CHAOTIC MOTION OF SHALLOW ARCH STRUCTURES UNDER 1 1-INTERNAL RESONANCE/

The present study investigates the global bifurcations present in the motion of the shallow arch structure subjected to a spatially and temp orally varying load under the conditions of principal subharmonic reso nance and one-to-one internal resonance near single-mode periodic moti ons. Unlike the case examined in a companion paper by the writers, the effect of dissipation is also included in the present study of the gl obal dynamics. By using a perturbation technique attributed to Kovacic and Wiggins we show the existence of Silnikov-type homoclinic orbit t o a saddle-focus fixed point in the perturbed system, and consequently the chaotic behavior. The results are also interpreted in terms of th e physical dynamics of the shallow arch system.