The Application Of Actual Traffic Condition To Bridge's Life Evaluation

Owing to the the increment of the bridge's usage period and adverse environment,many bridges are going into the agingtime. Traditional design theory have not concerned with the factors of traffic growth and vehicle load increasing, lots of bridges gradually appear destructive characters of high cycle and low stress, all of these factors result in bridge life shorten seriously. Therefore, it is a great significance to research the relationship between the traffic condition and the structure fatigue life.This article synthesizes the home and abroad research status about vehicle load distribution model, A week's vehicle weight data of freeway has been screened, simulated, and then K—S tested in the city of Chongqing, learning that the vehicle load distribution in Chongqing is accord with logarithmic normal distribution and recommended model in reliability norm, but the statistical average is larger. This article takes the Kuixing Bridge in chongqing as a support project, the distribution status of traffic, models of vehicle, axial distance has been counted, Statistical analysis shows that the effect of vehicle load from Kuixing bridge accord with logarithmic normal distribution and reliability norm, and shows that the linear relationship between vehicle load and load effect.Based on the home and abroad research situation of fatigue performance,We checked the structure fatigue strength of Kuixing bridge.Analysis shows that the fatigue strength of Kuixing bridge structure is satisfied with the norm.Then we calculated the fatigue stress of reinforcement, concrete under pulling. Existing fatigue life research is directed to equal amplitude and repeated stress level, but actual bridge's fatigue performance has the characteristics of multi-level, varing amplitude and change in high cycle. Therefore, according to the Miner damage criterion,We need to convert multipole variable amplitude stress level to equal amplitude and repeated stress level,and deduce the repeatingworking times,and estimate working age limit of the structure,then deduce the working times of Kuixing bridge. It is a modified method to the conventional bridge life evaluation, this research method has a great significance.