design of steel structures presentation of lecturenotes

DESIGN OF

STEEL STRUCTURES

Unit-I

INTRODUCTION

1 Compiled by Dr.Y.K.Sabapathy,Prof.,Civil

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UNIT I INTRODUCTION Properties of steel Structural steel sections Limit State Design Concepts Loads on Structures Metal joining methods using rivets, welding, bolting Design of bolted, riveted and welded joints Eccentric connections - Efficiency of joints High Tension bolts

SYLLABUS Unit-I


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BOOKS TEXT BOOKS 1. Dayaratnam, P., Design of Steel Structures, Second edition, S. Chand & Company, 2003. 2. Ramachandra, S. and Virendra Gehlot, Design of Steel Structures Vol. I & II, Standard Publication, New Delhi, 2007 REFERENCES 1. Teaching Resources for Structural Steel Design Vol. I & II, INSDAG, Kolkatta. 2. Gaylord, E.H., Gaylord, N.C., and Stallmeyer, J.E., Design of Steel Structures, 3rd edition, McGraw-Hill Publications, 1992 3. Negi L.S.. Design of Steel Structures, Tata McGraw Hill Publishing Pvt Ltd, New Delhi, 2007. 4. IS 800-2007 Indian Standard General Construction in Steel code of practice (3rd Revision).


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1. Introduction to steel 2. Properties of steel 3. Structural steel sections 4. Limit State Design Concepts 5. Loads on Structures 6. Metal joining methods using Rivets,

Welding, Bolting 7. Design of bolted, riveted and welded joints 8. Eccentric connections 9. Efficiency of joints 10.High Tension bolts

Topics


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Introduction to steel (as a structural material)


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STEEL - A CONSTRUCTION MATERIAL

Steel is the most commonly used structural metal in civil engineering due to its greater strength, good ductility and easy to fabricate.

Due to its high strength and relatively light weight (less dead weight) it can carry heavy loads.

Its due to the above reason steel has become an affordable material for making very long span structures.

e.g.Auditoriums, Stadiums, Halls, ..etc.

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STEEL - A CONSTRUCTION MATERIAL Due to steels good stiffness, the

defection need not be given special consideration.

Unlike concrete, steel members can be fabricated easily by drilling, cutting, etc..

Steel members can be joined easily by welding, reviting and bolting.

Most importantly the construction can be done at a faster.


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STEEL - A CONSTRUCTION MATERIAL Steel is a cheaper metal compared to other

metals.

Steel structures can be errected without any form work.

Mojor portions of the structure can be fabricated with more accuracy and good quality at factories far away from site and the transported to site.

Using steel structures we can alter or extend the structure easily at a later stage (which is not easy in concrete structures)

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STEEL STRUCTURES -LINK

South beijing railway station

TCS HQ SIRUSERI

HOWRAH BRIDGE

http://www.howrahbridgekolkata.gov.in/


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26,500 tons of steel

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PROMINENT STEEL STRUCTURES


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EIFFEL TOWER ,PARIS Erected in 1889 as the entrance arch to

the 1889 World's Fair.

It was named after the engineer Gustave Eiffel, whose company designed and built the tower.

The tower is 324 metres (1,063 ft) tall, about the same height as an 81-storey building.

7,300 tonnes of metallic framework, and a total weight of 10,100 tonnes.

18,000 metallic parts joined by 2,500,000 rivets.

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GOLDEN GATE BRIDGE, @ SAN FRANCISCO


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Total length of Bridge including approaches from abutment to

abutment: 1.7 miles = 8,981 ft = 2,737 m

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GOLDEN GATE BRIDGE

The maximum transverse deflection, at center span: 27.7 ft = 8.4 m


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WORLD TRADE CENTRE

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WORLD TRADE CENTRE 200,000 tons of steel used in the construction

of the World Trade Center complex

110 stories in each tower.

The World Trade Center towers used high-strength, load-bearing perimeter steel columns called Vierendeel trusses that were spaced closely together to form a strong, rigid wall structure, supporting virtually all lateral loads such as wind loads, and sharing the gravity load with the core columns.

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The core of each tower was a rectangular area 87 by 135 feet (27 by 41 m) and contained 47 steel columns running from the bedrock to the top of the tower.

The floors consisted of 4 inches (10 cm) thick lightweight concrete slabs laid on a fluted steel deck.


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WORLD TRADE CENTRE

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LONDON GAINT WHEEL


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LONDON GAINT WHEEL


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LONDON GAINT WHEEL

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Industrial structural members


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chute

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CHUTES for Conveying the Materials


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chute

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CHUTE DESIGN


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Chicagos WillisTower, or the SearsTower as it used to be called, just might be the worlds most famous steel building. It was the worlds tallest building when it was constructed in the 1970s.


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OTHER COMMONLY USED STEEL STRUCTURES

INDUSTRIAL STRUCTURES

- Roofing Structures,Lifting and hoisting Structures,chimneys,ducts,chuts

OFFSHORE STRUCTURES

POWER TRANSMISSION STRUCTURES

COMMUNICATION TOWERS

RECREATION STRUCTURES (Theme parks)


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DIFFERENT OFFSHORE STEEL STRUCTURES


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Design Through SACS


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OFF SHORE PLATFORM


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SACS SOFTWARE USED FOR DESIGN OF

OFFSHORE PLATFORMS

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DESIGN USING SACS SOFTWARE


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SACS

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OFFSHORE WIND MILLS STRUCTURES


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PROPERTIES OF STRUCTURAL STEEL

The major constituent of structural steel is Iron.

There are three commnly available commercial forms of steel namely Low Carbon Steel, Mild Steel (M.S.), High carbon steel which are based on the amount of carbon content in it.(as in table)


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CARBON CONTENT IN IRON AND STEEL

First the cast iron with 2% to 4 % cabon was found and used.

Then wrought iron was found in which the carbon content was less than 0.15%.

Later steel was found in which the carbon content upto 1.5%


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CARBON CONTENT IN STEEL Low carbon steel (carbon content 0% to 0.25%)

Medium carbon steel (carbon content 0.25% to0.75%)

Hight carbon steel (carbon content 0.75% to 1.5%)

Increasing the the carbon content increases the hardness and tensile strength,but reduces the ductility and toughness.

Hence a low carbon steel is prefered than high carbon steel for structural applications.

Morover, carbon content influences the weldability.


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STRUCTURAL STEEL

STRUCTURAL STEEL have carbon content less than

0.25%.

The minimum ultimate tensile strength varies between 410 MPa to 440MPa.

All the structural steel used in general construction, coming under the purview of this standard shall conform to IS 2062 (before fabrication )


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STRUCTURAL STEEL


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STRUCTURAL STEEL

HIGH CARBON STEEL whose ultimate strength ranges from 480 MPa to 550 Mpa are preferred for structures such as transmission line towers and microwave towers.


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Various types of steel are obtained by altering the carbon content by blowing oxygen through molten iron.

The steel so made is rolled to bring it to the required shape.

The rolled steel is reheated and passed between rollers to change its shape like plates,bars,steel sections,etc


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STEEL FOR MAKING VARIOUS SECTIONS


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I. Physical Properties

II. Chemical Properties

III. Mechanical Properties


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FIRE PROTECTION


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FIRE PROTECTION

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FATIGUE EFFECT


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BRITTLE FRACTURE


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CORROSION PROTECTION


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RAW STEEL BARS


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ROLLING OF STEEL TO REQUIRED SECTION


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ANGLE ROLLING - CURVED PROFILE SECTIONS (a recent development)


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SHAPES OF STEEL SECTIONS


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STRUCTURAL STEEL SECTIONS


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About Steel I -Sections

I-Sections are used as beams and columns.

The shape of I section is suited to resist

Bending Moment and Shear Force.

About 80% of bending is resisted by the flanges and the remaining by the web.

Nearly 95% of shear is resisted by the web and the remaining by the flanges.

Some times the flanges are attached with extra plates to resist more B.M.

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ABOUT I-SECTION


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1)

2)

3)

4)

5)

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Details of standard sections given in SP-6/STEEL TABLES


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(II) CHANNEL SECTION


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(II) CHANNELS


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(III)ANGLES

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EQUAL ANGLE UNEQUAL ANGLE

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T-section

NORMAL T-SECTION

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T-section


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(V) PLATES


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ROLLING FOR TUBULAR SECTION


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(V)PLATES


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Castellate beams


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(vii)Compound section


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AS PER SP-6


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Sectional properties to be known before Designing


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Sectional properties


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TERMINOLOGY


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TERMINOLOGY

Refer IS 800 for many terms used in steel structural design.

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STAGES IN DESIGN


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Initially in the first stage the architect plans and prepares the layout to suit the clients needs and then the structural engineer designs the structure based on the loads. In the second stage, the structural arrangment is then analysed.

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STAGES IN DESIGNING STEEL STRUCTURE


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DESIGN METHODS


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CHARACTERISTIC LOADS


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PARTIAL SAFETY FACTOR


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IS 800, TABLE 4, PAGE-29


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CHARACTERISTIC STRENGTH


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Design Strength as in IS 800


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DESIGN STRENGTH


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FACTORS AFFECTING ULTIMATE STRENGTH


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LIMIT STATE OF SERVICEABILITY


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DEFLECTION LIMITS

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DEFLECTION LIMITS


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OTHER LIMIT STATE OF SERVICEABILITY


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DEAD LOAD


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LIVE LOAD


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WEIGHTS OF BUILDING MATERIAL


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LIVE LOAD ON FLOOR


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LIVE LOAD ON ROOFS


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LIVE LOAD


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IS 875 PART-1 TO 5 CODE FOR DESIGN LOADS


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LIVE LOAD IMPACT AND VIBRATION


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Given in IS 875


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LIVE LOAD


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Given in IS 875

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Given in IS 875

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GANTRY GIRDER


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GANTRY GIRDER


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GANTRY GIRDER


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IMPACT ALLOWANCE FOR CRANE GIRDER


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Gantry Girders are subjected to the following loads

1)Vibration 2)Shock From Slipping Or Slings 3)Kinetic Action Of Accleration And Retardation 4)Impact Of Wheel Loads

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CRANE LOAD


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CRANE LOAD COMBINATION


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LOADS ON GANTRY GIRDER


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LATERAL SURGE


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TRACTIVE FORCE IN GANTRY GIRDER


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TRACTIVE FORCE


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IMPACT ALLOWANCE FOR LIFTING,HOISTING AND MACHINERY


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EFFECT OF WIND LOAD


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STRESSES DUE TO WIND LOAD


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STESSES DUE TO WIND LOAD IN COOLING TOWERS (CONCRETE STRUCTURE)


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WIND LOAD ON TOWERS


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WIND LOAD


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IS 875 FOR WIND LOAD


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SOFWARES FOR STEEL DESIGN


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End of introduction


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design of steel structures presentation of lecturenotes

Documents

structural steel design

steel members

reason steel

construction material

steel code of practice

structures metal

concrete structures

civil engineering