Seismic Behavior of Reduced Scale Bridge Models with Functional Bearings

本文旨在討論含功能性支承橋梁於地震下的行為。有鑑於國內現行橋梁耐震設計規範及修復補強策略，多偏重於橋柱塑鉸行為，但921集集大地震中並無明顯實例可供參考，若需符合規範要求，則政府單位須編列高額的橋梁補強經費。因此，本文由縮尺橋梁靜動態實驗與分析結果，探討橋梁使用功能性支承的成效。 本研究首先完成含橡膠支承縮尺單跨橋梁之擬動態與振動台實驗，根據實驗結果了解橋梁結構之力量傳遞路徑，並探討兩種試驗方式對描述橋梁動態行為的差異性。此外，本研究中採用非線性分析工具（SAP2000N）進行模擬，經實驗結果比對可獲致良好的結果，並針對磨擦係數與混凝土楊氏係數進行參數分析，量化支承滑動與橋柱勁度的影響。 為進一步了解多跨橋梁的動態行為，本研究執行含橡膠支承縮尺雙跨橋梁之振動台實驗。結果顯示，橡膠支承發生滑動後可降低橋面版加速度及橋柱剪力，有助於降低下部結構震害受損機會。因此，本研究建立合適的分析模型，能有效預測橋面版之最大位移與最大加速度反應，掌握落橋及橋柱損壞時機。Study on the seismic behavior of the bridge with functional bearings is presented in this thesis. In Taiwan, only a few studies draw attention on the bearing until 1999 Chi-Chi earthquake. Before that researchers are putting much effort on the bridge column to minimize damages under large ground motion, according to the specification of seismic design of Highway bridges or seismic retrofit manual. However, with small amount of retrofitted bridges being proved available in the earthquakes and limited national budget placed on the retrofitting plan of bridges, it is important to provide an economical approach by entitling appropriate function to the bearing system. In this study, two experimental programs were carried out to understand friction/sliding mechanism for the bridge equipped with rubber bearing and PTFE-rubber bearing. Firstly, by examining the performance of same reduced-scale single span bridge from both pseudo-dynamic test and shaking table test, it is found the loading path from superstructure to substructure well satisfies the relationship of force balance at anytime, no matter the bridge is sliding or not. Meanwhile, sliding of bearing contributes a fuse-like function to protecting columns from suffering large shear force. The major difference of obtaining structure responses via those two methods is due to the velocity-related behavior of friction coefficient, giving a conservative estimation of force from the shaking table test and displacement from pseudo-dynamic test, respectively. In addition, analytical results by utilizing SAP2000N are well satisfied with the experimental data. It is useful to perform a better parametric analysis when dealing with friction coefficient and the Young’s Modulus of concrete. The behavior of a reduced-scale two spans bridge with rubber bearings in the shaking table test was introduced in the second part of the study. From experimental data and analytical results, it can be found that the sliding of bearing could reduce the demand of inertial force of the girder, as a function of isolation by which the column shear force is largely reduced in the comparison of that from using an ideal hinge- and-roller bearing simulation. Finally, the proposed analytical model is useful to predict the maximum displacement. It is convenient to check the unseating length to avoid falling in a practical manner.誌謝 i 中文摘要 i 英文摘要 iii 第一章 緒論 1 1.1 研究動機 1 1.2 研究內容與架構 2 第二章 文獻回顧 4 2.1 前言 4 2.2 國內的橋梁設計規範 4 2.3 橋梁修復補強之策略 5 2.4 橡膠支承墊之性質與行為 7 2.4.1 橡膠支承墊之構造與特性 7 2.4.2 橡膠支承墊之垂直勁度 8 2.4.3 橡膠支承墊之水平勁度 9 2.4.4 橡膠支承墊之旋轉勁度 10 2.4.5 支承之磨擦性質 11 2.5 小結 14 第三章 含橡膠支承縮尺橋梁之擬動態試驗 15 3.1 前言 15 3.2 擬動態試驗簡介 15 3.3 縮尺理論 17 3.4 試體簡介與試驗配置 18 3.5 試驗規劃 19 3.6 試驗結果與說明 20 3.6.1 橋梁試體主要頻率 20 3.6.2 橋梁試體各構件反應 21 3.6.3 橋柱柱底剪力計算 25 3.6.4 橋梁試驗之力量傳遞路徑 27 3.7 建立橋梁數值分析模型 31 3.7.1 建立橋梁模型的基本概念 32 3.7.2 上部結構與下部結構 32 3.7.3 橡膠支承 32 3.7.4 止震鋼棒 35 3.7.5 分析結果與試驗結果之比較 35 3.8 小結 39 第四章 含橡膠支承縮尺雙跨橋梁之振動台試驗 40 4.1 前言 40 4.2 縮尺雙跨橋梁試體簡介 40 4.3 試驗配置 41 4.4 試驗規劃 42 4.5 試驗結果與說明 43 4.5.1 橋梁試體反應 43 4.5.2 橋梁試體主要頻率 44 4.5.3 橋梁構件之加速度歷時比較 45 4.5.4 橡膠支承墊之磨擦係數 45 4.6 建立橋梁數值分析模型 47 4.6.1 橋柱之剪力需求與剪力容量 48 4.6.2 橋面版加速度歷時比較 52 4.6.3 橋面版位移歷時比較 53 4.7 小結 54 第五章 結論與未來展望 55 5.1 結論 55 5.2 未來展望 56 參考文獻 5