Avaliação dos parâmetros de instabilidade global para edifícios

Abstract

With the advancement of technologies and structural analysis methods, constructions have ceased to be evaluated by simplified procedures, and have begun to use more precise and realistic models of the behavior of materials and structures. This progress has enabled buildings with more complex geometries, greater architectural diversity, and a significant increase in height and usable area, resulting in more efficient projects with better use of space. NBR 6118 (ABNT, 2023) defines the criteria for verifying global stability using the parameters γz and α, which are essential in evaluating second-order effects. Nonlinear analyses represent structural behavior more faithfully, especially when there are horizontal deformations generated by lateral actions. When these deformations interact with vertical loads, second-order effects arise, the proper consideration of which is fundamental to ensuring safety and performance. This work aims to analyze a multi-story building subjected to different structural modifications, in order to determine its degree of global instability using the parameter γz and to verify the need to consider second-order effects in the design. The results show that overall stability depends primarily on the geometry of the structure and the stiffness distribution among its elements. Increasing fck has a limited effect, while geometric changes, especially increasing the cross- sections of the columns, prove to be significantly more effective in improving stability.