橋梁基礎裸露之耐震性能現地實驗與成果探討

本文以一座因沖刷裸露問題而待拆除的橋梁為研究對象，進行3組反覆側推及1組擬動態實驗。橋梁建於1995年，受測試之3根單柱式橋墩斷面直徑1.8 m，其主筋比、箍筋比及高寬比分別為0.95%、0.294%、5.3～5.7。P2、P3、P4橋墩分別為擬動態實驗試體、標竿試體，沉箱沖刷裸露試體，對應之沉箱裸露深度為0 m、1.2 m及4 m。實驗結果顯示，當受到0.32 g設計地震作用時橋墩主要維持彈性，反覆側推下雖最大強度可達設計彎矩強度且最大層間位移角可達5%，但因耐震細節未滿足現行規範規定而發生橫向鋼筋鬆脫及主筋挫屈現象。本橋因座落於卵礫石層且基礎經擴座補強，即使沉箱裸露1/3長度對耐震性能影響有限。此外，本研究採用OpenSees進行有限元素分析，經驗證可有效預測橋墩之非線性靜力與動力行為。相關經驗與成果可提供規劃樁基礎橋梁現地實驗，及檢核既有橋梁耐震評估結果之參考。

關鍵字

現地實驗；橋墩；沖刷；耐震性能

並列摘要

This paper presented a series of in-situ seismic performance tests of a bridge before its demolition due to accumulated souring-induced problem. The experiment programs included three cyclical loading tests and one pseudo-dynamic test. Built in 1995, the tested three single piers was 1.8 in diameter with longitudinal ratio of 0.95% and lateral reinforce ratio of 0.294%. The aspect ratio ranges from 5.3 to 5.7. P3 column represents a benchmark specimen with exposed length of 1.2 m, while P4 was exposed up to 4 m. P2 was subjected to code-compatible ground acceleration and then followed by a one-cycle pushover test. Based on the test results, the bridge behaved mostly elastic under 0.32 g excitation. The ultimate lateral strength obtained could satisfy design target of plastic hinge moment, and the maximum drift ratio reached 5%. However, insufficient design of lateral reinforcement without seismic hook resulted in buckling of longitudinal reinforcements and loose of lateral reinforcements. Besides, it was due to gravel material and retrofitted caisson which provided large lateral resistance, even exposed 1/3 of the caisson length, the seismic performance among three piers had minor difference, and had been compared by the proposed analytical model in OpenSees with good accuracy. The experience learnt was hoped to beneficial the planning of in-situ test of a piled bridge with scouring issue, and to verify the seismic performance of bridges with similar conditions.

並列關鍵字

in-situ test ； pier ； scouring ； seismic performance

國際替代計量

橋梁基礎裸露之耐震性能現地實驗與成果探討

全文下載

主題瀏覽