Fire load assessment and thermo-mechanical analysis of RC buildings

Purpose To evaluate the influence of heating and cooling phases of fire on structural behaviour through cross-sectional analysis. The core objective is to develop parametric fire load density (FLDs) through field survey accounting role of modern materials and firefighting measures in evaluating the adequacy of fire-resistance rating (FRR) for reinforced concrete (RC) elements. The structural (axial and deflection) capacities indicative of performance are also assessed during both the heating and decay phases to quantify the resistance duration. Design/methodology/approach A field survey of 184 office rooms and 191 hostel rooms was conducted to determine realistic FLDs, including materials not addressed by code, occupancy type, floor area and ventilation, which influences fire dynamics. Utilising these data, Eurocode-based parametric fire curves were developed for thermo-mechanical analysis to examine the thermal response and subsequent degradation of RC components. Findings Flashover time has been reduced by more than 50% for the maximum FLD curve compared to standard curves. Firefighting measures reduce burning time to 80 min, causing 75–82% reduction in fire progression for the maximum FLD compartment, preventing structural degradation. The temperature field ratio of structural components revealed significant recovery of strength and stiffness in the cooling phase, which implicates structural capacity. Originality/value Highlights inadequacy of FRR by prescriptive procedures and advocates development of compartment-specific parametric fire models for building fire safety. Strongly emphasises performance-based assessment tailored to building topologies and their occupancy to assist in enhancing evacuation planning, fire safety contributing to resilience.