This research investigates the nonlinear mechanical properties and post-yield deformation mechanisms of hyperbolic paraboloid (hypar) shells inspired by the architecture of Félix Candela for the first time. Tubular structures derived from non-Euclidean hypar umbrellas with different number of edges and rise-to-area ratios were benchmarked against Euclidean thin-walled prismatic and pyramidal geometries under uniaxial quasi-static compression. For the same relative density, hypar structures exhibited markedly improved stiffness, strength, and energy absorption over their Euclidean counterparts. Moreover, the relative stiffness and strength exhibited by tubular structures based on hexagonal hypar umbrellas compared favorably with alternative lattice and honeycomb metamaterials. These findings highlight the attractiveness of hypars as novel (micro)architectures and provides further impetus towards the utilization of non-Euclidean geometries for ultra-light and ultra-stiff applications.

Relevant Publications

Wang, S., Dong, G., Walker, T., Sandford, H. (2025). Mechanical analyses of Félix Candela’s N-edged hyperbolic paraboloid umbrellas as tubular structures under uniaxial compression. Architecture, Structures and Construction, 5

Walker, T., Dong, G., Wang, S. (2024). Mechanical Performance of Mirrored Hypar Umbrella Sandwich Cells Through Compression Testing. Proceedings of the IASS Annual Symposium, Zurich, Switzerland

The striking tiled domes of the Ballet School of the Instituto Superior de Arte (ISA) in Havana are internationally acclaimed Cuban architectural icons. However, due to their deceptive tiled appearance and their only recently rediscovered hybrid tile–concrete construction system, the domes have eluded structural study and characterization. Yet, such studies are increasingly demanded not only because of their unique morphology and monumental status, but also because of their visible damage. This work defined a suitable numerical analysis method for diagnosing these hybrid structures by applying both linear elastic and nonlinear (using the damaged concrete plasticity constitutive model) numerical analyses. A site investigation campaign provided materials and geometric data that informed model creation and damage documentation which validated the analysis results.

A new synthesis of architectural and technical sources covering the development and spread of the hybrid structural system allowed the ISA domes to be placed, for the first time, in their proper structural context and, consequently, for their conception and design to be understood more fully. Because the investigation indicated significant risk of irreversible damage or failure without timely intervention, preliminary intervention explorations were conducted. Based on a holistic understanding of the structures, a technically, architecturally, and culturally optimal solution was identified.

Relevant Publications

Hughes, M., Celli, S., Heubner, C., Garlock, M., Ottoni, F., Del Curto, D., Wang, S., Glisic, B. (2023). Nonlinear finite-element analysis for structural investigation and preservation of reinforced hybrid thin tile-reinforced concrete domes of the historic school of ballet classrooms in Havana, Cuba. Journal of Performance of Constructed Facilities (ASCE), 37 (1)

Félix Candela was a celebrated builder of thin concrete hyperbolic paraboloidal (hypar) shells with a lasting legacy on the rationalist architectural movement of the 20th century. The iconic hypar umbrella became one of Candela most defining works of structural art due to its structural efficiency, economical constructability, and striking elegance. We employ finite element modeling to ascertain the structural performance of hypar umbrellas exhibiting three (triangular), four (square), and six (hexagonal) edges.

This research constitutes an ongoing effort aimed at revitalizing the adoption of thin hypar shells within contemporary architecture and engineering. By exploring the mechanisms governing their response, we present a pathway towards the potential reemergence of Candela's umbrellas to address the increasingly diverse challenges facing the structural engineering discipline in the 21st century.

Relevant Publications

ElDarwich, H., Mansouri, I., Garlock, M., Wang, S. (2024). Predicting maximum deflection of N-edged thin-shelled hyperbolic-paraboloid umbrella using machine learning techniques. Thin-Walled Structures, 205

Wang, S., Contreras-Jimenez, J. A., Jorquera-Lucerga, J. J., Garlock, M. (2022). Structural analysis of Félix Candela’s hexagonal hyperbolic paraboloidal umbrellas. Engineering Structures, 266

Wang, S., Garlock, M., Glisic, B. (2022). Geometric and area parameterization of N-edged hyperbolic paraboloidal umbrellas. Engineering Structures, 250

Wang, S., Levine, A., Garlock, M., Contreras-Jimenez, J. A., Jorquera-Lucerga, J. J. (2020). Structural evaluation of Félix Candela’s 8-sided hyperbolic paraboloidal umbrellas. Engineering Structures, 222