Stress concentrations in tubular gap K-joints: mechanics and fatigue design

The present paper offers a comprehensive study on stress concentrations in welded tubular steel gap K-joints and its implications on fatigue design. After presenting an extensive overview of the relevant literature, finite element results of stress concentration factors (SCFs) are reported and evaluated for various loading conditions. Emphasis is given to the SCF location as well as to the so-called `carry-over effectʹ. Critical points for the determination of hot-spot stress are identified. Finally, design guidance for the reliable determination of SCFs is provided to be used for the fatigue design of welded tubular K-connections. The SCF design values are presented in the form of graphs and equations in terms of the non-dimensional joint parameters, based on the numerical (finite element) results. The proposed SCF guidance can be easily implemented by design engineers, taking into account the effects of various joint parameters and can be used towards safer design of structures under repeated loading.