2006

Shear and Tension Capacity of Arc Spot Weld Connections for Multi-Overlap Roof Deck Panels
(In collaboration with Colin Rogers, McGill University).
The objective of this research was to evaluate the applicability of the current design provisions for arc spot welds in the case where multiple layers of sheet steel are connected to relatively thin framing members, as would be found in open web steel joists.

Arc-spot welds fabricated in multi-overlap configurations are found in roof deck construction when steel sheets are stacked at a sidelap or endlap. A welding technique that maximizes the quality of arc-spot welds when fabricated through several layers of thick sheets is presented. Welds test specimens were fabricated through 1, 2 or 4 layers of steel sheets with thicknesses ranging from 22 gauge (0.76 mm) to 16 gauge (1.52 mm). The most important factors to control during the welding of thick steel sheets are the current (high intensity), the electrode type (E4311) and the welding technique. Various sheet steel / weld configurations found in roof deck construction were included. Adequate weld quality could be achieved in all cases except that welds were undersized when the ratio of the thickness of the underlying material to total sheet thickness was less than 0.7. A total of 72 tension tests and 107 shear tests were completed. In the latter group, 31 shear specimens were loaded with a reversed cyclic protocol to gain insight into the behaviour of arc-spot welds subject to seismic loading. All other specimens were loaded under monotonically increasing displacement. The results were compared with the current provisions of the CSA S136 North American Specification for the Design of Cold-Formed Steel Structural Members. The CSA S136 equations for shear and tension resistance of arc-spot welds are generally conservative, even for welds fabricated through multi-overlap configurations with total sheet steel thicknesses exceeding the 3.81 mm limit. Nonetheless, modifications to the equation for the effective diameter and to Equations E2.2.1.2-2 E2.2.2-1, and E2.2.2-1 are recommended.

Selected Publications:
Guenfoud, N., Tremblay, R., Rogers, C.A. (2010), "Arc spot welds for multi-overlap roof deck", 20th International Specialty Conference : Cold-Formed Steel Design & Construction, St. Louis, USA, 535-549.

Guenfoud, N., Tremblay, R., Rogers, C.A., (2010), "Shear capacity and tension capacity of arc-spot welds for multi-overlap roof deck panels", Journal of Constructional Steel Research. Vol. 66 No. 8-9, 1018-1029.

Guenfoud, N., Tremblay, R., Rogers, C.A., (2010) "Experimental program on the shear capacity and tension capacity of arc-spot weld connections for multi-overlap roof deck panels", Research Report, Dept. of Civil, Geological and Mining Engineering, École Polytechnique, and Dept. of Civil Engineering & Applied Mechanics, McGill University, Montreal, Canada.