斜向开裂混凝土梁的瞬时及长期剪切变形

Instantaneous and Long-term Shear Deformations of Inclined Crack Concrete Beams

针对钢筋混凝土梁在斜裂缝出现之后剪切变形对结构挠度影响很大,且随着时间的推移影响不断增加的问题,开展了3根薄腹梁的抗剪性能试验,研究了斜裂缝出现之后,剪切变形对结构挠度的影响;根据变角桁架模型,考虑混凝土收缩徐变影响,量化分析了斜裂缝出现后的瞬时剪切变形及长期剪切变形,并与试验结果进行了比较;分析了影响剪切变形的参数,如混凝土强度、跨高比、剪跨比、配箍率和纵筋配筋率。结果表明:斜向开裂后混凝土梁的剪切变形对结构总变形影响较大;梁的跨高比对剪切变形与弯曲变形比值影响最大。

The structural deflection due to shear deformation could be of the same order of magnitude as deflection due to bending after the formation of inclined cracks,and the impact of shear deformation on structural deflection might increase as time went on.For this reason,the experiments on the inclined cracks of three thin-webbed girders were carried out.Base on the experiments,the effect of shear deformation of thin-webbed girder on structural deflection was studied after the formation of inclined cracks.Also,the quantitative analysis of instantaneous and long-term shear deformation were performed using variable truss model,taking account of cracks,concrete shrinkage and creep.Parametric analysis of concrete strength,span-height ratio,shear span ratio,stirrup ratio and longitudinal reinforcement ratio were conducted to identify their effects on shear deformation.Results show that the effect of shear deformation of thin-webbed girder on structural long-term deflection is significant.The span-height ratio has an important impact on the shear deformation and bending deformation ratio.