Evaluating the design strength of sheathing connection in CFS shear wall

Abstract

Construction using light gauge steel (LGS) is similar to the construction of structural steel frames. The steel used in the construction of light gauge is mostly cold form steel (CFS) which is molded into shape at room temperature. For LGS, two basic steel fram- ing components called studs and tracks are used. Tracks are vertical support members that function as top and bottom plates. Tracks run between horizontal framing members called plates (Fig. 1c). The studs are vertical support members running horizontally be- tween framing members called tracks. (Fig. 1b) The screws examined in this research proposal are used between stud and tracks. In cold form steel (CFS) buildings, seismic resistance is provided by sheathing braced & strap braced shear walls, which resist horizontal in-plane action. The walls are de- signed to withstand loads laterally via in-plane shear. The shear strength and performance of such panels are determined by the sheathing connection between the sheathing panel (OSB, GWB, gypsum, wood etc.) and CFS frame. Fasteners (nails and screws) are used between the sheathing panel and CFS frame to develop resistance against lateral loads. The current design method by the American Iron and Steel Institute (AISI) is unable in as it should be predicting the design shear strength of the sheathing braced shear walls through analytical design formula. The purpose of this research proposal is to suggest the design criteria to evaluate the ul- timate shear strength of the connection between the panel and steel frame utilizing the available experimental studies on them. The development of accurate design criteria will enable better design guidelines for structural engineers thereby leading to efficient use of CFS building systems. The multiple experimental studies examined in this research include self-drilling screws (SDS), screw diameter, the frame thickness, as well as also assessing the strength of the sheathing braced connections between cold formed steel systems and panels under monotonic and cyclic shear loads. This research proposal also has taken into consideration the study and failure of CFS panel sheathing connections; effect of the edge distance between the sheathing and the thickness of the boards on behavior and strength. In the realm of Cold-Formed Steel (CFS) structures, we can categorize connections into two main types: strap- bracing and sheathing braced connections. Strapbraced connections are used to join various parts of CFS skeletal systems, such as connecting beams to studs, trusses, and attaching tracks to studs. Research in the field of steel-to-steel connections, as documented in studies [3,4], delves into elements like connection pat- terns, how forces are transmitted, and the characteristics of fasteners. On the other hand, steel-to-sheathing connections serve the purpose of creating a ”stressed skin” effect between the structural framework and the sheathing material. These connections significantly influence the way wall panels behave, introducing nonlinear characteristics. Additionally, the sheathing boards provide essential bracing at specific fastener points, thereby enhancing the overall strength of the wall studs against buckling failure.