Flexural behaviour of Steel Timber Composite (STC) beams

Structural performance of a new type of lightweight steel-timber composite (STC) beam has been investigated by conducting four-point bending tests on 21 specimens. This paper presents key findings on its structural performance parameters such as failure modes, load-deflection response, load-slip response, load-strain response, and the ultimate bending capacity by grouping 21 specimens into 7 subgroups based on various geometric characteristics. In the proposed STC beams, glulam slabs were connected to the steel beams using high-strength bolts, and the effect of different thickness and width of glulam slabs on the structural behaviour of STC beams were carefully investigated. In addition, the effective bending stiffness, deflection, and bending capacity of the STC beams were theoretically calculated based on elastic theory and compared with experimental values. For all considered specimens, timber slabs and steel beams showed good composite action. Increasing the thickness and width of the timber slabs can effectively limit the lateral deformation of the specimens, improve the bending capacity of the specimens, and provides a secant stiffness to the STC beams. It was observed that for the whole cross section of STC beams, the plane section assumption is not applicable, but the strains on timber and steel seemed to satisfy the plane section assumption individually. r (Gamma) method has been observed to better reflect the deformation capacity of STC beams. Analytical equations were derived to predict the elastic bending capacity of STC beams, and comparison between theoretical and experimental values showed good agreement.