钢筋对混凝土收缩应力的影响

Effects of reinforcement bar on shrinkage stress of concrete

研究了钢筋对收缩应力的影响,提出了描述约束关系的新的力学模型。基于增量分析,严格推导了钢筋内约束系数(配筋构件相比素混凝土构件的收缩应力增幅)的表达式。研究表明,钢筋内约束系数随配筋率增大而线性增大,但增长速度(直线斜率)受外约束大小影响,外约束越大,增长速度越小。现有的以钢筋混凝土体为计算对象的收缩应力计算方法,一方面由于忽略了钢筋的内约束效应,另一方面错误地将钢筋内约束与骨料约束类同,因此将导致计算结果低估常规配筋构件的实际收缩应力约10%～40%。

The effect of reinforcement on the shrinkage stresses of concrete is studied.A new model is proposed for describing the restraining relationship.Based on the incremental analysis,the expression of the Interior Coefficient of Reinforcement,ICR,(that is,the shrinkage stress increment of the reinforced concrete member compared to that of the plane concrete member) is established.The research shows that the ICR is linearly increased with the reinforcement ratio,while its slope is determined by the magnitude of the exterior constraints.The slope decreases with the increase of magnitude of the exterior constraints.The current calculation method for shrinkage stress is based on the 'reinforcement concrete body'.It neglects the interior restraint effect of the reinforcement,while unreasonably looks the interior restraint of the reinforcement as that of the aggregates.Those will under-estimate the actual shrinkage stress of concrete by 10%～40%.