目前台灣地區大部份的老舊橋梁,普遍面臨著不符現行耐震設計規範要求及相關法規變革之考驗,更由於台灣屬於高地震發生區、特有海島型氣候或因不當超載使用等外在環境之影響,造成未達使用年限時,即發生結構劣化、功能不足的情況。本研究群近年來從事光學影像相關係數法的研究,並已自行開發分析軟體 ( DIC-C ),此種檢測方法是具有高精度、低成本以及非接觸式量測的特點,避免了佈放大量感應裝置於大型結構物所需的大量人力物力。 本研究利用數位影像相關係數法分析橋梁多點翼版位移監測資料,嘗試將其資料分析出橋梁破壞影響線以及以頻率域分解法(FDD?frequency domain decomposition ) 加以分析,求取振動頻率及振形,以辨識橋面板的振動頻率、阻尼比及模態來評估橋梁狀況。另外本研究也建立有限元素分析模型,模擬完整無損傷、有損傷之橋梁經由重車經過後,求出影響線以及橋翼板的振動頻率及振態等振動特性,並以此推測橋梁是否損傷。 分析結果顯示以有限元素模擬與實地檢測所得的橋梁位移有相近的趨勢,動態監測的結果則有待進一步的分析與確認。
Deteriorated bridges managed by the local authorities often lack sufficient resources for sophisticated long-term maintenance and monitoring programs. There is a great demand of low-cost and efficient monitoring techniques suitable for bridge management. Previous study has indicated that images recorded using consumer digital cameras and processed by digital image correlation methods (DICM) has the potential to fulfill such a need. Current research applies DICM to obtain the displacement data that can be further analyzed using frequency domain decomposition, or FDD. Two bridges with light traffic conditions have been investigated. The measured displacement data are in reasonable agreement with the simulated data using SAP2000. Modal analysis and FDD are also performed using the numerical model for the two bridges. The modal frequencies and damping ratio values are also obtained based on the field experiments but require further verifications with the numerical simulation.