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)

0.01350.72500.02680.02190.030919.34.8237.56.38
0.01800.94330.04060.03430.043524.26.0446.87.96
0.01800.94500.03850.03260.043036.69.1570.912.1
0.01800.94800.03760.03150.042643.510.984.414.3
0.02401.23330.05710.04760.057945.411.387.614.9
0.03001.53330.07100.06130.072273.518.414224.1
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)

0.01350.01800.01800.01800.02400.03000.01350.01800.01800.01800.02400.03000.01350.01800.01800.01800.02400.0300
Y.S.* (ksi)503350803333503350803333503350803333
2.0

2.0

S134134192223188234110113163187157202137142204234196253
D3755275225167018759001264125212391683210170999698697613251654
2.5

2.5

S868612314312115070731041201011298891131150126162
D1922702672643594484616476416348621076363510505500679847
3.0

3.0

S606085998410449507383709061639110487112
D111156155153208259267375371367499622210295292289393490
3.5

3.5

S444463736177363753615166454667766483
D70989796131163168236234231314392132186184182247309
4.0

4.0

S333448564759272841473951343551594963
D476665658810911215815615521026389124123122166207
4.5

4.5

S262638443746222232373140272840463950
D3346464562777911111010914818462878786116145
5.0

5.0

S212131363037181826302532222333373140
D243433334556588180791081344564636285106
5.5

5.5

S181825302531141522252127181927312633
D1825252534424361606081101344847476480
6.0

6.0

S151521252126121318211722151623262228
D142019192632334746466278263737364961
6.5

6.5

S131318211822101115181519131319221924
D111515152026263736364961212929283948
7.0

7.0

S1111161815199913151317111217191621
D91212121620212929293949172323233139
7.5

7.5

S1010141613178812131114101015171418
D71010101317172424233240131919192531
8.0

8.0

S881214121577101210139913151216
D68881114142020192633111615152126

* Y.S. = Yield Strength