混凝土独塔斜拉桥主梁裂后结构性能

Structural performance of cracked girder of a concrete cable-stayed bridge

针对一座主梁存在裂缝的混凝土独塔斜拉桥,考虑混凝土裂缝对材料本构关系的影响,对设计荷载作用下桥梁的整体与局部响应进行分析以评估其承载能力。结果表明,在最不利的工况中,开裂后主梁顶板、底板和斜腹板、直腹板上未开裂区域的主拉应力和主压应力都小于规范给出的强度标准值;裂缝法向和切向的压应力均小于规范强度标准值,裂缝切线和法线方向的拉应力在局部很小的范围内略高于规范的抗拉强度标准值。开裂区域局部承载力有所降低,但车辆荷载作用下裂缝不会进一步扩展。

A concrete single-tower cable-stayed bridge with a cracked main girder was taken for analysis.Considering the influence of cracks on the concrete constitutive model,the overall and local responses of the bridge under design load was analyzed to evaluate its bearing capacity.Analysis results show that under the most unfavorable working conditions,the principal tensile stress and the principal compressive stress of the uncracked areas on the top plate,bottom plate,inclined web and straight web of the cracked main girder are lower than the allowed values given in the Code.The normal and tangential compressive stresses of the cracking area are lower than the allowed values.The tensile stresses of the tangent and normal directions of the cracks are slightly higher in a very small local area than the allowed ones given by the Code.The local bearing capacity of the cracking area is reduced,but the cracks will not be further expanded under the vehicle load.