The Relationship Between Bridge's Performance,Maintenance Strategies And Cost

Currently, whole-life design for deteriorating bridges which is a kind of the newest design idea is proposed with the serious deteriorating bridges and the excessively high life cycle maintenance cost, which enables the bridge structures to find trade-off among life-cycle performance, serviceability and life cycle cost. The interaction of performance, maintenance strategy and life cycle cost during service life is investigated from bridge reliability index and condition index. The main work in this thesis is described as follows:(1) The thesis has studied the stochastic process models of bridge resistance and load effects, and established limit state equation based on time-variable reliability, and analyzed reliability of deterioration bridges by using the Monte Carlo simulation method. Simultaneously, a compartive reliability analysis of the domestic first experimental bridge, which is designed by whole-life design idea, has been performed based on this method. It is obtained that the whole life design can enhance bridge durability to a certain extent, and decrease the maintenance cost.(2) The thesis has established probability-based non-linear exponential deterioration model of reliability index and twice non-linear deterioration model of condition index. Combination with preventive maintenance strategy model, reliability index and condition index formulas at a random time during bridge service life have been derived out.(3) The thesis has analyzed the proposed deterioration model by using the domestic and foreign bridge datum, and established classification formulas of the bridge condition and probability formulas of the basic maintenance time based on reliability and conditional state. Probability of which state bridge belongs to and probability distribution of annual maintainence during service life have been simulated. Furthermore, the formulas of deterministic maintenance cost and probabilistic maintenance cost have been constructed. Besides, combination with the exponential deterioration model of reliability index and Frangopol's linear deterioration model, a comparative analysis has been carried out by using the discrete reliaibility index of Yaobei Bridge via the least twice multiplication method.(4) The thesis has programed bridge multi-objective maintenance decision-making computational procedure. Simultaneously, it has analyzed the performance index in bridge life cycle with seven kinds of maintenance strategies. Probabilitic annual maintenance cost and cumulative maintenance cost for each maintenance strategy have been computed. Besides, the maintenance strategy has been analyzed and optimized.(5) The thesis has programmed the optimal maintenance cost computational procedure under the optimal maintenance strtegy in life cycle. It has also analyzed the optimal maintenance time related to the optimal maintenance cost. It is concluded that the cumulative maintenance cost varies dramatically with the discount rate, and the optimal maintenance time is also different under different discount rate. Meanwhile, the economical comparative analysis has been performed to an experimental bridge based on whole-life design idea.