Experimental studies of timber to cold-formed steel connections with self-drilling screws

This paper examines the behaviour of connections comprising self-drilling screws, cold-formed steel (CFS) and timber. Initially, a series of tensile coupon tests and shear tests were conducted to determine the material properties of the CFS material and the shear capacity of the screws that were used in the study. Subsequently, the ultimate load-carrying capacity of the connections was determined by undertaking a series of pull-out tests. Four connection configurations were investigated where the screws were driven perpendicular to the steel-timber interface. An assessment of the type of timber; plywood and Balau hardwood, and the thickness of the steel; 1.2 mm, 1.6 mm, and 2.0 mm, used in the connections was also undertaken. It was seen that as the thickness of the CFS material increased, the failure mode changed from screw withdrawal to failure in the screw. When the same CFS material was used with Balau, only failure in the screws was observed. The performance of current design guidance in the Australian standard (AS1720.1), North American Specification and Australian/New Zealand Standard (AISI S100 & AS/NZS 4600), and Eurocode 5 was assessed by comparing the shear strengths obtained from the experiments. From the comparison results, it was found that the Eurocode 5 is the most effective while predicting the performance of specimens with plywood and Balau hardwood, being 7 % con-servative to the test results.