Steel Buildings in Europe

Part 6: Fire Engineering 6 - 40 floor were designed in accordance with the relevant Eurocodes for normal design. The floor was uniformly loaded using sand bags. The four steel columns and four boundary beams were fire-protected, but the two intermediate secondary beams were left unprotected. Figure 5.5 Details of full-scale fire tests on composite floor used in FRACOF 0 200 400 600 800 1000 1200 0 15 30 45 60 75 90 105 120 135 150 Time (min) Temperature (°C ) C B A Test A B C (a) Temperature of secondary beam 0 50 100 150 200 250 300 350 400 450 500 0 15 30 45 60 75 90 105 120 135 150 Time (min) Vertical displacement (mm) Central part of the floor Mid-span of unprotected central secondary beams Mid-span of protected edge secondary beams Mid-span of protected primary beams (b) Vertical displacements of the floor Figure 5.6 Results of full-scale fire tests on composite floors As shown in Figure 5.6, under the standard fire and applied loads, even when the temperature of the unprotected beam rose to 1040°C and the central deflection increased to 448 mm, the composite floor construction maintained its structural stability for more than 120 minutes. This demonstrates that the fire resistance of composite floors with unprotected secondary beams is much better than the 15 minutes predicted by standard fire tests. 5.2.1 Design concepts Based on the full-scale fire tests results and real fire observations, a new design concept has been developed to assess the fire performance of multi-storey steel framed buildings with composite floors.