Comparative study of deterministic and probabilistic fatigue assessment methods

Master's thesis in Structural engineeringThe subject of this thesis is to compare the use of a deterministic and probabilistic assessment methods in fatigue analysis. The thesis focuses on the nominal stress method in the stresslife approach. Three different assessment methods are presented and compared, the traditional method, the closed form method and the probabilistic method. The traditional method is the one described in DNV-RP-C203 (DNV, 2014). The closed form method involves using a Weibull distribution to represent the stress spectrum. The probabilistic method involves the use of Monte Carlo simulations to obtain the probability of failure Pf . The associated procedures of the three assessment methods above were verified by considering a simple example. The assessment methods were then used for fatigue analysis of two case studies for traffic loads on a bridge. A single-span and a three-span bridge is evaluated. An attempt on improving the traffic load model presented in the Eurocode (ECS, 2010a) is also proposed. Based on the research and the obtained results, possible limitations and shortcomings are discussed