Otimização do comportamento de sistemas estruturais pré-moldados de concreto com ligações viga-pilar deformáveis à flexão

Abstract

In order to obtain the best relation between the parts of a structural system of precast concrete, this work proposes to perform the optimization of plane frames with semi-rigid connections between beams and columns. For this, some frames were simulated numerically using the Finite Element Method, in which beams and columns were modeled by beam elements and the beam-column connections by spring elements, allowing the modification of its stiffness. The implemented objective function was based on the search of lowest stiffness connection, which would meet the global stability of the building. At the end of the process, a connection model with great stiffness was adopted to compose the frame, followed by checking the horizontal displacement maximum allowed. The importance of considering the stiffness connection is to avoid idealizations in design that tend to consider the connections as perfectly articulated or perfectly rigid. Connections in central column and corner column with fixity factor about 0.32 and 0.27, respectively, were responsible for reducing the bending moments at the base of the columns by 36%, while reducing the displacement at the top of the frame reached 76%. For a second frame, semi-rigid connections between beam and column averaging fixity factor of 0.33 were sufficient to satisfy the maximum allowable horizontal displacement and the acting moment at connection. This proves that even connections with low constraints provide significant gains from a structural point of view, without loss of the constructive aspects and assembly.