Structural behaviour of cold-formed steel to timber shear connections
File(s)
Author(s)
Vella, Nathan
Type
Thesis
Abstract
The behaviour of cold-formed steel-timber connections has been examined in this thesis. Experimental investigations have been conducted to determine the material and interaction properties of the three constituent components of the connection, namely the timber boards, the cold-formed steel beams, and the shear connectors. The effects of changes in various connection parameters on the performance of the connection under shear loading have been assessed through push-out testing, showing that a significant increase in connection stiffness can be achieved by adopting non-winged screws, inclined at 45° to the shear interface. An analytical model which can describe the load-slip response of cold-formed steel-timber connections, considering material damage and allowing for inclined screws has been developed and validated against experimental results. The understanding gained from the experimental investigation and the analytical model led to the development of innovative shear connectors, bespoke to cold-formed steel timber flooring systems. The innovative connectors, which are driven perpendicular to the shear plane thus simplifying the installation procedure, consist of fittings with a diameter larger than that of the ordinary screws, thus reducing the bearing stresses on the timber surface and consequently reducing the rate of embedment. Experimental results have shown that significant improvements in ultimate load and slip modulus can be achieved when replacing ordinary screws with innovative connectors. The analytical model was extended to cater for innovative connectors and its accuracy and applicability were validated. Finally, the performance of cold-formed steel-timber floors was assessed through four-point bending tests showing that significant improvement can be achieved when adopting innovative shear connectors. Existing design methods for the calculation of the effective flexural stiffness and moment capacity, have been extended to cater for varying connector strength, stiffness and spacing and their validity verified against the experimental results.
Version
Open Access
Date Issued
2023-05-21
Date Awarded
01/09/2023
License URL
Advisor
Gardner, Leroy
Buhagiar, Spiridione
Sponsor
Ministry for Education and Employment of Malta
Ayrshire Metal Products (Firm)
Publisher Department
Civil and Environmental Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)