直接基礎橋梁透過搖擺機制可以延長結構振動週期降低地表傳 遞至上部結構之地震力，於大地震中亦可藉由土壤塑性行為吸收地震 能量。橋墩高度改變將影響結構週期，亦將影響動力反應。本研究以 單跨鉸支承橋梁為研究對象，包含兩座等高橋墩試體與一座不等高橋 墩橋梁試體，進行一連串振動台實驗，並利用SAP2000 程式建立數 值模型，探討橋墩高度與不等高橋墩發生基礎搖擺時之動力反應差異， 並比較基礎尺寸及土壤勁度等因素之影響程度。 試驗結果顯示，試體於直接基礎搖擺反應下皆使橋墩頂位移增加， 但可降低傳至上部結構之地震力，而橋墩高度不同亦造成影響。此外 不等高橋墩橋梁試體採用鉸支承，由於橋面板束制兩橋墩之反應，導 致長短橋墩之側向反應差異不大，因此短橋墩底基礎產生較大旋轉角。;The rocking behavior of bridge with spread foundation considering the irregular height of piers is investigated in the research. In that purpose, there are three kinds of the models have been set up, including two equal height pier of the bridge model and one model combined by two unequal height piers. This research contains a series of shaking table tests, same while SAP2000 software is adapted to simulate the test results. The results show that different height of piers could cause a discrepancy of the contribution of the other factors to the rocking degree. But in general, the rocking mechanism leads to increase the displacement of the top of the piers, but also decrease the acceleration at the same time.
