# Numerical model of high-strength reinforced concrete columns subjected to the ultimate limit state of instability

## Palavras-chave:

Instability, High-strength concrete, Slenderness, Finite Element## Resumo

High-strength reinforced concrete columns have greater tendency to slenderness and to higher

compressive axial loads. Both aspects contribute to a significant magnified moment, and to a potential context to

lead those columns to instability failure. Although the second order effects can be determined by simplified

methods in some circumstances, the general method allows to identify the Ultimate Limit State of Instability

clearly and to evaluate the second order effects precisely. Thus, it is proposed the employment of general method

in two distinct two-dimensional models on finite element Abaqus software to obtain a load-deflection diagram.

The first model is a plane stress element with embedded reinforcement, with the Concrete Damaged Plasticity

representing the constitutive behavior of the concrete, and the second model adopts a beam element with the rebar

embedded into concrete section using Abaqus/Standard, with the Cast Iron Plasticity as a simplified representation

of the concrete. The adequacy of the models is validated by experimental data from literature. The results have

shown that two-dimensional model is effective to simulate the uniaxial bending High-strength concrete column

subjected to the Ultimate Limit State of Instability. In addition, the most simplified model, which adopts beam

element with rebar and neglects tensile strength, provides suitable load-deflection diagram. Therefore, this model

is recommended to represent such analysis.