大跨度板桁结合斜拉桥施工阶段温差效应研究

摘要

为了研究施工过程中温度场对板桁结合斜拉桥控制线形的影响效应,结合主梁温度场,对施工状态下的未铺装钢结构板桁进行了24 h连续测试.实测数据表明:在日照情况下,板桁结合主梁温度场为正温差梯度分布;在夜晚情况下,板桁结合主梁温度场为负温差梯度分布.利用实测温度场数据,建立有限元模型并进行了分析.研究结果表明:板桁温差效应对控制线形的影响明显.由板桁正温差引起的主梁竖向位移达到15.66 cm,上、下弦杆的纵向伸缩差达到1.66 cm;由板桁负温差产生的主梁竖向位移为2.15 cm,上、下弦杆的纵向伸缩差较小(0.23 cm).通过计算值与实测值进行对比,板桁温差效应占结构总响应的55%左右.%In order to study the effect of temperature field on the control linearity of plate-truss combined cable-stayed bridge during construction,combined with the specific background of the project,the 24 h continuous test of the temperature field of non surfacing steel structure plate-truss composite beam in the construction state is carried out.The measured data show that the temperature field of plate-truss composite beam is a positive temperature gradient distribution during the daytime sunshine.At night,the temperature field of plate-truss composite beam is with negative temperature gradient.The results of finite element analysis show that the effect of temperature difference of plate truss on the control line is obvious by using the measured temperature field data.The longitudinal displacement of the main girder caused by the positive temperature difference of the plate truss is 15.66 cm,and the difference of the longitudinal extension between the upper and lower chord is 1.66 cm.The vertical displacement of the main girder caused by the negative temperature difference of the plate girder is 2.15 cm,and the difference of longitudinal extension between the upper and lower chord is 0.23 cm.By comparing the calculated value with the measured value, the effect of temperature difference between the plate and the truss accounts for about 55% of the total response of the structure.