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 CategoryImportance Factor, Iw
ULSSLS
Low0.80.75
Normal1.00.75
High1.150.75
Post-Disaster1.250.75

Specified Snow Load

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

Importance CategoryImportance Factor, Iw
ULSSLS
Low0.80.9
Normal1.00.9
High1.150.9
Post-Disaster1.250.9

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 ModulusDeflection Moment of Inertia (in4)Specified Web Crippling Data
Midspan

(in3)

Support

(in3)

Pe1

End (lb)

Pe2

End (lb)

Pi1

Interior (lb)

Pi1

Interior (lb)

0.01801.04330.09420.08920.098854.113.510517.9
0.01801.04500.08860.08220.096182.020.515927.1
0.02401.36330.1360.1290.13310225.519733.4
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)

0.01800.01800.02400.01800.01800.02400.01800.01800.0240
Y.S.* (ksi)335033335033335033
3.0

3.0

S138197200131183189164228237
D3553454778518281145670652902
3.5

3.5

S10214514796134139120168174
D223217301536521721422411568
4.0

4.0

S781111127410310692128133
D150146201359349483283275381
4.5

4.5

S61888958818473101105
D105102141252245339199193267
5.0

5.0

S507172476668598285
D7775103184179247145141195
5.5

5.5

S415959395456496870
D585677138134186109106146
6.0

6.0

S354950334647415759
D4443601061031438481113
6.5

6.5

S294243283940354950
D3534478481113666489
7.0

7.0

S253637243435304243
D282738676590535171
7.5

7.5

S223232212930263738
D232231545373434258
8.0

8.0

S192828182627233233
D191825454460353448
8.5

8.5

S172525162324202829
D161521373650292940
9.0

9.0

S152222152021182526
D131318323142252433
9.5

9.5

S142020131819162324
D111115272636212128
10.0

10.0

S121818121617152121
D10913232231181824

* Y.S. = Yield Strength