Stress assessment in reinforcement for columns with concrete creep and shrinkage through Brazilian technical normative
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(2021) 43:6
TECHNICAL PAPER
Stress assessment in reinforcement for columns with concrete creep and shrinkage through Brazilian technical normative Alexandre de Macêdo Wahrhaftig1 · Kaique Moreira Matos Magalhães1 · Lázaro Sabas Marques Silva Cheles Nascimento2 Received: 1 July 2020 / Accepted: 16 November 2020 © The Brazilian Society of Mechanical Sciences and Engineering 2020
Abstract In this paper, the induced stress in longitudinal reinforcement bars with cross sections subjected to concrete creep and shrinkage was evaluated. The study was performed for a reinforced concrete column, with loading varying from zero—in which the structure is exclusively subjected to self-weight—to forces close to the loss of stability by bifurcation of equilibrium. A real precast concrete pole, extremely slender, with geometry varying lengthwise, was the structure chosen for the analysis. The aspects related to the material nonlinearity, as well as creep, shrinkage and the development of characteristic concrete strength, were taken into account following Brazilian normative recommendations in NBR 6118:2014 (Design of structural concrete—Procedure) by the Brazilian Association of Technical Standards (ABNT). The critical buckling load was defined according to the structural frequency by using particularly nonlinear formulations. The results were obtained for different instants without exceeding the expected time for convergence of results. The maximum relative value found for the reinforcement stress was 1.24% of the steel yield strength, eliminating the possibility of yielding material. Keywords Stresses · Reinforcement · Bifurcation of equilibrium · Analytical solution · ABNT NBR 6118:2014
1 Introduction This work follows on from two previous ones, representing the consolidation of the procedures performed so far. In the first investigation (Wahrhaftig et al. [1]), the analytical solution currently presented in the mathematical modeling was built and evaluated in comparison with the finite element Technical Editor: Andre T. Beck. * Alexandre de Macêdo Wahrhaftig [email protected] Kaique Moreira Matos Magalhães [email protected] Lázaro Sabas Marques Silva Cheles Nascimento [email protected] 1
Department of Construction and Structures, Polytechnic School, Federal University of Bahia (UFBA), Rua Prof. Aristides Novís, Nº 02, 5º andar, Federação, Salvador, BA CEP: 40210‑630, Brazil
Graduate Program in Civil Engineering (PPEC), Polytechnic School, Federal University of Bahia (UFBA), Rua Prof. Aristides Novís, Nº 02, 8º andar, Federação, Salvador, BA CEP: 40210‑630, Brazil
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method (FEM). In the second one (Wahrhaftig et al. [2]), aspects related to the limit states of design were analyzed considering the concrete creep only and the secant modulus of elasticity of the concrete. In the present article, the temporal homogenization of inertias of cross sections subject to creep, as well as the shrinkage of the concrete, was added to the calculations together with the initial modulus of elasticity of the concret
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