Life-Cycle Cost-based Bridge Whole-life Design Method

In recent years, life-cycle cost-based bridge whole-life optimum design method for infrastructure engineering, such as bridge, building, etc, has become a hot research topic in engineering field in home and abroad. Its research in home is still in beginning stage. Moreover, its use in engineering practice is absolutely fewer. Consequently, the work on bridge whole-life design method in this paper has an important theoretical meaning and engineering values.Based on the state-of-the-practice and state-of-the-art of the literature reviews, the related problems for bridge whole-life design methodology have been systematically studied. Hence, the work was summarized as follow:(1) Based on the corrected carbonation depth prediction model, the present study described how climate change predicted increases in CO2 levels will affect carbonation-induced corrosion damage and safety loss to prestressed concrete structures using the latest CO2 emission scenarios. The time-dependent structural reliability analysis of prestressed concrete bridge deck will the predict probability of corrosion initiation, mean propotion of corrosion damage and probability of structural collapse over the next 100 years considering several IPCC atmospheric CO2 emission scenarios and various corrosive environments. The influence of durability design specification and crack width on the mean proportion of corrosion damage was analyzed. Parameter sensitivity analysis was used to obtain the important influencing factors for time-dependent structural reliability.(2) The present study presented probabilistic whole-life cost calculation models. The modified event-tree modelling was used to demonstrate the effectiveness of the developed indirect maintenance cost models.(3) The present paper proposed the reliability index and condition index as indicators of bridge performance and deduced the interaction of maintenance interventions– life-cycle cost– bridge time-dependent performance. Based on the Particle Swarm Optimization (PSO), the present study developed multi-objective combinative maintenance optimization hybrid model to optimize the optimal combined maintenance interventions that corresponds to the minimal life cycle cost and maximum of reliability index and condition index in service time.(4) The present study developed the systematic framework and flowchart for whole-life optimum design method based on structural configuration and design details, and compared the differences and relationships between the whole-life design and conventional design method. The design work on an example bridge and the whole-life cost based bridge lane decision were employed to demonstrate the reasonability of bridge whole-life optimum design method.