Estudo comparativo de estratégias para simulação dos efeitos de 2ª ordem em pilares de concreto armado

Abstract

This dissertation aims to investigate the influence of second-order effects on reinforced concrete columns, considering approximation parameters and more rigorous analysis methods, which are compared and evaluated. For this purpose, it was decided to develop the studies using the commercial software TQS®, which presents, in addition to normative approximate methods for second-order local and global effects, a more rigorous strategy for structural processing, known as the Nonlinear Physical and Geometric Frame (NLFG). This module was adopted in the composition of the so-called reference model, serving as a benchmark for other approximate responses. Six different structural models of a commercial building were simulated, with five floors and a story height of 260 cm, varying the number of floors (5 and 8), considering three different story heights (260 cm, 390 cm, and 520 cm), besides the global second-order analysis and three local second-order analysis methods. The spans of the columns were analyzed concerning local second-order effects according to the following three strategies, in addition to the NLFG Frame method: Standard Column Method (SCM) with approximate stiffness, SCM with approximate curvature, and SCM coupled with M − N − 1/r diagrams. In general, regarding second-order effects, the study established a classification of the impact level of these effects on approximate methods, based on the applicability of parameter γz and the P − ∆ Method, which provided reliable responses in the evaluated scenario. Additionally, when analyzing the floors individually, the results showed that approximate methods tend to underestimate local second-order effects in intermediate story height sections. Moreover, the SCM with approximate curvature was the most conservative method compared to the others.