Second-order elastic-plastic analysis of plane frames

Methods for the elastic-plastic analysis of plane frames were developed in the 1960s, soon after the birth of the digital computer. Much of this early work was surprisingly sophisticated and, despite the passage of time, is still state-of-the-art and well worth re-visiting. In Europe, there is renewed interest in these methods of analysis motivated by the more stringent stability requirements of Eurocode 3 and the realisation that even the humble pitched-roof portal frame is surprisingly sensitive to second-order effects. This paper will review the current state of the art, comparing the influence coefficient and full iteration methods of elastic-plastic analysis and giving consideration to the problems of positioning plastic hinges below points of maximum bending moment in beams and the 'false mechanism' problem. Strain hardening in plastic hinges will also be considered together with the sensitive balance between strain hardening and second-order effects. (C) 2002 Elsevier Science Ltd. All rights reserved.