過去世界已發生多起橋梁損壞之大地震，各國於地震後不斷修正 設計規範。依據設計反應譜由橋梁週期求得地震加速度反應推算出橋 梁之受力，再進行設計與檢核。 相關研究已證明直接基礎之搖擺效應(Rocking effect)能降低傳遞 至上部結構之地震力且延長結構之週期，並藉由土壤進入塑性之行為 可吸收地震能量，能使橋柱底於大地震中所受損傷甚為輕微亦或無損傷。 現今日本、美國已經將直接基礎搖擺設計納入規範中供工程師參 考，然而台灣公路橋梁耐震設計規範目前未將搖擺設計納入，使設計 上有較為保守之情況。因此，本研究將探討日本道路橋梁示方書與美 國ASSHTO規範於目前台灣現有直接基礎橋梁之適用性，改變橋面板 質量、柱高、基礎尺寸與不同形式土壤彈簧繪製搖擺反應之反應譜， 發現非線性土壤彈簧下柱底剪力減少比例為19%。此外，研究將橋梁 搖擺反應加速度分解，試圖找出搖擺反應如何降低橋梁動力反應。;In the past, there have been many major earthquakes damaging bridges. Countries have modified their design codes after the earthquake. In addition, when engineers design the structure, almost using the design response spectrum to make sure about the force and check. According to passed research, it has been proved that the rocking effect of the spread foundation can reduce the seismic force and extend the period. It will absorb the seismic energy due to the behavior of the soil entering plasticity, and can make the damage of the bottom of the bridge slight or no damage. Nowadays, the United States and Japan has joined the rocking effect of the spread foundation into the specification for engineering. However, the code in Taiwan currently does not include the rocking effect and the spread foundation just can be designed as a fixed foundation without rocking. This makes the design conservative. Therefore, this study will refer to ASSHTO and Japan Specifications for Highway Bridge, and change the parameter like deck mass, column height, foundation size, and different forms of soil springs to make sure the respond of rocking effect. After drawing respond Spectrum and counting the percentages of absorbing the energy, found that the decreasing ratio of shear force at the bottom of the column under the non-linear soil spring is reduced by 19%. In addition, the study dismantled the acceleration of the deck to find out the meaning of the rocking respond.
