Temperature profile and resistance of flat decking composite slabs in- and post-fire

This paper presents the experimental and numerical results on fire resistance of the composite slabs using flat profiled decking with vertical webs and top flanges embedded in concrete based on a series of tests including heat transfer, ISO834 standard fire, and post-fire residual strength tests. The study aims to provide temperature profiles across the slab thickness for different standard fire durations, to demonstrate the effectiveness of embedded components and to determine post-fire residual strength of the composite slabs. Test results showed that when exposed to fire, the embedded vertical webs and top flanges of the flat decking sustained much lower temperature compared to that at the soffit. Therefore, the webs and the top flanges help to reduce the amount of fire reinforcement required at the bottom part of the composite slabs. The integrity of steel decking and concrete can be maintained even after four hours of standard fire, which eliminate concrete spalling and minimise post-fire damage. A simplified assessment approach to evaluate the post-fire residual strength of flat decking composite slabs was also proposed. The heat transfer and structural finite element models were developed and validated with the test results to study fire resistance of the slabs, and to compare its performance with the traditional trapezoidal and re-entrant composite slabs.