Stability of Z-Section Purlins Used as Temporary Struts during Construction

Abstract

The stability of Z purlins subject to combined axial force and biaxial bending due to self-weight (a situation that typically arises during construction) is investigated. Single, isolated purlins as well as purlins with one or more lines of bridging are considered. The purlin can thereby be supported at the ends in various ways: (1) a simple cleat plate connection with two bolts, (2) a semicontinuous connection obtained by lapping the purlin with an adjacent span, and (3) a cleat plate connection with fly-bracing. The beneficial effect of the end restraint provided by each of these different support conditions about both a horizontal and a vertical axis was measured experimentally. The experimental data served as input for (1) detailed finite-element models, and (2) a theoretical buckling analysis of Z-section columns. Based on this work, design guidelines are presented for Z purlins subject to combined axial force and biaxial bending.