抄録
In the plastic design or in the design of high-rise building based on the dynamie responce in elasto-plastic state, the beams and columns of a structure have to show enough ductility, that is, plate elements of beams or columns should not buckle until they perform adequate plastic deformation. It is important to find the relation between the critical strains and midth-thickness ratios of plate elements in the plastic range. Haaijer and Tanaka had already studied this problem, based on the plastic flow theory. In this paper, a new treatment of this theme was presented. Initial imperfections were assumed to be in-avoidable in actual plates, and on the basis of this assumption, the collapse model of the plate was created and the work theorem was applied to this model. The following formula was obtained for various boundary conditions of plates. const. =(t/b)[numerical formula] The formula was compared with test results founding a fairly good agreement.
