CONSIDERATIONS ABOUT APPROXIMATE AND RIGOROUS METHODS FOR SECOND-ORDER GLOBAL ANALYSIS IN BUILDINGS WITH REINFORCED CONCRETE STRUCTURES

Resumo

This paper presents an evaluation of the approximate methods for the calculation of plane
frames subjected to horizontal actions from wind force, considering the current numerical resources
available. In the past, it was common to use equivalent plane frame in the calculation of tall reinforced
concrete buildings, in the definition of ultimate limit states (ULS) and for the evaluation of the lateral
displacements of the building in service limit states (SLS). From these trivial analyzes, usually theorical,
verifications of the structure's instability parameters were made. It is known, however, that simplified
structural analysis, such as obtaining the parameters α and γz, causes eventual inaccuracy in the internal
forces and the deflection values of the building, since it is not considering the real three-dimensional
interaction among the main constituent elements of the structure: slabs, beams and pillars. In view of
the above, the purpose of this research was to make a comparison of the results obtained analytically in
a usual 9th floor reinforced concrete building, with the results of a 3D structural design and analysis
software in accordance with NBR 6118/2014. Finally, after a systematic analysis of the results obtained
from the analytical and numerical models of the pilot building, some considerations are made, especially
regarding the use of simplified structural analysis methods.