9. Non-structural Masses and Their Influence on Floor Natural Frequencies

Excessive floor vibrations are problematic and may potentially render a floor unfit for its intended use. A design-stage check of vibrational performance of a floor design would encompass design-stage estimates of floor dynamic characteristics such as floor natural frequencies. Non-structural masses such as furniture might be present on the in-service floor. For a prediction of floor dynamic characteristics it is not common to account for the fact that non-structural masses elevated above the floor plane may contribute with inertial energy as a result of their horizontal motion occurring during vertical floor vibration. The paper addresses this subject by setting up a finite element model for the floor, which also accounts for an elevation of the non-structural masses. It is shown how different configurations of non-structural masses influence floor natural frequencies. For the investigations, the elevations and weights of the masses are modelled as random variables and Monte Carlo simulations are used for setting up the random configurations of non-structural masses across the floor area.