Probabilistic fatigue life prediction of bridges using system reliability analysis and SHM-based Finite Element model updating

Abstract

Fatigue is one of the main causes of bridge failures. A bridge is designed with a particular service life, but after it is constructed, its strength degrades over time. Therefore, to effectively maintain and retrofit a bridge, it is essential to predict its remaining fatigue life. However, doing so is a very challenging task because fatigue life prediction should be based on the current condition of the bridge, and this obviously incurs many uncertainties. In addition, fatigue life prediction should be performed at the system level to take the structural redundancy of a bridge into account. This paper proposes a new approach based on the probabilistic fatigue life prediction of bridges using finite element (FE) model updating based on structural health monitoring (SHM) data. The proposed method involves three steps: (1) identifying the modal parameters of a bridge, such as the natural frequencies and mode shapes, from the ambient vibration under the influence of passing vehicles; (2) updating the structural parameters of an initial FE model using the identified modal parameters; and (3) predicting the probabilistic fatigue life at the system level by employing the updated FE model. The proposed method is applied to a numerical bridge example, and the analysis results are verified by comparing them with the results obtained from a Monte Carlo simulation.