橋梁三維極限破壞分析

None

陳鵬宇(Peng-Yu Chen)

指導教授 ： 李姿瑩

國立中央大學/工學院/土木工程學系/碩士(2014年)

摘要

摘要
現今世界先進國家耐震設計均朝向性能設計發展，相較於傳統耐震設計以結構所引致地震力為設計基礎，性能設計則以地震作用下結構性能表現為基礎，然而如何準確地預測橋梁各構件於實際地震下之耐震性能，以目前傳統結構動力分析技術，仍存在相當大的難度。
本研究採用了新近發展適用於處理大變形、大變位、材料非線性與剛體運動等問題之向量式有現元素法(Vector Form Intrinsic Finite Element , VFIFE)，向量式有限元素法可以同時考量橋梁於極限狀況下，各構件進入非線性之動力行為，如大梁間的碰撞、柱底塑鉸、橋面板掉落、防落拉桿斷裂以及最終崩塌情形。
過去VFIFE使用雙線性彈簧元素(Bilinear Spring)模擬所有非線性行為，即構件受力達一定強度，全斷面降伏並同時進入塑性行為，但此行為無法精準模擬真實斷面由外至內依序降伏之實際情況。故本研究引入纖維元素法(Fiber Element Method)於空間向量式有限元素法，以纖維元素之應力應變數值計算準確模擬塑鉸達極限破壞之高度非線性行為，配合Newmark-β法增量迭代計算程序，並經由算例分析，證實所發展之新元素與新分析方法之正確性。
本研究於空間向量式有限元素法中，建立橋梁三維非線性結構動力分析模型，以一座三跨隔震支承連續梁橋為目標橋梁，進行參數分析探討於三種不同測站之強震下，橋墩柱底塑鉸分別使用纖維元素與雙線性彈簧元素時，橋梁防止落橋裝置與支承、橋墩間之相互影響關係，並探討橋梁於地震發生時在極限狀態下之破壞模式。

關鍵字

空間向量式有限元素法 ； Newmark-β直接積分法 ； 纖維元素法 ； 極限狀態 ； 橋梁

並列摘要

ABSTRACT
Lately, modern bridge seismic design has been developed toward the seismic performance design on whole bridges as well as their elements. Based on the traditional dynamic analysis, it is difficult to predict the performance of the components of bridges, such as bearing, unseating prevention devices, and columns.
The Vector Form Intrinsic Finite Element (VFIFE) is superior in managing the engineering problems with material nonlinearity, discontinuity, large deformation, large displacement and arbitrary rigid body motions of deformable bodies. The VFIFE is thus selected to be the 3-D analysis method in this study. It is easily to predict the nonlinear behavior of bridges subjected to extreme earthquakes, such as impact between girders, plastic hinge, unseating of decks, fracture of unseating prevention devices, and collapse situation.
In order to analyze the real condition of the section, this study is aimed to develop the new model of Fiber Element that using stress-strain relation in plastic hinge zone to simulate high-degree nonlinear behavior of bridges by strong motion. Implicit time integration method (Newmark-β) is adopted to renew the iteration type of Fiber Element Method to calculate the element internal force. Finally, this study analyzes a three-span-continuous isolated bridge to investigate the extreme functions of the columns and unseating prevention devices between Fiber Element and Bilinear Spring, and predict the collapse situation of the target bridge.

並列關鍵字

3D VFIFE ； Newmark-β method ； Fiber element ； ultimate state ； bridge

參考文獻

[1] Ting, E. C., Shih, C. and Wang, Y. K., “Fundamentals of a Vector Form Intrinsic Finite Element: Part I. Basic Procedure and a Plane Frame Element,” Journal of Mechanics, Vol.20, No.2, pp. 113-122, 2004.

[2] Ting, E. C., Shih, C. and Wang, Y. K., “Fundamentals of a Vector Form Intrinsic Finite Element: Part II. Plane Solid Elements,” Journal of Mechanics, Vol.20, No.2, pp. 123-132, 2004.

[3] Shih C., Wang, Y. K. and Ting, E. C., “Fundamentals of a Vector Form Intrinsic Finite Element: Part III. Convected Material Frames and Examples,” Journal of Mechanics, Vol.20, No.2, pp. 133-143, 2004.

[4] Wang, C. Y., Wang, R. Z., Kang, L. C. and Ting, E. C., “Elastic-Plastic Large Deformation Analysis of 2D Frame Structure,” Proceedings of the 21st International Congress of Theoretical and Applied Mechanics (IUTAM), SM1S-10270, Warsaw, Poland, August 15-21, 2004.

[5] Wu, T. Y., Wang, R. Z. and Wang, C. Y., “Large Deflection Analysis of Flexible Planar Frames,” Journal of the Chinese Institute of Engineers, Vol. 29, No. 4, pp. 593-606, 2006.