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In low seismic regions where wind loading governs structural design, the use of high-strength cold-reduced sheet steels for tension strap braces is attractive, but is hindered by a lack of material ductility that causes these braces to fracture without yielding. The present work investigates the potential solutions through laboratory tests at the brace component and at the whole shear panel levels. The slot-perforated braces with square or rounded slot ends tend to fracture at or near a slot end, while those with pointed slot ends avoid fracture there. Finite element analyses were used to confirm the experimental findings. The rounded slot end is recommended from the fabrication and deformation capacity points of view. The shear panel test results show that a normal high-strength strap brace would fracture at a screwed end without yielding, while the recommended solution can ensure substantial yielding provided the ratio of net slotted section to gross section is lower than the connection efficiency defined in the present work. The shear panel's deformation capacity can be controlled via the slot length. The desired slot length can be split into multiple slot perforations along the brace to facilitate inline punching during fabrication. [ABSTRACT FROM AUTHOR]

The commentary to the North American cold-formed steel specification recommends physical testing to determine the performance of a bolted connection where the plies are not in contact with each other. This paper presents the laboratory test results of 120 such specimens with sheet thicknesses ranging from 0.55 to 3.0 mm, bolted with 10-, 12-, or 16-mm bolts. Finite-element analyses support the experimental finding that the bearing failure of an unconfined bolted connection is not associated with shear fracture but with crimpling of the critical ply. The bearing capacity varies with the square root of the bolt diameter and nonlinearly with the sheet thickness. Dimensionally consistent and continuous design equations are derived and verified against the results of the laboratory tests and finite-element analyses, the latter supplementing the former with configurations involving 8-mm bolts. The derived relationships between the bearing capacity and the sheet thickness and bolt diameter are also verified against 18 independent test results involving bolted connections through square hollow sections. The presented equation is significantly simpler but more accurate than those proposed in the literature for such connections. A resistance factor of 0.70 is recommended for use with the proposed design equations for determining the bearing capacities of unconfined bolted connections. [ABSTRACT FROM AUTHOR]

This paper investigated the potential applicability of the specification equation for the shear pull-out strength of a power-actuated fastener (PAF) connection to nail connections between steel sheets thinner than 2.9 mm. The tested G300, G450, and G550 specimens had thicknesses ranging from 0.6 to 2.4 mm, connected with 2.5- or 3.6-mm helically knurled nails. The pull-out strength is a function not only of the thickness of the member not in contact with the fastener head, but also of the other member's thickness. The member thicknesses have greater influence than the nail diameter on the pull-out strength, contrary to the design equation. Based on the test results of 93 shear nailed connections failing in pull-out, the paper proposes a design equation that is applicable to connections using helically knurled nails of steel sheets thinner than 2.9 mm. A group effect factor of 0.75 is suggested for serial nail connections based on the test results of 19 multiple nail connections. A resistance factor of 0.55 is recommended for use with the proposed equation for determining the pull-out strength of shear nailed connections in thin steel sheets. An additional finding is that the current design equation for the bearing and tilting strength of a PAF connection is applicable to connections in which the member not in contact with the fastener head is much thinner than the specification minimum of 3.2 mm, and in which the fastener diameter is smaller than the specification minimum of 3.7 mm. [ABSTRACT FROM AUTHOR]

This data paper presents the experimental investigation of unconfined cold-formed steel double-shear bolted connections where the applied load was stopped at different stages of loading (25% or 65% of the ultimate failure load under monotonic loading) followed by unloading, and finally reloading until failure. A total of 78 bolted connections of cold-formed steel subjected to loading–unloading and reloading conditions with sheet thicknesses ranging from 0.55 to 3.0 mm, bolted with 10, 12, or 16-mm bolts were investigated and compared to the identical specimens subjected to monotonic loading. The failure mode of the specimens tested under both loading conditions was bearing of the inner sheet. The test results show that ultimate capacities obtained from unloading and reloading tests were, on average, lower than those obtained from the monotonic tests. A similar trend was also observed for the displacement corresponding to the ultimate loads. However, the effects of sheet thickness and bolt diameter were found to be less critical. This study establishes a publicly available database of control cases to build the foundation for further study into similar loading regimes. This paper also alludes to several potential use cases for the available data. [ABSTRACT FROM AUTHOR]