Research On Life-Time Cost Of Steel-Concrete Composite Bridge Under Environment

The performance of composite steel-concrete bridge reduces over time by corrosion under marine environments. As a result, there is a need for inspection and maintenance in order to promise the safety performance of the bridge. However, inappropriate repair will result in higher life-cycle cost. In this study, the life-cycle cost of composite steel-concrete girder and maintenance strategies are analysed based on the MDP (Markov Decision Processes). The main work of this are as follows:(1) The endurance of composite steel-concrete girder are studied under marine environments, and durability of the concrete, steel stud and steel girder are analysed particular. And, the endurance models of concrete strength, section loss of the stud and girder over time are given by looking up domestic and foreign literature; A probabilistic bending resistance model for composite steel-concrete bridge is developed on the basis of an analytic formula that considers corrosion-related and time-dependent. Also, the time-dependent reliability model of the girder and the bridge are established.(2) The endurance of circular concrete filled steel turbular (CFST) stub columns are studied under marine environments, and the durability of the steel turbular are analysed particular; A probabilistic axial resistance model for circular CFST stub columns are developed on the basis of an analytic formula that considers corrosion-related and time-dependent; Also, the effects of the steel tube thickness and live load ratio on the time-dependent reliability are compared in this paper.(3) The life-cycle cost of composite steel-concrete bridges are studied, and the economic model of bridge are established here; By satisfying the objective of minimization of expected life-cycle cost and the reliability indexβ, the analysis model of bridges life-cycle costs were developed on the baisis of a MDP modeling approach; The optimal life-cycle costs and their associated maintenance policies are studied based on a hypothetical bridge. Also, The effects of initial bending resistance, environmental corrosion, failure loss and discount rate on bridge life-cycle costs, time-dependent reliability index and maintenance policy were discussed.