Experimental analysis of cold-formed steel-to-timber connections with inclined screws

Abstract

An experimental investigation into the behaviour of connections between cold-formed steel and timber components, formed with inclined screws, is presented. A series of material tests was firstly carried out to assess the behaviour and limitations of each component of the system under investigation. These were supplemented by three types of interaction test: timber embedment, screw head pull-through and screw thread withdrawal, all aimed at developing a better understanding of the behaviour of the different components of the connection. The slip modulus and peak load-carrying capacity of twelve connection configurations were determined through a series of push-out tests. The results obtained were compared to the typical benchmark arrangement in which the screws were driven in perpendicular to the steel-timber interface.Component variations included the type of timberparticle board and plywood, the thickness of the steel -1.5 mm and 2.4 mm thick, the inclination of the screws -0° and 45°, and the presence or not of wings on the screws. The results showed that non-winged screws inclined at 45° gave up to about a 30% increase in peak load-carrying capacity and about a 140% increase in slip modulus when compared to the reference specimen.

A literature review on cold-formed steel-timber composite structures

“…CLT and LVL). It is expected that the mechanical performance of the connection system CFS-CLT composite solutions had higher performance than the solution presented by Vella et al (2020), which was composed by CFS and wood-based panel. Connection systems proposed by Awaludin et al (2016), Loss et al (2016a), Hassanieh et al (2016c), andHassanieh et al (2017a) should be tested in CFS-CLT composite solution in order to analyze the improvement technologies that can achieve in mechanical properties.…”

“…According to Vella et al (2020), the inclined screws decrease the risk of the two composite members separating under shear stress due to the component of force within the connector that acts perpendicular to the shear plane. The authors carried out an experimental study on connections between CFS and wood-based panels (particleboard and plywood) formed with inclined screws.…”

“…This problem can be reduced through bracing, which can be provided by the timber member (e.g., particle boards, plywood panels, laminated veneer lumber, or cross-laminated timber), through an appropriate detailing. In recent years, the use of CFS beams supporting timber panels has gained market share as a flooring system in industrial and commercial buildings (Vella et al 2020). This composite solution requires an efficient connection system to guarantee the composite action, allowing a more efficient use of the materials, and decreasing the execution time.…”

Characterisation of material and connection behaviour in sheathed cold-formed steel wall systems – Part 1: Experimentation and data compilation

“…According to EN 1994-1-1 [37], push-out tests are the standard means for determining the shear behaviour and capacity of connectors in composite construction -see Figure 25 (b). Therefore, several researchers have adopted this approach to determine the shear behaviour of fasteners connecting coldformed steel sections and various types of boards, including plasterboards [38], timber based boards [5,39] and cement based boards [23]. The latter approach is considered to be more representative of how a typical stud column is loaded in practice, and is therefore employed herein.…”

The Evolving Basis for the Design of Light Gauge Steel Systems

“…Most of the conducted research has been focused on conventional steel-concrete beams 32,33,34 , while, more recently, timber and concrete systems have also been examined 35,36,37 . Predictive models describing the load-slip response of several shear connectors have been devised 38,39,40,41 while test methods for push-out tests 42 have been established to ensure that all the important features are captured. Finally, with sustainability gaining increasing prominence, attention has been also given to the demountability of the employed connectors in order to facilitate their disassembly for re-use and recycling purposes 43,44,45 .…”