Dynamic tests on a long-span, stressed-skin, timber floor

Abstract

ABSTRACT The design of timber floors is often governed by the fulfilment of serviceability requirements concerning human-induced vibrations. The stiffness and modal properties (eigenfrequency and damping ratio) are essential parameters for the design verification of timber floors against vibrations. In the present paper, a series of experimental tests (static tests, impact hammer modal tests, forced resonant vibrations and free vibrations) on a long-span, stressed-skin, timber floor are presented, together with predictions using a Finite Element model. Moreover, the effect of additional mass was investigated by adding extra weight in the mid-span. The modal properties obtained by different methods were in good agreement. The measured damping ratios were low, especially for the first two modes (of the order of 0.7% for the first mode and 0.8-1.0% for the second mode). The FE predictions were in good agreement with the experimental results regarding stiffness and the first two eigenfrequencies. However, the FE model overestimated the third eigenfrequency and underestimated the steady state accelerations observed under forced vibrations. A stiffness-proportional Rayleigh damping was found to describe best the energy dissipation.