Simulations of cable/anchor designs for cable-stayed bridges

Large-amplitude vibration of inclined bridge stay cables has been the subject of research during the last two decades. This paper considers the effects that anchor designs have on the dynamics of bridge stay cables. In essence, differences among anchor designs present variations in the stiffness of the boundary condition at the base of the cable. Two studies were conducted to understand anchor design effects. In the first, ANSYS finite element software is used to model the anchor as three simple spring elements oriented in the in-plane, out-of-plane, and axial directions. The stiffness of the out-of-plane spring element is varied while other values are held constant to examine the effect on the fundamental frequency of the cable. In the second study, in-plane and out-of-plane forces are applied to detailed Owensboro, Kentucky bridge anchor models using nonlinear static analysis in ANSYS. The resulting deflection of the anchor is used to assess the stiffness of the anchor. The cable tension load on the anchor is found to be an important factor in the stiffness of the anchor and on the dynamics of the cable. In the load range considered, the Owensboro anchors deflect linearly in all directions. Th e design of the anchors of the Owensboro Bridge can therefore be represented in models as infinitely stiff in the in-plane direction. Finally, modeling the Owensboro anchors, the effect on the fundamental frequency of the corresponding cables was determined to evaluate the effect of the anchor design on the cable response.