Behaviour of square hollow structural steel braces with end connections under reversed cyclic axial loading

Abstract

The hysteretic behaviour of nine square hollow structural steel (HSS) sections with gusset plate end con nections subject to inelastic cyclic loading has been examined by an experimental investigation. Brace slenderness ratio, width to thickness ratio, and to a lesser extent, the end connection were identified as the key parameters in the tests. It was shown that the effective slenderness ratio is the most important parameter governing the hysteretic behaviour. The out-of-plane deflection of the brace can be accurately calculated using a simplified geometrical model or a model calibrated against the test results. Reduced compressive capacity as specified by the current Canadian Standards Asso ciation (CSA) standard was nonconservative for the specific loading sequence employed in this series of tests. Quantification of the energy dissipation proved that the gusset plates account for a small percentage of the total energy dissipated. The experimental fracture life of the specimens proved to be most affected by the width to thickness ratio and the effective slenderness ratio. An empirical equation is proposed to more accurately determine the theoretical fracture life of an HSS brace.Key words: brace, hysteresis, steel, hollow structural section, cyclic, end connection, fracture, energy dissipation, compressive capacity, effective slenderness ratio.