New parametric equations for stress concentration factors in tubular K-joints under balanced axial loading

Abstract

An extensive parametric study is presented on stress concentrations in tubular K-joints calculated using thin shell finite elements. This study covers a comprehensive range of geometric joint parameters under balanced axial loading. The results of this investigation were used to assess the existing parametric equations of Efthymiou ( Proc. Conf. Recent Dev. Tubular Joints Technol., Surrey, 1988, p. 2-1) and Lloyds Register ( Proc. 1st Int. Soc. Offshore Polar Eng. Conf., 1991, Edinburgh). These equations predict stress concentration factors on the chord and the brace at selected locations as a function of the joint geometry, and are based upon databases which cover relatively narrow ranges of geometric parameters. The new database of thin shell finite element results was used to develop new parametric equations for estimating stress concentration factors on the chord and on the brace. The reliability of the proposed parametric equations was then assessed using the database of steel and acrylic joints published recently by the Department of Energy (Draft Background to New Fatigue Design Guidance for Steel Joints and Connections in Offshore Structures, 1995).