Steel Structure.pdf

8/16/2019 Steel Structure.pdf

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STEEL STRUCTURE

IN

BUILDING CONSTRUCTION



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1.0 Overview2.0 Application of steel structure

3.0 Specification of steel structure

4.0 Advantages and disadvantages of steelstructures

5.0 Structural Steel Section

6.0 Steel Frame Protection AgainstCorrosion and Fire

7.0 Structural Steel Connectors

LECTURE OUTLINE



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History..

• The Crystal Palace was a cast-iron and glassbuilding originally erected in Hyde Park, London,England, to house the Great Exhibition of 1851.

• More than 14,000 exhibitors from around theworld gathered in the Palace's 990,000 squarefeet (92,000 m2) of exhibition space to displayexamples of the latest technology developed inthe Industrial Revolution.

• The Crystal Palace's creator, Joseph Paxton,

was knighted in recognition of his work. Paxtonhad been the head gardener at Chatsworth, inDerbyshire.



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History..

• There he had experimented with glass and ironin the creation of large greenhouses, and hadseen something of their strength and durability,knowledge that he applied to the plans for theGreat Exhibition building.

• Planners had been looking for strength,durability, simplicity of construction and speedand this they got from Paxton's ideas. Theproject was engineered by Sir William Cubitt.



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http://en.wikipedia.org/wiki/File:Crystal_Palace_-_Queen_Victoria_opens_the_Great_Exhibition.jpg

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Eiffel Tower• The structure was built between 1887 and 1889 as the entrance arch for the

Exposition Universelle, a World's Fair marking the centennial celebration ofthe French Revolution.

• Eiffel originally planned to build the tower in Barcelona, for the UniversalExposition of 1888, but those responsible at the Barcelona city hall thoughtit was a strange and expensive construction, which did not fit into the designof the city.

• After the refusal of the Consistory of Barcelona, Eiffel submitted his draft tothose responsible for the Universal Exhibition in Paris, where he would buildhis tower a year later, in 1889. The tower was inaugurated on 31 March1889, and opened on 6 May.

• Three hundred workers joined together 18,038 pieces of puddled iron (avery pure form of structural iron), using two and a half million rivets, in astructural design by Maurice Koechlin.

• The risk of accident was great, for unlike modern skyscrapers the tower isan open frame without any intermediate floors except the two platforms.

• However, because Eiffel took safety precautions, including the use ofmovable stagings, guard-rails and screens, only one man died.

http://en.wikipedia.org/wiki/File:Tour_Eiffel_Wikimedia_Commons.jpg



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http://en.wikipedia.org/wiki/File:Vue_Lumi%C3%A8re_No_992_-_Panorama_pendant_l%27ascension_de_la_Tour_Eiffel_(1898).ogv

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• Date of birth: March 31, 1889 (hoisting the flag to the top), built for theUniversal Exhibition in celebration of the French Revolution.Age: 120 yearsContractor : Gustave Eiffel & CieEngineers: Maurice Koechlin & Emile NouguierArchitect: Stephen SauvestreStudies: Begun in 1884

Construction: 1887 to 1889 (2 years, 2 months and 5 days)Composition: 18,038 pieces, 2,500,000 rivetsWeight of the metal structure: 7,300 tonsTotal weight: 10,100 tonsHeight: 324m (height with flagpole)Coordinates : Latitude : 48º 51' 32" North

Longitude : 002º 17' 45" EastNumbers of visitors up to December 31, 2009: 249 976 000Distinctive feature: recognizable throughout the entire worldNumber of steps: 1665Owner : City of Paris



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STEEL STRUCTURE



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Over view

• Steel Structural is one of the basic materials

commonly used in structures, such as industrial and

commercial building, bridges etc

• It is produced in a wide range of shapes andgrades, which permits great flexibility in its usage.

• It is relatively inexpensive to manufacture and is the

strongest and most versatile material available tothe construction industry.



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• Because of this geometry and shape, steel

structure can provide very high stability over

long distances with relatively little weight ie

steel truss.• The development of this engineering

technique made the construction of the high-

rise and skyscraper possible.



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Steel structure refers to a building technique

with a ―skeleton frame" of vertical steel columns

and horizontal I-beams, constructed in a

rectangular grid to support the floors, roof andwalls of a building which are all attached to the

frame.



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APPLICATION OF STEEL STRUCTURE

• A wide variety of structures are erected

using structural steel.

• Basically, they can be listed as

buildings, bridges, and towers; most otherstructures are modifications of these three.

• Steel is construction material of choice for

commercial or industrial construction due toits advantages as compared to other

construction material.



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Steel Application in Construction

There are three basic types of steel in the

construction. These may be designated as :

• Engineering construction,

• skeleton construction, and

• long- span construction.



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Steel Application in Construction



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Planning and Economic

Planning :-• Design and produce/pre-fabricated at factory.

Quality control and bulk production

• Less site operation, create more space

• Less manpower• Need more plants

Economic :-

• Less weight, yet high bending moment• Long span and high-rise Capability

• Recycle and re-fabricated/dismantle



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Specification

Specification of steel can be determined

according to its:

• Shape and size

• How steel manufactured

• Composition of raw materials



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Structural Steel Shapes• Structural steel is manufactured in a wide

variety of cross-sectional shapes and sizes.

• Variety of shape:

i. W-Shape,ii. S Shape,

iii. C-shape,

iv. Steel Angles,v. Steel plate

vi. Steel Bar

http://tpub.com/content/engineering/14071/css/14071_29.htm

http://tpub.com/content/engineering/14071/css/14071_29.htm



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Structural steel shapes

and designations



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Steel Structural shapes



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W-shape (American Standard -

wide flange)• The W shape is the most widely used

structural member for beams, columns, and

other load-bearing applications. It has parallelinner and outer flange surfaces that are of

constant thickness.

• This flange design provides greater cross-

sectional area in the flanges, which results ingreater strength than is provided by the S-

shape



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S-shape (American Standard I-beam)

• This flange design provides less cross-sectional

area in the flanges, which results in less strength

than is provided by the W-shape,

• S-shape which has a slope of approximately 17degrees on the inner flange surfaces.



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C-shape (American Standard - channel)

• The C-shape is similar to the S-shape in thatits inner flange surface is also sloped

approximately 17 degrees. The C-shape is

especially useful in locations where a single

flat surface on one side is required. Whenused alone, the C-shape is not very efficient

as a beam or column.

• However, efficient built-up members maybe

constructed of channel assembled togetherwith other structural shapes and connected

by rivets or welds.



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• The W-, S-, and C-shape structural membersare designated by their nominal depth, in mm,

along the web and the weight, in kg, per

meter of length.

• A W150 x 30, for example, indicates a W-

shape that is 150mm deep along its web and

weighs 30 kg per linear meter. Hence a 20-meter length of this size W-shape would

weight a total of 600kg.





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STEEL PLATE

• Steel plate is a structural member that has awidth greater than 200mm and a thickness of6mm or more. Plates are generally used asconnections between other structuralmembers.

• They may also be used as componentparts of built-up structural members, such asthe built-up column



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STEEL PLATE

• Plates cut to specific sizes may be obtained inwidths ranging from 200mm to 3000 mm andmore various thickness.

• Plates are identified by their thickness, width,

andlength, all measured in mm; for example, PL 12 x 450 x 750



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Steel Bar

• Steel bar has a width of 200mm or less and athickness greater than 75-400mm.

• The edges of bars usually are rolled square, like universal mill plates. The dimensions

are expressed in a similar manner as that forplates; for instance, bar 150 x 12. Bars areavailable in a variety of cross-sectionalshapes:

round, hexagonal, octagonal, square, andflat



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Steel Bar

• Both squares and rounds are commonly usedas bracing members of light structures.

• Their dimensions, in inches, apply to theside of the square or the diameter of the

round.



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Advantages of Steel StructureSteel Structure Frame offer:

• Simple method and fast –speed upconstruction process

• Steel element comparatively small in size,

therefore lightweight structure and allow moreinternal space-long span structure

• Steel is a factory made, therefore high qualitystandard

• Reduce wastage, less site operation• Economic-recyclable

• etc



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Disadvantages of steel structure

• Structural movement-expansion

• Low thermal resistant

• Need extra protection against fire and

corrosion• Suitable for modern building design



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Steel frame Elements for Building

• Skeleton frame - column, beam

• Plane Frame - roof structure, beam (single

span structure)

• Portal Frame• Space frame

• Space deck



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http://www.steelframehousing.org

http://www.steelframehousing.org/

http://www.steelframehousing.org/



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• Portal column consisting of two "C" section purlins bolted together

The joints have a 10mm MS steel plate sandwiched between the "C"

sections

• Portal rafter consisting of two "C" section purlins bolted together• Fly brace, flat galv. strap bolted to rafter and roof purlins. Stiffens the

rafter

• Knee brace consisting of two "C" section purlins bolted together

• "Z" section purlin bolted direct (no cleat)through the bottom flange to

the portal rafter

• "C" section girt bolted direct (no cleat)through the flange to the portal

colum



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• Portal Frame



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Steel Structural Section

• Hot - Rolled Steel Section – Universal beam

– Universal column

– Angle Section – Channel Section

• Cold – Rolled Steel Section

– Metal roof, metal sheet, Profiled steel decking,solid slab floor

• Castela beam



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Hot Rolling Process

• Hot rolling is primarily concerned withmanipulating material shape and geometry rather than mechanical properties.

• This is achieved by heating a component or

material to its upper critical temperature andthen applying controlled load which forms thematerial to a desired specification or size.

• This method whereby industrial metal is passed

or deformed between a set of work rolls and thetemperature of the metal is generally above itsrecrystallization temperature.



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Cold Rolling Process

• Cold rolling is a metallurgical process in whichmetal is passed through a pair of rollers at a

temperature below its recrystallization

temperature.

• This process hardens the metal, by compressing

and stretching the metal crystals. During the

rolling process, the metal is annealed by heating

it above the recrystallization temperature afterevery few rollings, to prevent it from becoming

brittle and cracking



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Cold Rolling Process

• Most non-ferrous metals are rolled cold to makesheet. Steel is usually rolled hot, except when

thin sheet or special bars such as machine

shafts are being produced



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Universal Beam (UB)

M=Massperm,D=DepthofSection,B=WidthofSection,T1=Webthickness,T=FlangeThickness,R1=Rootradius,R2=ToeRadius,A=AreaofSection

SerialSize M D B T1 T R1 D1 A

mm kg mm mm mm mm mm mm cm2

914 x 419 388 920.5 420.5 21.5 36.6 24.1 791.5 493.9

- 343 911.4 418.5 19.4 32.0 24.1 791.5 436.9

914x 305 289 926.6 307.8 19.6 32.0 19.1 819.2 368.5

253 918.5 305.5 17.3 27.9 19.1 819.2 322.5



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Universal Column (UC)

M=Massperm,D=DepthofSection,B=WidthofSection,T1=Webthickness,T=FlangeThickness,R=Rootradius,A=AreaofSection

SerialSize M D B T1 T R1 D1 A

mm kg mm mm mm mm mm mm cm2

356 x 406 634 474.7 424.1 47.6 77.0 15.2 290.1 808.1

551 455.7 418.5 42.0 67.5 15.2 290.1 701.8

356 x 368 202 374.7 374.4 16.8 27.0 15.2 290.1 257.9

177 368.3 372.1 14.5 23.8 15.2 290.1 225.7

153 362.0 370.2 12.6 20.7 15.2 290.1 195.2



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Angle Section

M=Massperm,A=DepthofSection,B=WidthofSection,T=Webthickness

T=FlangeThicM=Massperm,A=DepthofSection,B=WidthofSection,T=Webthickness

SerialSizeLegLengths

AxBt M R1 R2 Area

mm mm mm kg mm mm cm2203 x 203 203.2 x 203.2 25.3 76.00 15.2 4.8 96.81

23.7 71.51 15.2 4.8 91.09

152 x 152 152.4 x 152.4 22.1 49.32 12.2 4.8 62.83

20.5 46.03 12.2 4.8 58.63



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Channel Section

M=Mass per m , D=Depth of Section, B= Width of Section, T1=Web thickness,T2=Flange Thickness, R1=Root radius, R2=Toe Rad, Area=Area of Section

SerialSize

M D B T1 T2 R1 R2 DT D/T Area

mm kg mm mm mm mm mm mm mm cm2

432 x102 65.54 431.8 101.6 12.2 16.8 15.2 4.8 362.5 25.7 83.49

381 x 102 55.1 381.0 101.6 10.4 16.3 15.2 4.8 312.4 23.4 70.19

305 x 102 46.18 304.8 101.6 10.2 14.8 15.2 4.8 239.3 20.6 58.83

305 x 89 41.69 304.8 88.9 10.2 13.7 13.7 3.2 245.4 22.2 53.11



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Steel Frame Protection

Against

Corrosion and Fire



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Steel Protection- against Fire

• Steel frame needs to be protected from fire because steel softens at high temperature and this can cause the building to partiallycollapse.

• At a temperature of around 550

C, steelworkloses its ―load bearing capacity‖. Unprotectedsteelwork could attain this temperature withinminutes of a fire breaking out.



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Steel Protection- against Fire

• Since, building regulations/legislation usuallydemands some form of fire protection isnecessary to protect the steel structure -allowing the fire brigade sufficient time to

bring the fire under control.



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Method of Steel Protection - against

fire• In the case of the columns this is usually

done by encasing it in some form of fire

resistant structure such as masonry, concrete

or plasterboard.

• The beams may be cased in concrete,

plasterboard or sprayed with a coating to

insulate it from the heat of the fire or it can beprotected by a fire resistant ceiling

construction.



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Method of Steel Protection - against

fire• Intumescent coatings (painting) are also

another method of attaining this additional fire

protection.



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Method of Steel Protection - against fire



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Up to 4 hours of fire protection is by

use of a high density rock mineral wool slab



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Steel Protection – Against Corrosion

Corrosion is a multifacetedphenomenon that adversely affects andcauses deterioration in metals throughoxidization. Millions of dollars of loss

throughout the metal industry can beattributed to metal corrosion

Corrosion of steel is an electrochemicalreaction that requires the presence ofwater (H2O), oxygen (O2) and ions suchas chloride ions (Cl—), all of which existin the atmosphere.



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The most common surface protectionmethods for steel are:

• anti corrosive paint coating

• hot dip galvanizing

• electroplating• spray galvanizing

• chromium plating

• aluminium spraying• rubberising

• coil coating of sheet steel



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• anti corrosive paint coating

WX618 Water-Based

transformation anti-rust

priming paint



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Coating Protection against corrosion

• The most common metallic coating used toprotect steel construction products is hot dip

galvanising. Very simply, the process involves

coating the surface of the steel with a very

thin coating of a corrosion-resistant metal,

usually zinc or an aluminium/zinc alloy.



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• Many flat steel construction products such ascladding and roofing products have an

organic coating for increased durability and

enhanced appearance. A range of different

coatings is available depending upon theproduct and the application. Coating

thicknesses vary from 15 to 25 micrometers

(0.6 to 0.8 mils). .



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Steel Frame Structures • The construction of a framework of structural

steel involves two principal operations:

fabrication and erection. Fabrication involves

the processing of raw materials to form thefinished members of the structure.



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Steel Frame Structures

• Erection includes all rigging, hoisting, or lifting ofmembers to their proper places in the

structure

and making the finished connections

between members.

• A wide variety of structures are erected using

structural steel. Basically, they can be list

ed as buildings, bridges, and towers; most otherstructures are modifications of these three.



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Steel Frame

• In steel frame (skeleton construction), all liveload and dead loads are carried by thestructural-frame skeleton. For this reason, theexterior walls are non bearing curtain walls.

• Roof and floor loads are transmitted to beamsand girders, which are, in turn, supported bycolumns. The horizontal members or beamsthat connect the exterior columns are called

spandrel beams.



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Steel Frame

• There is no limitation to the area of floor androof that can be supported using skeletonconstruction. One limitation on using skeletonconstruction, however, is the distance betweencolumns.



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Steel Frame-Long Span

• Oftentimes, large structures, such as aircr aft hangars, may require greaterdistances between supports than can bespanned by the standard structural steelshapes.

• In this case, one of several methods of long-span steel construction is used. One

method uses built-up girders to span thedistances between supports.



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• The built-up girder consists of steel platesand shapes that are combined together tomeet the necessary strength. The individualparts of these girders are connected bywelding or riveting.



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• Another method, which is usually moreeconomical, is to use a truss to span largedistances.

• A truss is a frame work of structural membersconsisting of atop chord, bottom chord anddiagonal web members that are usuallyplaced in a triangular arrangement.

• A trusses can be fabricated to conform to theshape of nearly any roof system.



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Steel Frame-Long Span• A third long-span method, although not as

versatile as trusses, is the use of bar joists.Bar joists are much lighter than trusses and arefabricated in several different types.

• One type is Prefabricated bar joists, designed

to conform to specific load requirements, areobtainable from commercial/factory producerie- space frame, space deck

• Other long-span construction methods involved

several different types of framing systems,which include steel arches, cable-hung frames,and other types of systems ie tension cablestructure, tension membrane structure.





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Structural Steel Connectors • There are four basic connectors used in

making structural steel connections. They arebolts, welds, pins, and rivets.

• Bolts and welds are the most commonconnectors used in military construction.

• Pins are used for connections at the ends ofbracing rods and varioussupport members thatrequire freedom of rotation.

• Commercial prefabricated steel assembliesmay be received in

the site with riveted connectors.



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Bolts• Bolts are used more than any other type of

connectors. They are easy to use and, in contrastto all other types of connectors, require littlespecial equipment.

• The development of higher strength steels and

improvedmanufacturing processes have resulted in theproduction of bolts that produce strong structuralsteel connections.

• Specifications for most bolted structural joints callfor the use of high-strength steel bolts tightened toa high tension.



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• Joints that are required to resist shear betweenconnected parts are designated as eitherfriction type or bearing type bolts connectors.

• Bolted parts

should fit solidly together when they areassembled and should NOT be separated bygaskets or any other type of compressiblematerial. Holes should be a nominal diameter,

not more that 2mm in excess of the nominalbolt diameter.

Bolts



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• When the bolted parts are assembled, all jointsurfaces should be free of dirt, and otherforeign material. Contact surfaces with friction-type joints must be free of oil, paint, or

other coatings.

Bolts



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Bolt and nut



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Welds

• Welding is a highly specialized skill, andwelding of load-bearing parts of a structure

should be performed only by properly

qualified personnel.

• They should have a general knowledge of theprincipal welding processes and the differe

nt types of welds and their applications.

• They should know how welding symbolsare used to identify welded connections

shown in working drawings.



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Welding Method

• The two principal welding processes usedin structural work are electric arc weldingand oxy-MAPP gas welding.

• In the electric arc welding process, weldingheat, sufficient to fuse the metal together, is

developed by an electric arc formed betweena suitable electrode (welding rod) and thebase metal (the metal of the partsbeing welded).



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Welding Method

• In the oxy-MAPP gas welding process,heat is obtained by burning a mixture ofMAPP gas and oxygen as it is dischargedfrom a torch designed for this purpose. Whileelectric arc welding is normally used formetals that are 3mm or larger in thickness,oxy-MAPP gas welding is usually restricted tothinner metals.

• The principal types of welds and welded j

oints that are suitable for structural work areas shown



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Types or welds



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Welded joints



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Rivets• Metal bolt or pin having a head on one end,

inserted through aligned holes in the pieces tobe joined and then hammered on the plain endso as to form a second head.

• rivet is a permanent mechanical fastener. Before

being installed a rivet consists of a smoothcylindrical shaft with a head on one end.

• The end opposite the head is called the buck-tail . On installation the rivet is placed in apunched or pre-drilled hole, and the tail is upset ,or bucked (i.e. deformed), so that it expands toabout 1.5 times the original shaft diameter,holding the rivet in place.



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http://en.wikipedia.org/wiki/File:Riveting.svg



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Steel connections



Steel connections

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Steel Structure.pdf