Author(s): Noor Kadhim Hammood and Samir Mohammed Chassib

Abstract: Fires represent one of the most serious sudden conditions affecting the safety and durability of concrete structures. High temperatures can degrade the mechanical properties and structural performance of reinforced concrete elements. This research aims to evaluate the structural performance of reinforced concrete slabs exposed to high temperatures using a gradual heating methodology based on standard fire curves (ISO-834 and ASTM E119), the type of concrete (normal weight and lightweight), the heating method, and the reinforcement ratio by increasing the reinforcement content by 20% in selected samples. Six slab samples (2250 × 1000 × 100 mm) were prepared using normal weight and lightweight concrete, with Alica aggregate used as a complete replacement for coarse aggregate in the lightweight mix. After standard curing, the samples were subjected to the specified heating regimes and then tested under bending load to failure. The research focused on key structural parameters such as ultimate load, deflection, stiffness, ductility, energy absorption, and failure modes. Experimental results showed that gradual heating facilitates realistic heat distribution within the concrete cross-section. At 800°C for 120 minutes, the decrease in ultimate load reached (21%), while the increase in deflection was (7%). Stiffness, ductility, and energy absorption were also affected by (1%). Although lightweight concrete offers better thermal insulation and lower self-weight, it exhibited greater degradation in load-bearing capacity and mechanical behavior at elevated temperatures. Consequently, the use of LECA as a 100% replacement for coarse aggregate was found to be ineffective under severe heat exposure due to the associated performance degradation.

DOI: 10.22271/27078361.2025.v6.i2b.81

Pages: 91-100 | Views: 140 | Downloads: 68

Download Full Article: Click Here