Modal testing of a 150-tonne concrete slab incorporating a false floor system

With the increase in use of slender forms of concrete floor construction, the incidence of problems with their vibration performance is becoming more frequent. Modal testing is being used by the authors to improve finite element models of such structures, in order improve understanding of their dynamic behaviour. This paper describes the finite element modelling, modal testing and finite element model correlation of a 150-tonne high strength concrete slab, before and after the installation of a non-structural raised access (false) floor. It is shown that the presence of the non-structural false floor alters the vibration performance of the slab by increasing both the stiffness and modal (viscous) damping ratios. These changes due to the false floor are generally beneficial when considering the vibration serviceability performance of the slab.