Estudo paramétrico de lajes nervuradas unidirecionais de concreto armado.

Abstract

Slabs are one of the structural elements that consume the most concrete in their design, a fact that justifies search for solutions that make better use of this system. As an evolution of solid slabs, ribbed slabs have been widely used in situations that demands large spans. The ribbed slabs molded in place by plastic formwork offer economic, environmental and constructive advantages. In order to provide designers with subsidies for choosing the formwork in a pre-dimensioning stage, the present work presents a parametric study of unidirectional ribbed slabs molded in place with reusable plastic formwork sold by the company Impacto Protensão®. In this artile, it is shown the influence of the variation of the span in wich the ribs are arraged (3 to 7 m), the concrete strength variation (25, 30 and 35MPa) and the accidental overload (0.5, 1.5, and 2 kN/m²). From the study, it was possible to notice that the best solutions tended to use formwork with 61cm of interaxis, rib with 7cm of width and and height with about 6% of the span. In most cases, for the reinforced concret it was adopted 4cm of cover and 25MPa strenght.