Stitch Spacing and End Fixity in Seismic‐Resistant Boxed Angle Braces

Abstract

The behavior of boxed double‐angle bracing members subjected to out‐of‐plane buckling under severe cyclic load reversals is investigated. Six full‐size hinged‐end and three fixed‐end bracing members made of double angles of A36 steel with welded stitches and end gusset plates were tested under large cyclic deformations representative of severe earthquakes. The effects of section configuration, stitch spacing, and end fixity were studied. The tests showed that boxed angles had a behavior much superior to the conventional back‐to‐back angles. Smaller stitch spacing in boxed angles increased the first buckling load and enhanced the postbuckling performance. Smaller stitch spacing, in general, and continuous stitch plate, in particular, significantly enhanced the performance of boxed angles by reducing section distortion. End fixity resulted in a twofold increase in the energy dissipation capacity and cyclic peak compression loads of the bracing members.