Quantitative Damage Evaluation of Concrete by AE Rate Process Analaysis

近年来，混凝土结构的劣化已成为一个公共问题，维修技术也受到了广泛的研究。对于战略性维修，不仅要评估混凝土的强度，而且要评估混凝土的损伤程度。在此基础上，将声发射技术与损伤力学相结合，提出了混凝土损伤的定量评估方法，并将冻融和碳化损伤混凝土试件作为受控损伤进行了试验研究。研究了基于混凝土单轴受压断裂行为的损伤定量评价方法。由于混凝土的声发射行为依赖于损伤程度，通过速率过程分析建立了一个关系式。采用Loland模型，应力和应变之间的关系建模，然后确定的损伤参数的适用性。通过声发射速率过程分析计算相对损伤，即初始杨氏模量与完整模量的比值，估计实际结构的初始损伤。估算结果与控制样品的实际损伤情况吻合较好。因此，一个数据库的构建应用所提出的方法，从现有结构的混凝土芯样。

In recent years, the deterioration of concrete structures has been a public problem, and maintenance techniques have been subjected to intensive research. For the strategic maintenance, it is of significant importance to evaluate not only the strength of concrete but also the degree of damage in concrete. Accordingly, quantitative damage assessment of concrete is developed and proposed by applying acoustic emission (AE) technique and damage mechanics.Concrete samples damaged by freezing and thawing and carbonation processes are examined as the controlled damage. The quantitative damage evaluation based on fracturing behavior of concrete under uniaxial compression is studied. Since AE behavior of concrete is dependent on the degree of damage, a relation is formulated by the rate process analysis. Employing Loland's model, a relationship between stress and strain is modeled, and then the applicability of the damage parameter is confirmed. By calculating the relative damage, which is evaluated as the ratio of initial Young's modulus to the intact modulus, from AE rate-process analysis, the initial damage of an actual structure is estimated. The results estimated are in remarkable agreement with the actual damages in the controlled samples. Consequently, a data-base is constructed to apply the proposed method to concrete core-samples taken from existing structures.