多項式摩擦單擺支承（polynomial friction pendulum isolator,PFPI），其曲面為六次方程式的新式變頻滑動支承，其隔震週期隨位移變化，分為兩階段，軟化段:利用回復勁度遞減之特性減緩結構加速度反應；硬化段:利用回復勁度遞增之特性降低結構位移反應。過去研究已證實將PFPI用於等高與不等高橋梁受近域地震與遠域地震皆能有良好之表現。 過去研究少有使用PFPI應用於曲橋之案例，本研究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)，建立有限元素分析模型，並延續前年度採用之橋面板構件，設計下部結構橋墩，進行振動台實驗，並比較不同角度震波情況下，對曲線橋梁之影響，探討支承與橋墩位移、支承遲滯迴圈及支承軸力試驗結果。另進行水平雙向震波試驗以驗證PFPI於曲橋之耐震性能。研究結果顯示當震波由橋軸方向輸入逐漸轉變為由垂直橋軸向輸入時，內外曲梁之支承垂直向軸力差異增大，水平剪力變化亦有相同情形。橋墩位移亦受到震波輸入角度影響，有相反方向之變化。 ;The Polynomial Friction Pendulum Isolator (PFPI) is a novel variable frequency sliding bearing with a sixth-degree equation surface. Its isolation period varies with displacement and is divided into two stages: softening stage, which mitigates structural acceleration response by utilizing the decreasing characteristic of restoring stiffness; and hardening stage, which reduces structural displacement response by utilizing the increasing characteristic of restoring stiffness. Past studies have confirmed that PFPI performs well when applied to both level and unlevel bridge structures under near-field and far-field earthquakes.
There have been few studies applying PFPI to curved bridges. This study employs the Implicit Dynamic Analysis Procedure based on Equivalent Nodal Secant Properties (IDAP-ENSP) to establish a finite element analysis model. Continuing from previous years, the study designs the substructure piers using bridge deck components, conducts shake table tests, and compares the impact on curved bridges under different earthquake wave angles. It investigates the effects on bearing and pier displacements, bearing hysteresis loops, and bearing axial force test results. Additionally, bi-directional horizontal seismic wave tests are conducted to verify the seismic performance of PFPI on curved bridges.
Results indicate that as seismic waves transition from axial to perpendicular input on the bridge axis, the difference in vertical axial forces between inner and outer curved beams increases, similarly affecting horizontal shear changes. Pier displacements are also influenced by the angle of seismic wave input, showing opposite directional changes.
