Design model for the compressive strength of angle members including welded end-joints

The practical design of single steel angle members in compression has to cover multiple effects. Due to the commonly eccentric connection on only one angle leg (bolted or welded), additional bending moments are acting on the member, leading to a complex load carrying behaviour with flexural and/or lateral torsional buckling phenomena. Furthermore, type and size of rotational restraints at the member’s ends (provided by the adjacent structure) significantly influence the compression member capacity of these members.

Within this paper, a recently developed design approach for hot-rolled angle members in compression is introduced. The presented method allows for calculating the internal forces based on elastic second order theory for an individual member with eccentricities and rotational spring stiffness at both ends. This calculation can be carried out by means of conventional structural analysis software. Detailed analytical models for the estimation of appropriate spring stiffness values for several practical applications in buildings with two-bolt connections have recently been presented by the authors. The proposed design method is now enhanced by means of additional formulae for angle members welded to the adjacent structure. Detailed background information on the derivation of these newly developed spring stiffness formulae is given. Finally, the accuracy of the design model for this enlarged range of application for angle members with welded joints is shown through comparison with sophisticated finite element calculations, code provisions (AISC 360 and EN 1993-1-1) and experimental tests from literature.