跨斷層橋梁之地震反應研究

Seismic Performance of Crossing-fault Bridges

10.6849/SE.202106_36(2).0004

洪曉慧(Hsiao-Hui Hung)；何蓮桂(Lian-Gui He)；何宜哲(Yi-Che Ho)；莊清鏘(Ching-Chiang Chuang)；黃仲偉(Chang-Wei Huang)

跨斷層橋梁 ； 非線性動力歷時 ； 多支承輸入 ； 地表位移輸入 ； Crossing-fault bridge ； nonlinear time history ； multiple excitation ； ground displacement input

結構工程

36卷2期（2021 / 06 / 01）

91 - 113

繁體中文

目前橋梁耐震規範主要是透過放大係數來考慮近斷層效應，對於跨斷層橋梁並無相關的規定。然而跨斷層橋梁在斷層線兩側由於會因地表相對錯動而導致不同的變形趨勢，因此在數值模擬上必須採用多支承非同步輸入，計算橋梁模型在地震作用下的結構地震反應。本研究之目的在建立以地表位移輸入法為基礎之多支承地震輸入方式，用以探討跨斷層橋梁受地震作用之反應。首先以近斷層地震的地表加速度歷時經數值積分得到對應的地表位移歷時，利用多支承位移輸入方式進行非線性動力歷時分析來模擬跨斷層橋梁的地震反應。並進一步比較地表位移分配方式、斷層穿越角度、橋面板支承形式等對於跨斷層橋梁受震反應之影響。數值模擬結果顯示非同步輸入地震歷時會使橋梁結構產生局部較大變形與內力；同步輸入地震歷時則會使橋梁結構產生較大的絕對加速度。此外，本文就位移的分配方式區分為絕對錯位和相對錯位兩種，數值結果顯示在內力計算的部分，相對錯位與絕對錯位所得之最大值差異不大；但變形的部分，絕對錯位所得之最大值往往高於相對錯位所得之最大值。模擬同時顯示斷層水平角45度的作用下，對於柱底扭矩會產生較明顯的放大，但其餘物理量會小於斷層水平角90度的作用。最後，本文依主梁與柱頂接合處不同的邊界條件，將橋型分為連續橋、簡支梁橋和構架橋等三種。構架橋與連續橋的最大歷時反應相當接近，簡支梁橋各項物理量的最大歷時反應相較於連續橋可能增大或減少。

The influences of near-fault earthquakes are taken into account only by the magnification factors in the seismic design code for highway bridges. There are no related specifications about crossing-fault bridges in the design code. However, cross-fault bridges which are subjected to different ground motions at opposite sides of the fault line suffer more attacks in earthquakes. In this study, the seismic responses of cross-fault bridges are simulated with the multiple-excitation method and solved by nonlinear dynamic time history analyses. The displacement time history of each excitation is obtained by integrating the acceleration time history of a near-fault ground motion. The influences of the velocity impulse and residual displacements of near-fault earthquakes on the seismic responses of cross-fault bridges are discussed. In addition, the effects of the boundary conditions of the bridge deck and the angle between the bridge and fault line on the seismic responses of cross-fault bridges are also elaborated here. Numerical results demonstrate that the multiple-excitation simulation obtained larger local deformation and internal forces. On the other hand, the single-excitation simulation obtained larger absolute acceleration. Moreover, the ground displacements from integration are further divided into absolute displacements and relative displacements, which are assigned to the ground motions at opposite sides of the fault line. Numerical results show that there are no obvious differences on internal forces between these two displacement distributions. However, the absolute displacement generates larger member deformation. Moreover, the torsions at the bottom of bridge columns are magnified when the fault angle is 45°. Finally, the influences of different boundary conditions between bridge slabs and columns on the seismic responses are investigated. The seismic responses of rigid connections are similar to those of pin connections while the seismic responses of simply supported bridges have different characteristics.

1. Goel, R. K.,Chopra, A. K.(2009).Linear analysis of ordinary bridges crossing fault-rupture zones.J. Bridge Eng.,14(3),203-215.
2. Goel, R. K.,Chopra, A. K.(2009).Nonlinear analysis of ordinary bridges crossing fault rupture zones.J. Bridge Eng.,14(3),216-244.
3. Goel, R. K.,Chopra, A. K.(2008).Analysis of Ordinary Bridges Crossing Fault-Rupture Zones.The 14th World Conference on Earthquake Engineering,Berkeley, CA.:
4. SeismoSoft, (2016), SeismoSignal documentation, http://www.seismosoft.com/seismosingal-documentation
5. 中野友裕、太田良巳(2007)。支持点の変位差を伴う橋梁の非線形動的応答解析。東海大学紀要工学部，47(2)，85-92。
6. 矢葺亘、野口邦生、真崎洋三、越智大三(2003)。断層変位を受ける PC ラーメン橋の耐震安全性に関する研究。コンクリート工学年次論文集，25(2)，1429-1434。
7. 周國良,李小軍,喻鈿,劉浪,李敏(2010)。結構地震作用的基底激勵模型及其適用性。建築結構學報，31(增 2)，82-88。
8. 柳國環,李宏男,田利(2009)。九江長江大橋在多點多維地震激勵下的反應分析。振動與衝擊，28(9)，204-209。
9. 惠迎新,王克海(2015)。基於多支承輸入位移輸入模型的跨斷層橋梁地震動輸入方法。東南大學學報，45(3)，557-562。
10. 惠迎新,王克海(2015)。跨斷層橋梁地震響應特性研究。橋梁建設，45(3)，70-75。
11. 惠迎新,王克海,何文杰(2016)。跨斷層橋梁非一致激勵輸入模型適用性研究。建築科學與工程學報，33(5)，100-107。
12. 楊慶山,劉文華,田玉基(2008)。國家體育場在多支承輸入作用下的地震反應分析。土木工程學報，41(2)，35-41。
13. 羅超,樓夢麟,桂國慶(2015)。大跨度結構多點地震反應計算方法的比較。同濟大學學報，自然科學版，43(1)，8-15。

1. 劉光晏,吳振揚(2021)。應用高強度鋼筋混凝土於斷層近域橋梁之耐震性能設計。結構工程，36(3)，71-92。