VIBOIS: wood floor vibration behaviour and walking comfort
Context of the study
Wooden floors are lighter than their steel and concrete counterparts, and are therefore more susceptible to vibration and acoustic problems. When walking, the dynamic load imposed by the user is likely to induce accelerations that could be detrimental to the comfort of the user or other occupants of the building. The ISO 10137 standard  defines acceptable acceleration thresholds.
Wooden floors must therefore take into account the vibration problem in their design, in addition to the static rigidity criteria. The VIBOIS project aims to provide a methodology for determining the properties of a floor during its design phase and to estimate the accelerations that could be induced by walking.
Work carried out
The project was carried out in three distinct aspects. CLT and OSB floors of different sizes were designed for laboratory tests. A numerical model was developed and validated with the help of the tests. Finally, formulas could be established on the basis of analytical considerations and the numerical model to allow simple calculation of the floor properties and to define a design methodology.
The modal analysis identifies the main deformations of the floor and the frequencies for which the floor is likely to resonate. The test is carried out using accelerometers glued to different points of a mesh drawn on the floor. Through these tests, it is possible to identify the frequencies and shape of the first modes of the structure.
A total of about 70 people walked on the two instrumented floors and the accelerations induced by their steps could be measured. These tests provide a statistical sample of individuals who used the floor to a greater or lesser extent depending on their gait. The objective is to arrive at a criterion that allows us to obtain conservative accelerations for the majority of the tests.