Life-cycle Based Design Strategies and Approaches of Bridges

The most important thing in life-cycle based design is how to achieve service life of the bridge. Sustainable development gives rise to a need for bridge design to seek appropriate methods and measures to assure satisfied service in life cycle of a bridge from planning, design, construction and management of service phase to demolishment and recycling of materials and components. Three design strategies and corresponding approaches are presented after analyzing the approaches of achieving design life of each component and the bridge. The components are divided into four different types on the consideration of maintenance, repair and replacement during life cycle of the bridge. The requirements of durability and maintenance, repair and replacement are determined based on the relation between each component and the bridge. It is suggested that each component should be designed according to one or the combination of three design strategies to assure the realization of design life of each component and the bridge and the assessment and the optimization of design alternatives should be implemented based on life cycle cost analysis. Finally, a procedure for life-cycle based design integrating durability design, replaceability design and life cycle cost analysis is presented to provide the reference for bridge designers.