钢筋混凝土梁非均匀收缩效应试验与数值模拟

Test and numerical simulation of nonuniform shrinkage of reinforced concrete beams

为研究钢筋混凝土梁在干燥及钢筋约束状态下非均匀收缩效应,提出能够考虑钢筋混凝土梁干燥收缩、徐变,钢筋约束影响的纤维梁单元分析方法。对密封及不同干燥条件下3组混凝土试块进行内部相对湿度测试,并对不同干燥条件及配筋条件下的5根小梁的自由收缩变形进行实测;利用收缩试验结果确定分析模型的计算参数,模拟干燥及配筋对钢筋混凝土梁收缩的影响。研究结果表明:干燥使混凝土截面内产生湿度梯度,改变混凝土截面特性,加速混凝土收缩,而钢筋约束将抑制混凝土收缩;截面干燥且配筋不对称时,钢筋混凝土梁将产生额外曲率;采用基于微预应力-固结理论的纤维梁单元分析方法,可以较好地模拟复杂干燥及配筋条件下钢筋混凝土梁非均匀收缩效应,钢筋混凝土梁收缩试验与数值模拟结果吻合较好;分析方法计算稳定具有较高计算效率。

In order to study the non-uniform shrinkage effect of reinforced concrete beams under drying conditions and restrained reinforcement conditions,a fiber beam element analysis method was proposed,which can take into account the effects of drying shrinkage,creep and reinforcement constraint on reinforced concrete beams.The internal relative humidity of three groups of concrete specimens was tested under sealed and different drying conditions,and the free shrinkage deformation of five beams under different drying conditions and reinforcement conditions was measured.The calculation parameters of the model were determined by the results of the shrinkage test,and the effects of drying and reinforcement on the shrinkage of reinforced concrete beams were simulated.The results show that drying results in a gradient of moisture in concrete sections,changes the characteristics of concrete section and accelerates concrete shrinkage,while reinforcement restraint inhibits concrete shrinkage.When the section is dry and the reinforcement is not symmetrical,extra curvature occurs in the reinforced concrete beam.The fiber beam element analysis method based on micro-prestressed solidification(MPS)theory can predict the non-uniform shrinkage effect of reinforced concrete beams under complex drying.The results of reinforced concrete beam shrinkage tests are in good agreement with the numerical simulation results.The method is stable and efficient.