We investigate the coupled axial–torsional vibration of pretwisted beams. The equations of motion governing the extension, torsion, and cross-sectional warping of pretwisted beams are derived from Hamiltons principle, and the common assumptions used to simplify the equations are carefully examined through scaling analysis. Inconsistencies in previous works—such as the neglect of spatial and tim...

A 54-story steel, perimeter-frame building in downtown Los Angeles, California, is identified by a wave method using records of the Northridge earthquake of 1994 (ML=6.4, R=32 km). The building is represented as a layered shear beam and a torsional shaft, characterized by the corresponding velocities of vertically propagating waves through the structure. The previously introduced waveform inver...

By using dissipative system Lagrange equation, the strongly nonlinear dynamic equation of torsional vibration system is deduced, which contains a class of square and cube nonlinear rigidity and combination harmonic excitations. Bifurcation characteristics of the strongly nonlinear system are analyzed in the autonomous and non-autonomous situations by means of singular point stability theory and...

This work is devoted to investigation of the known problem of the discrepancy between the experimental and theoretical values for the barrier to internal rotation of the molecules comprised of a benzene ring and a π-conjugated substituent, such as benzaldehyde and benzoyl fluoride. The possible reasons of such discrepancy are considered. As a result the conclusion was drawn that the origin of t...