Study On Detection, Evaluation, Maintenance And Reinforcement Technique For Fire Damaged Concrete Beam Bridges

With the development of the transportation systerm in China, the concrete beam bridges become the main type among the highway bridges. In recent years, the fire accidents on the bridges occur frequently. The physical and chemical effects of the fire make the mechanical property of the steel and the concrete change and the members damnify to some extent. The fire not only destroys the bridge structure, but also jeopardizes the well-balanced operation of the highway networks, especially the expressway networks.It is necessary to detect and evaluate the damnification timely after fire so as to provide the reliable data for the maintenance and reinforcement of the fire damaged bridges. Then the solutions shall be worked out to recover the bearing capacity and service property for the purpose of safe and open operation of the bridge.In the view of the special situation of the fire damaged bridge site, this dissertation introduces the programme and content of the detection and evaluation. It emphasizes the necessity of the premilinary detection and the importance of fire causation analysis. How to detect the damnification of different bridge type and different members according to different situation and fire cases is also investigated.This thesis discusses the effect on fire damage distribution and extent according to the characteristics of the fire source, the bridge structure and fire extinguishing methods. Also it evaluates item by item according to the loading state of different members, establishes the models, calculates the change of the bearing capacity after fire, and estimates the actual bearing capacity and service property.The feasible techniques, applicable scope and key art features of maintenance and reinforcement for different members were proposed in this thesis. Furthermore, the key applicable points of detection, evaluation and reinforcement were also investigated for different bridge types, fires and diseases according to the experiences of some fired bridges evaluation and reinforcment. Finally, the dissertation puts forward to some issues and prospects.