Shear performance of lightweight concrete filled hollow flange cold-formed steel beams

Concrete-infilled hollow flange cold-formed steel (CF-HFCFS) beams have gained attention in the construction practices owing to many benefits in terms of their structural performances and applicability. The concrete infill ensures better structural performance by restraining the buckling instabilities of thin-walled cold-formed steel elements. However, the shear strength characteristics of CF-HFCFS are not systematically explored yet and hence there is a lack of understanding on the shear strength characteristics of CF-HFCFS beams. Therefore, in this research, shear characteristics were investigated through numerical studies by establishing and analysing three-dimensional finite element (FE) models of CF-HFCFS beams. The developed FE models were verified against the experimental data in terms of failure modes, ultimate shear capacities, and load-displacement characteristics. Then a series of parametric analyses were carried out to investigate the shear behaviour of CF-HFCFS beams against the effects of geometrical (steel thickness, beam depth) and mechanical (yield strength of steel and compressive strength of concrete) properties to further verify the shear characteristics of CF-HFCFS. Lightweight normal and lightweight high strength concrete materials were considered as infill. Also, the influence of the concrete infill on the ultimate shear capacity of the CF-HFCFS beams was evaluated through parametric studies. The ultimate shear capacities were compared against the already available design provisions. Consequently, based on the data established through of parametric analyses, modified design provisions are developed to estimate the ultimate shear capacity of CF-HFCFS beams.