Abstract
This paper presents a method for obtaining the stiffness matrix of a released structure by augmenting the stiffness matrix of the original structure. A procedure is presented by which the modified structure can be analysed without reducing the complete modified stiffness matrix. Only the augmented portion need be reduced. The method is illustrated by applying it to the problem of calculating hinge rotations in the analysis of plastic frames. The new approach is shown to lead to considerable savings in computer time in this application.