混凝土中钢筋非均匀锈蚀的余弦函数模型的建立与理论分析

The development of rust expansion force of steel bar in concrete and reinforcement corrosion rate's time-varying property

首先将由钢筋锈蚀导致的混凝土保护层胀裂的非均匀锈胀力模型简化为余弦函数锈胀力模型,然后应用弹性力学理论推导余弦函数锈胀力模型的计算公式,并探讨了影响钢筋锈胀力的各个因素,认为:钢筋混凝土间隙越大,混凝土开裂所需的临界锈蚀率越大,临界锈蚀率随着混凝土弹性模量的增加而增加,混凝土强度等级越高,临界锈蚀率越高,随着钢筋半径的增加混凝土起裂所需的锈蚀率减小,随着膨胀倍数的增加临界锈蚀率不断下降,膨胀倍数在2.5之前临界锈蚀率下降速度最快,膨胀倍数在2.5之后下降速度较为平缓。

In this paper,first of aU,the model of non-uniform rust expansion force produced by crack of reintoreement concrete cover which is on the result of corrosion of steel bar is simplified as cosine functions model of the expansive force of the corrosion steel bars. Then the theory of elasticity mechanics is applied to deduce the formula of cosine function corrosive expansion force model, and each factors of the rust expansion force of steel bar are discussed, results：the greater the clearance existed in reinforced concrete is, the bigger the critical corrosion rate is needed when concrete crack;the critical corrosion rate increase as elastic modulus increases;the higher concrete strength level is, the higher critical corrosion rate is;with the increase of the radius of the steel bar, the corrosion rate decreases when concrete begins to crack; with＇ the increase of the expansion ratio, critical corrosion rate falls, when the expansion ratio is below than 2. 5 ,the critical corrosion rate drops fastest,when he expansion ratio is higher than 2.5 ,the speed decrease is more slow.