DYNAMIC STABILITY OF IMPERFECT FRAMES UNDER JOINT DISPLACEMENTS

In this investigation a nonlinear dynamic-stability analysis is perfor med on a two-bar geometrically imperfect frame subjected to an axial d isplacement of its joint, either suddenly applied or time dependent. T he dynamic response of the frame is governed by a coupled system of tw o one-dimensional partial differential equations for the axial and lat eral motion of each bar. One and two-mode solutions are thoroughly dis cussed for various geometric configurations of the frame. Dynamic buck ling occurs when the corresponding frame under static loading loses it s stability through a limit point. This happens for initial bar curvat ures above a certain critical value; below this value the frame is dyn amically stable. Numerical results are obtained by using Galerkin's me thod in connection with the seventh-order Runge-Kutta-Verner scheme wi th appropriate step size. The results of the one-mode solution are fou nd to be in excellent agreement with those of previous analyses.