Análisis no lineal de pandeo en columnas esbeltas de hormigón mediante la obtención de esfuerzos internos

Abstract

In this thesis, a static nonlinear method is proposed for analyzing slender, rectangular reinforced concrete columns and concrete filled steel columns. The main objective is to compute the geometric and the mechanical directrix of a slender column in order to determine the maximum permissible momentfor a given axial load. The method proposed is based on an iterative process, in which the neutral fiber depth and the radius of curvature are adjusted to obtain the mechanical directrix; the geometric directrix isdetermined through a sinusoidal distribution of the curvature. Once both directrices are obtained, the tangency point between them is determined, which represents the maximum eccentricity that the column can resist for a given axial load, including the second order effects. For the implementation of the methodology proposed, programs on MATLAB. With the results obtained from theseprograms,the method was validated through comparison with results obtained from the same examples through the ACI 318-11 code and AISC 360-10 code. A clear attribute of the method proposed is its versatility, which can be evidenced by the fact that it can be applied to the analysis of columns consisting of different types of materials, being necessary to incorporatethe respective stress-strain diagrams. In addition, the method allows the verification of the stability of a column for a given load combination without obtaining the iteration diagram, as well as the stress of the critical section on the point of failure, therefore proving to be optimal when compared to traditional iterative diagram methods.