Effective Limit Analysis Computational Approaches for the Structural Characterization of Nervi’s Palazzetto dello Sport

In this work, two formulations, and computational implementations, of Limit Analysis (LA), for large-scale 3D truss-frame structures are employed to efficiently investigate the limit elastoplastic response of the fascinating and well-known Palazzetto dello Sport (1957), located in the Flaminio district of Rome (Italy), designed by Pier Luigi Nervi. To this end, a spatial FEM modeling was first generated, whereby the characteristic inclined trestles and supporting skeleton of the above concrete shell dome were modelled according to the corresponding geometric characteristics and mechanical properties acquired by inspecting original design drawings and relevant bibliographic sources. In performing the structural Limit Analysis, the first algorithm step-by-step traces a fully exact evolutive piece-wise linear elastoplastic response of the structure, up to plastic collapse, by reconstructing the sequence of activation of localised plastic joints. The second algorithm, relying on a kinematic iterative direct approach, determines just the collapse mechanism and associated collapse load multiplier, but in a much shorter computational time, showing a rather impressive performance, in truly precipitating from above on the collapse load multiplier, by rapidly adjusting possible mechanisms to the sought collapse mode, in very few iterations. The performed investigation reveals the ingenuity of Nervi’s work, not only with respect to ordinary structural bearing tasks, within the elastic range of regular-service structural response, but also to post-yield performance and ultimate limit load capacity, up to possible ductile failure.