Macro-crack initiation life for orthotropic steel decks considering weld heterogeneity and random traffic loading

Abstract

This paper presents a multi-scale approach to predict the macro-crack initiation life (MCIL) of welded joints. This fully adaptive multi-scale technique is designed to take into account micro-scale material heterogeneity due to the existence of defects and to consider the uncertainties regarding defect occurrence and characteristics and traffic loading. The procedure of the proposed approach was introduced along with an orthotropic steel deck. Firstly, a homogenisation method was used to link defects in the heat-affected zone with the macro-scale structure. This allows for estimating the effective Paris constant, required for a Paris Law-based fatigue damage analysis. Secondly, a traffic flow, based on weigh-in-motion measurements, was used to simulate the load effects on the examined joint. Afterwards, the extended finite element method was adopted to calculate the stress intensity factors with respect to the weld geometries. Finally, the damage before macro-crack initiation was obtained using the Paris Law. In addition, Monte Carlo simulation was integrated within this multi-scale crack growth procedure to consider the randomness in pore and inclusion occurrence and characteristics. Hence, the MCIL is expressed in the form of a probability distribution. Results show that the proposed approach enables to provide a rational maintenance and inspection intervention time.

Keywords:

• Multiscale
• crack propagation
• crack initiation
• XFEM
• homogenisation
• weld defects
• traffic flow
• uncertainty