Framework for Reliability-Based Fatigue Life Evaluation of Deteriorated Steel Structural Members

Abstract

This thesis presents a framework for reliability-based fatigue life evaluation of deteriorated steel structural members. A technique is suggested to perform fatigue life evaluation when crack or corrosion is detected on deteriorated steel members. Firstly, fatigue lives associated with crack or corrosion are calculated based on the linear elastic fractures mechanics and the stress-strain approach. Stress concentration factors of corrosion pits are determined by finite element analysis and regression analysis for fatigue notch factors in the stress-strain approach. Secondly, scenarios according to the type of defect found in the inspection and the limit states for each scenario are set. Lastly, a case study is conducted for the existing steel bridge using field monitoring data and confirmed the effectiveness of the proposed procedures. A reasonable condition criteria for a deteriorated steel structural member is presented using the reliability index obtained from the reliability analysis. When the results are compare to the existing condition criteria, it is possible to present a quantitative measure and confirmed that the engineering basis can be secured because the criteria was set based on the reliability index.