Reliability-Based Calibration of Fatigue Safety Factors for Existing Steel Bridges

Abstract

This paper investigates the fatigue assessment of existing steel bridges. Measurements can be used to reduce uncertainties in the structural behavior and the effects of action. However, the treatment of the measured response is not clearly defined in today’s codes of practice. A reliability model is suggested that treats the uncertainties for bilinear fatigue endurance and the uncertainties in the measured response. A parametric study on the modeling of the load effect is performed and shows a significant influence on the reliability. The reliability model is used for calibration of the partial safety factors in a deterministic design equation. The suggested partial safety factors enable practical use of measured stresses in the fatigue assessment of existing steel bridges. A numerical example shows the merit of the proposed model and partial safety factors as an increase in fatigue life.