Authors: Angelo Luongo Daniele Zulli
Publish Date: 2011/02/01
Volume: 67, Issue: 1, Pages: 71-87
Abstract
In this paper an inclined nearly taut stay belonging to a cablestayed bridge is considered It is subject to a prescribed motion at one end caused by traveling vehicles and embedded in a wind flow blowing simultaneously with rain The cable is modeled as a nonplanar nonlinear onedimensional continuum possessing torsional and flexural stiffness The lower end of the cable is assumed to undergo a vertical sinusoidal motion of given amplitude and frequency The wind flow is assumed uniform in space and constant in time acting on the cable along which flows a rain rivulet The imposed motion is responsible for both external and parametric excitations while the wind flow produces aeroelastic instability The relevant equations of motion are discretized via the Galerkin method by taking one inplane and one outofplane symmetric modes as trial functions The two resulting secondorder nonhomogeneous timeperiodic ordinary differential equations are coupled and contain quadratic and cubic nonlinearities both in the displacements and velocities They are tackled by the Multiple Scale perturbation method which leads to firstorder amplitudephase modulation equations governing the slow dynamics of the cable The wind speed the amplitude of the support motion and the internal and external frequency detunings are set as control parameters Numerical pathfollowing techniques provide bifurcation diagrams as functions of the control parameters able to highlight the interactions between inplane and outofplane motions as well as the effects of the simultaneous presence of the three sources of excitation
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