基于碳化的既有钢筋混凝土桥梁耐久性的概率分析

Probability analysis for existing reinforced concrete bridges durability regarding carbonation

分析讨论了混凝土碳化机理及其影响因素,并探讨了混凝土碳化深度的预测数学模型,基于既有钢筋混凝土桥梁的实测数据,对碳化系数和混凝土强度进行回归分析,建立了根据混凝土强度预测碳化深度的数学模型。将混凝土强度,保护层厚度,计算模式不确定性系数作为随机变量,以混凝土的碳化深度作为一个随时间变化的随机过程,建立了混凝土碳化到钢筋表面的时变概率随机模型,并以一座实际桥梁为例,给出了在不同使用年限时混凝土碳化到钢筋表面的预测值。结果表明,该模型可用于大气环境下基于碳化的钢筋混凝土桥梁结构耐久性评估。

The mechanism of concrete carbonation and influencing factor, as well as the predicated model of carbonation depth of reinforced concrete structures are discussed and analyzed. According to the inspection results of existing reinforced concrete bridges, the mathematical model of carbonation depth based on concrete strength is established by regression analysis of concrete carbonation coefficient and strength. A time-varylng probabilistic stochastic model of concrete carbonation developing to the surface of the reinforcement is established by considering concrete strength, the thickness of concrete cover and the uncertainty coefficient of computation mode as random variables, and taking the carbonation depth of concrete structures as a stochastic process with time. It shows that the stochastic model can be used to durability assess of existing reinforced concrete structures in atmosphere environment.