Section moment capacity tests of rivet fastened rectangular hollow flange channel beams

• Investigated the section moment capacities of rivet fastened rectangular hollow flange channel beams
• Conducted 15 section moment capacity tests to determine their ultimate moment capacities
• Investigated the effect of rivet fastening on the flexural behavior and capacities
• Current design rules were inadequate for beams with larger rivet spacing.
• Proposed improved direct strength method based design equations

This paper presents the details of an experimental investigation on the section moment capacities of rivet fastened Rectangular Hollow Flange Channel Beams (RHFCB). The rivet fastened RHFCB is a new type of cold-formed steel section, an extension to the widely researched hollow flange beams, shown to have capacities more typically associated with hot-rolled steel beams. It is characterized by a unique geometry, consisting of two rectangular hollow flanges and a web. Unlike other cold-formed sections, the RHFCB has improved capacity due to its mono-symmetric shape and the absence of free edges. The RHFCB manufacturing involves fastening two hollow flanges to a web, utilizing inexpensive intermittent self-pierced rivet fastening. This enables designers to develop optimum sections with varying web and flange thicknesses, therefore delaying the onset of other buckling failures due to slender web element. Various researches have been carried out to investigate the behavior of continuously welded hollow flange beams but little is known on the behavior of RHFCBs. Hence this paper investigates the section moment capacities of rivet fastened RHFCBs. Fifteen section moment capacity tests were conducted to investigate the behavior of RHFCB flexural members. The reduction in section moment capacities from having continuous weld to intermittent rivet connection at its web-flange junction was also investigated. The ultimate moment capacities from the tests were compared with current steel design standards: AS/NZS 4600, AS 4100 and AISI S100. The paper also explores the suitability of the Direct Strength Method, with modification being proposed, from the results obtained from this investigation.