Development of Diagnostic Procedure for Concrete Structures

为了发展评估和检查技术，对诊断程序进行了研究。需要研究和实际应用的技术涉及裂缝、分层、表面损伤、钢筋腐蚀和结构完整性。为此，声发射(AE)方法、超声检测(UT)、红外热像、雷达、半电池电位等技术得到了新的发展和完善。研究结果如下：(1)改进了UT测量方法，提出了一种基于光谱信息的识别裂缝深度和表面劣化的新技术。(2)研究了声发射技术在混凝土芯材检测中的应用。在岩心试件声发射产生行为的速率过程分析和损伤力学分析的基础上，对岩心试件的损伤进行了定量评估。(3)研究了声发射波形的矩张量分析，提出了一种实用的识别裂纹位置、裂纹类型和裂纹方向的方法。(4)为了判断钢筋的腐蚀，提出了两步检测的方法。在第一步中，利用雷达技术确定加固位置。然后，根据钢筋表面的半电池电位，采用电荷模拟的方法对钢筋表面的腐蚀电位进行了解析估计。(5)研究了利用红外热像仪估算混凝土表面温度分布的方法。针对钢筋锈蚀问题，提出了一种基于边界元方法(BEM)的逆解方法。

Diagnostic procedure is investigated in order to develop the evaluation and inspection techniques. The techniques to be studied and to be practically applied are associated with crack, delamination, surface damage, corrosion of reinforcement, and structural integrity. For this purpose, acoustic emission (AE) method, ultrasonic testing (UT), infrared thermography, radar, and half-cell potential are newly developed and improved. The evaluation of structural integrity is also studied, including an expert system based on the data base of aging bridges.Results obtained are summarized, as follow :(1) The UT measurement was improved and a new technique based on the spectral information was developed to identify crack depths and surface deterioration.(2) AE application to core tests of concrete is investigated. On the dasis of the rate process analysis of AE generating behaviors in the core sample and the damage mechanics, a quantitative evaluation of damage in the core sample is developed.(3) A moment tensor analysis of AE waveforms was investigated and thus a practical procedure is developed to identify crack location, crack type, and crack orientation.(4) To estimate corrosion of reinforcement, two step inspection is proposed. At the first step, location of reinforcement is determined by employing the radar technique. Then, at the second, corrosion potentials on the reinforcement are estimated from half-cell potentials on the surface, by the charge simulation method analytically.(5) The infrared thermography was studied to estimate temperature distribution on concrete surface. Concerning the corrosion of reinforcement, an inverse solution based on the boundary element method (BEM) is newly developed.