三塔斜拉桥抖振的耦合行为研究

COUPLED BEHAVIOR IN BUFFETING RESPONSE OF THREE-PYLON CABLE-STAYED BRIDGE

三塔斜拉桥较为柔性,振动模态较为密集,对风更为敏感。以京沪高速铁路南京长江大桥为工程背景,基于多模态耦合振动分析理论,对三塔斜拉桥抖振的耦合性能进行了研究。分别采用多模态耦合抖振分析方法和非耦合的单模态SRSS(Square Root of Sum of Squares)方法对结构在设计风速下的抖振响应进行了分析,将两种分析方法所得抖振响应的均方根及功率谱密度函数进行比较。为明确模态间的耦合关系,进一步分析了结构抖振响应随参与分析模态数的变化情况。分析结果表明:三塔斜拉桥抖振响应存在明显的多模态耦合效应,模态间的耦合作用将增大结构的抖振响应。对于大跨度桥梁的精细化分析,抖振的耦合行为不容忽视。

Three-pylon cable-stayed bridges with two main spans are more flexible. The vibration modes of the bridge are close to each other. Based on the multimode coupled buffeting analysis, coupled behavior in buffeting response of three-pylon cable-stayed bridges is investigated. Buffeting response of a three-pylon cable-stayed bridge is analyzed at design wind speed by multimode coupled analysis method and one-mode SRSS method, respectively. The coupled effect is neglected in one-mode SRSS (Square Root of Sum of Squares) method. RMS (Root Mean Square) and PSD (Power Spectral Density) of buffeting response by the two methods are compared with each other. In order to indicate the coupled relations among the analyzed modes, the evolution of buffeting response with a number of modes is analyzed. It is shown that there is significant coupled behavior in buffeting response of three-pylon cable-stayed bridges. The coupled interaction among analyzed modes can increase the buffeting response. The coupled effect of buffeting response should not be neglected in the refined analysis of long-span bridges.