Fire design of slim‐floor beams

Abstract

AbstractSlim‐floor beams are a well‐known and cost‐effective solution that permits a significant reduction of floor thickness, and are increasingly used in industrial and commercial buildings. Since only their lower flange is exposed to fire, slim‐floor beams may also achieve higher fire resistance, in comparison to other types of composite beams that are not fully embedded in the concrete floor. Simplified models are available in Eurocode 4 Parts 1‐2 to evaluate the temperature distribution for partially encased and non‐encased composite beams. However this standard does not provide any simplified model to evaluate the cross‐sectional temperature field of slim‐floor beams. In this sense, different proposals have been evaluated in recent years in order to provide simplified models for temperature evaluation. The currently available models in the literature have shown their accurate behaviour providing results on the safe side, and are recommended for use in practice. Finally, this work shows that slim‐floor composite beams can provide good performance during a fire event. Specifically, 60 min of standard fire rating can be achieved for load levels lower than 0.5–0.6. Improved behaviour to achieve 90 or 120 min of standard fire exposure may also be reached by using innovative solutions, advanced materials or external protection.