Research Report RP16-1
The provisions of the AISI S100-12 standard for strength of arc spot welds loaded in shear and tension have not been revised since the 1999 standard. Since then, four new research studies have created and tested arc spot welded connections, expanding the database of available tests. Therefore, a reconsideration of both the resistance equations and the resistance and safety factors using the enlarged data base was undertaken. This study performed a comprehensive analysis of the entire arc spot weld data base, where 450 specimens were categorized by their respective failure modes to assess current AISI S100-12 resistance equations. Performance of the existing equations was re-evaluated and compared with the performance of equations used in previous AISI S100 editions.
This study found that current equations and resistance and safety factors for sheet tearing failure modes are conservative and could be relaxed for shear as well as tension loading. New distinctions are proposed to improve the performance of side-lap connection resistance calculations. Also, removing the upper limit and adding a lower limit to the effective weld diameter calculation sharpened accuracy for calculated weld resistance of arc spot welds made through thicker sheet connections. Most AISI S100-12 equations were found to be adequate and can be made less conservative, however current provisions for weld failure under tensile load were found to substantially over predict weld strength. Adjustments to the tension weld resistance equation are recommended by this study to improve performance, however future research on tension weld failure of combined sheet connections would be beneficial.
Civil, Architectural and Environmental Engineering
Wei-Wen Yu Center for Cold-Formed Steel Structures
American Iron and Steel Institute
01 Feb 2016
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American Iron and Steel Institute, "Resistance of Arc Spot Welds -- Update to Provisions" (2016). AISI-Specifications for the Design of Cold-Formed Steel Structural Members. 153.