Numerical Investigation into the Mechanical Performance of Hybrid Fiber-Reinforced Self-Compacting Concrete Beams at High Temperature
Mohamed Zitouni1, Belkacem Lamri2, Abdelhak Kada2, Mário Rui Arruda1,*
1 Structural Behaviour Unit, Department of Structures, National Laboratory of Civil Engineering—LNEC, Avenida do Brasil 101, Lisbon, Portugal
2 Laboratory Fire Safety Engineering of Constructions and Protection of their Environment LISICPE, Faculty of Civil Engineering and Architecture, Hassiba Benbouali University of Chlef, Ouled Fares, Chlef, Algeria
* Corresponding Author: Mário Rui Arruda. Email: 
Structural Durability & Health Monitoring https://doi.org/10.32604/sdhm.2026.081538
Received 04 March 2026; Accepted 30 April 2026; Published online 25 May 2026
Abstract
The use of self-compacting concrete (SCC) in structural elements has significantly increased in recent years due to its superior fresh properties, including high flowability, ease of placement, and ability to consolidate without vibration, making it particularly suitable for complex and densely reinforced structures. However, despite these advantages, SCC presents certain limitations when exposed to fire, which is considered one of the most severe threats to structural safety. This is mainly due to the lack of comprehensive understanding and design guidelines regarding its behaviour under elevated temperatures, particularly at the structural element level. This paper presents a numerical investigation of the mechanical behaviour of hybrid fibres reinforced self-compacting concrete (HFSCC) beams under high temperatures due to fire using a finite element (FE) model. Three beams are analysed, one without fibres (SCC), and the others, with hybrid fibres, having the fixed volume fraction (VF) of polypropylene fibre of 0.1% and a VF of steel fibres of 1% and 2%. All beams are simulated using ANSYS software and analysed at ambient and elevated temperatures at 400°C, 600°C, and 800°C. The numerical study is carried out to evaluate the behaviour of beams, considering geometric and material nonlinearities. The numerical results suggest that at room temperature (20°C), adding hybrid fibres, 0.1% VF of polypropylene, and VF of 1% steel to SCC beams increases ultimate load capacity by 17.9%, and with an increase in the VF of steel fibres to 2%, the load capacity further improves to 30.8%. At elevated temperatures (400°C, 600°C, and 800°C), the addition of hybrid fibres reduces the rate of reduction of ultimate load capacity of SCC beams, particularly significant when 2% VF of steel fibres are used.
Keywords
Mechanical behaviour; self-compacting concrete; hybrid fibres; high temperature; finite element
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