Reinforced Concrete Silo with Sacrificial Composite Coating Under Elevated Temperatures

Reinforced concrete silos are usually designed only for mechanical loading. This consideration is sufficient at ambient temperature. But at elevated temperature scenarios, temperature induced-instability comes into the picture. This can either lead to structural collapse or necessitates extensive repairs. In this study, thermo-mechanical behaviour of a reinforced concrete silo is investigated through finite element simulations under two fire exposure scenarios: one when it is subjected to fire from one side and other when it is subjected to fire from the bottom. 30-minute fire duration is taken following temperature-time profile as per External fire curve given by Eurocode 1. The effectiveness of a composite fire protection coating made up of heavy type gypsum and fibre glass insulation board in lowering temperature magnitude of the structure has also been studied. Its minimum thickness to maintain structural integrity for thirty minutes has been determined. In both fire exposure scenarios stresses and lateral displacements in silo increases and exceeds their permissible limits as set up by IS 456:2000. Seven thicknesses (3 cm to 9 cm) of composite coating were analysed under External fire curve. It was found that they are capable of reducing the peak temperature of fire in range of 93.87% to 96.6% respectively. Minimum thickness of 5 cm (silo heated from one side) and 4 cm (silo heated from bottom) of coating is required, which efficiently controls the ill effects of fire on structure.