Development of an early seismic damage detection technology for civil infrastructures

1.用于地震损伤检测的宽带光纤传感器的研制开发了一种用于土木结构健康监测的新型封装式大口径光纤布拉格光栅传感器，并验证了该传感器具有获得有效宏观应变分布的能力。此外，温度波动对土木结构的损伤识别和结构健康监测构成了很大的障碍。基于一座桥梁模型的温度和应变分布，利用多元回归和神经网络(NN)分析建立了一种新的温度效应对应变测量影响的补偿方法。用于地震损伤检测的宽带记忆传感器的研制利用偏振聚偏氟乙烯(PVDF)薄膜作为裂纹检测传感器，对铝试件和钢筋混凝土梁的裂纹发生和扩展进行了实验研究。结果表明，PVDF薄膜传感器能够较好地捕捉微裂纹的产生，并能更好地提供应变分布信息。研制了一套无线加速度传感器系统，并进行了初步的振动实验。实验结果表明，该无线加速度传感器系统适用于结构损伤监测的振动测量。地震健康诊断与分析系统的研制为了实时监测结构的健康状况，提出了一种利用大应变动态响应提取的模态参数进行弯曲结构损伤识别的两级策略。提出了一种多输入多输出的神经网络系统作为大跨度斜拉桥的损伤识别技术。基于多个位置的响应信息建立的神经网络系统能够掌握损伤位置和损伤程度。

1. Development of the broadband optical fiber sensor for seismic damage detectionA novel packaged long-gage FBG (Fiber Bragg Grating) sensor for health monitoring of civil structure has been developed and verified to have the ability to obtain effective macro-strain distributions. Moreover, temperature fluctuation poses a great obstacle in damage identification and structural health monitoring (SEM) of civil structures. A new compensation method of temperature effects on strain measurement has been modeled by using Multiple Regression and Neural Networks (NN) analysis based on temperature and strain distribution measured at a bridge model2. Development of the broadband memory sensor for seismic damage detectionExperimental study on application of PVDF (polarized polyvinylindene fluoride) film as a crack detection sensor was conducted to detect occurrence and propagation of cracks in aluminum specimen and RC beams. It is confirmed that the PVDF film sensor is able to catch the generation of micro-crack and provide information of strain distribution better than those of traditional strain gauge sensors. A wireless acceleration sensor system has been developed and was used for a rudimentary vibration experiment. The experimental results showed that the wireless acceleration sensor system is applicable vibration measurement for structural damage monitoring.3. Development of seismic soundness diagnosis and analysis systemIn order to monitor the soundness for real-time, a two-level strategy was proposed far damage detection in flexural structures using modal parameters extracted from dynamic macro-strain responses. And, a neural network system, which consists of multi-inputs and multi-outputs, was proposed as the damage detection technique of long-span cable-stayed bridge. The neural network system which was built based on response information of multiple locations is able to grasp damage location and damage extents.