OSCILLATIONS OF BRIDGE STAY CABLES INDUCED BY PERIODIC MOTIONS OF DECK AND OR TOWERS/

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 nonli near oscillations in inclined stay cables as a result of small anchora ge motions. Laboratory tests are performed to check the validity of th e model in some particular situations. Approximate analytic formulas a nd numerical solutions are obtained for the cable transverse displacem ents and the corresponding axial force oscillations. The behavior of i nclined stay cables is interpreted by comparison with similar horizont al or vertical cables subjected to appropriate components of the excit ation. It is shown that reasonably small anchorage amplitudes may lead to important cable oscillations when conditions are met for lower-ord er classical or parametric resonance of the cables.