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Slender open-section cold-formed steel members that contain flanges with edge stiffeners may buckle in different modes and with mode interactions. The element design approach (effective width method) has been shown to produce unconservative capacity predictions for a particular class of such members. This paper presents a modification to the effective width method derived from an investigation of the fundamental behavior of edge stiffened flange elements and sections that contain them. The modified element design approach is validated against the results of 913 compression and bending members collected from the literature, where all section and member buckling modes and interactions were evident. A section design approach is also presented which is directly in line with the element approach. The unified element and section approach is shown to provide accurate and reliable design solutions for cold-formed steel compression and flexural members. Proposals for the North American specification for cold-formed steel structures are presented. DOI: 10.1061/(ASCE)ST.1943-541X.0000120 CE Database subject headings: Cold-formed steel; Design; Buckling; Steel structures. Author keywords: Cold-formed steel; Design; Elements; Effective width method; Buckling; Strength.

Single point, self-drilling fasteners are commonly used in light-gauge steel constructions including domestic, agricultural, and industrial structures. Fasteners installed in practice often suffer from a variety of in situ conditions that can affect the capacity of the fastener, such as construction tolerances creating combined shear and bending in the fastener (rather than pure shear), overtorqueing the fastener which can cause stripping of the thread or shearing off the head, nonperpendicular insertion of the fastener and accidental impact on the structure creating dynamic loads on the fastener. This note describes a series of 120 single lap connection tests of single screw fasteners under a variety of the above-mentioned conditions, performed on fasteners of different gauge inserted into different thicknesses and grades of steel. A design equation is proposed to modify the nominal shear strength to account for these conditions. DOI: 10.1061/(ASCE)0733-9445(2007)133:6(895) CE Database subject headings: Drilling; Steel construction; Fasteners.

This paper presents a general design procedure for calculating the moment capacity of sections containing unstiffened elements with stress gradient. The method uses design equations for effective widths of unstiffened elements with stress gradients based on plate test results. Current international design provisions allow the capacity of sections that contain stiffened elements with stress gradients to be calculated on the basis of inelastic reserve capacity, whereas sections that contain unstiffened elements must be designed on the basis of initiation of yielding in the section. This paper presents methods for the calculation of the capacity where inelastic reserve capacity may be taken into account, for sections containing fully effective unstiffened elements with stress gradient. The methods are shown to be in good agreement with experimental data of I-sections and plain channels in minor axis bending. Particular attention is given to the effect of both the elastic buckling coefficient used in the effective width method, and the use of inelastic considerations, on the bending capacity. Specific design proposals are presented in the form of amendments to the current American and Australian standards for cold-formed steel structures, for elements (effective width equations) and sections in bending (inelastic reserve capacity equations). CE Database subject headings: Stiffening: Stress: Gradient: Computation; Plates; Thin wall sections; Bearing capacity.