Reliability assessment of Yonghe Bridge based on structural health monitoring

This paper presents the reliability estimation of Yonghe Bridge based on structural health monitoring technology. The data collected by structural health monitoring system can be used to update the assumptions or probability models of random load effects, which would give potential for accurate reliability estimation. The reliability analysis is based on the estimated distribution for dead, live, wind and temperature load effects. For the components with FBG strain sensors, the dead, live and unit temperature load effects can be determined by the strain measurements. For components without FBG strain sensors, the dead and unit temperature load and wind load effects of the bridge can be evaluated by the finite element model, updated and calibrated by monitoring data. By applying measured truck loads and axle spacing data from weight in motion (WIM) system to the calibrated finite element model, the live load effects of components without FBG sensors can be generated. The stochastic process of Live Load effects can be described approximately by a Filtered Poisson Process and the extreme value distribution of live load effects can be calculated by Filtered Poisson Process theory. By combination temperature and wind pressure distribution in the present design code and unit temperature and wind load effects, the extreme value distribution of temperature and wind load effects can be achieved. Then first order reliability method (FORM) is employed to estimate the reliability index of main components of the bridge (i.e. stiffening girder). Furthermore, practical damage situations are considered to evaluate the influence of certain elements failure on the reliability of undamaged components.