Life-cycle cost of civil infrastructure with emphasis on balancing structural performance and seismic risk of road network

The life-cycle cost (LCC) concepts and methods have impacted remarkably on the field of civil infrastructure. In this paper, LCC design concepts and methods are discussed with emphasis on bridges and road networks. The relationships among several performance measures are discussed. An attempt is made to provide rational balances of these measures by using a multi-objective genetic algorithm. Furthermore, LCC is evaluated focusing on the effects of earthquakes. At first, LCC analysis is formulated to consider the socio-economic effects due to the collapse of structures as well as the minimisation of lifetime maintenance cost. A stochastic model of structural response under earthquake effects is proposed. Then, the probability of failure of an individual bridge due to the earthquake excitation is calculated based on the reliability theory. In addition, LCC evaluations are performed not only for a single bridge but also for groups of bridges forming road networks.