This paper presents the thermal behavior simulation of high-strength high-volume fly ash nano-silica (HSHVFANS) reinforced concrete (RC) slab exposed to various fire curves using finite element (FE). The experiment includes a medium-scale furnace test (ISO 834 fire curve load, 120 min) of the HSHVFANS RC slab. Results show locations and depths of concrete spalling and temperature distribution at depths 30, 60, 90, and 200 mm. As limited numbers of thermocouples are utilized, and at that point, it may or may not spall, the temperature distributions at locations of spalling are simulated. For spalling of 5 mm (NS), the simulation curve maintains within the experimental results, but at a maximum of 23 mm (MS), the temperature rises significantly. The behavior of HSHVFANS RC slab exposed to HC, RABT-ZTV, and RWS fire curves is predicted using this model. The simulated temperature of reinforcement remains below critical (300 °C) for all fire curves loads except for RWS. For ISO 834, the fire-resistant periods of HSHVFANS RC by NS and MS models are 120 and 72 minutes respectively. For the HC and RWS, they are 120 and 46 to 55 minutes. The fire-resistant period of the HSHVFANS RC slab is significantly affected at maximum spalling depth. [ABSTRACT FROM AUTHOR]