基于响应面法的大体积混凝土开裂风险分析

温度荷载是造成施工期大体积混凝土开裂的主要原因。为了研究大体积混凝土的开裂风险,将影响混凝土温度场和应力场的物理力学参数作为随机变量,以混凝土抗拉强度与最大拉应力之差作为判断大体积混凝土开裂与否的准则,并依此建立功能函数。通过数值试验建立功能函数的响应面方程,以解决原功能函数无法显示表达的问题,最后采用JC法求解混凝土开裂可靠度指标。计算结果表明,与Monte-Carlo法的计算结果相比,所提出的大体积混凝土开裂风险计算方法得到的失效概率相对误差在4%以内,且计算效率高,精度满足要求,可应用于实际工程。

Study of Mass Concrete Cracking Risk Based on Response Surface Method

The mass concrete crack during construction period is mainly caused by temperature load. To study the cracking risk of mass concrete, this paper took physical and mechanical parameters, which influence concrete temperature field and stress field, as random variables and took the difference between concrete tensile strength and maximum tensile stress as criterion to judge mass concrete cracking. Thus, the performance function was established. By establishing response surface model, the problem that performance function cannot be expressed explicitly can be solved. Finally, the JC method was used to calculate reliability index of concrete. The results show that the relative error between the result calculated by the method proposed and Monte-Carlo method is less than 4%. This method is characterized by high calculation efficiency and accuracy. Thus, it can be applied in practical engineering.