考虑下层人非通道影响的大跨钢桁架拱桥抗风性能研究

Wind Performance Analysis of Large-span Steel Truss Arch Bridges Considering the Effects of the Underpass Pedestrian-non-motored Deck

大跨径钢桁拱桥是一种对风荷载较为敏感的桁架结构,现以株洲清水塘大桥为研究对象,开展了下层人非通道对全桥结构抗风性能的影响研究。首先建立了有限元分析模型,比较了有无下层人非通道对全桥结构振型与频率的影响。通过主梁节段模型风洞试验,开展了有无下层人非通道的主梁振动特性研究。研究表明,设置人非通道后,主梁涡激振动得到了显著抑制。之后,进一步通过节段模型测力风洞试验,对比了有无人非通道的断面静气动力系数的变化情况。主梁静气动力系数测力风洞试验结果表明,设置人非通道后,主梁阻力系数与升力系数均增大,升力矩系数未发生明显变化。最后,开展了全桥结构风荷载效应分析。结果表明,考虑人非通道后,主梁与拱肋横向位移极值响应有明显增大。其中,主梁横桥向位移增大约44%,主拱横桥向位移增大约18%。

Large-span steel truss arch bridges are highly sensitive to wind loads.Taking the Qingshuitang Bridge in Zhuzhou as the research object,the effects of the Underpass Pedestrian-non-motored Deck(UPMD)on the wind resistance performance of the whole bridge were investigated.Firstly,a finite element model of the bridge was established to compare the influence of the UPMD on the mode shapes and frequencies of the entire bridge structure.Through sectional model wind tunnel tests,the wind-induced vibration characteristics of the main deck,both with and without the UPMD,were studied.The test results show that the vortex-induced vibration of the main deck is significantly suppressed with the UPMD.Then,the static aerodynamic coefficient measurement wind tunnel test for the main deck was conducted.The results show that,with the UPMD,both the drag coefficient and lift coefficient of the main deck increase,while the pitching moment coefficient shows no significant change.Finally,a wind load effect analysis of the entire bridge structure was performed.The results show that,with the UPMD,the extreme response of the transverse displacement of both the main deck and the arch rib significantly increases.Specifically,the transverse displacement of the main deck increases by 44%,and the transverse displacement of the main arch increases by 18%.