既有结构混凝土累积损伤原位评估方法

AN IN-SITU EVALUATION METHOD FOR CUMULATIVE DAMAGE OF STRUCTURAL CONCRETE

为实现对长期承受疲劳作用的混凝土桥梁进行原位评估,该文提出了基于实测弹性模量的结构混凝土累积损伤评估方法。首先根据损伤力学的定义讨论了混凝土弹性模量的取值,建议混凝土的初始无损弹性模量采用静力弹性模量;然后根据混凝土应力-应变曲线和残余应变与累积应变的统计关系,提出混凝土静力等效应变和残余应变计算方法,以及混凝土损伤后强度的估算方法,给出了混凝土结构现场测试与分析的详细步骤和弹模比、残余应变的阶段特征值。在以上研究基础上,比较分析了混凝土变形模量、静力等效应变和残余应变损伤指标的应用效果,结果表明残余应变损伤指标的适用性最好,因此根据残余应变的实用限值将混凝土损伤程度划分为4个等级。最后,为了简化评估过程,提出了一种根据混凝土实测强度和弹模比的快速查表评估方法,直接得出混凝土的剩余强度和损伤等级,对工程实践具有参考价值。

In order to realize the in-situ evaluation of concrete bridges subjected to fatigue for a long time, an evaluation method for cumulative damage of concrete structures is proposed, based on unloading elastic modulus. First, the value of elastic modulus is discussed by the definition of damage mechanics and the concrete initial condition is suggested using the static elastic modulus. Then, according to the concrete stress-strain curve and the statistical relationship between residual strain and cumulative strain, the calculation method of static equivalent strain and residual strain concrete are proposed by unloading elastic modulus and the method for estimating the strength of concrete after damage. The detailed steps of field test and analysis and the phase characteristic value of elastic modulus ratio and residual strain are developed. Based on the above research, the indicator of residual strain is compared with the indicators of modulus of deformation and static equivalent strain to indicate the most effective for damage evaluation of concrete. Therefore, the concrete damage degree is divided into four grades by the practical limiting value of residual strain. Finally, according to the measured concrete strength and elastic modulus ratio, a look-up table assessment method is put forward to evaluate the concrete residual strength and damage degree so as to simplify the evaluation process and it can be used as a practical evaluated method for cumulative damage of concrete.