Testing and Analysis of Composite Cold-Formed Steel and Wood−Based Flooring Systems

Abstract

An experimental study has been conducted into the degree of composite action that can arise between cold-formed steel joists and wood-based flooring panels. A series of material, pushout and four-point bending tests have been carried out, and alternative means of shear connection, featuring fasteners and adhesives, have been investigated. It has been found that the spacing of the fasteners as well as the application of structural adhesive at the beam-board interface has a significant influence on the attained degree of shear connection and hence the moment capacity and flexural stiffness of the system. The highest degree of shear connection (up to about 60%) was obtained using the structural adhesive, bringing corresponding increases in capacity and stiffness of around 100% and 40% respectively over the bare steel.Smaller, but still very significant, increases in capacity and stiffness were achieved through the use of screws alone. Based on the results of the push-out tests, a load-slip relationship for screw fasteners in wood-based floorboards has been proposed; this is designed for use in future analytical and numerical models. The findings of this research demonstrate, for the first time, the benefits, in terms of enhanced structural performance and efficiency of material use, that can be derived through the practical exploitation of composite action in cold-formed steel flooring systems.

08.09: Design of cold‐formed steel composite flooring systems with partial shear connection

“…Degradation of the moment resistance with high levels of shear can be observed in Fig. 5, where the applied moment M Ed normalised by the moment capacity M c,Rd is plotted against the applied vertical shear force V Ed normalised by the shear resistance V b,Rd for all the physical tests and numerical simulations reported in [3] and [4] respectively. It is evident that an appropriate allowance should be made, accounting for the effect of the design shear force V Ed on the moment resistance M c,Rd .…”

“…The values of P b and P v can be either determined from Eqs. (1) and (2), respectively [3] or obtained from push-out tests.…”

“…spacing of cold-formed steel beams employed for the examined flooring systems is 600 mm. Since the conducted experiments and numerical simulations have shown that there is no shear lag for this spacing [3,4], the effective width of the floorboard b eff can be taken equal to the spacing of the beams (i.e. 600 mm).…”

“…Comparisons between the ultimate moment capacities M Rd and M lin,Rd predicted by the equilibrium and interpolation design methods respectively and those obtained from physical tests [3] and numerical simulations [4] M u have been made to assess the accuracy of the developed design method. In total, 78 comparisons have been performed, for which the mean M Rd /M u ratio was 0.92 while the mean M lin,Rd /M u ratio was 0.86.…”

“…Design expressions are presented for the calculation of the attained degree of shear connection of a system, and for the determination of bending resistance, shear resistance and flexural stiffness (for deflection and vibration checks). The theoretical background of the employed equations is described, and the accuracy of the proposals is assessed against the results obtained from physical tests and numerical analyses reported in the literature [3,4].…”