BUS5 Building structures 5: Fire safety

Transcription

1 Czech Technical University in Prague FACULTY OF CIVIL ENGINEERING Deptarment of Building Structures BUS5 Building structures 5: Fire safety Excercise 2 Fire Compartments, Fire Risk, Fire Resistance Grades Petr Hejtmánek

2 Building must be divided into Fire Compartments (FC) = elimination of fire and smoke development: fire = risk for building structures smoke products = risk for organisms (people, animals) Fire Compartment Praha Holešovice (Expo), 2008/10, fire of right wing of Průmyslový palác Fire Risk Factored Fire Load p v [kg/m 2 ] FRG I VII Fire spacing Praha Florenc, 2010/10 Required Fire Resistance (FR) for load-bearing and fire separating cons. 2 / 9

3 = space (room, group of rooms, whole building) divided form other spaces with fire separating constructions, i.e.: fire walls inner, exterior, between buildings load-bearing, non-load bearing fire ceilings (or roof) fire openings doors, gates, lids, windows, shaft doors Individual FC: Fire Compartment (FC) protective escape ways (PEW) flats and accomodation units (hotels) corridors connectiong flats and PEW (i.e. NPEW) shafts and technology cannals instalation, elevator, ventilating etc. technological rooms for ventilation, elevators, fire safety appliances, garages specific activities shopping, assembly, warehouses etc. Limited dimensions of FC (length and width) + maximal number of storeys of FC (height) in Lesson 1 3 / 9

4 Fire Risk Factored Fire Load p v [kg/m 2 ] Fire Load = volume of wood (kg) on a area (m 2 ) with same lower heating value as lower heating value of all combustible materials in specified area Factored Fire Load = Fire Load (both dead p s and live p n ) adjusted by coefficients (a, b, c) reflecting conditions of FC p v = a. b. c. ( p n + p s ) [kg/m 2 ] dead and live fire load [kg/m 2 ] influence of fire safety appiances (EFS, fire ventilation, sprinklers) c = 0,5 1,0 influence of windows dimensions b = 0,5 1,7 ratio of fire development speed of dead/live load a 0,9 1,1 4 / 9

5 Dead and live Fire Load p s + p n [kg/m 2 ] Lesson 1, Chart 5 5 / 9

6 Fire Resistance Grade (FRG) Lesson 1, Chart 8 Example: block of flats h = 27 m incombustible CS FC = flat p v = 40 kg/m 2 IV. FRG Poznámka: N FRG must not be applied O FC in one-storey buildings only 6 / 9

7 FC without Fire Load dividing constructions must be DP1 factored fire load p v 7,5kg/m 2 and coefficient a < 1,1 p v 3,5kg/m 2 a coefficient a > 1,1 I. FRG regardless to fire height In buildings with incombustible CS, FC without fire load could be: bathrooms, restrooms, cleaning chambers, laundry in block of flats corridors etc. p v [kg/m 2 ] is not computed in these cases: PEW there must not be any fire load p v, min. II. FRG flats, accomodation units, corridors, offices, etc. standarded value could be used FC without fire load I. FRG elevator and installation shafts p v is not computed, FRG dependant to media combustibility 7 / 9

8 Floor plans drawing of FC FLAT FLAT OFFICES FLAT FLAT N03.27 IV N = upper floor (event. P = basement), 03 = 3.NP, 27 = serial number of FC, IV. FRG S N01.15/N08 II shaft going from 1st to 8th floor, serial number 15, II. FRG B PEW type B (A PEW type A, C PEW type C) 8 / 9

9 Computation of Fire Load formula values result (incl. units) evaluation Example: FC 03 Cellar (N01.03 III) p v = 45kg/m 2 ( standarded value) III. FRG FC 04 Uninterrubable Power Supply room (P01.03 II) p n = 10kg/m 2, a n = 0,9, p s = 2kg/m 2 (door), a s = 0,9 p = p s + p n = = 12kg/m 2 a = (p n. a n + p s. a s ) / (p n + p s ) = (10. 0, ,9) / (10 + 2)= 0,9 indirectly ventilated b = k / (0,005. h s 1/2 ) = 0,005 / (0,005. 2,55 1/2 ) = 0,63 n = 0,005, S m = 4,2m 2 k = 0,005 c = 1,0 (no Fire Safety Appliances) p v = a. b. c. p = 0,9. 0,63. 1,0. 12 = 7kg/m 2 for 1st basement (same as h 22,5m) II. FRG FC 10 Flat installation shaft (S-P01.10/N 7 II) no computation p v distribution of incombustible substances in combustible pipes II. FRG 9 / 9