Considerations on the determination of the gamma z coefficient

Resumo

This paper is a study of the gamma z coefficient used to evaluate global second order effects in reinforced concrete structures. First of all, the influence of the structural model adopted to calculate the gamma z coefficient is evaluated. Next, a comparative analysis of the gamma z coefficient and the B2 coefficient, usually applied to evaluate second order effects in steel structures, is done. In order to develop the study, several reinforced concrete buildings of medium height are analyzed using ANSYS-9.0 [1] software. The results show that less refined analysis provides more conservative gamma z values. This means that when structures are analyzed using simplified models, large gamma z values do not necessarily imply significant second order effects. Furthermore, it was found that gamma z can be calculated from the B2 coefficients of each storey of the structures and that for all the buildings analyzed the average values of the B2 coefficients show close proximity to gamma z.