Toward the Simplified Design of Single-Angle Beam-Columns

Abstract

Single angle compression members are frequently used as diagonal and lacing members in trusses and in lattice towers. Within this context, connection geometries at the angle ends frequently involve attachment though only one leg of the angle cross-section; thus introducing loading eccentricities and their concomitant end moments. AISC requires that this case be treated as a beam-column involving second order amplification of moments. In contrast, ASCE recommends that the eccentricities in loading be treated though the use of modified effective length factors in conjunction with standard column design methodologies. Recent research by Mengelkoch and Yura compares the two approaches and makes additional recommendations. This latter research is at the heart of proposed modifications to the new combined specification. The current research expands on the new single angle design approach by studying additional column slenderness ratios, loading eccentricities, and varying degrees of rotational restraint at the column ends beyond what was considered by Mengelkoch and Yura.