A comparative study of the buffeting properties of FRP and steel box girder cable-stayed bridges

Abstract

基于某三跨钢箱梁斜拉桥的设计方案以及静力荷载作用下刚度等效的假设,类比设计了一座FRP斜拉桥。其桥面板、主梁以及斜拉索均采用FRP材料,桥塔采用传统的钢筋混凝土结构。采用谐波合成法模拟了主梁上各点的随机脉动风速时程,基于准定常假定,将脉动风速时程转化为抖振力时程,采用ANSYS软件对FRP斜拉桥进行抖振时域分析,并与钢箱梁斜拉桥进行对比。结果表明,FRP斜拉桥在抖振载作用下主梁竖向刚度与钢箱斜拉桥相比,有一定程度的减小,但FRP斜拉桥的竖向位移只是略有增加,总体易满足位移限值的要求。 In this paper,the time domain buffeting analysis of a three-span FRP cable-stayed bridge("FRP bridge"hereafter for brevity) is conducted.The FRP cable-stayed bridge has FRP deck systems,FRP main girders and FRP cables,it is formed based on the design scheme of a steel streamline shaped box girder cable-stayed bridge("steel bridge"hereafter for brevity) and the equivalent stiffness method.For cost effectiveness,the bridge tower is still made of traditional reinforced concrete.The wind field of the bridge is simulated and the turbulent wind speed time series are obtained based on the WAWS(Weighted Amplitude Wave Superposition) method.Afterwards,the turbulent wind speed time series are transformed to buffet force time series using the quasi-steady hypothesis.The buffeting analysis result of the FRP bridge is compared with that of the steel bridge.The analytical results reveal that compared with the steel bridge,the vertical stiffness of FRP cable-stayed bridge is decreased to a certain extent,and as a consequent,the vertical displacement of the FRP bridge is slightly increased but still within the displacement limit.