Large membrane roof analysis: Nonlinear modeling of structures, connectors, and experimental evidences

This work discusses the numerical and physical models developed for the design of a membrane roof for the Baptist Church of Fortaleza as well as the fabrication and construction of the actual membrane, comparing results of the models with those of the real structure. The roof area amounts to about 2,900 m2, a national record for flexible border membranes and, to the writers’ knowledge, the first case of a fully computer-assisted design process within Brazil. The paper initially outlines procedures to form finding, stress analysis, and patterning, and then focuses on the physical models developed to validate them. Finally, construction of the actual membrane is described, and comparison is made with the previous numerical and physical models. Determination of the mechanical properties of the fabrics used to construct the membrane is also briefly discussed. Additionally, analyses of the geometric configuration and definition of the structural response of typical connectors of such a tension structure, collecting and distributing stresses coming from sails and anchoring cables and elements acting to transfer loads to the foundations, are developed. Unilateral contact is considered to develop among the aforementioned connector and the cable/rings welded to the slabs and the redance, imposing localized directional variations to the cable; furthermore, geometric (large strains) and material nonlinearities are accounted for