Assessment of design codes for the in-service behaviour of steel-concrete composite slabs

Abstract

Abstract Steel-concrete composite slabs, also known as steel decking floor slabs or popularly as steel decks® have recent development and are advancing in Brazilian construction. There are relatively few researches about the long-term effects on composite slabs, and it has been identified that they can be significant in the evolution of deflections, mainly due to the effects of non-uniform shrinkage. However, there are no Brazilian references on the subject and Brazilian Code ABNT NBR 8800:2008 does not indicate any procedure for its evaluation. This paper presents a study on the serviceability limit state of excessive deflection with the application of two simplified approaches: Eurocode 4:2004 (European code) and AS/NZS 2327:2017 (Australian code), also comparing them against experimental results by the authors and literature. Due to the impermeability of the soffit face promoted by the steel decking, the occurrence of non-uniform shrinkage is a relevant aspect. As a consequence, the deflections were underestimated by Eurocode 4. At the same time, the simplified approach of AS/NZS 2327, which explicitly takes into account the non-uniform shrinkage, presented good accuracy when compared to the experimental values. Finally, authors indicate the use of more robust prediction models for the evaluation of deflections in composite floors.

Keywords

• composite structures
• profiled steel decking
• instantaneous and long-term deflections
• creep and non-uniform shrinkage
• cracking concrete