TABLE OF CONTENTS The columns in an actual structure are frequently subjected to compression combined with biaxial bending, i.e., to bending moments acting in two principal axes directions in addition to an axial compressive load. The biaxial bending moments may result from the space action of the entire framing system, and/or from an axial load biaxially located with respect to the principal axes of the column cross section. All columns in an actual building framed structure should therefore be designed as a biaxially loaded beam-column. It is the purpose of this chapter to review the existing design specification requirements for biaxially loaded beam-columns, to present the new design procedures developed from a computer model and refined to achieve both simplicity in use and, as far as possible, a realistic representation of actual strength, to compare the size of beam-column section required by the existing and proposed new design rules for several practical design problems, and to provide final confirmation of the validity of the proposed methods by extensive comparisons with test results on actual beam-columns.
The design of a biaxially loaded beam-column may be approached from the stand-point of a precise computer solution. This is destined to be complex, since even for the design of a section for strength only, neither the location nor the angular disposition of the neutral axis of the fully plastic cross section subjected to a given axial load and biaxial bending moments is known. In consequence, an iterative procedure must be followed. In...
