RANDOM VIBRATIONAL RESPONSE AND STABILITY STUDY OF LONG-SPAN BRIDGES

A random vibrational response study of a dynamical system is presented . In particular, suspension bridge stability analysis in the presence of turbulence is addressed. The effects of turbulence on the well-unde rstood deterministic stability of section models using aerodynamic fun ctions are explored emphasizing governing physical mechanisms. For thi s purpose, the primary emphasis is placed on the nonlinear control par ameter (square of the upstream flow velocity) and the resulting nonlin ear noise term. To this end, it is pointed out that the introduction o f ''nonwhite'' nonlinear noise for the excitation forces is of paramou nt importance. Further, it is concluded that this invoking of nonwhite noise is necessary to avoid inconsistencies involved with the usual a ssumption of Gaussian white noise. Finally, numerical simulation of no nwhite, nonlinear noise and subsequent integration of the single-degre e-of-freedom torsional equation of motion involving varying ''time sca les '' are carefully carried out. The numerical tests for sample stabi lity provide some new results that are consistent with existing experi mental observations.