Bridge Time-Variant Reliability Assessment Considering Resistance Deterioration and Load Change

With the bridge member resistance deterioration and traffic volume increasing on the bridge, bridge reliability considering time-variant factors has become an important problem. This paper presents a method to estimate the bridge safety performance based on time-dependent model of resistance decreasing and load change. Power form functions are used to fit the resistance degradation models in three environmental conditions, and time-dependent model of load increasing is built in accordance with traffic observation results somewhere. The results show that normal distribution probability model can be used to fit dead load time-varying model. In analysis, the most disadvantageous load combination effect is mainly considered, live load time-varying function approximately follows extreme type I distribution model. Finally the proposed approach combined with Monte Carlo method is used to assess the time-varying reliability index and the safe serving time of one prestressed concrete bridge in use.