Digital Nervi: Performance‐based design of lightweight isostatic ribbed slab with <scp>3D</scp> ‐printed concrete formwork

Abstract The material efficiency of cast‐in‐situ concrete floor slabs can be significantly improved through topology optimization and 3D‐printed formwork. The isostatic ribbed slab (IRS), a legacy of Pier Luigi Nervi, aligns the ribs with the isostatic lines of the principal bending moments. This work introduces the Functional IRS as a cast‐in‐situ lightweight concrete slab system using 3D‐printed permanent formwork. The Functional IRS serves as a compact functional ceiling plenum that integrates skylights and building devices such as air ducts. To create openings in ribs, the coupled pods (formwork) were developed to comply with the material‐extrusion 3D concrete printing (3DCP) process. A 1:5 scale mockup with curved supporting walls was constructed to verify the feasibility of the construction method. With supports of irregular shape, optimized IRS saves about 30% of the material compared to grid slab. The lightweight ‘digital Nervi’ slab presents a holistic response to global low‐carbon concerns by integrating computational optimization and additive manufacturing.