| 摘要: | 多項式摩擦單擺支承（polynomial friction pendulum isolator,PFPI），其曲面為六次方多項式的新式變頻滑動隔震支承，利用回復勁度遞減之軟化段減緩結構加速度反應，亦可藉由回復勁度遞增之硬化段降低結構位移反應，過去研究已證實PFPI應用於等高橋墩與不等高橋墩橋梁中，受近域與遠域震波皆發揮良好的隔震效果。
平面曲線橋梁，在靜載重時內外支承反力有一定之差值，通常在地震力作用時，容易使內支承與外支承反力相差值放大，若地震力太大，可能會使內支承反力降低到零使PFPI的支承產生上下分離的情形，進而產生落橋或是結構物傾倒。本研究針對PFPI隔震曲線橋梁進行設計，假設此橋梁受單向地震力並以不同角度影響橋梁，模擬PFPI之行為。另外為了避免支承超出位移限制，支承有加裝環形擋板，利用支承環形擋板避免支承水平分離避免落橋的情況產生。
本研究採用新隱式非線性結構動力分析方法 (New Implicit Nonlinear Dynamic Finite Element Method , NINDFEM) 建立有限元素分析模型，並與振動台實驗有良好的擬合。並比較不同角度震波的情況下，對曲線橋梁之影響，比較支承位移以及遲滯迴圈結果，給予設計上的建議。
;Polynomial friction pendulum isolator (PFPI) , whose curve is six power polynomials , is a new kind of variable frequency pendulum isolator. Using the softening section to reduce the acceleration response of the structure, on the other hand , the hardened section reduces the structural displacement response. Research in past has confirmed that when PFPI are applied on regular and irregular bridge, both the near and far seismic waves exert good isolation effects.
For a plane curved bridge, there is a certain difference between the internal and external support reaction forces under static load. Usually, when the seismic force acts, it is easy to enlarge the difference between the internal support and the external support reaction force. If the seismic force is too large, it may cause the internal support react that the reaction force is reduced to zero, the support of the PFPI will be separated, which will cause the bridge or the structure to fall. In this study, the PFPI seismic isolation curve bridge is designed. It is assumed that the bridge is subjected to seismic forces with different angles to simulate behavior of PFPI support .
In addition, to prevent the support from exceeding the displacement limit, that lead to falling bridge, the support is equipped with an annular baffle. To avoid falling bridge crank plate horizontal separation can be prevented by annular baffle.
In this study, New Implicit Nonlinear Dynamic Finite Element Method (NINDFEM) is used to establish the finite element analysis model, and it fits well with the shaking table experiment results. And compare with the reaction displacement,and hysteresis loop under the waves with different angle conditions., and give design suggestions based on the comparison results. |
