Behavior of shear connectors joined by direct fastening

Abstract

Direct fastening is an effective method to quickly and easily connect two steel components. However, the behaviors of this kind of connection have been rarely studied and there is no direct reference to them in current design specifications. Therefore, it is now timely to investigate the properties and behavior of this type of connection. In this paper, 11 coupons were tested at room temperature and 24 coupons were tested at high temperatures and after fire, to examine the deterioration of the mechanical properties of the steel. Moreover, 24 samples that were connected by direct fastening were tested at high temperatures and post fire conditions to study the deterioration in the shear strength of the fastener at different temperatures. Furthermore, 100 samples that were connected by direct fastening were tested in an ambient temperature to examine the effect of the number of fasteners, fastener spacing, fastener arrangement, knurled fasteners and protuberance. Based on the tested results, a modified expression for the yield strength of this kind of connection was proposed. Besides that, the bearing resistance versus displacement (BRVD) of the connections was numerically modeled and plotted into a simple curve based on the three key parameters of yield strength, effectiveness stiffness and ultimate displacement.