Dimensionnement d'une section en béton armé soumise à une enveloppe elliptique de sollicitations dynamiques combinées

Abstract

ABSTRACT Wind or earthquake dynamic actions produce combined efforts on structures (axial force, bending moment about one or two axes…) whose maximum values within a member section can often be represented by an elliptical envelope. The present paper describes a technique to optimize reinforced concrete sections subjected to this type of dynamic load by adjusting quantities of steel and/or concrete so that the interaction curves characterizing the resistance of the sections become tangent to the envelope of maximum combined forces. The method relies on a geometrical transformation from the original space of forces in which the envelope is an ellipse to a so-called « standard space » where it becomes the unit circle. In this latter space, the safety margin of the section has a very simple geometric expression and is measurable with well-known tools of reliability analysis. The section parameters (steel and concrete) can thus be adjusted in a efficient way.