CLT-steel composite slimfloor construction: An investigation of mechanical behaviour using finite element software

A new method of constructing multi-storey buildings has been investigated using Cross-Laminated Timber (CLT) panels acting as floor slabs with a steel framed support structure. Conventionally, concrete slabs are used for floor systems but timber panels weigh approximately one third of the equivalent concrete slabs, and hence the superstructure mass is significantly reduced, smaller sections can be used and thus less steel is needed overall. Further economy can be gained if composite action that can be generated between the CLT flooring and supporting steel beams. This paper presents the findings of a detailed finite element study to examine the composite performance of steel-CLT beams taking into account the method and degree of shear interaction, the determination of a suitable effective to width to account for shear lag, the position of the CLT relative to the beam (i.e. above the beam as in conventional composite construction or within the beam depth to form a slimfloor type system) and the layup and orientation of the laminations in the floor units. After briefly outlining the advantages of using a CLT-steel hybrid system, this paper explains how a detailed numerical model which captures the key features of the system was developed and validated and then present the results of a parametric investigation into the generation of composite action in a CLT-steel hybrid system.