civi454-chapt1and chap2 2016

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structor: Dr. Lucia Tirca

Winter 2016 Design of Steel Structures 1

Course Instructor:

Lucia Tirca, PhD., ing. (OIQ)

Department of Building, Civil, &

Environmental EngineeringConcordia University

[email protected]

DESIGN OF STEEL STRUCTURES

PEIs Confederation Bridge,

12.9Km, 62 piers, 11m wide, 1997

Royal Ontario Museum, Toronto Space Frame Structure

Imperial War Museum, England

Source: http://classes.uleth.ca/Royal Ontario Museum, Toronto

Source: www.tourcanada.comSource: www.torontoist.com/2007 Source: www.wikipedia.org

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Winter 2016 Design of Steel Structures 2

OUTLINE

Instructor: L. Tirca PhD., ing. (OIQ)

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1. Introduction

2. Loads on Structures (NBCC 2010)

3. Wind Load Calculation Procedure for Multi-Storey Buildings

4. Equivalent Static Force Procedure for Structures Subjected toSeismic Loading; Structural Irregularities

5. Roof and Floor Systems

6. Gravity Columns

7. Methods of Frame Analysis

8. Lateral Force Resisting Systems

9. Seismic Design: Concentrically Braced Frames

10. Seismic Design: Eccentrically Braced Frames

11. Seismic Design: Moment Resisting Frames

12. Introduction to Steel-Bridge Design
http://en.wikipedia.org/wiki/Image:LibeskindSpaceFrameTower.jpghttp://en.wikipedia.org/wiki/Image:LibeskindSpaceFrameTower.jpg


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1. Introduction

1.1 Introduction

1.2 Structural Engineering Project and Structural Engineering Science

1.3 Limit States


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Design of Steel StructuresWinter 2016

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1. Introduction

Canadian Standard Association (CSA)

CSA S16-09: Design of Steel Structures

1. Scope and application

provides rules and requirements for the design, fabrication, and erection

of steel structures;

design is based on limit states;

steel structures such as: bridges, antenna towers, offshore structures, andcold-formed steel structural members are not cover in this standard.

Structural members made of cold formed steel shall conform to CSA

S136: Cold Formed Steel Structural Members;

Structural members made of aluminum shall conform to CAN3-S157-M:

Strength Design in Aluminum.


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1.1 Introduction

(Source: CSA S16-09, Part 1)


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1. Introduction

National Building Canadian Code NBCC 2010

Part 4.1 Structural Loads and Procedures

Users Guide-NBCC 2010 Structural Commentaries (Part 4 of Division B)

help code users to understand and to apply NBCC 2010 requirements.

contains 12 structural commentaries and among them are mentioned

those referring to the estimation of snow loads, rain loads, wind loads,

and earthquake loads.


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1.1 Introduction (continued)

6

1. Introduction

NBC of Canada 2010

Source:http://www.nationalcodes.ca/nbc/index_e.shtml


Winter 2016 Design of Steel Structures

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1. Introduction

User's Guide - NBCC 2010, StructuralCommentaries (Part 4 of Division B)Commentary A: Limit States Design

Commentary B: Structural Integri ty

Commentary C: Structural Integri ty of Firewal ls

Commentary D: Detection and Vibration Cri teria for

Serviceabi li ty and Fatigue Limit States

Commentary E: Effects of Deformations in Bui lding

Components

Commentary F: Live Loads

Commentary G: Snow Loads

Commentary H: Rain Loads

Commentary I: Wind Load and Effects

Commentary J: Design for Seismic EffectsCommentary K: Foundations

Commentary L: Appl ication of NBC Part 4 of Division B for

the Structural Evaluation and Upgrading of Exist ing Bui ldings

(Source:



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https://commerce-irc.nrc-cnrc.gc.ca/nrcb2c/catalog/setCurrentItem


8

1. Introduction

1.2 Structural Engineering Projects and Structural Engineering Science

OWNER

Design/ Build

Contractor

Architect Structural

Engineer

Mechanical

Engineer

Electrical

Engineer

Geotechnical

Consultant

Common Organization Chart for Design/ Build Contract

Specialty

Engineer

Cost

estimation

Design of Steel Structures

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1.2 Structural Engineering Projects and Structural Engineering Science

Structural

Engineer

Preliminary

structural design

Estimation of loads

Structural analysis

Structural design

Coordination

and approval

Final structuraldesign

Verification of loads

Check building computer model

Build computer model

Revised

structural

designNoYes

Structural analysis

Structural designConstruction phase

Are the

requirements ofthe design code

satisfied?

Yes

Revised

structural

designNo

Are the

requirements of

the design code

satisfied?

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1. Introduction

10

1. Introduction


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1.3 Design Requirements

(Source: CSA S16-09, Part 6)

GENERAL

i) Limit states define various types of collapse and associated

deformations. Two limit states are defined in the code:

Serviceability limit states: referrer to serviceability (conditions that

restrict the intended use and occupancy of the structure) and include

deflection, vibration, and permanent deformation.

Ultimate limit states: referrer to safety and include strength,

overturning, sliding, and fracture.

ii) Structural integrity: the general arrangement of the structural

system and the connection of its members shall provide resistance and

stability under applied loading, while avoiding local failure.


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2.1 Importance categories for buildings

2.2 Dead Loads, D

2.3 Live Loads, L

2.4 Snow Loads, S

2.5 Wind Loads, W

2.6 Earthquake Loads, E



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(Source: NBCC 2010)

1) - Elementary and secondary schools;

- Community centers.

2) - Hospitals, blood banks;

- Power stations and electrical substations;

- Public water treatment and storagefacilities;

- Police and Firefighters stations;

- Radio, television stations;

- Telephone exchanges buildings.

1)

2.1 Importance categories for buildings

Importance categories for Buildings (Table 4.1.2.1)

2)

Dead load, DL

Live load, LL

Environmental loads:

- snow, SL ),

- wind, WL ),

- earthquake, E)

. Other specified loads: lateral

earth pressure including

groundwater, H; thermal, T.

)For determining: S, W, and E loads,

building shall be assigned an

Importance categories.


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Importance Factors (Table A-2)

(Source: Users Guide NBCC 2010)



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Importance

Category

Earthquake, IE Wind, IW Snow, IS

ULS SLS ULS SLS ULS SLS

Low 0.8 0.8 0.75 0.8 0.9

Normal 1.0 1.0 0.75 1.0 0.9

High 1.3 1.15 0.75 1.15 0.9

Post-

disaster

1.5 SeeCommentary J.

1.25 0.75 1.25 0.9

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Load combination (Table 4.1.3.2A)

(Source: NBCC 2010)



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Load combination (cont.)

(Source: NBCC 2010)



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7) The companion-load factor0.5 forl iv e lo ad L i n Tab le 4.1.3.2.A shal l b e

increased to 1.0 for storage occupancies, and equipment areas and service

rooms in Table 4.1.5.3.

8) Except as provided in Sentence (8), the load factor1.25 fordead lo ad D

f or s oi l, s up er imposed ear th , plants and trees in Table 4.1.3.2.A shall be

increased to 1.5, except that when the soi ldepth exceeds 1.2 m, the factor

may be reduced to 1+0.6/hs, but not less than 1.25, where hs is the depth ofsoil

in meters supported by the structure.

9) A principal load factor of 1.5 shall be applied to the weight of saturatedso il u sed i n l oad combinat io n(1) of Table 4.1.3.2.A.

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2.2 Dead Load, DL

(Source: NBCC 2010)

Total DL = Specified dead load + superimposed dead load

Specified dead load: the weight of structural members of the system (columns,

beams, braces, slabs, interiors and exteriors walls, roof, etc)

Superimposed dead load:

- the weight ofpartition walls (if it is not specified, consider 1kPa over thearea of floor being considered);

- the weight ofpermanent equipment(heating & air conditioning systems,

plumbing, electrical systems, and so forth);

- the weight of floor finish (ceramic, marble, granite, wooden planking, etc.)

- the weight of vertical load due to earth, plants, and trees , (for green roof).



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Manulife Centre - 44 Charles St. West, Toronto

2.2 Dead Load, DL (continued)

Underground parking

Ex: for green roof, the

superimposed dead

load could be between

2.4 kPa (grass) 10 kPa

(trees) .

Source: http://www.toronto.ca/greenroofs/what.htm



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Green roof on top of

building parking

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2.2 Dead Load, D (continued)

Material Weight [ kN/m3]

Aluminum

Structural steel

Concrete, reinforced

Brick

Wood

Earth:

- sand & gravel, wet

- sand and gravel, dry

25.9

77.0

23.6

18,8

6.3

18.9

15.7

Table 2.2 Unit Weights of construction materials



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(Source: CANAM Steel Deck Catalog)

Column

Beam (secondary

beams)

Girder (principal

beams)

Canam

composite-deck

Braces



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Roof

(Source: Steel Framed Low-Rise Off ice Building; Design Notes,

by Canadian Institute of Steel Construction)

G C

B1

Legend: C-column; G-girder; B1-beam




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Dead loadroof of 1- st. building: Dead load typical floor of office:

Steel deck 0.10kPa CANAM composite deck 2.50kPa

Gravel 0.35kPa Floor finishing 0.15kPa

Insulation 0.10kPa Mechanical & ceiling 0.45kPa

Ceiling and mechanical 0.40kPa Partitions 1.00kPa

Total roof Dead Load 0.95kPa Total floor Dead Load 4.10kPa

Dead loads for exterior walls: Ex. - curtain wall, 1.0kN/m2

Canam composite-deck P-3615 (38 mm steel deck + 87 mm concrete ~ 125 mm)

It can be selected P-3623 (51 mm steel deck + 74 mm concrete ~ 125 mm)

Source: Canam Steel Deck Catalog

Ex.: Superimposed dead load (typical floor), SDL = 0.15 +0.45+1.0=1.6kPa



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9.0m

9.0

9.0

Gravity

Column C2E

Tributary area C2E(A= 9x9 =81m2)

B

B1

G1 Girder, G1

Beam, B

B

1

B

2

3

B1

Tributary area B1

(A=3x9=18m2)

9.0

Dead load on beam B1

- Uniformly distributed load of the

deck-slab floor is 4.1 kPa (kN/m2),

therefore the uniformly distributed linear

load is 4.1x3.0=12.3kN/m .

- self-weight of the beam B1, 0.15kN/m.

Total DL: wDL=12.3+0.15=12.45kN/m

R1= R2=(12.45x9.0)/2=56.025kN

wDL=12.45kN/m

R1 R2

9.0R1G R2G

Dead load on girder G1

3.0 3.0 3.0

112.05kN56.025x2=112.05kN

wDL=0.25kN/m

B1

B1

3.0 3.0 3.0

R1G=R2G=112.05+(0.25x9.0)/2=113.18kN



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SFRS

SFRS

SFRS


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2.2 Dead Load, D (continued)

Building Section(Source: Steel Framed Low-Rise Offi ce Building; Design Notes,

by Canadian Institute of Steel Construction)

Building Elevation



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2.3 Live Load, LL

Extract from Table 4.1.5.3, NBCC 2010

Use of Area of Floor or Roof Minimum Specified Load, kPa

Assembly Areas: Arenas; Auditoria; Churches;

Dance floor; Entrance halls; Gymnasia;

Museums; Theatres; Grandstands, etc.

Assembly Areas with fixed seats: Churches,

Theatres. Office areas.

Classrooms with or without fixed seats

Balconies: exterior, interior and mezzanines

used by an assembly of people, storage areas

Mechanical, electrical room

Garages for passenger cars

Operation room, laboratories

Residential areas (hotels, apartments)

Garages for loaded buses and trucks

Roof

4.8kPa

2.4kPa

2.4kPa

4.8kPa

3.6kPa

2.4kPa3.6kPa

1.9kPa

12.0kPa

1.0kPa

(Source: NBCC 2010)



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2.3 Live Load, LL (continued)

(Source: NBCC 2010)



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Variation with Tributary Area (Part 4.1.5.9 of NBCC 2010)

1) An area used for assembly occupancies designed for a live load of less than

4.8kPa (e.g. classrooms, lecture hall etc.) shall have no reduction for

tributary area.

2) Where a structural member supports a tributary area of floor, roof or

combination thereof greater than 80 m2 used for assembly occupancies

designed for a live load of 4.8 kPa or more, or for storage, manufacturing,

retail stores, garages or as a footbridge, the specified live load due to use and

occupancy is the load provided in Table 4.1.5.3 multiplied by 0.5 + (20/A)0.5.

Herein, A is the tributary area in square meters.

3) Where a structural member supports a tributary area of floor, roof or

combination thereof greater than 20 m2 for any use or occupancy other than

those indicated in Sentences (1) and (2), the specified live load due to use and

occupancyis the load provided in Table 4.1.5.3 multiplied by 0.3 + (9.8/B)0.5.

Herein, Bis the tributary area in square meters for this type of occupancies.

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2.4 Snow and Rain Load

The design snow load, SL for a structure is based on the ground snow load for

each geographical area.

S = Is [SS (Cb Cw Cs Ca) + Sr] where:

Is the importance factor for snow (see Table A-2, NBCC 2010; slide 13);

Ss the 1-in 50 year ground snow load in kPa (Appendices C, Table C-2, NBCC10; slide 27);

Cb the basic roof snow load factor. In general Cb=0.8 and even greater for larger roof;

Cw the wind exposure factor (Cw=1). There are same exceptions when Cw=0.75;

Cs the slop factor (see 4.1.6.2. (5) and (6), NBCC 2010; slide 28);

Ca the shape factor (slide 28);

Sr the 1-in 50 year associated rain load in kPa (see Appendix C, Table C-2 NBCC 2010),but

not greater than SS (Cb Cw Cs Ca).

(Source: NBCC 2010)



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Loads on Structures

2.4 Snow and Rain Load (continued)

(Source: NBCC 2010)

) For building importance category see Table 4.1.2.1, shown in slide 12.

)


Fall 2016

BLDG490

28


2.4 Snow and Rain Load (continued); Appendice C, TABLE C-2

Source



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(CW could be reduced to 0.75 for a roof fully exposed to the wind.)

Evaluate Cs (the slop factor) and Ca (the shape factor) for:gable roof, flat roof, and shed (single-slope) roof

CS=1 300

CS=

(700-)/400300< 700

CS=0 >700

Unobstructed, slippery roof

(Sentence 4.1.6.2 (6))

CS=1 150

CS=

(600-)/450150< 600

CS=0 >600

Cs (Sentence 4.1.6.2 (5))

Source: Users Guide NBCC 2010 Structural Commentaries



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Non-slippery roof

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Example: 2.4.1. Determine the design snow loads for the roof of the gabled frame of an

commercial building located in Montreal and shown in Fig. 2.4.1. In the first case,a)consider the slope of the roof = 250and then, case b) = 450. Consider the

wind exposure factor, CW=1.0and the basic roof snow load factor, Cb=0.8.

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

SS =2.6 kPa & Sr=0.4 kPa (Table C-2, Appendices C, NBCC10)

Is= 1.0 (Table 4.1.6.2 and Table 4.1.2.1, NBCC10, building

category: normal);

Cb = 0.8; CW = 1.0;

Cs = 1.0 because 300 (Sentence 4.1.6.2. (5) NBCC 10);

Ca = 1.0 (see Fig. G-1, Structural Commentaries, NBCC10);

S =1.0 [2.6 (0.8 x 1.0 x 1.0x 1.0) +0.4] =2.48 kPa;

a)

= 250

Case II C a=1.25because >200((see Fig. G-1, Structural Commentaries, NBCC10))

S = 1[2.6(0.8x1.0x1.0x1.25) +0.4]=3.0 kPa; S = 3.0 kPa

wind

Fig. 2.4.1; a)

balanced snow

load

unbalanced snow load

Case I



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Example: 2.4.1.(continued) S = Is [SS (Cb Cw Cs Ca) + Sr]

SS =2.6 kPa & Sr=0.4 kPa (Table C-2, Appendix C, NBCC10)

Is = 1.0 (Table 4.1.6.2 and Table 4.1.2.1, NBCC10, building

category: normal)

Cb = 0.8; CW =1.0

Cs =(700-)/400; (300< 700) (Sentence 4.1.6.2. (5) NBCC 10)

Cs = (700-450)/400=0.625

Ca = 1.0 (see Fig. G-1, Structural Commentaries, NBCC10)

Case I. S =1[2.6 (0.8 x 1.0x 0.625 x 1.0) +0.4] = 1.7 kPa;

Case II. Ca = 1.25 because >200 (see Fig. G-1, Structural

Commentaries, NBCC10)

S = 1[2.6(0.8x1.0x 0.625x1.25)+0.4]= 2.025 kPa; S = 2.025 kPa

b)

=450

wind

unbalanced snow load

balanced snow

load

Fig. 2.4.1; b )



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2. Load on Structures (NBCC 2010)

2.4.1 Snow distributions and snow loading factors for lower

levels of adjacent roofs S = Is [SS (Cb Cw Cs Ca) + Sr]Ca varies with distance x from Ca(0) at x=0 to

Ca(xd) at x = xd.

Ca(0) = min



Fig. G-5, Commentary G

(h)/(CbSs)

F/CbWhere:

- specific weight of snow, = 3.0kN/m3

F factor is to be taken as the grater of F=2, or

F = 0.35( lc/Ss 6( hp/Ss)2)0.5 + Cb where

lc = 2w (w2/l) is a characteristic length where

w and l are the shorter and longer

dimensions of the upper roof.

xd = min5(h CbSs/)

5(Ss/)(F-Cb)

For 0


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Winter 2016 Design of Steel Structures (Source: Users Guide - NBCC 2010) Structural Commentaries

2.4.1 Snow distributions and snow loading factors for lower

levels of adjacent roofs

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2.4.1. Snow distributions and snow loading factors for lower levels of

adjacent roofs (continued)

Example based on Fig. G-5, Commentary G:



xd = min5(h CbSs/) = 5(2 0.8x2.4/3) = 6.8m

5(Ss/)(F-Cb) = 5(2.4/3)(3.2-0.8) = 9.6

h=2.0m

No. 1 No.2

Building No.1: w=30m; L=40m; hp=0

Building No.2: w=35m; L=50m

Pierrefonds, Qc: Ss = 2.4 kPa; Sr=0.4 kPa

Cb= 0.8 and Cs=1

lc = 2w (w2/l) = 2(30) (302)/40=37.5m

F =max F = 0.35[3(37.5)/2.4]0.5 + 0.8 = 3.20;

F = 2.

F= 3.20

Ca(0) = (3x2)/(0.8x2.4) = 3.13 and

Ca(0) = 3.20/0.8 = 4.0

Ca(0) = 3.13

S = 1x[2.4(0.8x1.0x1.0x3.13) + 0.4] = 6.4 kPa

h = h-(CbCwSs)/ = 2.0 (0.8x1.0x2.4)/3 =1.36m

x = 10h = 10x 1.36 = 13.6 m

Considering Ca(xd) = 1

S =1x[2.4(0.8x1.0x1.0x1.0) + 0.4] = 2.32 kPa

If we consider Cw = 0.75 S=1.84 kPa

Snow diagram:

xd

=6.8

x=10h =13.6

1.84kPa2.32kPa

6.4kPa

Ca(0) = min

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2.4.2 Snow distributions and snow loading for canopies or small roofs

adjacent to tall buildings (Paragraph 39, NBCC 2010 Structural Commentaries)



h > 20m

Canopy

A < 25m2

For small area lower roofs with a plan

area < 25 m2, situated at h > 20m, Ca = 1.0

If, h


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2.4.4 Snow distributions for areas adjacent to obstructions (Fig. G8)



(Source: Users Guide - NBCC 2010) Structural Commentarie

Areas adjacent to o bstru ction s (Fig. G-8). Consideration should also be given tot r iangular dr i f t loads adjacent to signi f icant ver t ica l obstruct ions, such as

elevator shaft, air conditioning and fan housing, small penthouse and wide chimneys.

The peak load adjacent to the obstruction in Fig. G-8 is assumed equal to:

0.67gh +Sr

where h is the obstruction in meters, g is the weight of snow in kN/m3.

Snow distribution has a triangular variation over a distance of 2h from the obstruction.

Meanwhile, the peak load need not be larger than 2S +Sr( where S is computed with

Ca(0) 2/Cb) nor is it necessary to consider the drift load if the width b of theobstruction in Fig G-8 is less than 3.0Ss/g.

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2.4.4 Snow distributions for areas adjacent to obstructions (Fig. G 8)


Winter 2016Design of Steel Structures (Source: Users Guide - NBCC 2010) Structural Commentaries

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2.4.4 Snow distributions for areas adjacent to obstructions (Fig. G-8)


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2.5 Wind Load, WL

Wind Loads are calculating based on the algebraic difference of the external

pressure or suction due to wind on part or all of a surface of a building, p and

the specified internal pressure or suction, pi.

The specif ied external pressure or suct ion due to windis: p = Iwq CeCgCp; where:

p the specified external pressure (kPa) acting statically and in a direction normal to

the surface either as a pressure or as a suction;

q the reference velocity pressure (kPa), based on a probability of being exceeded in

any one year of 1 in 50 (given in Table C-2, Appendices C of NBCC 2010);

Ce the exposure factoris calculated based on equations developed for

open terrain; rough terrain; and interm ediate terrain.

Cg the gust effect factor for the building as a whole is Cg=2.0 (see 4.1.7.1 (6));

Cp the external pressure coefficient (see Users Guide NBCC10, Commentary I)

Iw the importance factorfor wind load (see Table 4.1.7.1)

The specified internal pressure or suction due to wind is: pi = Iwq CeCgiCpi;where:

Cg i the gust effect factor is Cg i= 2.0(see NBCC10, 4.1.7.1 (6));

Cp i the internal pressure coefficient (see Users Guide NBCC10, Commentary I)

(Source: NBCC 2010)



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2.5 Wind Load, WL (continued)

(Source: Rogers, C., 2007)



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External pressure Internal pressure

External wind pressure is transferred

to external walls, roof elements and

braces if any.

Internal wind pressure has an effect

only on walls and roof elements.

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2.5 Wind Load (continued)


q NBCC10 (Appendices C)

H>60m

H/w >4

fn < 1Hz

Static procedure

CpCg Fig. I-7

H


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Summary of changes from the NBCC 2005:

-change to building height that triggers the use of the Dynamic or

Experimental Procedure from 120m to 60m;

- Introduction of 1Hz as the lowest natural frequency fn that triggers

the use of the Dynamic or Experimental Procedure;

- Introduction of 1/4Hz as the lowest natural frequency fn that

triggers the use of the Experimental Procedure;

- Removal of exposure C.

Notable changes in Commentary 2010:Introduction of equation to determine lowest natural frequency fn.

For details see Chapter 3.



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Wind exposure factor, Ce, as per article 4.1.7.1, NBCC2010

Source:http://www.nationalcodes.ca/nbc/index_e.shtml

h-the reference build ing heightabove ground

(but not less than 0.9) (but not less than 0.7)



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Source: Users Guide NBCC

Structural Commentary

46


2.5 Wind Load

(continued)



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Source: Users Guide NBCC Structural Commentary

Wind exposure factor,

Ce, dynamic procedure

Exposure A

Exposure B

Exposure C


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2.5 Wind Load (continued) Example 2.5.1:

B=12m; H=6.0m; L=24m; roof slope=50- low-rise build.

Building importance category: normal; Iw=1( see Table

4.1.2.1 and Table 4.1.7.1, slide 25)

Building is location on rough terrain in Montreal area.

Ce=0.7(h/12)0.3=0.7(6/12)0.3=0.57, (Ce, exposure factor.)

and Ce 0.7; Therefore Ce=0.7

Pressure coefficients CpCg are calculated inaccordance with Fig. I-7 (Commentary of NBCC)

p=Iw q(1/50)CeCgCp; (q(1/50)=0.4kPa, Appendices C)

End zones: p=1.0x0.4x0.7x1.95=0.55kPa Other zones: p=1.0x0.4x0.7x1.3=0.37kPa

Lateral wind load: W= (24-6)x6.0x0.37 +6x6.0x0.55=40+20 =60kN

Source: Commentary of NBCC2010

Figure I-7 External peak pressure coefficients,

CpCg, for primary structural actions arising fromwind load acting simultaneously on all surfaces

The end zone y= max (0.2B and 6m); y=6m

Gust-induced pressure coefficients CpCg are:

End zones (1E&4E): CpCg =1.15-(-0.8)=1.95 (algebraic diff.)

Other zones (1&4): CpCg= 0.75-(-0.55) =1.30 (algebraic difference)

End zone

other zone

Design wind pressure, p:



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2.5 Wind Loads (continued)

Example 2.5.2



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L w

h

L= 24m; w=12m; h=6.0m; Iw = 1

Location: Montreal; q1/50=0.4kPa

Building located on open terrain

Ce = 0.9

From Figure I-7, NBCC 2010,

Structural Commentaries and

zone 1 & 4

CpCg = (0.75 + 0.55) = 1.3

(in this example, the end zones are

neglected)

0.75 0.55

{ -(-0.55) = 0.55 }Physical diagram

p=1.0 x 0.4 x 0.9 x1.30 = 0.47kPawind

Totalwind force= p x A = 0.47(24x6) = 68kN

Total wind force on one braced frame is:

68/2 = 34kN and the factored force is

34 x 1.4 = 48kN (see Table 4.1.3.2 NBCC 10)


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2.5 Wind Loads(continued)

Use Figure I-15 for

middle- & high-rise

buildings.


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2.6 Earthquake Loads Earthquake is a sudden undulation of the earthssurface.

Table 4.1.8.4.A (NBCC 2010)

Site classification for seismic site response

F2

F3

F1

V

(Source: NBCC 2010)



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2.6 Earthquake Loads (continued)

Hazard spectra for Montreal (firm soil)

-0.1

0.1

0.3

0.5

0.7

0 1 2 3 4

Period T, sec

Spectral

AccelerationS(Ta)

(g)

NBCC 2005

NBCC 1995 (v x S)

Max Sa f or design 0.45g

Hazard spectra for Vancouver (firm soil)

0

0.20.4

0.6

0.8

1

0 1 2 3 4

Period T, sec

SpectralAccelerationS(Ta)

(g)

NBCC 2005

NBCC 1995 (v x S)

Max Sa for design 0.67g

Source: Users Guide NBCC

Structural Commentary

Probability of exedance 2% in 50 years or

return period 2475years

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(Source: NBCC 2010)


Winter 2016

2.5 Earthquake Loads (continued)CIVI 454

Location Sa(0.2) Sa(0.5) Sa(1.0) Sa(2.0)

Montreal, Qc. 0.64 0.34 0.14 0.048

Quebec, Qc. 0.55 0.32 0.15 0.052

Victoria, B.C. 1.2 0.82 0.38 0.18

Vancouver, B.C. 1,0 0.7 0.33 0.17

Ottawa, On. 0.67 0.32 0.14 0.045

Toronto, On. 0.28 0.14 0.055 0.016

For site class A to E, factors Fa and Fvare given in Table 4.1.8.4.

Spectral acceleration values for different locations (Appendices C, NBCC10)


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(Source: NBCC 2010)



2.6 Earthquake Loads (continued) Fa acceleration-basedsite coefficient

Fv velocity-based site

coefficient

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2.6 Earthquake Loads (continued)CIVI 454

For site class C

(Fa=1, Fv=1)

(RdR0 = 1)

Design spectrum

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 1 2 3 4

Period, T (s)

S(T)

Montreal

Quebec

Victoria

Vancouver

Ottawa

Toronto

Seismic load calculation is given in detail in Chapter 4.


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Winter 2016

2.5 Earthquake Load (continued)CIVI 454

Equivalent Static Force Procedure

V = S(Ta)MvIEW/(RdRo)

- V the minimum lateral earthquake force;

- S(Ta) design spectral acceleration values;

- Mv the higher mode factor (Table 4.1.8.11);

- IE importance factor for earthquake loads;

- W building weight*;

- Rd ductility related force modification factor;

- Ro overstrength factor

Vmin = S(2.0)MvIEW/(RdRo) Vmax = (2/3)S(0.2)IEW/(RdRo)

-100% Dead l oad , as d ef in ed i n

A r ti c le 4 .1.4.1. excep t t hat t he

m in im um part i t ion load as

def ined in Sentence 4.1 .4 .1 .(3)

need no t exceed 0 .5kPa;

- 25% of the desig n sn ow load

speci fied in 4.1 .6 .;

- 60% of the storage load for

ar eas u sed f or s to rag e ex cep t t hat park ing garages need no t

be cons ide red s to rage a reas ,

- 100% th e fu ll c on ten ts o f an y

tanks.

(Source: NBCC 2010)

W=

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Chapter 2: Questions?



civi454-chapt1and chap2 2016

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