Steel Str.assignment

8/12/2019 Steel Str.assignment

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Load & Resistance Factor Design (LRFD)1.4 D = 0.90 R (First load case)

1.56 D = R LRFD

F.S. = R/D = 1.56 LRFD, compared to:

F.S. = R/Q = 1.67 ASD

LOADS:1Dead Loads: Also known as gravity loads, includes the weight of the structure and all fixed

and attachments.

2Live Loads: Also belong to gravity loads, but their intensity and location may vary

(non-permanent loads).

3Highways / Rail Live Loads:

AASHTO, AREA3Impact Loads:

Associated with Live Loads.

4Snow Loads:

20 to 40 psf ( 1000 to 2000 Pa )Wind Loads:5Wind Loads: Static Wind Pressure = q CeCgCp

Where q = Dynamic pressure = 1/2pv2

Ce= Exposure Factor (1 to 2)

Cg= Gust Factor (above 2)

Cp= Shape Factor (about 1.5)

6 - Earthquake Load:

Latitude Load on structure.

7 - Thermal Loads:

For Indeterminate Structures.

8Other Loads:

e.g. - Rain Loads

- Ponding

- Hydrostatic Loads

- Blast Loads.

Structural steel:

Structural steel is steel constructionmaterial,aprofile,formed with a

specificshape orcross section and certain standards ofchemical composition and mechanical

properties. Structural steel shape, size, composition, strength, storage, etc., is regulated in most

industrialized countries.

Structural steel members, such as I-beams, have highsecond moments of area,which allow

them to be very stiff in respect to their cross-sectional area
http://en.wikipedia.org/wiki/Materialhttp://en.wikipedia.org/wiki/Profile_(engineering)http://en.wikipedia.org/wiki/Shapehttp://en.wikipedia.org/wiki/Cross_section_(geometry)http://en.wikipedia.org/wiki/Chemistryhttp://en.wikipedia.org/wiki/Second_moment_of_areahttp://en.wikipedia.org/wiki/File:I-Beam_002.JPGhttp://en.wikipedia.org/wiki/Second_moment_of_areahttp://en.wikipedia.org/wiki/Chemistryhttp://en.wikipedia.org/wiki/Cross_section_(geometry)http://en.wikipedia.org/wiki/Shapehttp://en.wikipedia.org/wiki/Profile_(engineering)http://en.wikipedia.org/wiki/Material


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Common structural shapes:

In mostdeveloped countries,the shapes available are set out in published standards, although

a number of specialist and proprietarycross sections are also available.

I-beam (I-shaped cross-section - in Britain these include Universal Beams (UB) and UniversalColumns (UC); in Europe it includes the IPE, HE, HL, HD and other sections; in the US it

includes Wide Flange (WF) and H sections)

Z-Shape (half a flange in opposite directions) HSS-Shape (Hollow structural section also known as SHS (structural hollow section) and

includingsquare,rectangular,circular (pipe)andellipticalcross sections)

Angle (L-shaped cross-section) Channel ( [-shaped cross-section) Tee (T-shaped cross-section) Rail profile (asymmetrical I-beam)

Railway rail Vignoles rail Flanged T rail Grooved rail

Bar, a piece ofmetal,rectangular cross sectioned (flat) and long, but not so wide so as tobe called asheet.

Rod, around orsquare and long piece ofmetal orwood,see alsorebar anddowel. Plate,sheet metal thicker than 6 mm or 1/4 in. Open web steeljoistWhile many sections are made byhot orcoldrolling,others are made bywelding together flat

or bent plates (for example, the largest circular hollow sections are made from flat plate bent

into a circle and seam-welded).Standard structural steels (USA):

Steels used for building construction in the US use standard alloys identified and specified

byASTM International.These steels have an alloy identification beginning with Aand then two,

three, or four numbers. The four-numberAISI steel grades commonly used for mechanical

engineering, machines, and vehicles are a completely different specification series.

The standard commonly used structural steels are:
http://en.wikipedia.org/wiki/Developed_countryhttp://en.wikipedia.org/wiki/Cross_section_(geometry)http://en.wikipedia.org/wiki/I-beamhttp://en.wikipedia.org/wiki/Hollow_structural_sectionhttp://en.wikipedia.org/wiki/Square_(geometry)http://en.wikipedia.org/wiki/Rectanglehttp://en.wikipedia.org/wiki/Circularhttp://en.wikipedia.org/wiki/Pipe_(material)http://en.wikipedia.org/wiki/Ellipsehttp://en.wikipedia.org/wiki/Cross_section_(geometry)http://en.wikipedia.org/wiki/Rail_profilehttp://en.wikipedia.org/wiki/Rail_tracks#Railhttp://en.wikipedia.org/wiki/Vignoles_railhttp://en.wikipedia.org/wiki/Flanged_T_railhttp://en.wikipedia.org/wiki/Tramway_track#Grooved_railhttp://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Rectanglehttp://en.wikipedia.org/wiki/Cross_section_(geometry)http://en.wikipedia.org/wiki/Sheet_metalhttp://en.wikipedia.org/wiki/Circlehttp://en.wikipedia.org/wiki/Square_(geometry)http://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Woodhttp://en.wikipedia.org/wiki/Rebarhttp://en.wikipedia.org/wiki/Dowelhttp://en.wikipedia.org/wiki/Sheet_metalhttp://en.wikipedia.org/wiki/Joisthttp://en.wikipedia.org/wiki/Hot_rollinghttp://en.wikipedia.org/wiki/Cold_rollinghttp://en.wikipedia.org/wiki/Rolling_(metalworking)http://en.wikipedia.org/wiki/Weldhttp://en.wikipedia.org/wiki/ASTM_Internationalhttp://en.wikipedia.org/wiki/AISI_steel_gradeshttp://en.wikipedia.org/wiki/AISI_steel_gradeshttp://en.wikipedia.org/wiki/ASTM_Internationalhttp://en.wikipedia.org/wiki/Weldhttp://en.wikipedia.org/wiki/Rolling_(metalworking)http://en.wikipedia.org/wiki/Cold_rollinghttp://en.wikipedia.org/wiki/Hot_rollinghttp://en.wikipedia.org/wiki/Joisthttp://en.wikipedia.org/wiki/Sheet_metalhttp://en.wikipedia.org/wiki/Dowelhttp://en.wikipedia.org/wiki/Rebarhttp://en.wikipedia.org/wiki/Woodhttp://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Square_(geometry)http://en.wikipedia.org/wiki/Circlehttp://en.wikipedia.org/wiki/Sheet_metalhttp://en.wikipedia.org/wiki/Cross_section_(geometry)http://en.wikipedia.org/wiki/Rectanglehttp://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Tramway_track#Grooved_railhttp://en.wikipedia.org/wiki/Flanged_T_railhttp://en.wikipedia.org/wiki/Vignoles_railhttp://en.wikipedia.org/wiki/Rail_tracks#Railhttp://en.wikipedia.org/wiki/Rail_profilehttp://en.wikipedia.org/wiki/Cross_section_(geometry)http://en.wikipedia.org/wiki/Ellipsehttp://en.wikipedia.org/wiki/Pipe_(material)http://en.wikipedia.org/wiki/Circularhttp://en.wikipedia.org/wiki/Rectanglehttp://en.wikipedia.org/wiki/Square_(geometry)http://en.wikipedia.org/wiki/Hollow_structural_sectionhttp://en.wikipedia.org/wiki/I-beamhttp://en.wikipedia.org/wiki/Cross_section_(geometry)http://en.wikipedia.org/wiki/Developed_country


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Carbon steels A36 - structural shapes and plate A53 - structural pipe and tubing A500 - structural pipe and tubing A501 - structural pipe and tubing A529 - structural shapes and plateHigh strength low alloy steels

A441 - structural shapes and plates A572 - structural shapes and plates A618 - structural pipe and tubing A992 - W shapes beams only

A270 - structural shapes and platesCorrosion resistant high strength low alloy steels

A242 - structural shapes and plates A588 - structural shapes and platesQuenched and tempered alloy steels

A514 - structural shapes and plates A517 - boilers and pressure vessels

STEEL CONSTRUCTION:Steel has been used in commercial construction for many years. In the past decade it has

been used more and more in residential construction. Steel studs construction has gained in

popularity because trees aren't cut to make studs, they also are price stable and don't fluctuate as

much as lumber. When lumber prices are up steel studs are an attractive option.

ADVANTAGES AND DISADVANTAGES: Steel is very useful in construction. There are many

advantages using steel in construction. That why many construction in the world use steel as main

materials for the construction. Some of ADVANTAGES of steel construction are:-
http://en.wikipedia.org/wiki/A36_steelhttp://en.wikipedia.org/wiki/A53_steelhttp://en.wikipedia.org/wiki/A500_steelhttp://en.wikipedia.org/wiki/A501_steelhttp://en.wikipedia.org/w/index.php?title=A529_steel&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=A441_steel&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=A572_steel&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=A618_steel&action=edit&redlink=1http://en.wikipedia.org/wiki/A992_steelhttp://en.wikipedia.org/w/index.php?title=A270_steel&action=edit&redlink=1http://en.wikipedia.org/wiki/A242http://en.wikipedia.org/wiki/Weathering_steelhttp://en.wikipedia.org/wiki/A514_steelhttp://en.wikipedia.org/wiki/A514_steel#A517http://en.wikipedia.org/wiki/A514_steel#A517http://en.wikipedia.org/wiki/A514_steelhttp://en.wikipedia.org/wiki/Weathering_steelhttp://en.wikipedia.org/wiki/A242http://en.wikipedia.org/w/index.php?title=A270_steel&action=edit&redlink=1http://en.wikipedia.org/wiki/A992_steelhttp://en.wikipedia.org/w/index.php?title=A618_steel&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=A572_steel&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=A441_steel&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=A529_steel&action=edit&redlink=1http://en.wikipedia.org/wiki/A501_steelhttp://en.wikipedia.org/wiki/A500_steelhttp://en.wikipedia.org/wiki/A53_steelhttp://en.wikipedia.org/wiki/A36_steel


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DISADVANTAGES:

Although there are many of advantages using steel in construction, steel also have

disadvantages in construction. Steel has a consistent quality because it is a

manufactured product and during construction there is not the 10-20% material waste

that is typically experienced with wood operations (Yost 1995). As previously discussed

steel also has its own disadvantages which were best identified by Yost (1995) as

Follow:

In many areas it is difficult to find framing crews that are trained in light steelconstruction. This disadvantage usually raises the overall project cost.

Because Steel studs are a poor insulator they suffer from thermal bridging whichreduces overall wall insulation value.

Even though steel components will not burn they will actually fail (collapse) before awood component in a house fire.

Steel is an excellent thermal conductor requiring additional exterior insulation orthermal breaks to overcome this disadvantage. Thermal conductivity is probably the

most serious of steel's disadvantages.

Steel components can rust if left exposed in marine climates. Finding steel roof trusses is difficult in most areas so it is common to used wood roof

trusses (and sometimes floor trusses).

In addition to the labor training required to convert to the use of steel, builders andlaborers must obtain some new tools not presently used by carpenters. The

combination of additional training and tools translate to increased costs of construction

for a short period of time.

Because light-gauge steel frame construction is relatively new and innovative within theresidential construction industry, it is not only unfamiliar to craftsmen but it is also

unfamiliar to engineers and code officials.

STEEL CONSTRUCTION


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STEEL CONNECTIONS:

INTRODUCTION:

Connections are structural elements used for joining different members of a

structural steel framework. Any steel structure is an assemblage of different members such as

beam, columns, and tension members, which are fastened or connected to one another,

usually at the member ends. Many members in steel structures may themselves be made of

different components such as plates, angles, Ibeams, or channels. These different components

have to be connected properly by means of fasteners, so that they will act together as a single

composite unit. Connections between different members of a steel frame work not only

facilitate the flow of forces and moments from one member to another, but also allow the

transfer of forces up to the foundation level1.

IMPORTANCE

A structure is only as strong as its weakest link. Unless properly designed and detailed, the

connections

may become weaker than the members being joined due to following reasons1:

a. A connection failure may lead to a catastrophic failure of the whole structure.b. Normally, a connection failure is not as ductile as that of a steel member failure.c. For achieving an economical design, it is important that connectors develop full or little

extra strength of the members it is joining.

To properly design a connection, a designer must have a thorough understanding of

the behavior of the joint under loads. Different modes of failure can occur depending on the

geometry of the connection and the relative strengths and stiffnesss of the various

components of the connection. To ensure that the connection can carry the applied loads, a

designer must check for all perceivable modes of failure pertinent to each component of the

connection and the connection as a whole

COMPONENTS OF A CONNECTION:

Connections mainly include any or in combination with some of the components given below:

Bolts (Shop or Site) Welds (Shop or Site) Connecting Plates Connecting Angle Cut sections


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CLASSIFICATION OF CONNECTIONS:

Connections are basically classified:

1-According the type of connecting medium used:

Bolted connections welded connection boltedwelded connections riveted connections

2- According to the type of internal forces the connections are expected to transmit:

Shear (semi rigid, simple) connections moment (rigid) connections

3- According to the type of structural elements that made up the connections: Singleplateangle connections doublewebangle connections topand seatedangle connections, Seated beam connections, etc.

4- According to the type of members the connections are joining:

Beamtobeam connections columntocolumn connections (column splices) beamtocolumn connections Hanger connections Column base plate, e

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