搖晃機制在高橋墩橋梁減震之應用

Abstract

未來我國東部公路、中橫以及南橫等計畫國道橋梁多須縱橫於高山縱谷之間，配合工址特殊地形、地貌以及景觀，長跨徑、高橋墩橋梁乃必然之發展趨勢。儘管目前隔震、消能技術在橋梁工程之應用已臻成熟，但長跨徑、高橋墩橋梁之結構特性卻不同於一般橋梁，其長周期特性使得習用之隔、減震裝置或設計方法並不適用。因此，本研究將搖晃機制引入高橋墩橋梁之減震設計，並針對一A字型橋墩構架建立數值模型以預測其受震反應。同時，本研究亦完成搖晃橋柱縮尺模型之振動台試驗，以驗證晃動機制之減震功效，並據以修正數值模型。試驗結果顯示，搖晃機制可有效降低上部橋構之加速度反應，且地震強度愈大減震效益愈顯著；此外，數值模擬預測與試驗結果亦相當吻合。

The national highways in the eastern Taiwan under planning are expected to lie in between mountains and valleys. To accommodate the in-situ geographical and scenic conditions, construction of long-span and high-pier viaducts is necessitated. In spite the seismic isolation and energy dissipation technology has been matured in bridge application, the customary seismic isolation design is not applicable to long-span and high-pier viaducts with inherently long-period dynamic characteristics. In this study, the rocking mechanism is introduced for aseismic design of high-pier viaducts. An analytical model for seismic response analysis of A-frame rocking structures is developed. Meanwhile, a series of shaking table tests of a scaled-down rocking pier model has been carried out to verify the effect of rocking mechanism in seismic response mitigation, and the analytical model is modified accordingly. Experimental results show that the rocking mechanism effectively reduces the acceleration response of the superstructure, and the stronger the earthquake, the better the control efficiency. Moreover, numerical simulations show very good agreement with the test results.