| 摘要: | 傳統摩擦單擺支承(FPS)隔震週期與近域地震相近，易產生共振現象，而勁度可變式滑動隔震支承(Sliding Isolators with Variable Curvature, SIVC)可改善此缺點，其隔震週期隨位移變化，可分為兩階段:軟化段支承勁度隨位移增加而減小，可減緩結構之加速度反應；硬化段內支承勁度隨位移增加而增加，其可降低結構之位移反應。此效果可有效減少共振情形發生，更可降低橋面版位移。前人研究中，證實將SIVC中曲盤為六次方程式之多項式摩擦單擺支承(Polynomial Friction Pendulum Isolator, PFPI)用於等高或不等高之直線橋梁均可充分發揮其隔震效果，無論於近/遠域震波中皆有良好之表現。
但過去文獻少有使用PFPI於曲橋之案例，本研究延續前人水平曲梁橋之研究結果，數值分析方面採用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)，比較
含PFPI單、多跨曲橋於各種變因下之動力行為，改變參數為曲率、不同支承配置與震波輸入角度，另採多組不同震波進行分析，並將PFPI支承以FPS替代後比較其分析結果。而研究數據顯示曲梁曲率半徑減少、震波輸入角度越大，支承反力與大梁內力差值增加，而不同配置亦造成相異之力學行為。兩種支承比較中，PFPI隔震支承支承反力雖大於FPS，但PFPI隔震支承位移遠小於FPS，證明PFPI於水平曲梁橋下亦有良好的隔震表現。
另外為更加貼近真實情況，本研究亦採用真實雙向震波數據進行分析，從結果可發現除震波輸入角度影響不明顯外，其行為與單向震波分析類似；針對橋墩柱底的塑鉸行為另以Takeda模型進行模擬，可觀察到影響主要發生在大梁內力，加上Takeda模型後單跨大梁內力減少、多跨斷面內力增加。
;The traditional Friction Pendulum System (FPS) isolator has an isolation period similar to near-field earthquakes, making it prone to resonance. However, the Sliding Isolators with Variable Curvature (SIVC) can address this drawback. The isolation period of SIVC varies with displacement and can be divided into two stages: the softening stage, where the bearing stiffness decreases with increasing displacement, reducing the structure′s acceleration response; and the hardening stage, where the bearing stiffness increases with increasing displacement, thereby reducing the structure′s displacement response. This effect can effectively reduce the occurrence of resonance and further decrease the displacement of the bridge deck. Previous studies have confirmed that the Polynomial Friction Pendulum Isolator (PFPI) with a polynomial friction pendulum of sixth-order equation in the SIVC can fully exhibit its isolation effect when applied to straight bridges of equal or unequal height, performing well under both near-field and far-field seismic waves.
However, there have been few cases in the literature using PFPI for curved bridges. This study extends previous research on horizontally curved girder bridges. In the numerical analysis, an Implicit Dynamic Analysis Procedure based on Equivalent Nodal Secant Properties (IDAP-ENSP) was used to compare the dynamic behavior of single-span and multi-span curved bridges with PFPI under various conditions. The parameters varied included curvature, different support configurations, and seismic wave input angles. Multiple sets of different seismic waves were analyzed, and the results were compared with those where PFPI supports were replaced by FPS. The research data showed that as the radius of curvature of the girder decreased and the seismic wave input angle increased, the difference in bearing reaction forces and internal forces of the girders increased, and different configurations also resulted in varying mechanical behaviors. In the comparison between the two types of supports, while the bearing reaction force of the PFPI isolator was greater than that of the FPS, the displacement of the PFPI isolator was significantly smaller than that of the FPS, proving that the PFPI exhibits good isolation performance in horizontally curved girder bridges.
Moreover, to better simulate real conditions, this study also used real bi-directional seismic wave data for analysis. The results indicated that, apart from the input angle of the seismic wave having an inconspicuous effect, the behavior was similar to that of the unidirectional seismic wave analysis. For the plastic hinge behavior at the base of the pier columns, the Takeda model was used for simulation. It was observed that the impact mainly occurred in the internal forces of the girders. With the addition of the Takeda model, the internal forces of the single-span girders decreased, while the internal forces of the multi-span sections increased. |
