Relationship of structural durability with structural safety and serviceability in whole life-cycle

In current reliability analysis and design of structures,the influence of durability on structural safety and serviceability is not yet taken into account,due to the lack of durability failure criterion,and the differences in understanding durability concepts.In view of these problems,this paper analyzes the basic concepts of safety,serviceability and durability and clarifies their connotations,from the perspective of the life-cycle design of structure..And through the analysis of the influence of various factors on structural resistance changes,and the process of structural performance with time changes,the authors indicate that during the life-cycle of structure,the durability of different levels influencing on structural safety and serviceability will produce different effect,and the relationships among the three are interactive,and the durability of structures is redefined.Besides,the new idea of performance based limit state design is proposed,which indicates that the limit state of durability can be defined based on different performance requirements.The failure probability of structure or service life is seen to have larger difference,if different performance limit states are used for the same structural element.