Innovative prefabricated lightweight slab system of high structural performance

Abstract

This paper presents a new pre-fabricated lightweight slab system where the relatively high post-cracking tensile capacity of steel fibre reinforced concrete (SFRC) is combined with the high ductility and tensile strength of optimized shape profiles made by cold formed steel sheets for a synergetic result in terms of structural performance. The SFRC fills the longitudinal steel profiles (girders) that have openings in the web for materializing SFRC shear mechanisms that provide very high shear resistance to the slab. This slab system (designated by PreSlabTec) includes a SFRC deck of 40 mm thickness and lightweight blocks serving as permanent moulds to the SFRC and thermal insulation. The transversal stiffness is assured by thin wall tubular steel profiles that remained anchored in the girders due to their openings. PreSlabTec is simple and fast of executing and was conceived for being produced in an automation process of prefabrication industry. For assessing the performance of the PreSlabTec in serviceability and ultimate limit state conditions, an extensive program with almost real scale prototypes was executed and tested under loading configurations for flexural and shear failures. For the flexural loading configurations, the PreSlabTec demonstrated a very high load carrying capacity and ductility performance. The PreSlabTec never failed in shear, despite the very exigent shear loading configurations adopted. The long-term deflection was also experimentally evaluated for the standard design requirement for slabs of residential buildings, and a relatively low average creep coefficient of 0.13 was obtained. Finally, the theoretical approach for the design of PreSlabTec is described and its good predictive performance is demonstrated.