Optimal strengthening strategy on deteriorated concrete bridges based on multi-attribute utility approach
Morikawa Hidenori; Katayama Ken-ichi
Abstract:This paper describes a method of predicting the degradation in safety and determining the optimum time and degree of strengthening for existing concrete bridges. Degradation in safety is predicted by using a degradation curve based on material tests on the target bridge and statistical data for safety evaluation. For strengthening of bridges, the external prestressing is used to improve the stiffness and load carrying capacity. For optimization of strengthening, a multi-attribute utility function is introduced to express a multiple objective function as the measure of effectiveness of design lifetime, safety and load carrying capacity. The optimization problem is one of determining the optimum time and degree of strengthening in order to maximize the utility function. A genetic algorithm is applied to the procedure of searching global extreme values of the objective function. The proposed method is applied to an actual bridge of 41 years old. Remaining life and the optimum strengthening method for extending the lifetime to the expected value are shown and suitability of the method is discussed. Key Words:Optimization, Strengthening, Deterioration, Concrete bridge, Utility, Genetic algorithms, Maintenace