Análise de vibrações em pisos mistos aço/concreto

Abstract

The improvement of design and construction methods have made possible to build long span floors systems. Unfortunately, their low stiffnesses made them susceptible to vibrations problems due to human activities such as walking, dancing, exercising and audience participation. Long span floor systems have their natural frequency reduced to the point where they approach or equalize the forcing frequencies; as a result, the vibration grows to large amplitudes.This paper presents an analytical study of the dynamic response of composite floors, of usual dimensions, due to human activities. An extensive numerical analysis is developed based on the finite element method. A computational program was used to proceed the dynamic analysis and the development of the numerical model. The floorsystem was modeled with shell elements to represent the concrete slab and beam elements for the steel beam with full interaction between them. For the dynamic analysis a harmonic load was applied on the floor to simulate human activities. In the computational results has been observed that the acceleration response overcomes the standard suggested limits in the analysed problems. Another analysis consisted in reducing the floor to a single degree of freedom system. Simple design methods and formulae for calculating the system natural frequency, displacements and accelerations were used and the results showed that their utilization is valid only for a preliminary analysis.