Avaliação dos parâmetros de instabilidade global de estruturas simétricas de concreto armado aporticadas

Abstract

Technology‟s advancement in civil engineering made possible the construction of buildings more and more tall and slender. The choice for this type of building is justified because it shelters a great number of people and/or services in a smaller area projection. The importance of studying global stability of reinforced concrete structures is justified by these changes in high building standards. The NBR 6118 (ABNT, 2014) indicates two parameters for verification of global stability of a reinforced concrete building: alpha instability parameter ( and gamma-z coefficient (

). The non-linear structural analysis is perfomed in search of a response from the structure closest to reality in which it is inserted, considering the deformed configuration generated by horizontal loads, with cause a displacement in the same direction of its application originating the first order moments of the structure, while vertical loads associated with these displacements generate second order moments. This work presents a study of symmetrical concrete-frame structures to evaluate which impact these project changes brings to global instability parameters: change in the number of stories, fck (concrete compressive strength) and direction of the central columns, classifying in nonsway or sway frames to know whether or not consider the second order effects in the structural analysis resulting in design choices with more stable structures from the point of view of the building as a whole.