| Many concrete bridges have different degrees of durability problem for the effects of loads and bad environment.For the golas of reducing or avioding the serious consequences from deteriorating of durability ,a evaluation method for bridge's durability is need.This method need to find out the durability situation of concrete bridges timely and will not cost much to monitor the bridges.The main contents in this paper are as follow:(1)The factors that effecting the durability of concrete bridge are studied andsummarized,and then a three-layer evaluation model for durability of concrete bridge is builded base on the fuzzy evalution theory.(2)The durability evaluation and prediction are combined by introducing the time variate to the indicator layer of the evaluation model,so durability can also bo preidicted in the evaluation model. The values of these durability factors at different times are calucated using their own time-varied predict model,and the factors are evaluated according to their own membership degree function.If any factor can not be predicted or has not been predicted yet,it's durability evaluation vectors at different times is assessed by combined the bridge maintenance standard and it's servce life statistics data.(3)The evaluation vectors of indicutor layer at different times are taken as input data of the evaluation model,so the durability evaluation vectors of the whole bridge at different times are got. Uncertain judgement matric ,group judgement theory ,set-value stastical theory are introduced to the calculation of weight values of durability factors. Asymmetric approach degree method is also introduced in this paper to detemined the durability grades at different times of the bridge .(4)A bridge is calculated using the methord in this paper.Durability grades of this bridge at different times are calculated and compared to the result of practical detection and evaluation,which indicates that the time-consided evaluation methord in this paper is feasible. |
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