新旧混凝土板桥横向拼接后的收缩徐变效应分析  

Analysis of Shrinkage and Creep Effects on Newly-built and Existing Concrete Slab Bridge After Lateral Jointing

作　　者：涂兵[1] 方志[1] 

机构地区：[1]湖南大学土木工程学院,湖南长沙410082

出　　处：《中国公路学报》2016年第10期66-76,共11页China Journal of Highway and Transport

基　　金：国家自然科学基金项目(51278182)

摘　　要：为更好地分析拼宽桥梁结构在新旧混凝土收缩徐变差作用下的受力机理,以1座钢筋混凝土简支板桥的横向拼宽为例,基于弹性力学平面应力问题的逆解法和混凝土徐变计算的按龄期调整有效模量法,推导了由混凝土收缩徐变差引起的拼宽后结构平面内应力和位移的解析表达,并与既有文献中的试验结果进行对比,验证了所提公式的适用性。实例分析结果表明:对于新旧梁跨径均为8m,宽度分别为9.5,12.5m的情形,拼接缝位置附近的新梁沿纵桥向受拉,旧梁受压,且纵桥向正应力沿梁横向呈明显的非线性分布;远离接缝界面而靠近自由边界的新、旧梁上会分别出现压应力和拉应力,新、旧梁中的最大拉应力分别为2.8,0.3 MPa;新、旧梁在拼接缝位置处4.8 MPa的剪应力和主拉应力的最大值均位于梁端部;新、旧梁混凝土强度比和宽度比主要影响旧梁自由边位置处的拉应力,对结构其他部分的应力影响较小。In order to analyze the stress mechanism of widened bridge based on the shrinkage and creep differences between the newly-built and the existing concrete accurately, taking the lateral joint width of a simply-supported reinforced concrete slab bridge as an example, the analytical expressions of stress and displacements of the widened structure in the girder plane caused by the shrinkage and creep differences were deduced by incorporating the inverse method for plane stress problems in elastic mechanics and the age-adjusted effective modulus method for concrete creep effect calculation, and the proposed formulas were verified by comparing its results with the test results from relevant literatures. The results show that for the newly-built and existing bridges with span of 8 m and width of 9.5 m and 12.5 m respectively, the newly-built beam near the joint interface bears tensile along the longitudinal direction and the existing bridge bears compressive stress, and the lateral distribution of longitudinal normal stress on the cross section of the widened structure is nonlinear obviously; stress and tensile stress respectively appear in the newly-built beam and existing beams near the free boundary and far away from the joint interface, and the maximum tensile stresses in the newly-built and the existing beams are 2.8 MPa and 0.3 MPa, respectively. The maximum shear stress and tensile principal stress of 4.8 MPa on the joint interface are located at the both ends of the beams. The ratios of concrete compressive strengths and widths between the newly-built and the existing structures mainly affect the tensile stress at the free boundary of the existing structure while show insignificant influence on stress of other locations.

关 键 词：桥梁工程 混凝土板桥 弹性力学逆解法 拼宽 收缩徐变 拼接缝 界面应力 

分 类 号：U448.33[建筑科学—桥梁与隧道工程]