Identificação das propriedades dinâmicas em estruturas reticuladas por meio de análise numérica e experimental

Abstract

The identification of modal parameters is very important to guarantee the structural stability because of their influences on structures dimensions and on structures operation over the years. These dynamic properties, such as frequencies, mode shapes and damping ratios can be found using computational programs or identification methods for experimental models. Usually, the structures are subject to natural or environmental excitations, like winds and traffics, for example. However, the ambient vibration measurement implies the use of identification methods that consider only the structure response (output-only). The Modal Analysis methods can operate in time domain or in frequency domain which are two perspectives of data analysis. The first considers continuous time or discrete time and the other applies the data to obtain the power spectrum density. Therefore, the present study considered a steel beam with zero degrees of freedom and used both computational and experimental model analyzes. The output-only methods applied were the Peak Picking Method (FELBER, 1993), in frequency domain, and the Reference-Based Covariance-Driven Stochastic Realization (SSI-COV/ref) (PEETERS; DE ROECK, 1999), in time domain. Due to inaccuracies on data acquisition process, the results were compared and the methods performances verified. In conclusion, the computational model and experimental model analyzes were consistent and the identification methods performances depends on structure studied.