Analysis of Deflections in Elastic-Plastic Frames

A method is proposed to compute deflections throughout an elastic-plastic plane frame. It is related to the Williot-Mohr analysis for trusses. After the force analysis, all frame joints are pinned and member ends allowed to rotate. Continuity is then restored where required by movement of the pinned mechanism in beam and sway modes. The method is extended to statically indeterminate frames with force analysis by relaxation. Examples illustrate the application. The method is simple in concept and is suitable for practical use. The influence of the spread of the plastic hinges is explored in an appendix and found to be unimportant under normal circumstances with concentrated loads.