GALLOPING ANALYSIS FOR 2-DEGREE-OF-FREEDOM OSCILLATOR

A comprehensive analysis is presented for the galloping of an oscillator that may vibrate both transversely and torsionally. Explicit solutions are given for the conditions needed to initiate galloping and also for the ensuing nonlinear periodic responses. Internal resonance as well as previously considered nonresonance responses are treated consistently by employing an averaging method. The usefulness and advantages of the analytical formulation are demonstrated by using square prismatic and bluff structural angle sections. Analytical predictions are verified by their close agreement with numerically integrated data from the original equations of motion. A variety of responses is shown to be possible for certain parameters. Moreover, it is demonstrated that the twist can be instrumental to galloping in plunge. © ASCE.