Steel Buildings in Europe

Title Worked Example – Fire safety strategies and design approach of steel floor beam 6 of 10 6 - 54 Gas and member temperature rise 0 100 200 300 400 500 600 700 800 900 1000 0 10 20 30 40 50 60 Time (minutes) Temperature (  C) Gas Unprotected section 5mm board protection 10mm board protection 20mm board protection Critical temperature Temperature rise of gas and beam due to exposure to natural fire 3.3.2. Load resistance Design effects for fire design In accordance with the simplified rule in EN 1991-1-2, the design effect of actions for fire situation, can be determined by reducing those for normal design by a factor  fi . For office buildings, the combination factor for accidental action of fire with the variable action 2.1 fi    = 0,3, and the reduction factor:  fi = G k Q k fi k k G Q G Q      = 1,35 3,5 1,50 3, 0 3,5 0,3 3, 0      = 0,477 Therefore, the design effect of actions for fire: Bending moment: M fi,Ed = η fi M Ed = 0,477  169,5 = 80,9 kNm Shear force: V fi,Ed = η fi V Ed = 0,477  96,9 = 46,2 kN Section classification For fire design, the value of ε is equal to 85% of that for normal design ε = y 0,85 235 f = 275 235 0,85  = 0,72 EN 1993-1-2; §4.2.2