Comparing Analysis of Elastic, Plastic and Elastoplastic of Single-layer Orthogonal Grids with Regards to both Large and Small Displacements with Nonlinearity Behavior of Material Modeling in both Real Behavior and using Plastic Hinges

By the growing interest in space structure using, the need for precise analysis and design of these structures is more than ever sensed. plane single-layer orthogonal grids are types of space structures which used in the bridge decks, ships and covering of the ceilings with short opening. In the aspect of the presence the different methods to analyze these structures and in the spite of the determined and simple relations are obtained to analyze and design single layer grids by plastic method, it is necessary to aware of the effect of theories and also the role of each theory in the result of the analysis in order to acquire a precise and accurate analysis of the structure. First, in this paper, analysis and design of plane grids has been stated by the means of upper bound and lower bound methods, which led to find closed from relationships Then, nonlinear analysis (elastoplastic) is carried out by considering different kinds of material modeling methods and geometric nonlinear behavior.The analysis is also carried out without considering each nonlinear effects in single layer grids by SAP and ABAQUS softwares. The results are compared to the each other and the plastic analysis. the effects of the simplifying hypothesises in the analysis results are investigated and the allowable applications of each analysis method described.