Relações entre o coeficiente gama-z e o parâmetro de instabilidade global alfa para concretos de classe II

Abstract

Historically, there has been an increase in the construction of increasingly tall and slender buildings, due to the greater concentration of people and economic activities in the city, thus making urban plots more and more expensive, the most daring architectural projects that require more constructive techniques modern. In these buildings the second order effects are more accentuated and the use of high performance concrete represents a good option, when choosing the fck to be adopted. ABNT NBR 6118: 2014 recommends the analysis of global instability using the alpha parameter and / or the gamma-z coefficient. Although this coefficient is obtained through procedures that involve a much larger amount of calculations than the one used to calculate the alpha parameter, it is the most used. In this way, we seek, in this TCC - which can be characterized as a continuation of recently published Course Conclusion Papers - expressions of the second and third degrees that make it possible to obtain the z-range, mainly due to the alpha) and the presentation of tables indicating their values for class II concretes. Therefore, starting from data contained in the dissertation entitled EFFECTS OF SECOND ORDER ON ARMED CONCRETE BUILDINGS, presented to USP by Regina Maria dos Santos Carmo in 1995 and using what has already been defined as an equivalent reduction factor (FReq), we proceed corrections (or updates) with a view to adjusting the quantities involved in their combination due to the new recommendations of the current version of the above applicable norm.