Umbrella and Gable Roofs

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Title: Umbrella and Gable Roofs

Author(s): W. C. Schnobrich

Publication: Special Publication

Volume: 110

Issue:

Appears on pages(s): 89-114

Keywords: bending; edge beams; finite element method; reinforced concrete; hyperbolic parabolic shells; membrane theory (shells); prestressing; roofs; shells (structural forms); structural design; Design

Date: 11/1/1988

Abstract:
Umbrella and gable configurations are two of the most popular hyperbolic parabolic geometries. Early design of those shells was accomplished through the use of membrane theory. This determinant theory predicted overall behavior of these shells as a double cantilever beam for the inverted umbrella and as a simple beam for the gable shell. As long as the dimensions of these shells were small enough, this theory was adequate. However, with increased spans and with flatter applications, the theory proves to be inadequate. Bending solutions achieved by a finite element analysis prove to be necessary. Results from such analysis demonstrate the influence of several design parameters. The major role played by the dead weight of the edge and ridge beams is demonstrated.