Design Strength of Concentrically Loaded Single Angle Struts

In practice, the majority of single angle struts are eccentrically loaded, and an attempt to calculate exactly the strength of such members is a task of formidable complexity. Therefore, the designer often relies on approximate methods and guidelines, in which the key ingredient is the value of the design strength when the strut is loaded concentrically (AISC 1986, ASCE 1988, and Adluri and Madugula 1992). In this brief note, a step-by-step solution and load tables are presented for the determination of the design strength of concentrically loaded single angle struts according to the AISC 1986 LRFD Specification. Equation A-E3-7, of Appendix E of the LRFD Specification requires the computation of the torsional-flexural buckling stress as the smallest of the three roots of a cubic equation.