脊背橋動力試驗之模擬分析

Abstract

近年來脊背橋已有運用在台灣之案例。由於台灣位於地震頻繁之區域，有必要對脊背橋之動態特性進行探討。本研究主要針對脊背橋在地震作用或車行載重下之模擬分析，探討其動態特性。論文內容分成三大部分來探討。首先，量得素地之微地動反應，識別出基地之顯著週期。再利用有限元素軟體SAP2000建立橋梁模型，比較不同鋼纜預力值對模態之影響；並模擬地震反應，以不同數量之預定量測點反應識別脊背橋之動態特性(頻率、阻尼比與模態)，並與理論值比對，驗證識別結果之正確性。最後，利用SAP2000模擬車行載重之分析，討論不同車流下之動力放大係數。

Extra-dosed bridges have been used in Taiwan where earthquakes occur frequently. It is necessary to investigate the dynamic properties of extra-dosed bridges in depth. The main purposes of the work are to determine the dynamic properties of extra dosed bridges from its simulated responses of dynamic tests. This thesis includes three subjects : (1) to determine the predominant period of the site where the extra-dosed bridge will be built from the ambient vibration responses of the ground；(2) to identify the model parameters of the extra-dosed bridge under consideration from its simulated earthquake responses, which are computed by the commercial finite element package SAP2000；(3) to estimate the dynamic amplification factors of the bridge from its simulated responses under different traffic loads.