Experimental and numerical modal analysis of a lightweight composite slab supported by cellular beams

In the current paper, the dynamic behaviour of a lightweight composite floor, consisting of a steeldeck-concrete slab supported by cellular beams is examined. An attempt is made to simplify the cellular beams to beams with a constant cross section, and the steeldeck-concrete slab to a plate with constant thickness and orthotropic material properties. These equivalent elements are used to set up a modal analysis of the complete floor, and it is found that a determining factor in the dynamical behaviour of this lightweight floor is the choice of the boundary conditions. In order to improve the correspondence between the experimental data and the finite element model, an updating procedure is applied, where the values of the orthotropic material properties of the equivalent slab, as well as the parameters describing the support conditions, are adjusted to obtain a mimimal discrepancy between the modal properties of the model and those of the real floor. Finally, the measured response of the floor under a footfall excitation is compared to an estimation from a simplified procedure, and to the response of the updated FEM model.