DIRECT ELASTIC-PLASTIC LIMIT LOAD AND SHAKEDOWN ANALYSIS OF STEEL SPACE TRUSSES WITH LARGE DISPLACEMENTS

A direct method for elastic-plastic limit load and shakedown analysis of steel space trusses with large displacements is treated in this paper. The incremental method for the geometrically nonlinear analysis of space trusses, developed by one of the authors was modified to account for yielding and plastic strains in the bars of the truss. The new method has been implemented in computer software. The examples in this paper show that the direct analysis of space trusses with large displacements can be implemented successfully for both the limit and the shakedown analysis of space trusses on the Java platform. The algorithms cover a wide range of elastic-plastic truss behavior: purely elastic behavior, shakedown, ratcheting and collapse due to the formation of a mechanism. The sequence in which the bars yield, the load levels at which this occurs, the accumulation of the plastic strains in the bars, the residual stresses in the bars and the node displacements during ratcheting can all be evaluated. The computer application is therefore suitable as a test platform for elastic-plastic truss behavior. It can be applied to many other problems of elastic-plastic space truss analysis

steel space trusses, large displacements, plasticity, limit analysis, shakedown