Experimental study on the interaction of pullout-by-shear and pullout-by-tension of power-actuated fastener connections in high-strength cold-formed steel

The current Australian/ New Zealand Standard (AS/NZS 4600:2018) and the North American Specification (ANSI/SDI AISI S100-24) for the design of cold-formed steel structures address the pullout behaviour of power-actuated fastener (PAF) connections under shear and tension actions separately, while the interaction effects due to combined shear and tension on PAF connections are required to be assessed through appropriate testing. However, limited experimental data on the PAF connections using high-strength cold-formed steel (CFS) are available to support the design of PAF connections under combined loading conditions. This paper investigates the pullout behaviour of PAF connections subjected to combined shear and tension through an experimental program comprising 98 tests on steel connections joining CFS sheets to hot-rolled steel (HRS) plates using PAFs with premounted washers. An innovative experimental apparatus (test rig) was designed and fabricated to enable testing under various loading conditions: pure shear, pure tension, and combined shear-tension. The test variables included all scenarios of fastener penetration (full, partial, and embedded), different fastener diameters, and varying thicknesses of CFS sheets and HRS plates. Each specimen configuration was tested under different loading angles, ranging within 0◦, 15◦, 30◦, 45◦, 60◦, 75◦, and 90◦, where 0◦ and 90◦ represent pure shear and pure tension loading conditions, respectively, and the others imply combined shear-tension. From the experimental results, the pullout resistance of PAF connections under combined shear-tension loading is mostly a linear combination of shear and tension. Failure modes and load-displacement characteristics were found to be consistent across the tested specimens. The findings provide valuable experimental evidence to support the design of PAF connections under combined shear and tension.