| 摘要: | 本研究為含抗拉拔裝置及多項式摩擦單擺支承(Polynomial Friction Pendulum Isolator，PFPI)之單跨曲線橋梁振動台實驗。過去研究已證明PFPI之六次方多項式曲面能根據支承位移提供不同勁度，以避免遭遇近域地震時發生支承位移過大之情形。然而過去研究結果顯示，PFPI應用於曲線橋梁時，內外支承反力存在差異之特性會在地震力作用時被放大，甚至使PFPI上下分離，進而導致落橋風險。為此，本研究新增抗拉拔裝置於單跨曲線梁橋，以避免PFPI發生上下分離之情形，同時限制PFPI最大位移。
本研究首先探討曲線橋梁遭遇單向震波時，震波輸入角度對於曲線橋梁之影響，以了解不同震波輸入角度情形下曲線橋梁之動力行為差異。實驗結果顯示單向震波輸入的角度不同會造成橋墩位移反應、支承垂直向反力變化以及抗拉拔裝置作用時機不同，進而影響PFPI以及整體橋梁的動力行為。另為觀察抗拉拔裝置作用時對曲線橋梁之影響，本研究以相同震波對有無安裝抗拉拔裝置之曲線橋梁分別進行實驗，並比較兩者之支承位移、橋墩頂部位移、支承反力以及遲滯迴圈等差異。比較結果顯示，抗拉拔裝置在作用前並不會造成任何影響，當其作用時，會限制支承位移，瞬間增加支承反力以及支承回復力，且其作用力會造成該瞬間橋墩位移增加。本研究另選取實驗所測得之最大震波數據與基於等效節點割線特性之隱式動力分析程序(Implicit Dynamic Analysis Procedure based on Equivalent Nodal Secant Properties，簡稱為IDAP-ENSP)數值分析結果進行比較，兩者結果擬合良好，並以該數值模型進行三向震波分析，以模擬曲線橋樑遭遇三向地震時之行為。
;This study focuses on a shaking table test of a single-span curved bridge equipped with uplift restraint devices and Polynomial Friction Pendulum Isolators (PFPI). Previous studies have demonstrated that the sixth-order polynomial surface of PFPI can provide varying stiffness based on the displacement of the isolator, thereby preventing excessive displacement during near-fault earthquakes. However, previous research also revealed that when PFPI is applied to curved bridges, the difference in reaction forces between the inner and outer isolators tends to be amplified under seismic forces, potentially causing the PFPI to separate vertically, leading to the risk of bridge collapse. To address this issue, this study introduces anti-uplift devices to the single-span curved bridge to prevent vertical separation of the PFPI and to limit the maximum displacement of the PFPI.
This study first investigates the impact of seismic wave input angles on curved bridges subjected to unidirectional seismic waves, aiming to understand the differences in dynamic behavior of curved bridges under varying input angles. Experimental results indicate that changes in input angles of unidirectional seismic waves lead to variations in pier displacement responses, vertical reaction forces of the isolators, and the activation timing of the anti-uplift devices, thereby influencing the dynamic behavior of both the PFPI and the overall bridge structure.
To examine the effects of anti-uplift devices on curved bridges, experiments were conducted on curved bridges with and without anti-uplift devices under identical seismic waves. The differences in isolator displacements, pier top displacements, isolator reaction forces, and hysteresis loops were compared. Results show that the anti-uplift devices do not affect the structure before activation. When activated, they limit isolator displacements, instantly increase reaction forces and restoring forces of the isolators, and momentarily increase pier displacement due to their action.
Additionally, the maximum seismic wave data obtained from the experiments were compared with numerical analysis results derived from the Implicit Dynamic Analysis Procedure based on Equivalent Nodal Secant Properties (IDAP-ENSP). The results showed good agreement. This numerical model was further used for three-directional seismic wave analysis to simulate the behavior of curved bridges under tri-directional earthquakes. |
