Estudo do controle de vibrações em pisos por meio de absorvedores de massa sintonizada

Abstract

The progress of structural analysis and design techniques regarding to the production of structural materials with improved mechanical properties has been allowing, in recent years, the construction of lighter, more slender and more flexible structures. The increase in the slenderness of the structural elements has been leading to the occurrence of problems related to the excessive vibration of the structures, especially in building floor slabs. The excessive vibrations in floor slabs can be reduced in an efficient way by fixing in the inferior part of the slab a Tuned Mass Damper (TMD). This device consists of a mass connected to the structure through a spring placed in parallel to a damper. The present paper has the goal evaluate the efficiency of TMDs for vibration control in prefabricated reinforced concrete floor slabs and timber slabs subjected to the action of human-induced vibrations. After an analysis of the international literature on vibration control, it was selected a more adequate design method to the TMD. The method was tested in a mathematical model of a concrete slab subjected to the action of walking of one person. On purpose, the slabs studied in this paper presented resonance with the 2nd harmonic of loading. For a loading of normal walking, with frequency of the fundamental harmonic in 2.24 Hz for the concrete slab and 2.15 Hz for the timber slab, the maximum acceleration in the midspan reached, in both cases, such magnitude that causes discomfort to the users. The TMD was designed according to Moutinho’s (1998) abacuses, with the goal of limiting the peak of acceleration in 0.5% of g, in the simulation with the TDM installed in the concrete slab, the acceleration in the midspan decreased to 0.3% of g, being considered acceptable. The method was also tested for a timber slab, however it would be necessary to add a superior mass than recommend by the literature, therefore adding a TMD to the structure would not be practicable. It can be concluded that, when plausible the implement of a passive control system, such as the case of the concrete slab, the design method through abacuses proposed by Moutinho (1998) is easily applicable and leads to satisfactory results.