Journal of the Brazilian Society of Mechanical Sciences and Engineering
versão impressa ISSN 1678-5878
SOARES FILHO, M.; GUIMARAES, M. J. R.; SAHLIT, C. L. e BRITO, J. L. V.. Wind pressures in framed structures with semi-rigid connections. J. Braz. Soc. Mech. Sci. & Eng. [online]. 2004, vol.26, n.2, pp. 174-179. ISSN 1678-5878. http://dx.doi.org/10.1590/S1678-58782004000200010.
In the analysis and design of framed structures, the traditional methods are based on the simplified assumption that the joints are completely either pinned or rigid. However, the experimental investigations show that the frame connections present an intermediate behaviour between these two extreme cases. The present work is concerned with the dynamic elastic analysis of semi-rigid plane frames subjected to wind pressures. The dynamic excitation induced by the wind is estimated by adopting the simulation method of Monte Carlo. The wind flutuation pressures are decomposed into a limited quantity of harmonic components that are then combined many times, making possible the accomplishment of a probabilistic analysis and the choice of a characteristic response. The frame is considered as a set of contiguous bar elements, connected to each other at the nodes, and the connections are modelled as zero-length rotational springs. A nodal description of the kinetic and kinematic laws is given under the restriction of small displacements. The behaviour of the frame material and connections is described by linear elastic moment-rotation relationships, which are presented in the stiffness form. In order to take into account the effect of the semi-rigid behaviour of beam-to-column connections, the mass and stiffness matrices are developed as the sum of the conventional finite element matrices and correction matrices that incorporate the flexibility of the end joints. The problem of forced vibrations is then solved by means of the numerical integration of the motion equations.
Palavras-chave : Semi-rigid frames; wind forces; vibration analysis; dynamic response.