Global stability analysis of reinforced concrete buildings using the γ z coefficient

V V S Vieira,L A C M Veloso,S J Rodrigues Junior

doi:10.1590/s1983-41952017000500010

Abstract

Abstract Global stability analysis is becoming increasingly important in the design of reinforced concrete buildings, especially in the slender ones, due its sensitivity to lateral displacement. The loss of stability is usually associated with the intensity of the second order effects and, in that sense, the gamma-z (γz) coefficient is an important evaluation parameter for this problem. This work aims to verify the γz efficiency as a global stability parameter based on the buckling load factors of the structures and their respective critical buckling modes. To this purpose, a comparative analysis is performed in several idealized structures, from which an approximate equation for calculating the critical load factor based on the γz coefficient is obtained. This equation was verified by numerical analysis of Finite Elements Method models of real reinforced concrete buildings. It was concluded that the proposed equation presents satisfying results within a certain range of γz.

Highlights

The global stability verification is a fundamental requisite on the design of a reinforced concrete building for it doesn’t present future problems that would affect its safety and, increase its risk of collapse
Global stability analysis is becoming increasingly important in the design of reinforced concrete buildings, especially in the slender ones, due its sensitivity to lateral displacement
A comparative analysis is performed in several idealized structures, from which an approximate equation for calculating the critical load factor based on the γz coefficient is obtained

Summary

Introduction

The global stability verification is a fundamental requisite on the design of a reinforced concrete building for it doesn’t present future problems that would affect its safety and, increase its risk of collapse. Most precise global stability analysis is not a simple process, being sophisticated computational resources necessary It evaluates the current condition of the structure regarding its stability limit through the relation of its critical load to the applied vertical load. This paper aims is to establish a relation between the γz coefficient and the critical global buckling load factor according to concepts presented on the literature and trough the analysis of idealized structures with simplified geometry. This relation will further be transformed into an approximate equation which allows to estimate the critical load factor from the γz coefficient. For the modeling and processing of the structures, both idealized and real buildings, the computational software SAP2000® V16.0.0, one of the most known structural analysis systems in the market, was used

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