General Failure Analysis of Skeletal Plane Frames

Abstract

A finite beam column element computer program for the structural analysis of proportionally loaded plane frames is described. The load-deflection curve is followed up to frame collapse based on either nonlinear elastic, plastic-linear elastic, or plastic-nonlinear elastic behavior. The program uses the stiffness method of analysis and incorporates an iteration process which employs various extrapolation formulas to accelerate the convergence. Any combination of the following nonlinear effects may be included: member stability, member axial shortening due to curvature, change of frame geometry, plastic hinge rotation at the full plastic moment of resistance, or at the moment reduced by the member axial load, the direct axial plastic deformation associated with the rotation of a hinge and the unloading of plastic hinges.