Verificação da estabilidade de pilares esbeltos de concreto de alta resistência submetidos à flexo-compressão normal segundo o método geral

Abstract

This paper presents the verification of stability of slender columns by using the General Method. Restricted to the case of the standard flexo-compression, constant rectangular section and symmetrical armor along the column, the study applies to high-strength concrete, recently included in ABNT NBR 6118:2014. For a discussion of the theme, it was made use of the entire formulation based on concrete stress-strain diagram in the parabola-rectangle shape. Initially, we studied the characteristics of materials: concrete and structural steel; the ultimate limit state of instability (ELU-I), characteristic of slender bars, to better define the balance settings on the straight and bent shape; the physical nonlinearity (concrete is a material that does not follow Hooke's Law) and geometric mandatorily required in the calculation of slender columns; and of course, the theory of second order. He presented the roadmap for preparing diagrams M-N- 1/r and monitoring stability bars by General Method, based on the Analogy of Mohr. Finally, presented are two stabilities verification examples bars subjected to flexion-compression, the first bi-supported and the second clamped-free; and scaled to an intermediate pillar, with all the steps of the procedures in a clear and didactic way