Stochastic Stability of Bridges Considering Coupled Modes: II
Publication: Journal of Engineering Mechanics
Volume 115, Issue 2
Abstract
A modified stochastic averaging technique is employed to calculate stability boundaries for the second‐order statistical moments for bridges under turbulent wind excitations. Assuming that the structural motion is dominated by a coupled critical mode, contributions from other more stable coupled modes are accounted for approximately in the averaging. When the dimension of the state space for the combined structure‐fluid system is large this mathematically approximate procedure is numerically much more efficient than the exact procedure used in Part I. The accuracy of this procedure is first tested in the case of 2‐DOF structural models, capable of vertical and torsional displacements, for which the exact results are known. New results are then obtained from structural models with an additional degree of freedom in the sway motion. Turbulence is shown to play two opposite roles in the process. It destabilizes the critical mode if the critical mode were to act alone, however, it also promotes the participation of other more stable modes that transfer the vibrational energy away from the critical mode. Thus, turbulence can be beneficial when the second effect is greater.
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Information & Authors
Information
Published In
Journal of Engineering Mechanics
Volume 115 • Issue 2 • February 1989
Pages: 384 - 400
Copyright
Copyright © 1989 ASCE.
History
Published online: Feb 1, 1989
Published in print: Feb 1989
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