Remote vibration measurement system for spatial measurement of civil structures

为了利用振动测量技术对结构进行局部损伤检测，需要对结构的高阶固有频率进行振动模态的测量和识别。此外，这些模式的测量变得越来越重要，因为在城市地区需要评估环境振动/噪声对周围住宅的影响，以确保生活舒适度。然而，在土木结构中，由于尺度和环境噪声的影响，空间振动和扰动的测量困难，使得传统方法（如加速度计）对高阶模态的识别精度降低。此外，密集分布的测量往往是昂贵的，因为加速度计的设置需要在高处工作，并为工人建造临时支架。本课题研究了激光多普勒测振仪在大空间土木结构在环境振动等微观振动作用下的振动特性可靠测量中的适用性。 ...更多信息 离子。该技术通过激光扫描表面实现远距离测量，消除了高空危险劳动。在这项研究中，非平稳的，和随机分量的测量环境振动被消除扫过的感兴趣的区域和叠加的时间历史记录重复。通过这种方式，即使不知道输入激励，也可以通过将环境振动假设为平稳过程来高精度地识别较高模式的固有频率和模式形状。然后，将损伤后的实测模态频率和振型与损伤前的实测数据进行比较，反求出刚度变化的位置和程度，从而指示结构的损伤程度。通过附加质量板的振动实验，验证了该方法的有效性。最后，在实际高架道路上进行了现场测量，验证了测量方法的适用性。少

In order to detect local damage in structures using vibration measurement, measurement and identification of vibration modes with higher natural frequencies is needed. Also, measurement of these modes is increasingly becoming important as evaluation of environmental vibration/noise effect to surrounding residence is required in urban areas to ensure living comfort. However, in civil structures, the difficulties of measuring spatial vibration and disturbance decrease the identification accuracy of higher modes by conventional methods, such as accelerometers, because of its scale and high level environmental noise. Besides, densely distributed measurement tends to be costly since setting of accelerometers requires works at high positions with construction of temporary support for workers. In this project, applicability of Laser Doppler Vibrometer is studied to reliably measure vibration characteristics of spatially large civil structures under microscopic vibration such as ambient vibrat … More ion. By this technology, remote measurement can be achieved by scanning of surface by Laser beam, which potentially eliminates dangerous labor works at high position. In this study, non-stationary, and random components in measured ambient vibration are eliminated by sweeping the area of interested and stacking the time histories recorded repeatedly. In this way natural frequencies and mode shapes of higher modes can be identified with high accuracy by assuming the ambient vibration as a stationary process even without the knowledge of input excitation. Then, the measured modal frequencies and mode shapes after damage and measured data before, damage are compared to inversely solve the location and extent of stiffness change which will indicate the degree of damage in the structure. The method is demonstrated by experiments of plate vibration with additional mass which simulates local stiffness degradation. Finally, field measurement was conducted at actual elevated highways, and the applicability of the measurement is demonstrated. Less