集鹿大橋震害評估與修復之研究
Date Issued
2004
Date
2004
Author(s)
周智傑
DOI
zh-TW
Abstract
A disastrous earthquake struck central Taiwan at 01:47 of September 21, 1999 (Taiwan local time). The Seismology Center of the Central Weather Bureau (CWB) determined the magnitude of this earthquake to be ML 7.3 (CWB) and MW 7.7 (Harvard CMT). The earthquake caused heavy casualties and structural damages to bridges and buildings.
In the damaged areas, the only cable-stayed bridge, called Chi-Lu, was in the final stages of completion at the time of the earthquake. This bridge connected Chi-Chi to the small town of Lu-Ku across the Juoshuei River. Viaducts ran from both banks of the river to the ends of the cable-stayed bridge. The bridge, designed by T.Y. Lin International, was supported on a single pylon, which was connected to the center of the girder by two rows of cables.
In this article, the damages suffered by the Chi-Lu cable-stayed bridge are reported. Severe damage occurred in the deck on the southern side of the bridge. Additional damage occurred in the pylon. Below the girder, the central pier showed evidence of only minor cracking. However, above the girder there were severe spalling of the cover and a crack extended upward nearly to the level of the lowest cables. The seismic performance of the bridge was evaluated by computer modeling. The damages predicted by the computational results were compared to those incurred on the bridge.
Besides, in order to provide limited transportation service for small car after completing first stage retrofit, the Taiwan government asked NCREE to plan a loading test for traffic safety. In this test, there were four parts of design loadings would be considered, torsion, full loading on one span of the bridge, full loading on both spans of bridge and increasing loading gradually. About the results of the loading test, it will be compared with the numerical analysis results, and find the reason for the difference between the two results.
To evaluate the structural safety of the bridge during retrofit phases, the ambient vibration method was applied to measure the time-history vibration data for identifying the dominant frequencies. Then, an empirical method was used to calculate cable forces from measured frequencies. Further, several important parameters used in calculation formula were verified in the arranged tests stage-by-stage in accordance with the retrofit schedule.
In the future, for the safety purpose of the long-term service, it is important to realize the stress status of Chi-Lu cable-stayed bridge. Because of the change of the structural system during retrofit, it is difficult to determine the internal force of the Chi-Lu cable-stayed bridge by only numerical analysis. Therefore, a procedure for determining the internal force of the bridge is brought out in the article. It firstly transfers the structure of the Chi-Lu cable-stayed bridge to be determinate status by using the experimental data of lift-up test and amberiment vibration measurement, and then the stress status of the bridge can be obtained conducting through numerical analysis.
Subjects
鋼纜索力
載重試驗
集鹿橋
斜張橋
破壞
橋梁內力
Chi-Lu Bridge
cable stayed bridge
loadin
damage
SDGs
Type
thesis
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