1、 ASCE STANDARD ASCEISEIISFPE 29-05 American Society of Civil Engineers Standard Calculation Metho,ds for Structural Fire Protection AE-L, - - Structural Eng/neerlng mnstlfufe *.,Allowing formula: where s = spacing of ribs or undulations t = minimum thickness t, = equivalent thickness calculated in a
2、ccordance with item b, above 2.3.4 Multiple-Wythe Walls For walls consisting of two or more wythes of differ- ent types of concrete, the fire resistance rating shall be determined in accordance with the graphical or numeri- cal solution in Sections 2.3.4.1 and 2.3.4.2, respectively. 2.3.4.1 Graphica
3、l Solutiorz For walls consisting of two wythes of different types of concrete, the fire resistance rating shall be determined from Figure 2- 1. The fire resistance rating shall be the lower of the two ratings determined by assuming that each side of the wall is the fire-exposed side. 2.3.4.2 Nuineri
4、cal Solution For walls consisting of two or more wythes of different types of concrete, or one or more wythes of TABLE 2-1. Fire Resistance of Concrete Walls, Floors, and Roofs Minimum Equivalent Thickness for Fire Resistance Rating (hrs) Concrete Aggregate Type in. mm in. rnm in. mm in. mm in. mm S
5、iliceous 3.5 89 4.3 109 5.0 127 6.2 157 7.0 178 Carbonate 3.2 81 4.0 102 4.6 117 5.7 145 6.6 168 Lightweight 2.5 64 3.1 79 3.6 91 4.4 112 5.1 130 STANDARD CALCULATION Ml3HODS FOR STRUCTURAL FIRE PROTECTION Fire-Exposed Wythe Carbonate Fire-Exposed Wythe Siliceous k 5 0 22 3 A or the fire resistance
6、rating of the floor or roof shall be maintained by other approved methods. 2.4.3 Two-Course Floors and Roofs The fire resistance rating of two-course floors and roofs consisting of a base slab of concrete with a topping (overlay) of concrete with a different type of aggregate is indicated in Figure
7、2-4. If the base slab of concrete is covered with a topping (overlay) of terrazzo or gypsum wallboard, the thickness of terrazzo or gypsum wallboard shall be converted to an equivalent thickness of concrete by multiplying the actual thick- ness by the appropriate factor listed in Table 2-4. This equ
8、ivalent concrete thickness shall be added to the base - - slab thickness and the total thickness used to determine the fire resistance of the slab, including topping, from Table 2- 1. 2.4.4 Insulated Roofs The fire resistance rating of roofs consisting of a base slab of concrete with a topping (over
9、lay) of cellu- lar, perlite, or vermiculite concrete or insulating boards and built-up roof shall be determined from Figure 2-5 (a) or (b). Where a three-ply built-up roof is installed over a lightweight insulating concrete topping, Siliceous Sand-Lightweight Top Course Material or Carbonate or Ligh
10、tweight Gypsum wallboard* 3 2.25 Terrazzo 1 0.75 * Applies only to roofs. 10 minutes shall be permitted to be added to the fire resistance rating calculated from Figure 2-5 (a). 2.5 CONCRETE COVER OVER REINFORCEMENT Minimum concrete cover over positive moment reinforcement for floor and roof slabs a
11、nd beams shall be determined by Sections 2.5.1 through 2.5.3. Concrete cover shall not be less than required by ACI 3 18. For purposes of determining minimum concrete cover, slabs and beams shall be classified as restrained or unrestrained in accordance with Appendix A. 2.5.1 Cover for Slab Reinforc
12、ement The minimum thickness of concrete cover to posi- tive moment non-prestressed and prestressed reinforce- ment (bottom steel) for different types of concrete floor and roof slabs for fire resistance ratings of I to 4 hours shall be not less than the thickness indicated in Table 2-5. For floor or
13、 roof slabs consisting of two or more courses of different types of concrete, the cover requirements shall be based on the type of concrete used for the base slab, provided the base slab is not less than 1 in. (25 mm) thick. Table 2-5 shall apply to one-way or two-way cast-in-place or precast solid
14、or hollow-core slabs with flat undersurfaces. 2.5.2 Cover for Non-Prestressed Reinforcement in Beams The minimum thickness of concrete cover to positive moment non-prestressed reinforcement (bot- tom steel) for restrained and unrestrained beams of different widths for fire resistance ratings of 1 to
15、 4 hours for all types of concrete shall not be less than the thickness indicated in Table 2-6. Values in Table 2-6 for restrained beams apply to beams spaced more than 4 ft (1,2 19 mm) on center. For restrained beams and joists spaced 4 ft (1,2 19 mm) or less on center, 314 in. (19 mm) cover is ade
16、quate for fire resistance ratings of 4 hours or less regardless of the width of the beam. Cover for intermediate beam widths shall be determined by direct interpolation. ASCWSEIISFPE 29-05 SAND-LIGHTWEIGHT CONCRETE . . ., . . Carbonate Base Siliceous Base 25 51 76 102 127 mm 25 51 76 102 inches 0 12
17、3 4 THICKNESS OF NORMAL WEIGHT CONCRETE BASE SLAB NORMAL WEIGHT CONCRETE SAND-LIGHTWEIGHT CONCRETE Carbonate Overlay Siliceous Overlay mm mm 25 51 76 102 127 25 51 76 102 127 5 127 5 127 inches inches THICKNESS OF SAND-LIGHTWEIGHT CONCRETE BASE SLAB FIGURE 2-4. Fire Resistance of Two-Course Concrete
18、 Floors and Roofs (Source: Abrams, M. S., and Gustaferro, A. H. (1968). “Fire endurance of two-course floors and roofs.“ Portland Cement Association Research and Development Bulletin RD048. Used with permission.) 2.5.2.1 Calculating Cover cover of the individual bars. For corner bars (i.e., bars The
19、 concrete cover for an individual bar is the equal distance from the bottom and side), the mini- minimum thickness of concrete between the surface of mum cover used in the calculation shall be one-half the bar and the fire-exposed surface of the beam. For the actual value. The actual cover for an in
20、dividual bar beams in which several bars are used, the cover, for the shall not be less than one-half the value shown in Table purposes of Table 2-6, is the average of the minimum 2-6 or 314 in. (19 mm), whichever is greater. STANDARD CALCULATION METHODS FOR STRUCTURAL FlRE PROTECTION Carbonate Base
21、 (25) (5 1) (76) (102) . : : - CELLULAR CONCRETE . : : . .: ,.: .: “ :;., CONCRETE ,: ;. ,: ,j: . . , .:, Siliceous Base (25) (5 1) (76) (102) Sand-Lightweight Base (25) (5 1) (76) (102) THICKNESS OF CONCRETE BASE SLAB IN INCHES (mm) -: . . PERLITE CONCRETE :-. ; . . . : . . CONCRETE : : . .:,. . :j
22、 . . . . e, U Carbonate Base Siliceous Base Sand-Lightweight Base (25) (5 1 ) (76) ( 102) 02) 3 a 2 0 “ (51) 2 (51) 2 (5 1) rn2 8iZ 1 I= P) 24 (25) 1 (25) 1 (25) .i! 0 22 b 0 1234 0 1234 0 1234 THICKNESS OF CONCRETE BASE SLAB IN INCHES (mm) : VERMICULITE CONCRETE .: . . . . .: . . .;. : : ; ; . : .
23、. Carbonate Base Siliceous Base Sand-Lightweight Base (25) (51) (76) (102) (102) (25) (51) (76) (102) (102) (25) (51) (76) (102) (102) (51) 2 (5 1) (25) 1 (25) 1 (25) 0 1234 0 1234 0 1234 THICKNESS OF CONCRETE BASE SLAB IN INCHES (mm) FIGURE 2-5. (a) Fire Resistance of Concrete Roofs with Overlays o
24、f Insulating Concrete (Source: Abrams, M. S., and Gustaferro, A. H. (1970). “Fire resistance of lightweight insulating concretes.“ Portland Cement Association Research and Development Bulletin RD004. Used with permission.) 2.5.3 Cover for Prestressed Reinforcement types of concrete for fire resistan
25、ce ratings of 1 to 4 in Beams hours shall be not less than the thickness indicated in The minimum thickness of concrete cover to posi- Table 2-7 (a) and (b). Table 2-7 (a) shall apply rive moment prestressed reinforcement (bottom steel) to beams of all widths, provided the beam cross- for restrained
26、 and unrestrained beams of different sectional area is not less than 40 sq in. (25,806 mm2). Carbonate Base (25) (51) (76) 3 MINERAL BOARD Standard 3-ply Built-up Roofing . .: ,CONCRETE . . : .-. . . Siliceous Base (25) (51) (76) (102) (76) (5 1) 1 fsi 1 2 3 4 (25) 0 Sand-Lightweight Base (25) (51)
27、(76) (102) 3 (76) THICKNESS OF CONCRETE BASE SLAB, INCHES (mm) n GLASS FIBER BOARD Standard 3-ply - Built-up Roofing -.;:. .CONCRETE . , . , ,- Carbonate Base Siliceous Base Sand-Lightweight Base THICKNESS OF CONCRETE BASE SLAB, INCHES (mm) FIGURE 2-5. (b) Fire Resistance of Concrete Roofs with Boar
28、d Insulations (Source: Abrams, M. S., and Gustaferro, A. H. (1968). “Fire endurance of two-course floors and roofs.“ Portland Cetnerzt Association Research and Development Bulletin RD048. Used with permission.) Table 2-7 (b) shall apply to beam widths equal to or cover specified from the two tables
29、shall be used. greater than 8 in. (203 mm). As an alternative, for Values in Table 2-7 (a) and (b) for restrained beams beams with cross-sectional areas equal to or greater shall apply to beams spaced more than 4 ft (1,2 19 mm) than 40 sq in. (25,806 mm) and widths equal to or on center. For restrai
30、ned joists spaced 4 ft (1,219 mm) greater than 8 in. (203 mm), the minimum concrete or less on center, 314 in. (19 mm) cover shall be STANDARD CALCULATION METHODS FOR STRUCTURAL FIRE PROTECTION TABLE 2-5. Minimum Cover for Non-Prestressed and Prestressed Reinforcement in Concrete Floor and Roof Slab
31、s Thickness of Cover for Fire Resistance Rating - - - Concrete Aggregate Restrained Unrestrained TY pe 4 hr or less I hr 1.5 hr 2 hr 3 hr 4 hr Minimum cover for non-prestressed reinforcement in concrete floor or roof slabs in. mm in. mm in. mm in. mm in. mm in. mm Siliceous 314 19 314 19 314 19 1 25
32、 1114 32 1518 41 Carbonate 314 19 314 19 314 19 314 19 1 114 32 1 114 32 Sand-lightweight 314 19 314 19 314 19 314 19 1 114 32 1 114 32 Lightweight 314 19 314 19 314 19 314 19 1 114 32 1 114 32 Minimum cover for prestressed reinforcement in concrete floor or roof slabs Siliceous 314 19 I118 29 1112
33、38 1314 44 2318 60 2314 70 Carbonate 314 19 1 25 1318 35 1518 41 2118 54 2114 57 Sand-lightweight 314 19 1 25 1318 35 1112 38 2 51 2114 57 Lightweight 314 19 1 25 1 318 35 1 112 38 2 51 2 114 57 TABLE 2-6. Minimum Cover for Non-Prestressed Reinforcement in Concrete Beams Thickness of Cover for Fire
34、Resistance Rating Beam Width 1 hr 1.5 hr 2 hr 3 hr 4 hr Restrained or Unrestrained in. mm in. mm in. mm in. mm in. mm in. mm - - - - - Restrained 5 127 314 19 314 19 314 19 1 25 1114 32 Restrained 7 178 314 19 314 19 314 19 314 19 314 19 Restrained 210 2254 314 19 314 19 314 19 314 19 314 19 Unrestr
35、ained 5 127 314 19 1 25 1114 32 - - - - Unrestrained 7 178 314 19 314 19 314 19 1314 44 3 76 Unrestrained 210 1254 314 19 314 19 314 19 314 19 1314 44 considered adequate for fire resistance ratings of 4 hours or less, regardless of the cross-sectional area or width. Cover for intermediate beam widt
36、hs of Table 2-7 (b) shall be determined by direct interpolation. When computing the cross-sectional area of beams cast monolithically with the supported slab for use in Table 2-7 (a), the cross-sectional area of the portion of the slab having a width not exceeding three times the average width of th
37、e beam shall be permitted to be included with the cross-sectional area of the beam. Where the thickness of concrete cover exceeds 2.5 in. (64 mm), stirrups or hoops with a cover of 1 in. (25 mm) and spaced not to exceed the depth of the beam shall be provided. The minimum cover for non-prestressed p
38、ositive moment reinforcement in prestressed concrete beams shall be determined in accordance with Section 2.5.2. 2.5.3.1 Calculating Cover The concrete cover for an individual tendon is the minimum thickness of concrete between the sur- face of the tendon and the fire-exposed surface of the beam; ex
39、cept for ungrouted ducts, the assumed TABLE 2-7. (a) Minimum Cover for Prestressed Reinforcement in Concrete Beams 40 sq in. (1,016 sq mm) or Greater in Area Regardless of Beam Widths Thickness of Cover for Fire Resistance Rating Cross-Sectional Area 1 hr 1.5 hr 2 hr 3 hr 4 hr Concrete Aggregate TY
40、e in.2 mm2X103 in. mm in. mm in. mm in. mm in. mm RESTRAINED All Carbonate or siliceous Carbonate or siliceous Lightweight or sand-lightweight UNRESTRAINED All Carbonate or siliceous Carbonate or siliceous Lightweight or sand-lightweight TABLE 2-7. (b) Minimum Cover for Prestressed Reinforcement in
41、Concrete Beams 8 in. (203 mm) or Greater in Width Thickness of Cover for Fire Resistance Rating Beam Width 1 hr 1.5 hr 2 hr 3 hr 4 hr Concrete Aggregate TY pe in. mm in. mm in. mm in. mm in. mm in. mm RESTRAINED Carbonate or siliceous Carbonate or siliceous Sand-lightweight Sand-lightweight UNRESTRA
42、INED Carbonate or siliceous Carbonate or siliceous Sand-lightweight Sand-lightweight * Not practical for 8 in. (203 mni) wide beam, but shown for purposes of interpretation. 13 STANDARD CALCULATION METHODS FOR STRUCTURAL FIRE PROTECTION cover thickness is the minimum thickness of concrete 3. the mai
43、n longitudinal reinforcement in the column between the surface of the duct and the surface of the has cover of not less than required by Section 2.6.1. beam. For beams in which several tendons are used, the cover, for purposes of Table 2-7 (a) and (b), is the average of the minimum cover of the indi
44、vidual tendons. For corner tendons, the minimum cover used in the calculation shall be one-half the actual value. For stemmed members with two or more prestressing tendons located along the vertical centerline of the member, the average cover shall be the distance from the bottom of the member to th
45、e centroid of the ten- dons. The actual cover for an individual tendon shall not be less than one-half the value shown in Table 2-7 (a) or (b) or 1 in. (25 mm), whichever is greater. 2.6 REINFORCED CONCRETE COLUMNS The least dimension of reinforced concrete columns of different types of concrete for
46、 fire resistance ratings of 1 to 4 hours shall be not less than the dimensions indicated in Table 2-8. 2.6.1 Minimum Cover for Reinforcement The minimum thickness of concrete cover to the main longitudinal reinforcement in columns, regardless of the type of aggregate used in the concrete, shall not
47、be less than I in. (25 mm) times the number of hours of required fire resistance, or 2 in. (51 mm), whichever is less. 2.6.2 Columns Built into Walls The minimum dimensions of Table 2-8 shall not apply to a reinforced concrete column that is built into a concrete or masonry wall, provided all of the
48、 follow- ing are met: 1. the fire resistance of the wall is equal to or greater than the required rating of the column; 2. openings in the wall are protected in accordance with the general building code so that no more than one face of the column will be exposed to fire at the same time; and 3.0 STA
49、NDARD METHODS FOR DETERMINING THE FIRE RESISTANCE OF TIMBER AND WOOD STRUCTURAL ELEMENTS 3.1 SCOPE Chapter 3 contains methodologies for determining the fire performance of large section timbers and wood structural elements. The procedure for determining the fire resistance of a heavy timber member is based on a mathematical model and on testing that demonstrated the intrinsic ability of larger wood members to sustain a structural load during severe fire exposure. The second part of this Ch
