人行拱橋顫振與抖振分析

FLUTTER AND BUFFETING ANALYSIS OF PEDESTRIAN ARCH BRIDGES

林堉溢(Yuh-Yi Lin) ； 羅元隆(Yuan-Lung Lo) ； 陳柏勳(Po-Shiun Chen) ； 黃明慧(Ming-Hui Huang)

《中國土木水利工程學刊》 29卷1期 (2017/03) Pp. 27-36

https://doi.org/10.6652/JoCICHE/2016-02901-04

摘要

長跨徑人行拱橋近年來深受工程師青睞，此類型之橋梁除了滿足交通需求外，更扮演當地景觀地標的角色。因為人行拱橋的橋面板較窄，大多採用單拱設計，而單拱構造缺乏側向支撐，拱橋順風向之氣動力反應也越趨明顯。基於此，本文建立一數值分析模式，以主樑斷面及橋拱斷面之顫振導數及風力係數為基礎，推導人行拱橋整體結構之顫振與抖振理論。並採用兩範例來探討加入橋拱風力對整體顫振臨界風速與抖振位移反應影響。結果顯示，橋梁顫振之臨界風速主要受主樑氣動力行為控制，橋拱順風向顫振導數對顫振影響並不顯著。抖振分析方面，兩例之計算結果都顯示拱風力對拱及主樑垂直向反應影響不大，但對於順風向及扭轉向反應有顯著影響。當橋面高度之平均風速60 m/s 時，加入橋拱風力對第一範例中主樑順風向與扭轉向之抖振位移反應分別提高1.9% 及44.11%；對第二範例則分別提升了11.99% 及133%。由於影響顯著，因此分析時須詳加考慮。

關鍵字

人行拱橋 ； 斷面實驗 ； 顫振 ； 抖振

並列摘要

The long-span arch bridges have been a favorable choice for the pedestrian bridge design during the past decade in Taiwan. It is because this type of bridges not only satisfies the transportation demands but also forms a landmark structure in local areas. Among these bridges, a single arch design is often adopted; however, due to its narrow bridge deck, the single arch lacks lateral support and the significant drag response along the arch cannot be negligible. In this paper, an analytical approach based on flutter and buffeting theory associated with the identified information from section model tests is proposed. Two examples are provided to demonstrate the validity and the applicability of this proposed approach and to investigate the effects of the forces acting on the arch on the flutter wind speeds and buffeting responses of the bridges. The results show that the critical flutter wind speeds are dominated by the flutter derivatives of bridge decks. The increases of the critical flutter wind speeds with the consideration of flutter derivatives of arches are less than 1%. For the buffeting responses, the effects of the forces acting on arches are insignificant on vertical responses of arches and bridge decks and significant on both drag and torsional responses. In Example 1 incorporating forces acting on the arch into the analysis, the drag and torsional responses of the bridge deck increase 1.9% and 44.1%, respectively. In Example 2 incorporating forces acting on the arch into the analysis, the drag and torsional responses of the bridge deck increase 11.99% and 133%, respectively. Since the effects of the forces acting on the arch on the responses of the arch and the bridge deck are significant, these forces should be considered in the analysis.

並列關鍵字

pedestrian arch bridge ； flutter ； buffeting ； section model test