not only estimate the maximum displacements of bridges, but can also discriminate the damage indices between the bridge columns, where the Park and Ang's damage index (DI) is considered a promising performance indicator due to its good relationship with the strength capacity state and actual visual damage condition of the bridge column regardless of the imposed loading history. To realize the accuracy and reliability of the proposed method, a hypothetical case study bridge was constructed and analyzed using various structural analysis programs and seismic evaluation methods. It was found that the proposed method can receive satisfactory estimates of the maximum displacement and DI for both far-field and near-fault ground motions when compared to the nonlinear time history analysis results of the bridge. In contrast, the AASHTO's and Caltrans' methods cannot reflect the response amplification effects caused by the frequency-content characteristics of near-fault ground motions and would therefore significantly underestimate the inelastic responses of bridges. When applying the proposed method to bridges having unequal-height columns and subjected to longitudinal seismic actions, it was found that for the short column of the bridge, the AASHTO's regularity criteria (maximum bent/pier stiffness ratio of 4 for the three-span case study bridge) would lead to a DI of approximately 3.5 times that of the tall column, resulting in significant damage localization and hence decreasing the overall lateral deformation capacity of the bridge.

並列關鍵字

reinforced concrete ； bridge ； seismic evaluation ； damage index ； near-fault ； inelastic displacement spectra