Research On Performance Monitoring System And Damage Identification Method For Civil Engineering Structures

Recently, structural health monitoring in civil engineering has received considerable attention with the development of super long-span structure and super high-rise building. In this dissertation, performance monitoring system and damage identification method for civil engineering structures are theoretically and experimentally researched. A novel cement-based piezoelectric sensing system for measuring structural dynamic response and monitoring traffic flow is developed and an artificial neural network method for damage identification based on statistical properties of structural responses is proposed for structural health monitoring. The research works and innovations in this dissertation are as follows:(1) On the basis of the cement-based piezoelectric composite, the cement-based piezoelectric sensor is developed and checked by the basic performance experiments such as frequency independence and linearity. Besides, the calibration process is adopted to ascertain the parameters of the sensor including: scope, sensitivity, linearity, hysteresis, threshold and so on. The research shows that the developed sensor is suitable to apply in structural performance monitoring because of its good frequency independence and linearity between the input force and output voltage.(2) Composed of the cement-based piezoelectric sensor, a small-scale charge amplifier, a multi-channel data acquisition device, and software for data storage and processing, the cement-based piezoelectric sensing system is developed. The sensing system is applied to measure the dynamic stress in a short column and a reinforced concrete frame and monitor the traffic flow. The results of the tests indicate that the cement-based piezoelectric sensing system can correctly measure the dynamic stress in the structure and accurately monitor the flows of both person and vehicle. Also, the vehicle can be classified by the amplitude of the sensor's response to the pulse loading.(3) Based on the theory of structural random vibration, the relationship between statistical properties, including the mean and variance, of the structural dynamic responses, including displacement, velocity and acceleration, and structural damage location and extent is obtained. Through sensitivity analysis, the variance of structural dynamic displacement is selected as novel damage index for structural damage identification. The dynamic response of a three-span continuous beam is numerically...