Comportement plastique de structures en portiques.

Abstract

The plastic analysis of structures is easy and straightforward for simple structures, the complete study could be done manually. Once the structure is more than one span and one level, the problem gets worse and the determination the collapse load and the collapse mechanism becomes more complicated and requires the use a digital program or calculation software. In the present work, a numerical program in Matlab using the finite element method for successive linear analysis has been developed for the load factor calculation by adopting the approach of first-order plastic hinges. The program is based on step by step method and is developed by adopting the theory of plastic hinges as an approach to determine the collapse load and the collapse mechanism of such structures in flexure and considering the interaction of bending moment and axial force. The program has the ability to generate interaction diagrams for frames of more than one level and more than one span. This permits the prediction of the nature failure mechanisms depending on the ratio between concentrated vertical loads, V, and horizontal loads, H (α=V/H). The approach used in the present work has been found in a good agreement with the limit analysis for the determination of the true failure load factor and the mechanism corresponding. The approach is very similar with the principal of virtual work method for the construction of interaction diagrams, V-H.