STEEL

I welcome to the limit state design of steel structure class the limit state design

of steel structure has been introduced in our Indian code in 2007 before that we use

to design the steel structure by the use of working this method and from 2007 onwards

the coder provision has been changed and in 2007 the IS 800-2007 has been published

where the entire code has been discussed on the basis of limit state design method

Now coming to this course actually this today I will discuss about the probable content

of the course which I am going to cover in next 60 lectures and the what are

the books you can follow that I will I will inform and what are the code require for

learning this course all also will be told today and also I will show you some uhh steel

rolled section What are their property have the parameters are vary and means (what) how

the parameters are considered Which parameters are considered Uhh which are given in the

uhh IS handbook that SP-6 uhh that also I will just give you touch on that right

Now coming to the limit state design of steel structure one thing we can say that nowadays

in every city or every country uhh whenever you see some These are mostly built with the

steel Steel has lot of advantages which I will come later uhh and because of its advantageous

uhh properties uhh (we) the designer prefer for uhh designing the structure with the steel

and steel structures are means steel are massively used particularly in uhh bridge structure

and also in transmission tower refinery well structure in sometimes some water tank also

are made of steel structure some high buildings uhh many industrial buildings uhh all are

made of steel structure and steel you know that uhh it is much stronger than compared

to uhh the conventional constructional material like concrete uhh compared to its high means

strength to weight this is very uhh high means its weight its very less and strength is very

high It is much ductile compared to concrete and because of its advantages for its means

properties Uhh designer prefers steel structure though it is costly So if we design properly in a

cost effective way the cost can be minimized without compromising the safety Uhh therefore

we need to know the design procedure properly and may be in later uhh by knowing the design

procedure we can make uhh computer code uhh we can generate some computer algorithm uhh

by the use of mat lab or any other uhh standard language like C language C plus plus java

or we can use excel sheet also uhh then in steel design you will see uhh when we are

going to design we have to iterate it we need to iterate it Uhh the design process means

we will assume certain uhh member with certain dimensions and we will check certain uhh checks

uhh from limit state point of view from ultimate strength point of view from serviceability

criteria point of view We will check certain steps and if we see the checks are not satisfying then we have

to increase the size and if we see it is satisfying then we can go for this particular section

but what happens uhh that uhh while we do for iteration In case of limit state design

there are lot of uhh procedures uhh means procedures or calculations are there So it is very difficult to do by hand manual calculation So if you can develop uhh computer algorithm

of if you can develop an excel sheet then just by putting the value you can check whether

it is okay or not and in some cases we have seen that when designer is saying that uhh

the assume section is okay then they have simply going with that session but that is not economic because may be with some laser section the same uhh with same loading it

may be safe So we must go for the laser section so sometime designer does not want because uhh lot of

calculations have to be done It is a tedious process So I will suggest you that if you

know the design algorithm if you understand the design process of a particular member

then you make a customize program at your own requirement and then go for the uhh this

program for design of the section and in that way you can make that design optimized economic

and cost effective Now coming to the uhh anatomy of the structure we will see that any steel structures are

having uhh these type of uhh members like one is beam Beam is basically a flexural member

where the flexural come into picture So we need to know the design of a flexural flexible

member of the beam then it will come the column Column also uhh takes column takes basically

the compressive load uhh along with that certain certain excentive load also it takes care

so sometimes moment also come into picture uhh that column has to be design accordingly

So we will go through that column Floor basically carries the load and that load is transferred to the beam and column

uhh then bracing system is an important system in case of uhh uhh steel structure because

you see here if we see these are the bracings Uhh bracings has been provided just to increase

the load carrying capacity in terms of horizontal load when horizontal load is moved the we

can provide certain bracing in certain places so that the system became uhh became stronger

Now all the super structural load are going to the foundation so we need to know the foundation

design also So there in foundation we will see the slab base gusset base base plate and

how the load from the super structure has been transferred to the sub-structure by the

use of base plate and uhh other members that we will see and another important part we

we do not generally come across in case of RCC structure that is connection Uhh these connections is important editions we know the (rule) rolled steel sections are

available or some other type of sections also can be made available in terms of built up

section etcetera but uhh it need to be joint properly So joint means basically joining

of uhh beam and column beam and column when you are going to join you have to join either

by the use of bolt rivet or weld connection So in in fact when I will be going to teach this subject so first I will discuss about

the connection because if we know connection then we can go the further things and in uhh

design means in steel design as a whole connection plays a very important role we do not give

much importance to the connection though but uhh we have to make detailing means I I would

go I will recommend that when we are going to do design a entire system we have to specially

look for the connections and we have to design connections properly so that load is transfer

from one system to another system one member to another member properly uhh sometimes moment

also has to be transfer sometimes only axial force So on the basis of the requirement we

have to uhh decide what type of connections will be going for

So syllabus which I am going to cover uhh I am briefly discussing but it is a tentative

because I do not know how much time I will get to finish uhh so first module will be

including the introduction and which we will discuss about steel uhh member means steel

material as a structural material and we will discuss its advantages and disadvantages of

the steel because unless we know the disadvantages of steel we will not make uhh use properly

So we must know the advantages and disadvantages and accordingly which we should try to use

that then we will go for different types of sections I S rolled sections which are available

in the market those and their properties are given in the code that we will see then we

will go for some material overview means how the steel behaves uhh with uhh increase of

load means how stress strain varies in case of steel and how the chemical properties uhh

deep mean how chemical properties uhh means how the mechanical properties are dependent

on chemical properties of the steel that we will discuss then basis for structural design

will be discuss means what type of structural design we are going for uhh in this course

that we will discuss that is the limit state method and what are the basis of design of

that structural philosophy that will be discussed and a course loading and load combination

Different types of loads come into picture those we will be discuss briefly and their combinations then we will come to the module 2 which is comprising of connections So different

type of connections we will discuss and in that connection we will discuss about the bolted connections its advantages and disadvantages uhh then design of bolted connections its

efficiency and design of joints then welded connections advantages and disadvantages of

welded joints design of weld connections fillet weld butt or group weld plug and slot weld

So these are the topics uhh probable topics I am going to cover

Then in next module we will discuss about the eccentric connections because sometimes connections uhh become eccentric in terms of its loading So uhh different type of eccentric

connections are uhh observed so we will discuss about that then bolt and welded connection

uhh with load lying in plane of joint and load lying perpendicular to the plane of joint

Different type of means two type of eccentric and connections are observe one is load lying in plane of joint and load lying perpendicular to the plane of joint

Then we will discuss about the design of eccentric connection using bolts and weld that mens uhh sometimes we will use bolt and we will see how the design procedure is uhh is proposed

and also same thing for weld connections and in module 4 we will discuss about the design

of tension members In tension member we will first come into different type of failures

mean in case of tension member what are the failures occurs that we will see then we will

find out the gross and net sectional area then rupture of critical section then strength

calculation block shear failure uhh then slenderness ratio of the member and then we will come

to design of tension members considering all this and then gusset plates lug angle tension

splices uhh design of tension members subjected to axial and bending those things will be

discussed So tension member we will means in this module we will cover these aspects

In module 5 we will discuss about the compression member In compression member first we will

see what are the type of failure occurs in case of compression member and accordingly the uhh strength calculation will discuss and then slenderness ratio of the compression

member how to calculate we will find out and then design of the compression member and

then design of eccentrically loaded compression member that means when moment also will come into picture then how to design the compression member that will be discuss

Then built-up compression member means sometimes uhh the rolled steel section is not sufficient

for uhh withstanding the huge amount of load So in that case we will go for built-up compression

member and that is design procedure also will be discussed for the built-up compression

member then for built-up compression member we need to add the lacing systems So design

of lacing system and design of batten plates will also be discussed in this module

And in module 6 we will discuss about the flexural member which is called basically beam So we will give you some introduction to flexural member and then design procedure

of beam uhh and beam will be basically two types one is uhh design of laterally supported

beam and laterally un-supported beam So both the cases design uhh procedure will be discussed

considering laterally supported and laterally un-supported beam and also will be discuss about the built-up beams and uhh design of purlins also will be introduced in this module

Then we will come to column base column base we will be discuss basically base slab and

and this gusseted base So slab base and gusseted base which are uhh which are the element through

which the super structure load will be coming to the soil to the sub-structure So uhh design

of the gusseted base and slab base along with base plate will be discussed here and if we

get time then we will discuss about the gantry girder because in steel structure gantry girder

is an important component uhh which we need to know and design and the codal aspects are

available on design criteria on gantry girder So in last module we will discuss about the

design aspects of gantry girder mean various type of loads will be there So what are the

loads coming into gantry girder and how to design the gantry girder will be discussed

Now I would suggest to follow along with my lecture these two books These books are very

well written uhh one book is design of steel structure written by Dr Subramanian Narayanan

who has directly involved with the development of I S 800 2007 code So he has written this

book which is uhh very exostively written and well means well documented and another

book also you can follow that is written by S K Duggal it is Tata McGraw Hill publication

limit state design of steel structure and the first book was published by Oxford publication

So there than these two books you can follow some other books also if you want uhh but

I have seen many books are available in which design calculations are not given properly

but in these two books will means you can follow and we can get properly the design

calculation and procedures and very well documented in a simplified manner it is written so you

can follow this you can go for some reference also uhh like design of steel structure by

Elias Abu-Saba uhh this is CBS publication this also you can use as a reference book

Then design of steel structure by E H Gaylord at all by McGraw Hill and structural steel

work by S S Ray Blackwell science So as a reference books you can follow however I will

suggest you to at least follow one text book which has been suggested in earlier in earlier slide that si either uhh Dr subramananyns book or S K Duggals book

Now these codes are require while uhh we learn the design of steel structure first is that

uhh earlier code words IS: 800 1984 which is based on working this method Now the coder

provision has been changed and uhh in IS 800-2007 the code of practice for general construction

in steel has been given in which the limit state design method has been followed Uhh

so when you follow my lecture I will suggest you to uhh see to with the this code because

lot of codal permissions are there which has to be follow and while listening my lecture

uhh if you follow the codes and if you open the code also at the same time it will be

easier to understand uhh the lecture and it is easier to under means follow the code also

and uhh we have a handbook that is SP 6(1)-1964 handbook for structural engineers where the

uhh indian steel rolled section properties are given Uhh all the standard rolled section properties like ISMB means I section channel section

T section angle sections uhh so all the rolled sections properties are given in that IS handbook

So we should follow that also and also we can follow this IS 808-1989 where certain

properties are given certain properties of uhh steel load section and also you can use

steel table of any standard publication where the properties are given right Other than

that I will suggest you to follow this code of practice for design loads other than earthquake

for building and structure that is IS 875- part I to part V I will come uhh come with

this code in details later and also IRC code vehicle load in bridge structure may be useful

apart from this for seismic consideration IS 1893-2002 also will be you can use

Now coming to rolled steel section I have told that different type of rolled sections

are available in the market and their properties are given in IS handbook in SP-6 so like here

I have shown that indian standard junior beam which is termed as JB also uhh sorry So Indian

standard junior beam ISJB uhh Indian standard light beam ISLB or LB and Indian standard

medium weight beam that is available Indian standard wide flange beam So different type

of I sections are available in the code Indian standard heavy weight beam ISHB Indian standard

column section SC like this you will get uhh like

Now say I section what I was discuss that uhh I will discussing that ISMB ISLV ISJB

so in all this beam section or I section uhh this looks like this if you see it is uhh

we have a slop here and we have curve here uhh so that the stress concentration does

not develop here and also here also you have curve Now uhh the overall depth of I section

is called D in the SP-6 the properties of I sections are given in terms of say suppose

if you say ISMB uhh 250 that means it will effect to a particular I section of medium

beam ISMB the 250 means the overall depth of the will be 250 right So D will be 250

overall depth Now if this 250 depth of beam is uhh means if you select then automatically you will

find what will be the width of the flange This portion is called flange and uhh this

width of flange is called b and sometimes we call bf also b or bf and this is the portion

of OF and this OF thickness is called t regeneration tw tw (we) you have to call Now what will

be the thickness of flange Thickness of flange vary from here to here if you see here thickness

of flange is much higher than this place So thickness of flange is measure at b minus

t by 4 distance that means this is total b this is t so b minus t by 2 is this this distance

and middle of that is the b minus t by 4 t is the tw thickness of width so at that position

we find the thickness of the flange either capital T we mention as T of tf also we call

tf also So if you see in the SP-6 the properties of I section then can find out uhh suppose if

it is ISMB 250 then its depth is 250 its width its cross sectional area and the geometrical

properties everything is mentioned there not only the geometrical properties but also the

say suppose Ixx Iyy that means moment of inertia about xx abut yy and then we can find out

Rxx means radius of direction about x direction about y direction so all the details then

z section modulus uhh Ze Zp those things also you will find out then what will be that gauge

distance uhh between these two means where the bolt uhh bolt or rivet will be placed

So that gauge distance also uhh standard for particular section so all the relevant properties

you can find pout from that code right

So this is another section which is called as channel section This channel section are

mainly used for uhh column this channel sections are used so Indian standard junior channel

ISJC Similarly ISLC Indian standard light channel Indian standard medium weight channel

ISMC like these channel sections are available in the code also So here also ISMC 400 means

the depth D will be 400 ISMC 400 means the depth will be 400 overall depth will be 400

So once depth 400 other properties are uhh given in the SP-6

So this is the bf this this is called bf width of the flange bf and this is tf or T that

is b minus t by 2 at B minus t by 2 that is defined and T is basically tw thickness of

web then what will be the radius of curvature here means R1 and this is R2 that also are

standard that is given it Then Cxx Cyy that also Cxx means this is Cyy this is Cyy and

uhh this is Cyy and uhh this is means D by 2 right and so these are the properties flange

slop alpha will be this so these are the standard property which are given in the code and it

looks something like this and in the code means actually in place of XX it is written

ZZ means Izz Rzz and this important yy this is how uhh it will be consider

This is angle section angle sections are of 2 types one is uhh Indian standard equal angle

and another is Indian standard unequal angles Equal angle means its leg is leg length will

be same Here Indian standard equal angle the both the leg length will be same but if it

is unequal then it is unequal angle So standard writing is ISA 90 by 90 by 6 that means the

length of the leg is 90 in this also it is 90 and thickness of the leg is 6 mm and of

course uhh also we find out all other properties uhh of the angle section which is shown here

So if you see uhh in the codal provisions angle sections are given like uhh this is

root radius R1 this is toe radius R2 these are also standard and uhh Cxx Cyy that means

uhh center of gravity in x and y then what will be the Ixx Iyy IUU means in major axis

minor axis IBB so Rxx Ryy RBB RUU all these properties are given which will be required

for calculation of different stresses on the section So for designing of the uhh member

using angle section we need different properties geometrical property which are available in the SP-6

This is another section which is called section Indian standard normal Tee section and uhh

here also in case of T section the total h is the depth and uhh other details I am not

going in details you can find out in the code This is rolled steel bar Indian standard round

section ISRO is called and Indian standard square section This is square bar uhh so this

type of bars are also available and which can be used for design of different type of

members Then uhh suppose ISRO 100 in rolled steel section if you see ISRO100 that means

it is a round section of diameter 100 round section of diameter 100 again ISSQ50 means it is a square section of each side 50 mm ISSQ 50 means this is square section of 50

mm So this is how it is designated Then rolled steel sheet and strips are also used those are also available Indian Indian

standards steel sheet section Indian standard steel sheet section and Indian standards steel

strip section okay So if uhh actually if we write 50 FT that means a flat of 50 mete 50

millimeter width and 8 mm thickness are used So this is how letter F uhh means width and

uhh and sorry uhh this thickness and width are defined in this way 50 F 8

Then square hollow section this also uhh are used

So this square hollow section and hollow pipe sections are also used in design of steel

members So in this first lecture what we could see is that Indian uhh rolled sections are

available steel rolled sections are available uhh and its geometrical properties are given

in SP-6 which will be frequently used for design of uhh structural members right So

uhh with this I will have to conclude todays lecture next day we will discuss about the

uhh material properties of the steel and its advantages and other details thank y