闭口型压型钢板-再生混凝土组合楼板抗火性能研究

Recycled aggregate concrete (RAC) composite slabs with closed-profiled steel decking offer the combined advantages of composite structures and utilization of solid waste. However, the thermal and mechanical properties of RAC at high temperature are significantly different from those of normal concrete, which further results in the difference of fire resistance between RAC and normal concrete structural members. Therefore, the fire resistance of RAC composite slabs with closed-profiled steel was experimentally and numerically studied based on the load-bearing failure criteria in this paper. The main investigated parameters included coarse recycled aggregate replacement rate, type of steel deck and load ratio. The developments of deflections and temperatures at different locations within the slabs were emphatically analyzed, and a simplified formula for predicting the fire resistance was developed. Results show that the steel deck remains bonded to the concrete and the integrity of the slabs is effectively maintained even after exposure to fire for 90 minutes. The temperatures recorded at the embedded decking rib are noticeably lower than those at the decking soffit. Additionally, the RAC slab exhibits lower temperatures at the same positions than the normal concrete slab. Furthermore, the fire resistance of the RAC slab is minimally affected by the replacement rate of coarse recycled aggregate. There is a modest improvement of 1.2% to 9.2% in fire resistance than the normal concrete slab. The capacity of all composite slabs far exceeds the minimum fire resistance requirement of 90 minutes. In conclusion, the proposed formula can yield a good prediction for the fire resistance of this type of composite slabs by considering the bending contribution of the embedded decking rib.