Predictivity of CNC machine-induced vibrations on inter-story floors based on coupled experimental-numerical investigations

Machine-induced vibrations and their control represent, for several reasons, a crucial design issue for industrial buildings. A special attention is required, at the early design stage, for the structural and dynamic performance assessment of the load-bearing members, given that they should be optimally withstand potentially severe machinery operations. To this aim, however, the knowledge of the input vibration source is crucial, in the same way of a reliable description of the structural system to verify. In this paper, a case-study eyewear factory built in Italy during 2019 is investigated. The poor customer / designer communication on the final equipment of the factory resulted in various non-isolated Computer Numerical Control (CNC) vertical machinery centers mounted on the inter-story floor, that started to suffer for pronounced resonance issues. Following the past experience, the paper investigates the efficiency of a coupled experimental-numerical method for generalized predictive and characterization studies. Based on on-site experiments, the most unfavorable machine-induced vibration source and operational conditions are first described, among the available working processes. The experimental outcomes are then assessed and integrated with the support of Finite Element (FE) numerical simulations, to explore the resonance performance of the floor. The predictability of marked resonance issues is thus analyzed, with respect to the reference performance indicators.