S形曲线钢箱梁斜拉桥沥青混凝土摊铺温度效应分析

Analysis of Temperature Effect on an S Cable-Stayed Bridge with Steel Box Girder During Asphalt Concrete Placement

大连滨海大道西延伸线张柏2号高架桥主桥为(50+96+192+70)m S形曲线钢箱梁斜拉桥,桥面铺装层采用热浇注式沥青混凝土摊铺方法施工,摊铺过程中出现了结构位移和应力较大等异常情况。为了解异常情况产生的原因,采用ANSYS软件建立全桥有限元模型(钢箱梁采用壳单元模拟),分析摊铺过程中温度引起的桥塔纵、横向位移,以及主梁纵向、竖向位移和纵向应力。结果表明:摊铺温度导致结构产生较大的位移和应力,主梁和桥塔纵向位移均达22.8 cm,主梁最大竖向位移为25.9 cm,钢箱梁最大拉应力为143 MPa;摊铺过程中,结构纵、横向均存在较大的位移差和应力差,导致变形不协调和局部应力过大;结构位移、应力的计算值与实测值基本一致。该类桥梁施工时应调整摊铺工艺,降低摊铺温度效应。

The Zhangbai No.2 Viaduct is part of the west extension of the Seaside Avenue in Dalian,the main bridge of which is an S cable-stayed bridge with steel box girder and with spans of 50,96,192 and 70 m.The asphalt concrete deck pavement took form by hot pouring method.During the placement of the asphalt concrete,abnormal conditions,like oversized structural displacement and stresses,were observed.To investigate the causes of the abnormal conditions,the software ANSYS was used to build the finite element model of the overall bridge(steel box girder was modeled by shell elements),to analyze the longitudinal and transverse displacement of the pylons as well as the longitudinal and vertical displacement and longitudinal stresses of the main girder that were all caused by temperature variation in the placement process.The results demonstrate that the temperature variation during the placement of the asphalt concrete induced large structural displacement and stresses,the maximum longitudinal displacements of the main girder and pylons all reach up to 22.8 cm,the maximum vertical displacement of the main girder is 25.9 cm,and the maximum tensile stress of the steel box girder is 143 MPa.In the placement process,big displacement and stress differences in both the longitudinal and transverse directions exist in the structure,resulting in unbalanced deformation and oversized local stresses.The computed and measured data of the structural displacement and stresses are basically in accord.During the construction of the bridge of such type,the placement technique should be adjusted,so as to reduce the temperature effect of asphalt concrete placement.