Tables4 structural design for fire conditions
Steel Columns
PDF page 315 · AISC 360-22
11 tables appear under this heading.
1. PDF page 315
| Assembly | Item Number | Fire-Protection Material Used | Minimum Thickness of Insulating Material for Fire-Resistance Times, in. (mm) | |||
|---|---|---|---|---|---|---|
| 4 hrs | 3 hrs | 2 hrs | 1 hr | |||
| 1. Steel columns and all of primary trusses | 1-1.1 | Carbonate, lightweight, and sand-light-weight aggregate concrete, members 6 in. × 6 in. (150 mm × 150 mm) or greater (not including sandstone, granite, and siliceous gravel)[a] | 2½ (63) | 2 (50) | 1½ (38) | 1 (25) |
| 1-1.2 | Carbonate, lightweight, and sand-light-weight aggregate concrete, members 8 in. × 8 in. (200 mm × 200 mm) or greater (not including sandstone, granite, and siliceous gravel)[a] | 2 (50) | 1½ (38) | 1 (25) | 1 (25) | |
| 1-1.3 | Carbonate, lightweight, and sand-light-weight aggregate concrete, members 12 in. × 12 in. (300 mm × 300 mm) or greater (not including sandstone, granite, and siliceous gravel)[a] | 1½ (38) | 1 (25) | 1 (25) | 1 (25) | |
| 1-1.4 | Siliceous aggregate concrete and concrete excluded in Item 1-1.1, members 6 in. × 6 in. (150 mm × 150 mm) or greater[a] | 3 (75) | 2 (50) | 1½ (38) | 1 (25) | |
| 1-1.5 | Siliceous aggregate concrete and concrete excluded in Item 1-1.1, members 8 in. × 8 in. (200 mm × 200 mm) or greater[a] | 2½ (63) | 2 (50) | 1 (25) | 1 (25) | |
| 1-1.6 | Siliceous aggregate concrete and concrete excluded in Item 1-1.1, members 12 in. × 12 in. (300 mm × 300 mm) or greater[a] | 2 (50) | 1 (25) | 1 (25) | 1 (25) | |
| 1-2.1 | Clay or shale brick with brick and mortar fill[a] | 3¾ (94) | – | – | 2¼ (56) | |
| 1-4.1 | Cement plaster over metal lath wire tied to ¾ in. (19 mm) cold-rolled vertical channels with 0.049 in. (1.2 mm) (No. 18 B.W. Gage) wire ties spaced 3 to 6 in. (75 to 150 mm) on center; plaster mixed 1:2.5 by volume, cement to sand | – | – | 2½[b] (63)[b] | ⅞ (22) | |
2. PDF page 316
| Assembly | Item Number | Fire-Protection Material Used | Minimum Thickness of Insulating Material for Fire-Resistance Times, in. (mm) | |||
|---|---|---|---|---|---|---|
| 4 hrs | 3 hrs | 2 hrs | 1 hr | |||
| 1. Steel columns and all of primary trusses | 1-5.1 | Vermiculite concrete, 1:4 mix by volume over paperbacked wire fabric lath wrapped directly around column with additional 2 × 2 in. 0.065 / 0.065 in. (No. 16/16 B.W. Gage) (50 × 50 mm 1.7 / 1.7 mm) wire fabric placed ¾ in. (19 mm) from outer concrete surface; wire fabric tied with 0.049 in. (1.2 mm) (No. 18 B.W. Gage) wire spaced 6 in. (150 mm) on center for inner layer and 2 in. (50 mm) on center for outer layer | 2 (50) | – | – | – |
| 1-6.1 | Perlite or vermiculite gypsum plaster over metal lath wrapped around column and furred 1¼ in. (31 mm) from column flanges; sheets lapped at ends and tied at 6 in. (150 mm) intervals with 0.049 in. (1.2 mm) (No. 18 B.W. Gage) tie wire; plaster pushed through to flanges | 1½ (38) | 1 (25) | – | – | |
| 1-6.2 | Perlite or vermiculite gypsum plaster over self-furring metal lath wrapped directly around column, lapped 1 in. (25 mm) and tied at 6 in. (150 mm) intervals with 0.049 in. (1.2 mm) (No. 18 B.W. Gage) wire | 1¾ (44) | 1⅜ (35) | 1 (25) | – | |
| 1-6.3 | Perlite or vermiculite gypsum plaster on metal lath applied to ¾ in. (19 mm) cold-rolled channels spaced 24 in. (600 mm) apart vertically and wrapped flatwise around column | 1½ (38) | – | – | – | |
| 1-6.4 | Perlite or vermiculite gypsum plaster over two layers of ½ in. (13 mm) plain full-length gypsum lath applied tight to column flanges; lath wrapped with 1 in. (25 mm) hexagonal mesh of 0.035 in. (0.89 mm) (No. 20 Gage) wire and tied with doubled 0.049-in.- (1.2-mm-) diameter (No. 18 B.W. Gage) wire ties spaced 23 in. (580 mm) on center; for three-coat work, the plaster mix for the second coat shall not exceed 100 pounds (45 kg) of gypsum to 2.5 ft³ (0.071 m³) of aggregate for the 3 hour system | 2½ (63) | 2 (50) | – | – | |
3. PDF page 317
| Assembly | Item Number | Fire-Protection Material Used | Minimum Thickness of Insulating Material for Fire-Resistance Times, in. (mm) | |||
|---|---|---|---|---|---|---|
| 4 hrs | 3 hrs | 2 hrs | 1 hr | |||
| 1. Steel columns and all of primary trusses | 1-6.5 | Perlite or vermiculite gypsum plaster over one layer of 1/2 in. (13 mm) plain full-length gypsum lath applied tight to column flanges. Lath tied with doubled 0.049 in. (1.2 mm) (No. 18 B.W. Gage) wire ties spaced 23 in. (580 mm) on center and scratch coat wrapped with 1 in. (25 mm) hexagonal mesh 0.035 in. (0.89 mm) (No. 20 B.W. Gage) wire fabric; for three-coat work, the plaster mix for the second coat shall not exceed 100 pounds (45 kg) of gypsum to 2.5 ft3 (0.071 m3) of aggregate | – | 2 (50) | – | – |
| 1-7.1 | Multiple layers of 1/2 in. (13 mm) gypsum wallboard[c] adhesively[d] secured to column flanges and successive layers; wallboard applied without horizontal joints; corner edges of each layer staggered; wallboard layer below outer layer secured to column with doubled 0.049 in. (1.2 mm) (No. 18 B.W. Gage) steel wire ties spaced 15 in. (380 mm) on center; exposed corners taped and treated | – | – | 2 (50) | 1 (25) | |
| 1-7.2 | Three layers of 5/8 in. (16 mm) Type X gypsum wallboard;[c] first and second layer held in place by 1/8-in.-diameter by 13/8-in.-long (3-mm-diameter by 35-mm-long) ring shank nails with 5/16-in.- (8-mm-) diameter heads spaced 24 in. (600 mm) on center at corners; middle layer also secured with metal straps at mid-height and 18 in. (450 mm) from each end, and by metal corner bead at each corner held by the metal straps; third layer attached to corner bead with 1-in.- (25-mm-) long gypsum wallboard screws spaced 12 in. (300 mm) on center | – | – | 17/8 (47) | – | |
4. PDF page 318
| Assembly | Item Number | Fire-Protection Material Used | Minimum Thickness of Insulating Material for Fire- Resistance Times, in. (mm) | |||
|---|---|---|---|---|---|---|
| 4 hrs | 3 hrs | 2 hrs | 1 hr | |||
| 1. Steel columns and all of primary trusses | 1-7.3 | Three layers of 5/8 in. (16 mm) Type X gypsum wallboard,[c] each layer screw attached to 15/8 in. (41 mm) steel studs, 0.018 in. (0.46 mm) thick (No. 25 carbon sheet steel gage) at each corner of column; middle layer also secured with 0.049 in. (1.2 mm) (No. 18 B.W. Gage) double-strand steel wire ties, 24 in. (600 mm) on center; screws are No. 6 by 1 in. (25 mm) spaced 24 in. (600 mm) on center for inner layer, No. 6 by 15/8 in. (41 mm) spaced 12 in. (300 mm) on center for middle layer and No. 8 by 21/4 in. (56 mm) spaced 12 in. (300 mm) on center for outer layer | – | 17/8 (47) | – | – |
| 1-9.1 | Minimum W8×35 wide-flange steel column (W/D ≥ 0.75; W/D is the weight-to-heated perimeter ratio, where W = weight of shape and D = heated perimeter) with each web cavity filled even with the flange tip with normal weight carbonate or siliceous aggregate concrete, 3,000 psi specified compressive strength with 145 pcf ± 3 pcf unit weight (21 MPa specified compressive strength with 2 300 kg/m³ ± 48 kg/m³ unit weight). Reinforce the concrete in each web cavity with minimum No. 4 (13 mm) deformed reinforcing bar installed vertically and centered in the cavity, and secured to the column web with minimum No. 2 (6 mm) horizontal deformed reinforcing bar welded to the web every 18 in. (450 mm) on center vertically. As an alternative to the No. 4 (13 mm) rebar, 3/4-in.-diameter by 3-in.-long (19-mm-diameter by 75-mm-long) headed studs, spaced at 12 in. (300 mm) on center vertically, shall be welded on each side of the web midway between the column flanges. | – | – | – | See Note [f] | |
5. PDF page 319
| Assembly | Item Number | Fire-Protection Material Used | Minimum Thickness of Insulating Material for Fire-Resistance Times, in. (mm) | |||
|---|---|---|---|---|---|---|
| 4 hrs | 3 hrs | 2 hrs | 1 hr | |||
| 2. Webs or flanges of steel beams and girders | 2-1.1 | Carbonate, lightweight, and sand-light-weight aggregate concrete (not including sandstone, granite, and siliceous gravel) with 3 in. (75 mm) or finer metal mesh placed 1 in. (25 mm) from the finished surface anchored to the top flange and providing not less than 0.025 in.² of steel area per ft (53 mm²/m) in each direction | 2 (50) | 1½ (38) | 1 (25) | 1 (25) |
| 2-1.2 | Siliceous aggregate concrete and con-crete excluded in Item 2-1.1 with 3 in. (75 mm) or finer metal mesh placed 1 in. (25 mm) from the finished surface anchored to the top flange and providing not less than 0.025 in.² of steel area per ft (53 mm²/m) in each direction | 2½ (63) | 2 (50) | 1½ (38) | 1 (25) | |
| 2-2.1 | Cement plaster on metal lath attached to ¾ in. (19 mm) cold-rolled channels with 0.04 in. (1 mm) (No. 18 B.W. Gage) wire ties spaced 3 in. to 6 in. (75 mm to 150 mm) on center; plaster mixed 1:2.5 by volume, cement to sand | – | – | 2½[b] (63)[b] | ⅞ (22) | |
| 2-3.1 | Vermiculite gypsum plaster on a metal lath cage, wire tied to 0.165 in. (4.2 mm) diameter (No. 8 B.W. Gage) steel wire hangers wrapped around beam and spaced 16 in. (400 mm) on center; metal lath ties spaced approximately 5 in. (125 mm) on center at cage sides and bottom | – | ⅞ (22) | – | – | |
6. PDF page 320
| Assembly | Item Number | Fire-Protection Material Used | Minimum Thickness of Insulating Material for Fire-Resistance Times, in. (mm) | |||
|---|---|---|---|---|---|---|
| 4 hrs | 3 hrs | 2 hrs | 1 hr | |||
| 2. Webs or flanges of steel beams and girders | 2-4.1 | Two layers of 5/8 in. (16 mm) Type X gypsum wallboard[c] are attached to U-shaped brackets spaced 24 in. (600 mm) on center. 0.018-in.- (0.46-mm-) thick (No. 25 carbon sheet steel gage), 15/8-in.-deep by 1 in. (41-mm-deep by 25 mm) galvanized steel runner channels are first installed parallel to and on each side of the top beam flange to provide a 1/2 in. (13 mm) clearance to the flange. The channel runners are attached to steel deck or concrete floor con- struction with approved fasteners spaced 12 in. (300 mm) on center. U-shaped brackets are formed from members identical to the chan- nel runners. At the bent portion of the U-shaped bracket, the flanges of the channel are cut out so that 15/8-in.- (41-mm-) deep corner channels can be inserted without attachment parallel to each side of the lower flange. As an alternative, 0.021 in. (0.53 mm) thick (No. 24 carbon sheet steel gage) 1 in. × 2 in. (25 mm × 50 mm) runner and corner angles shall be used in lieu of channels, and the web cutouts in the U-shaped brackets shall not be required. Each angle is attached to the bracket with 1/2-in.- (13-mm-) long, No. 8, self-drilling screws. The vertical legs of the U-shaped bracket are attached to the runners with one 1/2-in.- (13-mm-) long, No. 8, self-drilling screw. The completed steel framing provides a 21/8 in. (53 mm) and 11/2 in. (38 mm) space between the inner layer of wallboard and the sides and bot- tom of the steel beam, respectively. The inner layer of wallboard is attached to the top runners and bottom corner channels or corner angles with 11/4-in.- (31-mm-) long, No. 6, self-drilling screws spaced 16 in. (400 mm) on center. The outer layer of wallboard is applied with 13/4-in.- (44-mm-) long, No. 6, self-drilling screws spaced 8 in. (200 mm) on center. The bottom corners are reinforced with metal corner beads. | – | – | 11/4 (31) | – |
7. PDF page 321
| Assembly | Item Number | Fire-Protection Material Used | Minimum Thickness of Insulating Material for Fire-Resistance Times, in. (mm) | |||
|---|---|---|---|---|---|---|
| 4 hrs | 3 hrs | 2 hrs | 1 hr | |||
| 2. Webs or flanges of steel beams and girders | 2-4.2 | Three layers of 5/8 in. (16 mm) Type X gypsum wallboard[c] attached to a steel suspension system as described in Item 2-4.1 utilizing the 0.018-in.- (0.46-mm-) thick (No. 25 carbon sheet steel gage), 1 in. × 2 in. (25 mm x 50 mm), lower corner angles. The framing is located so that a 21/8 in. (53 mm) and 2 in. (50 mm) space is provided between the inner layer of wallboard and the sides and bottom of the beam, respectively. The first two layers of wallboard are attached as described in Item 2-4.1. A layer of 0.035-in.- (0.89-mm-) thick (No. 20 B.W. Gage), 1 in. (25 mm) hexagonal, galvanized wire mesh is applied under the soffit of the middle layer and up the sides approximately 2 in. (50 mm). The mesh is held in posi- tion with the No. 6 15/8-in.- (41-mm-) long screws installed in the vertical leg of the bottom corner angles. The outer layer of wallboard is attached with No. 6 21/4-in.- (56-mm-) long screws spaced 8 in. (200 mm) on center. One screw is also installed at the mid-depth of the bracket in each layer. Bottom corners are finished as described in Item 2-4.1. | – | 17/8 (47) | – | – |
8. PDF page 322
| W'/D = W/D + 50h/144 | (A-4-25) |
| W'/D = W/D + 0.0008h | (A-4-25M) |
9. PDF page 323
| C1, C2, C3, and C4 = material-dependent constants prescribed in specified rated assembly | |
| D | = heated perimeter of the column, in. (mm) |
| R | = fire resistance, min |
| W | = weight of columns, lb/ft (kg/m) |
| h | = thickness of sprayed fire-resistant material, in. (mm) |
10. PDF page 327
| Property | Normal Weight Concrete | Lightweight Concrete |
|---|---|---|
| Thermal conductivity, Kc | 0.95 Btu/hr-ft-°F (1.64 W/m-K) | 0.35 Btu/hr-ft-°F (0.61 W/m-K) |
| Specific heat, cc | 0.20 Btu/lb-°F (0.840 kJ/kg-K) | 0.20 Btu/lb-°F (0.840 kJ/kg-K) |
| Density, pc | 145 lb/ft3 (2 300 kg/m3) | 110 lb/ft3 (1 800 kg/m3) |
| Equilibrium (free) moisture content, m, by volume | 4% | 5% |
11. PDF page 327
| Unit Density, dm, lb/ft3 (kg/m3) | Unit Thermal Conductivity Kc, Btu/hr-ft-°F (W/m-K) |
|---|---|
| Concrete Masonry Units | |
| 80 (1 300) | 0.207 (0.36) |
| 85 (1 400) | 0.228 (0.40) |
| 90 (1 400) | 0.252 (0.44) |
| 95 (1 500) | 0.278 (0.48) |
| 100 (1 600) | 0.308 (0.53) |
| 105 (1 700) | 0.340 (0.59) |
| 110 (1 800) | 0.376 (0.65) |
| 115 (1 800) | 0.416 (0.72) |
| 120 (1 900) | 0.459 (0.80) |
| 125 (2 000) | 0.508 (0.88) |
| 130 (2 100) | 0.561 (0.97) |
| 135 (2 200) | 0.620 (1.1) |
| 140 (2 200) | 0.685 (1.2) |
| 145 (2 300) | 0.758 (1.3) |
| 150 (2 400) | 0.837 (1.5) |
| Clay Masonry Units | |
| 120 (1 900) | 1.25 (2.2) |
| 130 (2 100) | 2.25 (3.9) |