Detection of damage and loading on the bridge and its service structure by raser doppler vibrometers

确定结构在使用寿命期间所受的外力对结构的设计和维护具有重要的实际意义。尤其是动态测量识别，由于其在测量方面的相对优势，引起了人们的广泛关注。本研究利用激光多普勒测振仪，实验确定了3种不同类型的力，即冲击力、惯性力和声压。采用的辨识方法有：伪逆法和正则化法。对每种识别方法和每种实验情况的误差进行了评估，表明所提出的方法对各种载荷情况具有广泛的适用性。对激光多普勒测振仪在螺栓连接损伤识别中的应用进行了实验研究。验证了利用LDV仔细测量的模态特性变化可以检测螺栓松动。

Identification of external forces applied on a structure during its operational life is of practical importance for structural design and maintenance. Especially, identification using dynamic measurement has attracted much research interest because of its relative advantage in measurement. In this study, forces in 3 different types are identified experimentally, i.e, impact-force, inertia force and sound pressure using Laser Doppler Vibrometers. Identification methods employed are : pseudo-inverse method and regularization method. Error obtained from each identification method and each experimental case is evaluated and the proposed method is shown to have wide applicability to various loading cases.Damage identification of bolted joints by Laser Doppler Vibrometers is also studied experimentally. It was confirmed that detection of loosened bolts can be made from the change of the modal property measured carefully by LDV.