Recommendations for Refined Preventive Maintenance Management of Concrete Bridges in China Based on Environmental Risk Zoning

Service environment has an important influence on the durability of concrete bridges. Environmental factors are often considered in the design stage, however, they tend to be ignored in the process of maintenance management. It is of great significance in prolonging the service life of a bridge to pay attention to the influence of the environment on the deterioration of the bridge during the preventive maintenance process. Concrete carbonation, chloride ion corrosion, sulfate corrosion, concrete cracking, concrete abrasion, and freeze-thaw damage are the main causes of decline of bridge durability. Based on these six kinds of distress, indexes of environmental zoning are proposed. For this purpose, variable weight theory is introduced into the matter-element extension model, and the comprehensive environmental risk values of various regions are calculated. The environmental risk zoning map of the concrete bridge's location is then drawn using data visualization software (Tubiaoxiu). These maps show that the east, south, and southwest of China are the most high-risk areas for the deterioration of concrete bridges, and the validity of the results is proved by the distribution of collected bridge collapse accidents. Through the environmental risk zoning map, managers can intuitively grasp the degree of environmental risk in each region in real time. This approach could help bridge management department to implement differential management of concrete bridges in different regions, adjust bridge maintenance intervals dynamically, predict the state of bridges scientifically, and realize refined preventive maintenance management.