Avaliação econômica da utilização de ligações rígidas viga-pilar em estruturas multipisos de concreto pré-moldado

Abstract

The type of beam-columm connection adopted in a precast structure can generate great economic impacts, as floors are added. Civil construction is considered backward when compared to other industrial branches, considering that, generally, the works have low productivity, great waste of materials and low quality control. An alternative to improve such indices is the use of precast structures, as this technology can reduce construction time, contribute to better quality control and waste of materials, in addition to facilitating the organization of the construction site. The beam-columm connection is one of the most important issues in the design of precast structures and they are divided into articulated, semi-rigid and rigid. In this course conclusion work, articulated and rigid connections were mainly addressed, especially with regard to stability and economy in relation to multi-floor precast concrete structures. To evaluate the connections, the two types of connections were applied in different frames, which have 3 spans of 8 meters (two side spans and a central span) with 1, 2, 3, 4 and 5 floors and a ceiling height of 4 meters. To define the dimensions used in the columns, square sections were considered, which were defined according to the stability parameters α and coefficient γz. In this way, the highest value among the verified methods was considered and the limiting values were adopted for the structure to be considered fixed nodes, that is, to neglect the second efforts. To economically evaluate the models, the indices that were considered to estimate which connection would be more advantageous were: the kilograms of steel in the rigid connections (considered as reinforcement with continuity), the volume of concrete in the frames (calculated by the sum of the cubic meters of concrete of columns and beams) and the kilos of steel consumed by the columns. Thus, it was found that as floors were added, the frames that presented articulated connections, when compared to the frames that have rigid connections, became more unstable, and, consequently, caused an increase in the sections of the columns, thus raising the material costs. Advancing in the study, it was found that the models that have articulated connections offered greater economic advantages when applied with 1 and 2 floors, while those with rigid connections had better financial performance in the frames with 3, 4 and 5 floors.