结合梁斜拉桥悬臂施工阶段剪力滞效应分析

摘要

为研究结合梁斜拉桥在悬臂施工阶段剪力滞效应的分布规律,以厦漳跨海大桥南汊主桥为背景,在实桥中布设4个测试截面,并采用ANSYS软件建立主梁有限元分析模型,对施工阶段结合梁的剪力滞效应进行现场测试和数值分析.分析结果表明:结合梁斜拉桥主梁在斜拉索轴向荷载和竖向荷载产生的弯矩共同作用下,存在较为显著的负剪力滞效应;在整个悬臂施工阶段,各截面有效宽度系数为0.85～0.95.根据分析结果,建议在对悬臂施工阶段进行应力验算时,混凝土板的应力应按初等梁理论计算的结果提高15％考虑;设计过程中可以忽略小纵梁对桥面结构剪力滞效应的影响,计算结果偏于安全.%To study the distribution law of the shear lag effect of composite girder cablestayed bridge at cantilever construction stage,the south main bridge of the Xiazhang Sea-Crossing Bridge was cited as an example.4 measured sections were selected on the bridge,the software ANSYS was used to set up the finite element analysis model for the main girder of the bridge and the shear lag effect of the composite main girder at the cantilever construction stage was measured in field and numerically analyzed.The results of the analysis indicate that under the joint action of the bending moment produced by axial load and vertical load of the stay cables,the main girder of the cable-stayed bridge presents obvious negative shear lag effect.In the whole cantilever construction stage,the effective width coefficients of the different sections range from 0.85 to 0.95.With reference to the analysis,it is proposed that the stress checking calculation of the construction stage should be made and the stress of the concrete deck slabs should be considered 15％ higher than the results calculated according to the preliminary beam theory.In the design,the influence of the stringers on the shear lag effect of the deck structure can be neglected and the calculation will tend to be safe.