Quantitative Damage Evaluation of Concrete by AE Rate Process Analaysis

近年来，混凝土结构的老化已经成为一个普遍的问题，维修技术也受到了广泛的研究。对混凝土进行强度评估和损伤程度评估对战略性维护具有重要意义。据此，提出了应用声发射技术和损伤力学对混凝土损伤进行定量评价的方法。冻融和碳化过程对混凝土试样的破坏作为控制破坏进行检验。研究了基于单轴压缩混凝土断裂行为的损伤定量评价方法。由于混凝土的声发射性能与损伤程度有关，因此通过速率过程分析建立了一种关系。采用Loland模型，建立了应力应变关系模型，验证了损伤参数的适用性。在声发射速率过程分析中，通过计算相对损伤（初始杨氏模量与完整模量之比）来估计实际结构的初始损伤。估算结果与对照样品的实际损伤值有显著的一致性。因此，构建了一个数据库，将所提出的方法应用于从现有结构中获取的混凝土芯样。

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.