Applications of Flow-Drilled Connections in Modular Construction

Abstract

AbstractThe use of modular construction is on the rise due to the increased speed, efficiency, and quality that it brings in comparison to traditional construction practices. The emphasis on efficiency in modular construction makes it imperative for the accompanying connection methods used to be efficient as well. A proprietary method of modular steel construction currently exists that utilizes modules made from hollow structural steel (HSS) members. The tubular geometry of the HSS members used in these modules limits the access of bolts in bolted connections to only one face of the HSS member. This access limitation prevents the use of nuts as well. A potential method to efficiently use these one-sided connections is using flow drilling and flow tapping techniques. This paper explores and presents the findings of an extensive experimental parametric study to examine the structural behavior of flow drilled connections on HSS members under shear and tension loads. The parameters considered were HSS wall thickness, screw threads per unit length, screw hole drilling technique, and tapping technique. This resulted in a total of 150 specimens, half of which were subjected to axial tension and half in shear. The results of this study showed that flow drilled connections can significantly increase the tension capacity of one-sided connections in comparison to standard drilled connections but does not have a great influence on the shear capacity. This study also identified potential failure modes and developed analytical equations that can be used to predict the sequence of failure of the connections.