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)

0.01801.04330.08470.08840.075458.014.511118.8
0.01801.04500.07780.08220.070787.822.016828.5
0.02401.36330.1280.1300.11410927.220735.2
0.03001.69330.1750.1760.15217644.033556.9
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)

0.01800.01800.02400.03000.01800.01800.02400.03000.01350.01800.02400.0300
Y.S.* (ksi)335033333350333333503333
4.0

4.0

S70971061447310310814591128134181
D114107173230274257414552216202326434
4.5

4.5

S55778411458818511572102106143
D8075121161192180291387152142229305
5.0

5.0

S4562689247666993588286116
D585588118140132212282110104167222
5.5

5.5

S375156763954577748687196
D44416688105991592128378125167
6.0

6.0

S314347643246486441576081
D343251688176123163646097129
6.5

6.5

S263740552839415535495169
D27254054646097129504776101
7.0

7.0

S233235472434354730424459
D2120324351487710340386181
7.5

7.5

S202830412129314126373852
D171626354239638433314966
8.0

8.0

S172426361826273623323445
D141322293432526927254154
8.5

8.5

S152223321623243220283040
D121118242927435722213445
9.0

9.0

S141921281420212918252736
D10915202423364819182938
9.5

9.5

S121719261318192616232432
D9813172019314116152432
10.0

10.0

S111617231216172315212229
D7711151816273514132128

* Y.S. = Yield Strength