Steel Buildings in Europe

Title Worked Example – Fire safety strategies and design approach of steel floor beam 8 of 10 6 - 56 The reduction factor for effective yield strength can be obtained for: θ a = 500  C k y, θ = 0,780 θ a = 600  C k y, θ = 0,470 By interpolating for θ a = 594  C, k y, θ = 0,46 The κ 1 and κ 2 factors are as previously obtained. The moment resistance of the fully restrained beam with non-uniform temperature along the depth of its cross-section: M fi,Rd = 1 2 pl,y y y, θ   W f k = 6 3 10 0,7 1,0 275 628 10 0,46      = 113 kNm > 80,9 kNm  OK The shear resistance can be obtained as follows: V fi,Rd = M0 v y y, θ 3  A f k = 3 1, 0 275 0, 46 2567   = 187,5kN > 96,6 kN  OK The 3 side box protected section with 10 mm fire boards, is safe.  OK 3.4. Make use of tensile membrane action Full size fire tests and real fire investigations have resulted in the conclusion that the use of composite floors with steel decking leads to a much higher fire resistance than predicted by the simple calculations adopted by the Eurocode and shown in this example. Section 8. As long as the slab is well supported against its vertical deflection along lines which divide it into reasonably square areas, it is has been shown that tensile membrane action can be developed as a load bearing mechanism, consequently providing a reserve load carrying resistance that simplified models do not account for. As a result, it could be assumed that the beam in this example could be left unprotected, while maintaining the level of safety required by EC3. This construction system has been shown to provide a higher fire resistance for secondary beams but not for primary beams, and therefore care must be taken when adopting this solution. 3.5. FRACOF The FRACOF software can be used to determine whether or not unprotected secondary steel beams are adequate when composite construction is used.