engleski

Parametric Torsion Response of Simple Symmetric Structure

The observation of buildings subjected to strong earthquakes showed that even symmetric structures could exhibit torsional vibrations. Building Codes include only a simple design provisions to account for accidental torsion in symmetric and asymmetric buildings. The structural response associated with accidental torsion is not amenable to calculation in structural design, but research has demonstrated deficiencies in this code provision. The research of torsion in symmetrical structures usually starts from the assumption that a small eccentricity and one-plane symmetry of the structure exist. This paper is based on the simple total plane symmetry model: a rectangular rigid slab with uniform mass distribution supported by four equal, elastic, rectangular columns. The nonlinear influence of axial forces connects torsion and lateral deflection during model vibrations. The paper investigates the vibrations stability of described model and the indices for the occurrence of torsional resonance. The stability of vibrations was investigated parametrically in the sense of Liapunov. The equation which connects the parameters in the case of the bifurcation is found out analytically and confirmed numerically. Some unstable self-excited vibration solutions are shown.

vibration; stability; torsion; bifurcation

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