The Time-varied Relaibility Analysis And Service Life Prediction Of The Bridge Structure Based On Long-term Health Monitoring Data

With the influence of many factors such as natural environment, loads and so on, the structure component of existing concrete bridge will generate local damage(e.g. cracks, corrosion). The carrying capacity of the bridge decays over time, which will affect the service life of the bridge structure. Taking Zhaoqing West River Bridge as the engineering and using long-term health monitoring system designed by our team, we monitored the real-time temperature, strain of the bridge. Based on long bridge health monitoring data, this paper analysised the time-varied reliability and explored the remaining life of the bridge. The main research contents were as follows:(1) The bridge health monitoring system setting for the background bridge of the thesis was introduced. The temperature and strain data on different sections of the bridge were collected, and the data were preprocessed to de-noising and corrected of effect of shrinkage creep and temperature with relevant treatment methods.(2) The factors, which influence the resistance of structures, such as carbonation of concrete, change of concrete strength with time, and reinforcement corrosion, were taken into account in the thesis. A deterministic function was defined to describe the effects of them. The time-varied attenuation model of the structural resistance of the existing reinforced concrete bridge was built, and the time-varied resistance moment R(t) was defined. Besides, according to the long-term health monitoring data, the load bending moments were calculated. The original discrete load bending moments were processed with probability method, and the probability model of the load effect of the bridge was received. Finally, the time-varied load moment S(t) was calculated.(3) Based on the long-term health monitoring data of the existing reinforced concrete bridge, it found that the load bending moment probability distribution was in conformity with the gaussian distribution. The reliability performance function with the box beam bending moment load S(t) and the resistance effect R(t) was built. It successfully realized the evaluation of the structure time-varied reliability with the changing load effect and the decayed resistance. A method to assess the time-varied reliability and to predict the service life was summarized in the thesis.(4) The load effect and resistance of the Zhaoqing West-River Bridge were treated as a random process, to assess the time-varied reliability of the statistical monitoring time intervals. The curve of time-varied reliability of the bridge was fitted with the calculated reliability samples. So it provided a reference model to predict the remaining life of the bridge. Finally, it provided an optimization strategy for bridge maintenance and reinforcement using the prediction model based on time-dependent reliability.