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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 better analyze the mechanical mechanism of spliced wide bridge structure under the effect of shrinkage and creep of new and old concrete, taking the lateral splicing width of one reinforced concrete simply supported slab bridge as an example, based on the inverse solution of plane stress of elastic mechanics and the concrete The age-dependent effective modulus method of creep calculation is used to derive the analytic expression of the stress and displacement in the plane after splicing width caused by the shrinkage and creep of concrete. Compared with the experimental results in the existing literature, it is verified that The applicability of the formula. The case study shows that the new girders near the splice joint are tensioned along the longitudinal bridge and the old girders are compressed, and the longitudinal bridge to the normal stress Along the beam horizontal obvious non-linear distribution; away from the seam interface and near the free boundary of the new and old beams will appear respectively compressive stress and tensile stress, new and old beams in the maximum tensile stress of 2.8,0.3 MPa; new , And the maximum value of 4.8 MPa shear stress and the main tensile stress of the old beam at the splice joint are all located at the end of the beam. The strength ratio and the width ratio of the old concrete beam and the old concrete beam mainly affect the tensile stress at the free edge position of the old beam, The rest of the structure has less effect on stress.