On the Shifted Integration Technique in the Finite Element Analysis of Framed Structures and Axi-Symmetric Shell Structures

Abstract

The present study is concerned with the physical explanations of the linear and the cubic finite elements for beams and axisymmetric shells through the comparisons of their strain energy approximations with those of the Rigid Bodies-Spring Models which are the discrete elements suitable to the plastic collapse analysis using the concepts of plastic hinges and hinge lines. The established conditions for the equivalence between these two modelings, which are given as the relations between the locations of the numerical integration points and those of the occurrece of plastic hinges, can be conveniently used in the economical plastic collapse analysis of framed structures and axisymmetric shells where the locations of plastic hinge formations are controlled by the movement of numerical integration points. Some numerical results are shown in order to prove numerically the obtained relations and to verify the validity of the proposed shifting technique of numerical integration points, which is identified as 'the shifted integration technique' in the present paper.