预应力混凝土简支箱梁裂缝损伤参数影响分析

Parameter influence analysis of existing simply-supported box girder bridge based on crack feature

针对开裂损伤后的在役预应力混凝土简支箱梁桥,将承弯段受拉裂缝和剪弯段斜裂缝作为主要特征裂缝,建立基于主要裂缝统计特征参数的开裂预应力混凝土箱梁损伤计算模型;将受弯裂缝总宽度、斜裂缝数量和斜裂缝高度作为3个敏感变量,分别进行参数影响分析,以确定其对结构控制截面变形和应力的影响。研究结果表明:承弯区受弯裂缝总宽度对结构的内力和变形影响较大,造成结构抗弯刚度明显减小,变形增大,压区应力增加;斜裂缝数量对结构内力和变形有一定影响,但影响程度明显小于承弯段受弯裂缝;斜裂缝高度对结构的内力和变形影响均较小。因此,在结构设计中,应特别注意受拉区混凝土压应力储备,防止拉区开裂造成的刚度退化。

Aimed at the cracking of simply-supported box girder bridge, the simulation calculation model was presented based on the primary statistical cracks which included the tension cracks in the mid-span and oblique cracks near the shear moment regions. The sum width of tension cracks, number of oblique cracks and height of oblique cracks were taken as three sensitive parameters to study their effects on the structural deformation and stress respectively. The results show that the sum width of tension cracks and the number of oblique cracks greatly influence the structural deformation and stress, whereas the height of oblique cracks has the least effects. Therefore, the concrete tress in the tension region must be sufficient to prevent the deficient of rigidity caused by the cracking. 7 tabs, 13 figs, 10 refs.