Foundation of correlation parameters for eliminating pulse shape effects on dynamic plastic response of structures

The theoretical foundation of Youngdahl's correlation parameters, which have been used to eliminate pulse shape effects in the dynamic plastic response of two-dimensional structural members, is studied in the present paper with the aid of bounds obtained for a rigid-plastic material. It is shown that Youngdahl's empirical estimate for the structural response time is, in general, a lower bound on the actual response time. A lower bound expression is obtained for the maximum final displacement of a two-dimensional structural member when subjected to an axisymmetrically loaded transverse time-dependent pulse, which depends only on Youngdahl's correlation parameters, and offers a theoretical foundation for the validity of Youngdahl's correlation parameter method.