冻融环境钢筋混凝土梁抗弯承载力研究

摘要

To learn more about the deterioration law of loading capacity of concrete structure under freezing and thawing environment,this paper studied the capacity properties of full-scale (150 mm×300 mm×2 700 mm)reinforced concrete beam by using the methods of air-freezing and air-thawing,which is similar to atmospheric environment.The loading capacity of overall computational model and hierarchical computational model were established.The research result showed that:the member sectional strain subjected to air-freezing and air-thawing followed the plane section assumption.When freeze-thaw cycle increased,the capacity of RC beam decreased,but the rate of decline increased.The span deflection of RC beam decreased with the increasing of freezing and thawing cycle,and it shown that a linear response relationship between them.Through compared the model of this paper to the result of testing and the model of specification,applicability of the model of this paper was proved,and the hierarchical computational model was better than others.The durability life of concrete structure in practical project under freeze-thaw environment based on the bearing capacity calculation model is predicted,and the prediction results of this method compare with other methods,the engineering applicability of model is proved.%为更好地研究冻融环境下混凝土结构承载性能退化规律,采用与大气环境冻融作用方式相同的气冻气融试验方法,对足尺150 mm×300 mm×2 700 mm钢筋混凝土梁冻融后的承载性能进行系统研究,建立冻融后整体承载力计算模型及考虑损伤层的分层承载力计算模型.研究结果表明:气冻气融作用后试验梁正截面应变仍符合平截面假定;其正截面抗弯承载力随着冻融次数的增加而降低,且下降速度随冻融次数的增大而增大;梁的跨中挠度随冻融次数的增加逐渐降低,且两者之间呈明显的线性响应关系;与试验结果及规范计算模型对比,整体承载力计算模型及分层承载力计算模型均具有合理的适用性,且分层计算模型更能充分发挥截面在不同状态下的承载能力.基于承载力计算模型对某实际工程中的混凝土结构进行冻融环境下耐久性寿命预测,并与其他预测方法进行比较,表明计算模型的工程适用性.