Beam Web Strength under Pairs of Concentrated Compression Loads

Section K1 of the AISC allowable stress design and load and resistance factor design specifications prescribes a set of requirements by which the strength of the web of a flexural member or column must be evaluated when the web is subjected to a concentrated load. All of the work upon which these requirements are based consider only single point loads. Loading conditions may exist in which a beam is loaded by a pair of compression loads that are spaced in relatively close proximity. Application of the Section K1 provisions without consideration of the spacing of these loads may yield unconservative results. This paper derives means of evaluating when two compressive loads of such a pair may be considered to act independently and how they may be treated if they are close enough to interact with each other with respect to the strength of the web.