Eduardo Torroja's CASA factory roof: An unbuilt Structural Art masterpiece

Eduardo Torroja was one of the most innovative structural engineers of the 20th century. His legacy can be seen in the form of some of his remaining works and the memory of others that have now disappeared. Torroja's structures have attracted a lot of attention in recent years, thanks in part to the publication of studies on some of his projects, such as, for example, the Frontón Recoletos, the Zarzuela Racecourse and the San Nicolás Church. However, up to now very little attention has been paid to his other legacy, consisting of designs that were never actually built. Some of the most important of these designs include the roof of the Tachira Club in Caracas, Venezuela, and the roof of the CASA factory in Seville, Spain. This paper studies in detail the CASA factory roof, which is a little known structure designed by Torroja in 1938. The roof covers a space measuring 230 m × 81.4 m in plan with a series of vaulted shells supported by parabolic arches. The study starts with a finite element analysis of the roof subjected to its self-weight, which helps to better understand the roof's general structural behaviour. Then the roof reinforcement is obtained considering both the loads and materials used by Torroja and the loads and materials suggested by current building codes. The comparison of the results of both procedures leads to some interesting conclusions, and clearly shows the technical problems of building today the innovative designs that Torroja successfully built in his time. Finally, the roof is also analysed from the perspective of Structural Art, which is important in the development of the discipline of structural criticism, and demonstrates the inspirational power of the best works of structural engineering.