Fatigue Safety Monitoring and Fatigue Life Evaluation for Existing Concrete Bridges

摘要

This paper firstly combines acoustic emission (AE) technique with monitoring of traffic loads and dynamic strain in healthy monitoring of concrete bridge structures. AE sensors and strain gauges were located on the web zone, deck plate and bottom plate of the box girder of Yaoxian Bridge, weigh-in-motion system (WIM system) was located in the pavement. Three monitoring systems clock was set synchronizedly, so they could monitor AE information, vehicles information and dynamic strain at the same time. Through the amplitude distribution and b-value analysis of AE signals, it finds the monitored bridge is in good service condition. The fatigue life of steel bars as well as strands in the box girders was calculated based on recorded data. Then, based on fatigue failure mechanism of concrete bridges, fatigue life evaluation approaches using S-N curves and fracture mechanics are presented. The evaluation results show that the fatigue life of the bridge is over 200 years, longer than the design service life. Finally, based on current study, it concludes that acoustic emission is an effective technique to evaluate existing concrete bridges.