Numerical studies into factors affecting structural behaviour of composite cold-formed steel and timber flooring systems

Lightweight flooring system made up of cold-formed steel joist, and timber floorboard is widespread but the benefits of composite action that arise due to the interaction of top flange of cold-formed steel joist and the bottom surface of timber floorboard as a result of mobilising the shear connection are not considered in their design. A three-dimensional (3D) finite element model was developed and validated against the experimental results for cold-formed steel and particle board flooring system. The validated numerical model was used for parametric studies to investigate the influence of various factors that affect the structural behaviour of the composite flooring system. The results from the parametric studies showed that higher strength and stiffness values of engineered timber product, as well as their increased thickness, enhances the moment capacity and stiffness of the flooring system. The reduction in the spacing of the cold-formed steel joist was found to increase the stiffness and hence the load-carrying capacity of the flooring system. The high strength to weight ratio of cold-formed steel flooring system is also demonstrated in this study. A simplified design method is proposed herein to predict flexural capacity of composite beams taking into account for the composite action. The finding in this study indicates that the design and construction of composite cold-formed steel and timber flooring system should be subjected to availability of the engineered timber product in the region,choice of timber floorboard thickness and joist spacing can be based on the ultimate strength and serviceability requirements of the flooring systems to make it cost-effective.