Fire resilience of reinforced concrete parking garage slabs under electric vehicle fire scenarios

Abstract

Abstract

Purpose This study aims to evaluate the structural integrity of reinforced concrete slabs subjected to electric vehicle (EV) fire exposure. A coupled numerical framework is employed to quantify the effects of EV fire thermal loading on reinforcement temperature, load-bearing capacity and time to failure and to compare these results with those obtained under the ISO 834 standard fire. The objective is to determine whether current fire design provisions adequately preserve structural integrity under emerging EV fire scenarios and to identify critical parameters influencing integrity loss, particularly concrete cover thickness. Design/methodology/approach A multi-physics numerical framework was developed combining computational fluid dynamics (CFD) and nonlinear finite element analysis. EV fire scenarios were simulated to obtain realistic temperature–time histories, which were applied as thermal boundary conditions in sequentially coupled thermal and thermomechanical analyses of reinforced concrete slabs. Concrete behavior was represented using the concrete damage plasticity model, with temperature-dependent material properties defined according to EN 1992-1-2. The models were calibrated and validated against full-scale experimental data. Structural integrity was assessed based on reinforcement yielding, stress redistribution and reduction in load-bearing capacity during fire exposure. Findings EV fires produce higher early-stage temperatures than the ISO 834 standard fire, accelerating reinforcement heating and reducing structural integrity in slabs with limited concrete cover (=15 mm). In these cases, earlier steel yielding led to reductions in fire resistance of up to 26% compared to ISO-based predictions. For concrete covers = 20 mm, the thermal barrier provided by concrete preserved reinforcement capacity and structural integrity within the 60-min exposure. The results demonstrate that integrity loss is governed primarily by reinforcement degradation and that adequate concrete cover remains the critical parameter for maintaining load-bearing capacity under EV fire scenarios. Research limitations/implications The analysis considers simply supported one-way slabs subjected to a single-vehicle EV fire scenario derived from numerical simulation. Multi-vehicle fire spread, ventilation variability, spalling and bond degradation effects were not explicitly modeled. Experimental validation was limited to standardized fire exposure, and direct full-scale testing under EV fire conditions remains unavailable. Despite these limitations, the study provides quantitative insight into integrity loss mechanisms under non-standard fire loading. Future research should address more complex structural systems, boundary conditions and probabilistic fire scenarios to support integrity-based performance assessment of infrastructure exposed to EV fires. Practical implications The results indicate that reinforced concrete slabs designed according to current code provisions generally preserve structural integrity under EV fire exposure when the fire resistance rating is at least 60 min and the concrete cover is not less than 20 mm. Reduced cover thickness significantly increases vulnerability due to accelerated reinforcement heating and earlier yielding. The findings support integrity-based fire assessment by identifying concrete cover as the governing parameter in maintaining load-bearing capacity. Designers of parking structures and infrastructure exposed to EV fires may consider enhanced fire resistance requirements to ensure adequate structural robustness. Social implications The rapid growth of EV adoption introduces new fire scenarios that may affect the structural integrity of parking facilities and infrastructure. Understanding how reinforced concrete slabs perform under EV fire exposure is essential to prevent premature structural failure, economic losses and potential threats to public safety. This study provides evidence-based guidance for maintaining load-bearing capacity under emerging fire hazards, contributing to safer infrastructure design. By supporting integrity-oriented fire assessment, the findings help reduce societal risk associated with structural collapse in enclosed spaces where EVs are increasingly present. Originality/value This study provides one of the first integrity-focused assessments of reinforced concrete slabs subjected to EV fire exposure. By integrating realistic EV fire thermal loading with nonlinear thermomechanical analysis, the research moves beyond standardized ISO 834 assumptions and quantifies integrity loss in terms of reinforcement yielding and fire resistance reduction. The work identifies concrete cover thickness as the governing parameter controlling structural robustness under emerging fire hazards. The findings contribute to the limited body of knowledge on integrity-based evaluation of reinforced concrete structures exposed to non-standard fire scenarios.