Análise da influência de vigas de transição sobre os efeitos de segunda ordem globais de torção em edifícios de concreto armado

Abstract

Population growth, economic growth, and technological advancements have allowed for the construction of multi-story, high-rise, and slender buildings. These buildings generally have design criteria that require greater attention to stability and user comfort, including the assessment of building torsion. Most current architectural designs feature large openings, common in recreational areas or garages. This increases the use of the transition beam solution, which supports the pillars serving the upper floors and has large dimensions and reinforcement configurations to resist generated forces, often of great magnitude. Verifying global second-order effects is an important analysis to ensure stability and comfort for users. NBR 6118:2014 specifies methods for verifying these effects, but the suggested methods only consider translational floor displacements, which can cause problems in analyzing effects caused by rotational displacements. Franco (2003) presented a simplified method for analyzing these effects, taking into account the γθ coefficient. This study evaluated the influence of the positioning of transition beams on the global second-order effects related to the torsion of slender buildings, using the γθ coefficient. Four different building models were analyzed, all with 40 floors and a height of 120 meters, with 2 models having regular geometry and 2 models having irregular geometry. One of the regular floor plan models and one of the irregular floor plan models had a rigid core (wall pillars). The transition beams were located on the first floor of the buildings, in the positions of the façade portals, to simulate their common use in openings. The results indicated that for the majority of the models with regular floor plans, the value of the γθ coefficient decreased with the arrangement of transition beams, while for the models with irregular floor plans, the use of the transition beam caused an increase in the same coefficient. The analysis also indicated that the models with a rigid core in their floor plan had an increase in the value of the γθ coefficient when the transition beams were positioned