General – Presented in the load tables are maximum uniformly distributed specified loads.

Steel – Conforms to ASTM A653/A653M or A792/A792M. Grade 33/230; Yield stress 33 ksi/230 MPa and tensile stress 45 ksi/310 MPa. Grade 50 /345; Yield stress 50 ksi/345 MPa and tensile
stress 65 ksi/450 MPa; Grade 80 /550; Yield stress 80 ksi/550 MPa and tensile stress 82 ksi/565 MPa.

Finishes – A25/ZF75, G90/Z275 or AZ50/AZM150. For heavier metallic coatings, refer to ASTM A653/A653M or A792/A792M.

Load Tables – The following information regarding the determination of the specified wind and snow loads is contained in the 2010 Edition of the National Building Code of Canada (NBCC). Importance factors are applied to both strength (ULS) and serviceability/deflection (SLS) limit state design considerations. A lower load factor for wind of 1.4, instead of 1.5 for live and snow loads, is now being used. This lower load factor for wind somewhat offsets the higher wind loads (1 in 50 year return) that are now listed in the NBCC by geographic location. The importance  category of the end use of the building/structure must also be recognized, such as Normal or Low.

All of this will impact how the load tables are to be used. In an effort to help the design professional with the load tables, the information below was taken directly from Division B, Part 4 (Structural Design) of the NBCC.

Specified Wind Load

W = Iw qCeCgCp

Importance Category Importance Factor, Iw
ULS SLS
Low 0.8 0.75
Normal 1.0 0.75
High 1.15 0.75
Post-Disaster 1.25 0.75

Specified Snow Load

S = Is [Ss (Cb Cw Cs Ca) + Sr]

Importance Category Importance Factor, Iw
ULS SLS
Low 0.8 0.9
Normal 1.0 0.9
High 1.15 0.9
Post-Disaster 1.25 0.9

The importance factors, Iw and Is, have been incorporated in the load tables, as well as the importance category. The parameters in the boxed-in portion of Equations [1] and [2] must be determined by the design professional in accordance with the NBCC.

Strength – The maximum uniformly distributed specified load based on strength in the load table must be equal to or greater than the specified live load.

Serviceability (Deflection) – The maximum uniformly distributed specified load based on deflection in the load table must be equal to or greater than the specified live load. The effective
moment of inertia for deflection determination was calculated at an assumed specified live load stress of 0.6Fy.

EXAMPLE (Use of Load Table)

Deckmate Roof (Normal Importance Category)
Given: (Imperial units)
(LLF = 1.5 and Is = 0.9)
~ Deck thickness, t = 0.024 in
~ Triple span continuous, L = 6.0 ft each span
~ Bearing length, N = 3 in
~ L/240 deflection limit
~ Specified Loads

1) Dead load (DL)

a) Deck 1.36 psf

b) Superimposed 9.50 psf; DL = 10.86 psf

2) Snow Live load (LL) LL = 40 psf
The live load is the value of the boxed-in portion of the specified snow load expression [2].
Solution:
Strength “S”
1) Specified load [LL +0.833DL] = 49.0 psf
2) Maximum specified load (from Load Table)
Is 59 psf

Since 59 > 49.0 … OK

3) Check web crippling (N = 3 in)
a) End reaction = 0.400(49.0)6 = 118 lb/ft (from section property table)

Pe = Pe1 + Pe2 [N/t]1/2= 102 + 25.5[3/0.024]1/2 = 387 lb/ft
Since 387 > 118 … OK

b) Interior reaction = 1.10(49.0)6 = 323 lb/ft
(from section property table)
Pi = Pi1 + Pi2 [N/t]1/2= 197 + 33.4[3/0.024]1/2 = 570 lb/ft
Since 570 > 323 … OK

Deflection “D”
From table L/180 = 113 psf
For L/240, multiply 113 by 180/240 = 84.8 psf
Since 84.8 > 40 … OK

  1. Based on ASTM A 653 structural
  2. Values in row “S” are based on
  3. Values in row “D” are based on deflection of 1/180th
  4. Web crippling not included in strength See example.
  5. Limit States Design principles were used in accordance with CSA Standard S136-12

SECTION PROPERTIES | Per Foot of Width
Base Steel Thickness (inches) Weight [G90] (psf) Yield Stress (ksi) Section Modulus Deflection Moment of Inertia (in4) Specified Web Crippling Data
Midspan

(in3)

 Support

(in3)

 Pe1

End (lb)

 Pe2

End (lb)

 Pi1

Interior (lb)

 Pi1

Interior (lb)
0.0135 0.72 50 0.0268 0.0219 0.0309 19.3 4.82 37.5 6.38
0.0180 0.94 33 0.0406 0.0343 0.0435 24.2 6.04 46.8 7.96
0.0180 0.94 50 0.0385 0.0326 0.0430 36.6 9.15 70.9 12.1
0.0180 0.94 80 0.0376 0.0315 0.0426 43.5 10.9 84.4 14.3
0.0240 1.23 33 0.0571 0.0476 0.0579 45.4 11.3 87.6 14.9
0.0300 1.53 33 0.0710 0.0613 0.0722 73.5 18.4 142 24.1
LLF = 1.50; IMPF = 0.90; NORMAL OCCUPANCY = 1.0
LOAD TABLE | Maximum Uniformly Distributed Specified Loads (psf).
Span Length (ft) 1-Span

Base Steel Thickness (inches)

 2-Span

Base Steel Thickness (inches)

 3-Span

Base Steel Thickness (inches)
0.0135 0.0180 0.0180 0.0180 0.0240 0.0300 0.0135 0.0180 0.0180 0.0180 0.0240 0.0300 0.0135 0.0180 0.0180 0.0180 0.0240 0.0300
Y.S.* (ksi) 50 33 50 80 33 33 50 33 50 80 33 33 50 33 50 80 33 33
2.0

2.0

 S 134 134 192 223 188 234 110 113 163 187 157 202 137 142 204 234 196 253
D 375 527 522 516 701 875 900 1264 1252 1239 1683 2101 709 996 986 976 1325 1654
2.5

2.5

 S 86 86 123 143 121 150 70 73 104 120 101 129 88 91 131 150 126 162
D 192 270 267 264 359 448 461 647 641 634 862 1076 363 510 505 500 679 847
3.0

3.0

 S 60 60 85 99 84 104 49 50 73 83 70 90 61 63 91 104 87 112
D 111 156 155 153 208 259 267 375 371 367 499 622 210 295 292 289 393 490
3.5

3.5

 S 44 44 63 73 61 77 36 37 53 61 51 66 45 46 67 76 64 83
D 70 98 97 96 131 163 168 236 234 231 314 392 132 186 184 182 247 309
4.0

4.0

 S 33 34 48 56 47 59 27 28 41 47 39 51 34 35 51 59 49 63
D 47 66 65 65 88 109 112 158 156 155 210 263 89 124 123 122 166 207
4.5

4.5

 S 26 26 38 44 37 46 22 22 32 37 31 40 27 28 40 46 39 50
D 33 46 46 45 62 77 79 111 110 109 148 184 62 87 87 86 116 145
5.0

5.0

 S 21 21 31 36 30 37 18 18 26 30 25 32 22 23 33 37 31 40
D 24 34 33 33 45 56 58 81 80 79 108 134 45 64 63 62 85 106
5.5

5.5

 S 18 18 25 30 25 31 14 15 22 25 21 27 18 19 27 31 26 33
D 18 25 25 25 34 42 43 61 60 60 81 101 34 48 47 47 64 80
6.0

6.0

 S 15 15 21 25 21 26 12 13 18 21 17 22 15 16 23 26 22 28
D 14 20 19 19 26 32 33 47 46 46 62 78 26 37 37 36 49 61
6.5

6.5

 S 13 13 18 21 18 22 10 11 15 18 15 19 13 13 19 22 19 24
D 11 15 15 15 20 26 26 37 36 36 49 61 21 29 29 28 39 48
7.0

7.0

 S 11 11 16 18 15 19 9 9 13 15 13 17 11 12 17 19 16 21
D 9 12 12 12 16 20 21 29 29 29 39 49 17 23 23 23 31 39
7.5

7.5

 S 10 10 14 16 13 17 8 8 12 13 11 14 10 10 15 17 14 18
D 7 10 10 10 13 17 17 24 24 23 32 40 13 19 19 19 25 31
8.0

8.0

 S 8 8 12 14 12 15 7 7 10 12 10 13 9 9 13 15 12 16
D 6 8 8 8 11 14 14 20 20 19 26 33 11 16 15 15 21 26

* Y.S. = Yield Strength