Oscillations of Bridge Stay Cables Induced by Periodic Motions of Deck and/or Towers

Abstract

This paper deals with the oscillations of bridge stay cables that may be excited by wind or by traffic-induced periodic motions of the deck and/or towers. A theoretical model is developed for the study of nonlinear oscillations in inclined stay cables as a result of small anchorage motions. Laboratory tests are performed to check the validity of the model in some particular situations. Approximate analytic formulas and numerical solutions are obtained for the cable transverse displacements and the corresponding axial force oscillations. The behavior of inclined stay cables is interpreted by comparison with similar horizontal or vertical cables subjected to appropriate components of the excitation. It is shown that reasonably small anchorage amplitudes may lead to important cable oscillations when conditions are met for lower-order classical or parametric resonance of the cables.