Test #2 investigates the influence of the slab reinforcement on the structural integrity of the 9.1 m × 6.1 m steel-concrete composite floor subjected to combined mechanical loads and compartment fire exposure. The fire test bay was situated on the ground floor in the middle edge bay of the two-story test building. The floor slab in the test bay was reinforced with 9.5 mm diameter deformed bars placed 30 cm on-center (230 mm2/m). The test floor was hydraulically loaded to 2.7 kPa to mimic the code-prescribed gravity loads for fire conditions. Natural gas burners created a peak gas temperature exceeding 1100 °C below the test floor. The test fire lasted about 131 min, but the hydraulic loading was not removed until the test floor cooled down over 2 hours after the fire was extinguished. This experiment confirmed that the steel reinforcement played a vital role in maintaining the integrity of the composite floor under prolonged compartment fire exposure. The mid-panel vertical displacement increased at a rate less than 1 mm/°C as the protected steel beams were heated to 850 °C on average. The peak vertical displacement of the test slab was recorded 475 mm surpassing the displacement limit prescribed in the standard fire test. Although the test slab developed extensive surface cracks, it successfully contained the test fire underneath while sustaining the imposed loads. When the test floor was loaded again after it cooled down to room temperature, it retained the post-fire flexural strength exceeding 90 % of the ambient strength, calculated using the measured mechanical properties, of the composite secondary beam prior to fire exposure.
Spreadsheets containing the Test #2 data can be downloaded here (Click Link).