Experimental and numerical modal analysis of the steel frame

Resumo

In engineering, it is extremely important to direct research towards the identification and understanding of dynamic behavior in structures, as dynamic loads are present in all types of structures, including civil construction. Dynamic loads can range from the interaction of the wind with the structure to people's footsteps and car movements, and cause vibrations. These vibrations can cause damage to the structure and users, depending on their intensity and duration. For this, the structures are dimensioned and designed to support all the efforts required, this includes vibrations and other dynamic actions. Thus, the present work aims to determine the dynamic properties of a steell frame through a numerical and experimental modal analysis.
The steel frame is made of cold-rolled A36 steel. The profiles of the columns and beams are formed by cold rolled profiles forming sections of the type closed stiffened double u-profile and hat profile, respectively. The beams are joined to the columns by rigid connections. The dimension of the steell frame is 2m in height by 1m in width and length, approximately. Numerical analysis was performed by the Finite Element Method using shell elements. In the experimental analysis, the structure was excited by an impact hammer and the vibration response was measured by piezoelectrics accelerometers. The frequency domain method Rational Fractional Polynomial (RFP) was used to estimate the natural frequencies, mode shapes and damping factor. There was a good agreement between the experimental results and the numerical values obtained by the proposed procedure.