Abstract:

In order to accurately evaluate the durability of concrete bridges, an evaluation model based on NRS and D-S evidence theory was proposed. Firstly, according to the structural characteristics of concrete bridges, the durability evaluation index system was constructed, and the durability evaluation database was established. Secondly, combined with the database, the basic reliability distribution of different evaluation indexes was determined by using the upper and lower approximation definition of NRS, and the evidence discount factor was constructed based on the comprehensive weight of each index to realize the correction of the initial basic reliability distribution. Then, through the fusion of D-S evidence theory synthesis rules, the confidence of durability state grade proposition was obtained, and then the durability state grade was determined according to the maximum subordination principle. Finally, the measured data of several existing concrete bridges were used to verify the example. The results show that the durability evaluation results obtained by this model are consistent with the field measurement results. Compared with the traditional evaluation model, it can not only evaluate the durability of concrete bridges more accurately, but also reflect its deterioration trend of durability through confidence, which can provide an objective reference for the maintenance, reinforcement and maintenance of concrete bridges.

Key words: neighborhood rough set (NRS), concrete bridges, evaluation of durability, basic reliability distribution, comprehensive weight, D-S evidence theory