Web crippling tests of Rivet Fastened Rectangular Hollow Flange Channel Beams under Two Flange Load Cases

Abstract

Cold-formed steel beams Web crippling Combined web crippling and flange crushing ETF and ITF load cases and experiments a b s t r a c t Recent research on hollow flange beams has led to the development of an innovative rectangular hollow flange channel beam (RHFCB) for use in floor systems. The new RHFCB is a mono-symmetric structural section made by intermittently rivet fastening two torsionally rigid closed rectangular hollow flanges to a web plate element, which allows section optimisation by selecting appropriate combinations of web and flange widths and thicknesses. However, the current design rules for cold-formed steel sections are not directly applicable to rivet fastened RHFCBs. To date, no investigation has been conducted on their web crippling behaviour and strengths. Hence an experimental study was conducted to investigate the web crippling behaviour and capacities of rivet fastened RHFCBs under End Two Flange (ETF) and Interior Two Flange (ITF) load cases. It showed that RHFCBs failed by web crippling, flange crushing and their combinations. Comparison of ultimate web crippling capacities with the predictions from the design equations in AS/NZS 4600 and AISI S100 showed that the current design equations are unconservative for rivet fastened RHFCB sections under ETF and ITF load cases. Hence new equations were proposed to determine the web crippling capacities of rivet fastened RHFCBs. These equations can also be used to predict the capacities of RHFCBs subject to combined web crippling and flange crushing conservatively. However, new capacity equations were proposed in the case of flange crushing failures that occurred in thinner flanges with smaller bearing lengths. This paper presents the details of this web crippling experimental study of RHFCB sections and the results.

Web crippling capacities of rivet fastened rectangular hollow flange channel beams under one flange load cases

“…The web crippling test results of rivet fastened RHFCBs with their flanges unfastened and fastened to supports under EOF and IOF load cases are given in Tables 5 and 6. The rivet fastened RHFCBs, including the rivet spacing, were built based on the recommendations in Steau et al [16]. Rivet spacing was maintained at 100 mm.…”

“…The web crippling failures occurred within the clear height of the web under the load. This is common for hollow flange channel beams, irrespective of welding or rivet fastening at the web to flange juncture (see Keerthan and Mahendran [17] and Steau et al [16]). Hence the web crippling failures observed in the tests confirms the suitable use of d 1 for rivet fastened RHFCBs in the web crippling design equations.…”

“…However, past research is primarily based on experimental studies of open cold-formed steel sections (C-, Z-, hat-shaped and built-up sections). Limited research has been conducted on the web crippling behaviour of channel beams, lipped channel beams and hollow flange channel beams under EOF and IOF load cases (Keerthan and Mahendran [17]; and Gunalan and Mahendran [18]) when compared with End Two Flange (ETF) and Interior Two Flange (ITF) load cases (Young and Hancock [19]; Macdonald et al [13]; Uzzaman et al [20]; Keerthan et al [21]; Sundararajah et al [22,23]; and Steau et al [16]). Only few researchers have considered channel beams with flanges fastened to supports (Young and Hancock [19]; and Janarthanan et al [24]).…”

“…Forty-eight rivet fastened RHFCBs with their flanges unfastened (24 tests) and fastened (24 tests) to supports were considered. The rivet fastened RHFCB test specimens were fabricated based on the method used in Steau et al [16]. The rectangular hollow flanges in these specimens were first cold-formed using a press-braking method.…”

“…Hence it is not applicable to the rivet fastened RHFCBs. Unlike other open coldformed steel sections, rivet fastened RHFCB may also be subjected to flange crushing, combined web crippling and flange crushing and lip failures [16].…”