Projeto e análise de escada helicoidal em concreto armado

Abstract

Helical staircases are very appreciated structures in architecture. Due to the great complexity of design, engineers must analyze them carefully in order to ensure the safety of the structure, correctly evaluating the influence of the efforts involved. This paper compares two empirical methods of design of helical staircases formed by a central beam of reinforced concrete and steps overlapping it, in order to evaluate them and understand their differences when subjected to static loads. The design methods used were those of G. Prudon and José Milton de Araújo, defining, first, the acceptable dimensional limits of a helical staircase. The staircase was chosen with a usual geometry of commercial works, where the ceiling height is usually higher, with a height of 7 meters, a 360 ° floor plan and width of 1.6 meters, in order to avoid results with minimum reinforcement rates. Once the geometry was defined, the distributed load recommended by NBR6120/1980 was applied along the centroid of the cross section of the helical beam to the ultimate limit state, in order to obtain the demands of each method. From the loads, the longitudinal flexural reinforcement was designed by rosette abacuses. The torsional longitudinal reinforcement and the transverse reinforcement were dimensioned according to the recommendations of NBR6118/2007. The methods were quite similar in their results, but the method that presented the lowest armature rate was that of G. Prudon, being 2.70%.