Abstract
In this work, the influence of the modulus of elasticity, the loss factor and the density of reinforced concrete on the vibration transmission index ([Formula: see text]) of a reduced concrete bench was evaluated. An experimental modal analysis based on the Operating Deflection Shape (ODS) methodology is carried out on a reinforced concrete slab (1.20 × 0.80 × 0.20 m) supported on four concrete pillars, applying four sources of distinct impacts: mallets of 1 and 4 kg, impact machine and one person jumping. The experimental results served to validate the finite element bench model (FEM) considering both the first four modes of slab vibration and the adjustment of the elasticity and shear modulus, the loss factor and the density of the concrete using the NSGA genetic algorithm-II. The [Formula: see text] index between the slab and the columns was determined experimentally, numerically and analytically, according to the Gerretsen model. The FEM model showed a percentage difference in the frequencies of the vibration modes less than 10% concerning the tests for the [Formula: see text] index. The influence of density and the modulus of elasticity mainly in the direction perpendicular to the plane of the structure modify the values of the frequencies of the vibration modes by up to 10% without interfering in the modal forms of the structure. In addition, the internal loss factor alters the amplitude of the [Formula: see text] results by an average of 10 dB. Finally, it is shown that the stiffness varies according to the orthotropy of the material. It was possible to conclude that the computational model showed good convergence in results ([Formula: see text]%) when compared with the [Formula: see text] experiments, with the same varying along the frequency, different from what is proposed in the analytical and normative models. This fact proves the hypothesis raised that structural couplings in practice generate significant interference in the results, as happens in residential buildings, with the test bench being an important experiment for initial predictions with little interference from energy transmission to the environment.
Published Version
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