大跨度中承式拱桥的耦合频域抖振分析  

Coupled Buffeting Analysis of Long-Span Half-Through Arch Bridge in Frequency Domain

作　　者：晏致涛[1] 李正良[1] 黄汉杰[2] 

机构地区：[1]重庆大学土木工程学院,重庆400045 [2]中国空气动力研究与发展中心,四川绵阳621000

出　　处：《华南理工大学学报（自然科学版）》2009年第8期110-115,共6页Journal of South China University of Technology(Natural Science Edition)

基　　金：重庆市科委攻关项目(CYB-DQ-H-0002)

摘　　要：大跨度中承式拱桥的主拱风荷载相互干扰,其抖振响应具有多模态耦合的特点.文中基于结构的固有模态坐标,考虑风速沿主拱高度的变化,推导了拱桥结构的节点等效气动抖振力公式.同时,考虑作用于主拱的干扰风谱、风载的空间相干性及主桥与主拱的多模态耦合效应,进行了大跨度中承式拱桥的耦合频域抖振有限元分析.最后以重庆菜园坝长江大桥为例,计算了桥梁结构节点位移和单元脉动内力的功率谱密度和方差响应.分析表明,高阶模态对于大跨度中承式拱桥抖振响应具有较大的影响.此类大跨度中承式拱桥的抖振响应中水平脉动风速功率谱和竖向脉动功率谱的贡献较大,交叉脉动风功率谱可以忽略;与SRSS法相比,CQC法更好地考虑了多模态及模态耦合的影响.The wind loads on the main arch of a long-span half-through arch bridge interfere with each other, and the buffeting response is in a coupled multimode. In this paper, based on the inherent modal coordinates of the structure, the nodal equivalent aerodynamic buffeting forces of the bridge are formularized by considering the wind speed varying with the main-arch height. Then, the spatial coherence of the disturbed wind spectrum of the main arch and the natural wind loads, as well as the multimode coupling of the responses of the main bridge and the main arch, is taken into consideration, and the coupled buffeting of the long-span half-through arch bridge in frequency domain is analyzed via the finite element method. Finally, with the Caiyuanba Yangtze River Bridge in Chongqing as an illustrative example, the power spectrum density and variance response of both nodal displacements and pulsed elemental internal forces of the bridge are obtained. The results show that （ 1 ） the high-order mode greatly affects the buffeting response of the long-span half-through arch bridge; （2） for such types of large-span half- through arch bridges, the horizontal and vertical pulsed wind-speed power spectra play an important role in the buffeting response, while the cross power spectrum of fluctuating wind can be ignored ; and （3） the CQC method con- siders the effects of multi-modal and modal coupling much better than the SRSS method.

关 键 词：拱桥 气动耦合 抖振响应 有限元法 

分 类 号：U441.3[建筑科学—桥梁与隧道工程]