Life Span Prediction Of Enhanced Bridge Based On Reliability Theory

Bridge construction in modern China has had a history of several decades of years, in theever-increasing volume of traffic and environmental loads,with the bridge becomingolder,The gradual accumulation of durability damage affecting the structure of resistance,more and more bridges have passed into the phase of structural system ageing, Reinforcementand reconstruction of the bridge to solve this problem is an effective way to study. Bridgestrengthening has become a rather mature and widely used technology, whose relevantcontents have been studied by the structure engineering. The forecast of the rest life span of abridge after strengthening provides the time for the following bridge detection andstrengthening, avoiding the occurrences of early abandonment or waste of resource, or evencollapse of bridge structure,it is conducive to highway bridges for the management ofscientific management and conservation.This thesis sums up the domestic and foreign development and latest achievements of thestudy on bridges’ reliability and durability after strengthening and proposes a formulacalculating the reliability after reinforcement on the basis of previous researches byscholars.For durability testing and calculation of parameters of random,the use of reliabilitymethods for reinforcement of the old bridge component and the reinforcement of thedurability of wood can be analyzed,by reference to the literature and combined with the actualsituation,carried out on the target value of reliability,Respectively the two types of limit statefor carbonation of reinforced concrete and rust expansion cracking used reliability analysis.Moreover, according to the corrosion mechanism of the steel and concrete structure,this thesis analyzes and improves the predictive models of both concrete carbonation depthand steel collision after bridge strengthening. It adopts k_d=0.66, the delay coefficient, in thepredictive model of concrete carbonization depth after the carbon fiber is reinforced.Furthermore, it works out that the delaying time ratio of the steel collision of the concretebridge structure after the reinforcement of carbon fiber is k_b=0.4and the damping ratio ofsteel collision in the structure after the reinforcement of bonding steel plate is k_b’=0.8. Theabove results predicts the rest life span of a bridge after strengthening by practical engineeringcase, from which one can find the feasibility of predicting life span after bridge strengtheningby means that mentioned above.