Canadian Steel Codes IP 10-5

8/13/2019 Canadian Steel Codes IP 10-5

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Codes and Standards

Steel-Reuse Information Paper No.4

FACILITATING GREATER REUSE AND RECYCLING OF STRUCTURAL STEEL IN THE CONSTRUCTION AND DEMOLITION PROCESS

Action Plan 2000on Climate Change

www.reuse-steel.org


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APPENDIX: Research notes

Structural steel standards

C.E.S.A. S16-1935 – Steel Structures for Buildings until 1948

Composite construction allowed – Type-A and Type-B

C.E.S.A.-S39: Mild structural steel

C.E.S.A.-S40: Medium structural steel

Table 3 Steel Properties. (from C.E.S.A. S16 – 1935)

ElongationSteel type Chemical Analysis

Yield stress(psi)

Tensilestrength(psi) 8” gauge (%) 2” gauge (%)

Mild

P acid 0.06

P basic 0.04

S 0.05

Medium

Cu 0.20

33,000min 0.5 oftensile strength

60,000 –72,000

1.5E6/(tensilestrength)

22

Standards Material Properties after 1950:

CSA-G 40-1: General requirements for delivery of rolled steel plates, shapes and bars for structural use

CSA-G 40-2: Structural steel rivets

CSA-G 40-3: Mild structural steel

CSA-G 40-4: Medium structural steel

CSA-G 40-5: Carbon steel plates of structural quality, plates 2” and under in thickness

CSA-G 40-6: Structural silicon steel

General notes:

• All revised and reissued in 1959; G40-1 reissued in 1959 and last revised in 1963• G40-1 1959 has section headings• Ladle analysis of molten steel from each heat of open-hearth or electric furnace is required by the

Manufacturer to determine the percentage of carbon, manganese, phosphorous (P) and sulphur(S); of copper when copper (Cu) steel specifies; any other elements specified or restricted by theapplicable specifications.

• Check analysis by the purchaser


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• Manufacturing process: open hearth or electric furnace; basic oxygen process added in 1959• Marking of steel required, typically of each piece but how to be done is vague (die stamp is referred

to for plates).

• Tensile test and bend test (cold steel bent through 180°without cracking on outside; ratio of insidediameter to thickness specified) are prescribed; two of each per each heat. Speed of loading forloads over one half of the yield is defined. The test specimen is either flat bar 9” long (8” gaugelength) of actual material thickness or greater thickness than 1.5” when ¾” thickness can be usedor 2.5” long (2” gauge length) rod test can be done.

• G40.3-1959: Structural Steel for Locomotives and Cars – change from mild steel previously used.• G40.7-1959: Steel Sheet Piling introduced.

Table 4 Steel Properties. (from G40 series 1959)

ElongationSteel type Chemical* Analysis

Yield stress(psi)


P acid 0.06P basic 0.04

S 0.05

Mild

Cu 0.20

27,000 50,000 –62,000

24 27

P acid 0.06

P basic 0.04

S 0.05

Medium

Cu 0.20

33,000 60,000 –72,000

21 22

P acid 0.06 Grade A 24,000 45 – 55,000 27 30

P basic 0.04 Grade B 27,000 50 – 60,000 25 27S 0.05 Grade C 30,000 55 – 65,000 23 25

Carbonplates

Cu 0.20 Grade D 33,000 60 – 72,000 21 22

C 0.40

P acid 0.06

P basic 0.04

S 0.05

Siliconsteel

Silicon 0.2

45,000 80,000 –95,000

16 17

* Based on ladle analysis

• G40.3-1959, Structural steel for locomotives and cars• G40.5-1959, Low and Intermediate tensile strength carbon steel plates of structural quality. Plates

2inches and under in thickness


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CSA G40.1-1966: General requirements for delivery o f steel plates, shapes, sheet pi ling and bars,for structural use

Major differences in comparison with 1959 edition:

• Number of tests required is more precisely defined if there is a variation in tests from differentheats or when the product size is less than 50 tons.

• It deals more elaborately with steel marking, especially for rolled sections which should be hot diestamped or embossed along the length of the web section of each piece or cold die stamped at oneend of the web section of each piece. Remarking is required of all unmarked pieces removed frombundles and pieces cut from marked pieces. Colour marking is introduced (reference to ASTM

A36).

CSA G40.8-1960: Structural steels with improved resistance to brittle fracture

This standard introduced three different grades of steel, namely A, B and C with the same strength butdifferent chemical composition and different impact tests results (Grade A suitable for above zero Fconditions, B for moderate cold temperatures and C for severe cold temperatures -25F to -60F). Themaximum thickness of material covered by this Standard is 1.5 inches. The minimum yield strength is40,000 psi for thicknesses up to 5/8” (38,000 psi for thickness between 5/8” and 1” and 36,000 psi for over1” thickness). The tensile strength for all grades is between 65,000 and 85,000 psi. The thickness isrelated to web thickness for rolled sections. The minimum elongation in 8 inches is 20%. Marking of steelshould be in accordance with G40.1 with colour marking as follows:

• Grade A: primary white plus secondary red• Grade B: white• Grade C: primary white plus secondary yellow• Welding for surface repair should be done using low hydrogen electrodes E60XX or E70XX.

CSA G40.12-1964: General purpose steel

This new standard covers steel plates, shapes and bars used for riveted, bolted or welded connections inthe structural field. It covers materials up to 2.5 inches thick. Steel can be manufactured by either openhearth, electric furnace, or the basic oxygen process, with material over 1.5 inches thick required to bemade using a fine grain steelmaking practice.

Table 5 Steel composition. (from G40.12)

ElongationSteel type Chemical* Analysis Max.

Yield stress(psi)


C 0.22 (0.25)

P 0.04 (0.05)

S 0.05 (0.06)M 1.50 (1.55)

GeneralPurpose

StructuralSteel

Si+ 0.15-0.30(0.13-0.33)

44,000(40,000 forthickness >1.5”

62,000 20 23 forthicknesses>1.5”

* First value is from ladle analysis; value in the bracket from check analysis.+ Applies to material over 7/8” thick.


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Colour identifying this steel is green.

CSA G40 series - 1971

G40.3, originally mild structural steel is not included.

G40.4-1959 and subsequently revised is referenced here. No change in properties from 1950 versionexcept in chemical composition acid and basic phosphorus is deleted and replaced by the maximumpercentage of phosphorus of 0.040 from ladle analysis and 0.050 from check analysis. The colour markingfor this steel is orange.

G40.6 is withdrawn

Structural shapes were required to be embossed at intervals along the length of each structural memberwith the producer’s name or brand. Color marking scheme introduced.

CSA G40.20-1973: General requirements fo r rol led or welded structural quali ty steel

This new standard defines products and processes, chemical composition, testing (types, specimens,method and frequency), defects, tolerances and their repair and markings. It applies to all types of steelsdescribed in G40.21-1973. Section 15 deals with welded shapes which in turn refers to CSA W59.1 forwelding specification.

CSA G40.21-1973: Structural quality s teels

This is a new standard dealing with six types of structural quality plates, shapes, and bars for generalconstruction and engineering purposes. It is to be used in conjunction with G40.20-1973, Generalrequirements for rolled or welded structural quality steel. Standards G40.4-1959, G40.5-1959, G40.7-1959and G40.8-1971 are referred to in this standard. It introduces different type of steel as described below:

• Type G – General Construction Steel: meets the minimum strength, chemical composition may notmeet welding under normal field condition or controlled shop conditions. Bolted application.

• Type W – Weldable Steels: meet the minimum strength requirements. Suitable for weldedconstruction where notch toughness at low temperature is not of a prime importance. Application inbuildings, compression members of bridges.

• Type T – Weldable Low Temperature Steels: used where the notch toughness at low temperatureis a prime consideration, eg. Tension members of bridges.

• Type R – Atmospheric Corrosion Resistant Structural Steel: these steels have corrosion resistance4-times of regular carbon steels. Copper content not exceeding 0.02 percent. Suitable for exposed,unpainted application. Weldable, similar to type W.

• Type A - Atmospheric Corrosion Resistant Structural Steel with Improved Low TemperatureProperties: similar to type R but has an improved notch toughness at low temperature.

• Type Q – Quenched and Tempered Low Alloy Steel Plate: exhibits a very high yield strength andgood resistance to brittle fracture. May be weldable, but caution should be exercised so that theheat affected zone does not impact adversely its properties. Application in bridges.


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Table 6 Steel types and grades (reproduced form G40.21- 1973.)

Yield Strength, KsiType

33 38 42 44 50 55 60 70 100

G 33G 50G 60G

W 33W 38W 42W* 44W 50W 55W* 60W 70WT 38T 44T 50T 55T* 60T 70T

R 50R

A 50A 60A

Q 100Q

* Available in hollow sections only.

Plates, bars and structural shapes are available in all grades except 42, 55 and 100. The chemicalcomposition and tensile strength tests are conducted on all type. In addition to these tests, grades T,A andQ have impact tests and grain size tests. The steel manufacturing process is one of the following, basicopen hearth, basic electric furnace or basic oxygen process. Special delivery conditions such as stress

relieved, annealed, normalized can be specified. Chemical and mechanical properties are given. Theappendix contains the table of equivalencies with ASTM, BS and ISO.

CSA G40.20-1976: General requirements fo r rol led or welded structural quali ty steel

This is a new edited version of 1973 standard. The references, text and tables revised but there are nosignificant differences in comparison with the previous standard. Amended in 1979 and 1980.


There are no changes to types but grade 42 was eliminated and grade 33 is only available for type G andintroduces grade 70A. Revisions published in1980.

CSA G40.20-M1978: General requirements for rolled or welded st ructural quality s teel (SI units)

This is a new edition of CSA G40.20-1976 which is in metric units.


This is a new addition of CSA G40.20-1976 which is in metric units.

CAN3-G40.20-M81: General requirements for ro lled or welded structural quality steel

This is the second edition of this Standard published originally in1978. Revised and re-published in1987and 1992.

CAN3- G40.21-M81: Structural quali ty steels

This is the second metric edition of this standard. It includes revisions to the imperial version of thestandard. Revised and re-published in 1987and 1992.

CAN/CSA G40.20-87, General Requirements for Rolled or Welded Structural Qualit y Steel

This is the third edition of this standard which was originally published in 1973. It includes all amendmentspublished so far as well as amendments approved but not released. This Standard is in imperial units.


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CSA G40.20/G40.21-98: General requirements for rolled or welded structural quality steel/ struc turalquality steel

CSA G40.20/G40.21-04: General requirements for rolled or welded structural quality steel/ struc turalquality steel

CAN/CSA-S6-00: Canadian highway bridge code

Section 14.6 deals with the strength determination of existing bridge structures. According to this clause,the material strength can be determined adopting one of the following methods:

1. Review of original structural drawings and documents (the specified minimum yield strength ofsteel, compressive strength of concrete, yield strength of reinforcement). The values of yieldstrength from mill certificates should not be used but the guaranteed minimum strength for the steelspecified should be used.

2. Test of samples from the bridge or its components. Samples should not compromise the structuralstability, or integrity of the member. Location of each sample and its orientation should be recorded

and any other information which may be useful when interpreting the test results. The test resultsshould be evaluated and converted to the nominal material strength using A14.1 or other Approvedmethod. See below.

3. Estimation by considering the date of construction. In the absence of more specific information, S6recommends the use of the following values:

Table 7 Default steel strength values (from CAN/CSA-S6-00)

Date of bridge construct ion SpecifiedFy, MPa

SpecifiedFu, MPa

Before 19051905 – 1932

1933 – 1975 After 1975

180210

230250

360420

420420

4. Other approved methods.Equivalent material strength f rom tests

Testing in accordance with CAN/ CSA-G40.20-M. At least three specimens should be tested. The yieldstrength is recorded for each test; if the coupon was taken from the flange, then its yield strength cam beincreased by a factor of 1.05.

f y = (f y average – 28)exp(-1.3ksV), wheref y is yield strength to be used in the design check

f y average is the average yield stress from the tests

V is the coefficient of variation

ks is the modification factor for coefficient of variation depend on number of strength tests n (see Table 8below)


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Table 8 Coefficient of Variation Modification Factors ks (from CAN/CSA-S6-00)

n ks

3 3.46

4 2.34

5 1.926 1.69

8 1.45

10 1.32

12 1.24

16 1.14

20 1.08

25 1.03

30 or more 1.00

Resistance of steel members:

There is an Adjustment Factor U which modifies the material factor. U varies from 1.00 for flexure, to 0.87for shear, 1.01 for tension and compression, 1.27 for bolts and 1.32 for welds.

National Bu ilding Codes

First National Building Code, 1941

The NBC 1941 requires that the alteration and repair of an existing building in access of 50% of theassessed value must bring the entire building to its requirements for new construction.

Change in the use of an existing building results in the need for entire building to comply with therequirements for new construction. The exemption applies to change in occupancy for which it can bedemonstrated that the existing structure is capable of supporting new occupancy with loading described inSection 3.6. If only portion of a building has a change in occupancy, only that part of the building must bebrought to the codes standards, provided there is a separation between the tow parts.

Additions greater than 50% of the area of the existing building must have fire separation complying with a“special occupancy separation’ (cl. 4.2.3.3) unless the existing building, addition and alterations are incompliance with the new code.

Structural alteration shall be made to conform to the standards for new buildings. But the extent of suchwork is to be determined by the authority having jurisdiction.

New materials and methods of construction are permitted provided their suitability and working stressesdetermined by a publicly owned or recognized laboratory are approved by authority having jurisdiction.

Steel

Medium structural steel conforms to C.E.S.A. S40-1935

Mild structural steel conforms to C.E.S.A. S39-1935


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Special steels conform to specifications approved by the authority having jurisdiction

Unidentified structural steel is required to be tested by an approved laboratory in accordance with A.S.T.M.Standard E8-40T, Method of Tension Testing of Metallic Materials.

Mild steel: the unit working stress permitted shall be 90% of those permitted for Medium Structural Steel.

Unidentified structural steel: the unit working stress shall not exceed 6/10 of the yield point stressdetermined in accordance with A.S.T.M. Standard E8-40T, but in no case shall the stresses exceed thosefor mild structural steel.

Loading

Floor loads: (in pounds per square foot)

Sleeping rooms or domestic rooms 40

Office 50

Corridors in hotels, hospitals 50

Corridors in public buildings 100

Assembly halls with fixed seating 60

Public spaces, dance halls, grandstands 100

Retail shops and stores 100

Wholesale shops and stores 125

Factories 125

Garages for passenger cars 75

Garages for trucks and busses 150

Sidewalks, driveways 250

Reduction of live load:

Beams and girders: 15% when area supported by a member exceeds 200 square feet

Columns, piers, walls, and foundation: the percentage reduction given in Table 1 (Section 3.6) and it isrelated to area supported (indirectly as the table deals with number of floors) and type of loading.

Combination of wind and live load: for consideration of stresses in a structure and on the foundation from acombination of dead, live and wind, the assumed live load on floors can be reduced by one-half, providedthe stresses or bearing pressure are not less than those resulting from a combination of dead and live

loads.Ceiling load: 10 psf; ceiling joists must be able to support this load

Snow load L:

Roof with slope 20° or less shall be designed for snow load of 20 to 40 psf depending on the location.

L = S + R,


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Where: L is snow load

S is sum of average snow falls in January, February and March, in inches over number of years

R is sum of average rain falls in January, February and March, in inches over number of years

L (in) Live load due to snow (psf)

Less than 20 20

20 – 30 30

More than 30 40

Roofs with slopes in excess of 20°, shall be designed for snow load L1

L1= L [1- 0.023 (α – 20)]

Minimum total load on roof member for slopes less than 20° and area less than 500 sqft shall be designedfor 50 psf (wind + snow) but excluding wind.

Wind loads:

On vertical surfaces:

Wind pressure: 0 to 300 ft 20 psf

Over 300 ft increase by 0.025 lb/ft of height

On plane sloping roofs (slopes both ways from the ridge)

Windward face: measured normal to the plane of the roof

20° or less -12psf

20° to 30° (1.2α – 36)30° to 40° (0.3α – 9)

60° 9

Leeward face: suction of 9 psf

Allowance for internal pressures or suctions:

In normally enclosed buildings with percentage of openings n:

Normal suction: (4.5 + 0.15n), or 9 psf, whichever is less

Normal pressure: (4.5 + 0.25n), or 12 psf whichever is less

For structures having open sides, e.g., grandstands

Open side facing the wind: a pressure 12 psf

Close side facing the wind: a suction 9 psf


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Earthquake loads:

The design provisions for every structure located in a region where destructive earthquake is probable (St.Lawrence basin- major shocks and elsewhere in Canada –ref. “Seismology in Canada” Canada Year Book,1938, pp.27-29):

F is a horizontal force applied at structures’ centre of gravityW is the total dead load

C is a constant depends on the soil conditions at the location

C = 0.02, where soil allowable pressure more than 2000 psf

C = 0.04, where soil allowable pressure less than 2000 psf

For components: C = 0.25 for cantilevered parapets, walls, ornamentation, appendages

C= 0.05 for bearing walls, curtain walls, enclosure walls, panel walls.

The NBC 1953

This code is set up a set of by-law requirements.

This code has climatic information which includes winter design temperatures (based on 2.5 % - i.e., 2.5%of temperatures fall below the listed value), mean annual total degree-days, min. January temperature, 15minute rainfall, mean annual precipitation, maximum snow load on a horizontal surface, computedmaximum gust speed, winter wind directions, earthquake probability.

New materials and methods of construction are permitted provided their suitability and working stressesdetermined by a publicly owned or recognized laboratory are approved by authority having jurisdiction.

Loads:

The minimum loads are given.

Occupancy loads:

No change from the previous code; see Table 3.2.

Snow load:

Roof with slope 20° or less shall be designed for the uniformly distributed snow load L obtained from Chart8, Part 2 of this NBC.

For roofs with a slope x greater than 20, the snow load L1shall be determined as follows:

L1= L [1- 0.0233 (x – 20)]

The code suggests that loads in excess of those given may occur, where the following conditions arepresent, the shape, differences in roof levels, insulating qualities or orientation of a building or proximity toother buildings. No provisions for snow accumulation given.

Rain:

Load resulting from 24 hour rain accumulation on the roof should be used.


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Wind:

Structures of buildings less than 50 ft in height and where adequate transverse shear resistance is providedby walls or bracing members to which wind load is transferred by floor or roof diaphragm do not need to bedesigned for wind if approved.

Calculation of wind load P:p = 0.00256 Cs (Ch V30)2 , { or = Cs(p) where p is from Table 4.1.A.1} where

Cs is coefficient consisting of the sum of appropriate coefficient from Table 4.1.1 together withappropriate internal pressure factors.

Ch is velocity height coefficient, Ch= (Hh/H30)1/7 for h up to 1000 ft.

Internal pressures coefficient:

One side open: + 0.5

Normal air infiltration: + 0.2

Wind overturning moment shall not exceed 75% of the moment of stability resulting from the dead load ofthe building, unless the building or structure is anchored to resist the excess overturning moment.

Earthquake

In earthquake zones (see Chart 11 of Part 2) all buildings with the exception of non-combustibleconstruction Group C Division 2 – One- or two-family dwellings must be designed to resist the horizontalforce F applied in a horizontal direction at each floor or roof level.

F = CW,

Where: C is the numerical constant from Table 4.1.2

C = 0.15/ (N + 4.5), where N is number of storeys

There were three zones assigned:

Zone 1 C

Zone 2 2C

Zone 3 4C

W is the total dead load (live load should be included for warehouses and storage tanks).

Steel

Structural steel is to conform to CSA G40.4. “Mill test reports properly correlated to the materials shallconstitute sufficient identity of any material as to specifications.

Unidentified structural steel: can be used if approved. Test if required shall be carried by an approvedtesting laboratory in accordance with CSA G40.1. The test results shall be used to determine the workingstresses.

The NBC 1953 was revised in 1960. In 1965 new addition of the code was issued as the first edition ofwhat was anticipated a five-year cycle.


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The NBC 1965

It is still intended as by-law which will be accepted by local municipality.

Live load

There are no changes in live loads due to occupancy or rather “loads due to use”. There are two live loadreduction factors, one (0.5 + 15/√ A) for buildings used for storage, manufacturing, garage or assemblyapplied when a member support an area in excess of 900 sq. ft. and another factor (0.3 + 10/√ A) for anyother occupancy when a member supports an area in excess of 200 sq. ft.

Minimum loads for railings separating a change in elevation in access of 18 in., 150 lf/ ft laterally and 100lb/ ft vertically to be considered separately from lateral load.

Vibration due to equipment and machinery: it gives the magnification factor for equipment weight or its liveload.

Snow load

It introduces modification of 80% (Cb= 0.8) to ground snow load given in the Supplement 1.

Design snow load = Cbx ground snow load

Supplement No. 3 gives factors to account for snow accumulation. It also allows reduction of Cbto 0.6 forexposed roofs. The ground snow load contours changed slightly as well as the magnitude of the snow load.Generally, there is no significant change in snow load for most locations.

Wind load

The minimum design wind load is given in climatic information included in Supplement No.1. This loadshould be modified for height above 40 ft. Or the following formula can be used:

qh= q30(h/30)1/5

The change in the exponent results in slightly greater values for design wind pressure.

The minimum design load acting on a surface is again given as an algebraic pressure difference on bothsides of the surface. Assistance with pressure coefficients is provided in Supplement No.3.

Rain load

There is no change in rain load.

Earthquake load

Significant changes in the determination of earthquake loading.

The minimum base shear V = KWW is total dead load, including storage and weight of equipment and machinery,

K = R* C*I*F*S

R is the earthquake factor obtained from climatic information in Supplement No.1. It is a measure ofearthquake intensity.

C is a coefficient which reflects type of construction;


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C = 0.75 for steel or reinforced concrete framed buildings with moment resisting connections, andsufficiently stiff floors diaphragm, and the frame alone must be able to carry 50% of the design based shearor shear walls reinforced in a ductile manner to carry design shear forces.

C = 1.25 for all types of buildings

I is importance factor;I = 1.3 for important bldg’s. such as hospitals, power plants and large occupancy and 1.0 for the others.

F reflects foundation conditions; F = 1.5 for buildings found on highly compressible ground and F = 1.0 forall other soil conditions

S reflects number of storeys

N is number of storeys

S = 0.25/(9 + N)

The distribution of the base shear V to shear at Fx each floor is in accordance with the ratio of (floor weightwx x height above the base hx) to the sum of (floor weight x height above the base) for all storeys.

Also for the first time the overturning moment at base is given as M =∑ Fxhx.

Structural Steel

All structural steel should be accompanied by a Certified Mill Test Report, or Manufacturer’s certificate. Thefabricator shall if requested provide an affidavit confirming that fabricated steel meets the specifications.Unidentified steel should be tested to identify both physical and chemical properties of steel in accordancewith G40.1-1966. Steel then classified and appropriate allowable unit stress is determined.

The NBC 1970

This edition of the code contains for the first time the limit on lateral deformations; storey deflection to

storey height of 1/500 and total deflection to total height of 1/500. It introduces T load; load due tocontraction or expansion due to temperature changes, shrinkage, moisture, creep or differential settlement.The load combinations which have to be considered in structural engineering design. The load combinationfactor is introduced for the first tome; 1.0 for combination dead and live; 0.75 for combination of dead withlive load and wind or earthquake; 0.65 for combination of dead load with live load and wind or seismic loadand temperature.

Dead load

The weight of permanent equipment and forces due to prestressing are added to the list of dead loads tobe considered.

Live load

There is no significant change in live loads; except more guidance is given to circumstances when live loadconditions were not covered.

Snow load

No significant changes to snow load occurred.


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Wind load

The impact of wind is defined by designed wind pressure p:

p = qCeCgCp.

This approach is similar to current NBC. The mean hourly wind pressures q which are used are not

significantly different from

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Canadian Steel Codes IP 10-5