Determinação numérica dos coeficientes de pressão em telhados paraboloides hiperbólicos: um estudo de caso

Abstract

In the study of wind loads in buildings, the aerodynamics of roofs with parabolic shape, which causes complex pressure distributions due to their sensitivity to wind, is often omitted and neglected by several codes and norms, including ABNT NBR 6123:1988, in force in Brazil. In this way, computer simulations are a viable and reliable alternative. Here, was considered the wind action in an innovative project constituted of parabolic and circumferential generatrices: the Church of Saint Francis of Assisi. Designed by Brazilian architect Oscar Niemeyer in Belo Horizonte, Brazil, two paraboloid vaults and three circular arches of reinforced concrete composed its structure. This work generated great international recognition for the architect after 1943, as the design of the roofs did not require walls. For geometry modeling, were adopted the Autodesk AutoCAD software and the models were considered in a control volume. The simulations were performed using the Ansys Workbench software and the RNG K-Epsilon turbulence model. The wind speed at different heights was calculated using the Power-law approximation. A basic wind speed of 30 m/s was adopted and the mesh used was composed of tetrahedrons. To validate the methodology, different models with hyperbolic-paraboloid roofs from the literature were considered. Besides, the visualization of the flow around the geometry from the streamlines, the wind profile, and the analysis of the isobaric lines of the external pressure coefficients for different directions of incidence, as well as the influence of topography and architectural elements that make up the building were presented.