Elastic‐Plastic Analysis of Steel Space Structures

Abstract

A new concept of instantaneous secant stiffness is proposed and used for nonlinear elastic‐plastic analysis of steel space structures, which replaces the Newton‐Raphson technique (the instantaneous tangent stiffness method). It is found to be more stable and converges rapidly. The technique is iterative‐incremental based on the displacement approach, and gives a lower bound second‐order solution of collapse load. The analysis accounts for deformations while writing equilibrium equations. The external loads are applied in appropriate increments and iterations are carried out during each increment considering the latest geometry until the unbalanced loads become negligible. A suitable search technique is proposed to detect development of a plastic hinge. The plastic hinges are introduced at the locations indicated and the analysis continued until collapse occurs. An example is presented to explain the proposed method of analysis.