考慮支承邊界條件的跨斷層橋梁分析

Effect of boundary conditions at supports on the Seismic Response of Bridges Crossing Fault-rupture Zone

黃立誠(Li-Cheng Huang)

指導教授 ： 黃仲偉 ； 張高豪

中原大學/工學院/土木工程研究所/碩士(2020年)

https://doi.org/10.6840/cycu202000736

摘要

過往橋梁模型分析研究中，上部結構與下部結構間大多採用理想化支承型式，與現實中所使用的支承墊有所差異。前者過度加強了支承束制且忽略支承墊本身的摩擦力。因此本研究主要在探討橋主梁支承型式對橋梁受地震反應的影響為何：以多跨理想化支承之簡支橋為基礎，比較使用摩擦支承墊、不同間係值、不同強度止震塊以及不同摩擦係數支承墊在近斷層以及跨斷層的受震反應。後續加上簡支橋補強以及比較簡支橋、構架橋和連續橋等三種常見橋梁在近斷層以及跨斷層的受震反應。
本研究採用有限元軟體SAP-2000進行多點位移歷時輸入的動力非線性分析，探討近斷層與跨斷層的差異、跨斷層地震位移輸入角度的差異，以及使用不同橋主梁支承型式對橋梁受震反應的影響。數值模擬的結果顯示：跨斷層地震輸入角度的差異，對橋梁而言會產生平行錯動、擠壓、拉伸等不同運動形態，導致橋主梁在行車向產生擠壓、落橋等現象。而使用摩擦支承墊的橋梁會增加橋主梁在垂直行車向以及行車向的相對位移量，但能大幅減低橋柱的柱底剪力；而間係值與止震塊，雖能有效控制橋面板垂直行車向以及行車向的相對位移量，但會造成橋柱產生脈衝剪力。再者，橋梁連續化能夠避免橋主梁在輥支承處發生落橋，但在橋台輥支承處仍然會產生行車向大位移，應特別注意。構架橋與連續橋不產生主梁相對柱頂位移，但構架橋會有較大的柱底剪力且有較小的塑性比。

關鍵字

支承條件 ； 跨斷層 ； 摩擦支承墊 ； 非線性動力歷時 ； 位移輸入

並列摘要

In the past, most research used idealized supports between the superstructure and the substructure in the numerical bridge models. However, idealized supports are different from the bearing pads in reality since idealized supports have higher restraint and ignore the friction of the bearing pads. This study explores the influences of the support types of the main girders in bridges on the seismic responses. The seismic responses of a multi-span bridge with different friction coefficient bearing pads, different gap-values, and different rigidities of shear keys, under near-faults and crossing-faults earthquakes are investigated and compared those of a bridge with idealized supports. Furthermore, this study also compares the seismic responses of the retrofit simple support bridge with those of the traditional simply supported bridge, frame bridge, and continuous bridge under the near-fault and crossing-fault earthquakes.
The commercial finite element software, SAP-2000, is utilized to perform dynamic nonlinear transient analyses under multi-excitation displacement time-history inputs. Parametric studies are carried out to discuss the effects of the fault angle, bearing support types, and excitation types. The results of the numerical simulation demonstrate that different fault angles under crossing-fault earthquakes will cause different failure patterns, such as parallel movements, squeezing, and stretching, for the multi-span bridge. In addition, the bridge with friction bearing pads will increase the lateral and longitudinal relative-displacements on the bridge girders, but friction bearing pads can greatly reduce the shear force at the bottom of piers. Moreover, the gap-value and the shear key can effectively control the lateral and longitudinal relative-displacement on the bridge girders, but the shear key will cause the pulse shear at the bottom of piers.
Furthermore, the continuity of the main girder can prevent the falling of bridge decks during earthquakes, but there would be a large longitudinal displacement at the roller supports of the abutments. Framed bridges and continuous bridges do not have such large longitudinal displacement at main girders, but framed bridges will have larger shear forces and smaller rotations at the bottom of the column

並列關鍵字

support condition ； crossing-fault ； friction bearing pad ； nonlinear dynamic analysis ； displacement time-history input

參考文獻

1. Goel, R. K. and Chopra, A. K., (2008), Analysis of Ordinary Bridges Crossing Fault-Rupture Zones, Report. No. UCB/EERC-2008/01, Earthquake Engineering Research Center, University of California, Berkeley, CA.

2. Goel, R. K. and Chopra, A. K., (2009a), “Linear analysis of ordinary bridges crossing fault-rupture zones,” J. Bridge Eng., 14(3), pp. 203-215.

3. Goel, R. K. and Chopra, A. K., (2009b), “Nonlinear analysis of ordinary bridges crossing fault rupture zones,” J. Bridge Eng., 14(3), pp. 216-244.

4. Goel, R. K., Qu, B., Rodriguez, O., and Tures, J., (2012a), Bridge Design for Earthquake Fault Crossings: Synthesis of Design Issues and Strategies, Structural Engineering and Applied Mechanics Bridge, REPORT No. CP/SEAM-2012/01.

5. Goel, R. K., Qu, B., and Rodriguez, O., (2012b), “Analysis of curved bridges crossing fault rupture zones”, 15th WCEE, Lisbon.