Basic requirements of structural analysis & design

1. BASIC REQUIREMENTS OFBASIC REQUIREMENTS OF
STRUCTURAL ANALYSIS & DESIGNSSTRUCTURAL ANALYSIS & DESIGNS
GOODGOOD MORNINGMORNING

2. It is very essential for aIt is very essential for a
structural engineer to know thestructural engineer to know the
basic requirements beforebasic requirements before
going for the Structuralgoing for the Structural
Analysis and DesignAnalysis and Design..

3. What is AnalysisWhat is Analysis? : It is to analyse the? : It is to analyse the
behaviour of a structure for its functioningbehaviour of a structure for its functioning
for the design period, for the intended usefor the design period, for the intended use
depending up on the purpose and materialsdepending up on the purpose and materials
to be used. All structures are analysed byto be used. All structures are analysed by
the linear elastic theory to calculate internalthe linear elastic theory to calculate internal
actions produced by design loads.actions produced by design loads.
TheThe material strength to be assumed shallmaterial strength to be assumed shall
be characteristics values in thebe characteristics values in the
determination of elastic properties ofdetermination of elastic properties of
members irrespective of the limit statemembers irrespective of the limit state
being considered.being considered.

4. In analysis, mainly BendingIn analysis, mainly Bending
Moment, Shear Force,Moment, Shear Force,
Deformation, Torsion &Deformation, Torsion &
Deflection are computed forDeflection are computed for
design loads & forces.design loads & forces.

5. 4/28/2018 HDBRTS CO. LTD.
WhatWhat isis DesignDesign?? :: ItIt isis toto fixfix thethe sectionsection ofof eacheach
membermember ofof thethe structure,structure, dependingdepending upup onon thethe
characteristicscharacteristics ofof thethe materialsmaterials beingbeing usedused forfor thatthat
member,member, toto resistresist andand sustainsustain thethe BendingBending Moment,Moment,
ShearShear Force,Force, TorsionTorsion && DeflectionDeflection asas computedcomputed byby
AnalysisAnalysis forfor designdesign loadsloads && forcesforces soso thatthat thethe stressstress
developeddeveloped willwill bebe wellwell withinwithin thethe permissiblepermissible
limitslimits..
TheThe designdesign isis donedone inin suchsuch aa wayway thatthat thethe structurestructure
willwill performperform satisfactorilysatisfactorily duringduring itsits designdesign periodperiod
toto sustainsustain allall loadsloads andand deformationsdeformations ofof normalnormal
constructionconstruction andand use,use, andand adequateadequate durabilitydurability &&
resistanceresistance withwith anan appropriateappropriate factorfactor ofof safetysafety..

6. 4/28/2018 HDBRTS CO. LTD.
DesignDesign:: BasicallyBasically wewe havehave threethree methodsmethods ofof designdesign
ofof reinforcedreinforced cementcement concreteconcrete structuresstructures andand
structuralstructural membersmembers..
1.1. WorkingWorking stressstress methodmethod
2.2. UltimateUltimate loadload methodmethod
3.3. LimitLimit statestate methodmethod..
CommonCommon assumptionsassumptions forfor allall thethe threethree areare
 TheThe distributiondistribution ofof strainstrain acrossacross aa sectionsection isis
consideredconsidered asas linearlinear..
 TheThe strengthstrength ofof concreteconcrete inin tensiontension isis usuallyusually
neglectedneglected exceptexcept inin dgndgn.. ofof liquidliquid retainingretaining strsstrs..

7. 4/28/2018 HDBRTS CO. LTD.
DesignDesign::
1.1. WorkingWorking stressstress methodmethod:: StrStr isis analysedanalysed byby
classicalclassical elasticelastic theorytheory.. NoNo attentionattention isis givengiven toto
thethe conditioncondition thatthat arisearise atat thethe timetime ofof collapsecollapse..
TheThe workingworking loadsloads areare fixedfixed byby limitinglimiting thethe
stressstress inin concreteconcrete andand steelsteel toto aa fractionfraction ofof thethe
stressesstresses atat whichwhich thethe materialmaterial failsfails whenwhen testedtested
asas cubescubes && cylinderscylinders forfor concreteconcrete andand barsbars inin
steelsteel.. TheThe ratioratio ofof yieldyield stressstress ofof steelsteel oror thethe
cubecube strengthstrength toto thethe correspondingcorresponding permissiblepermissible
oror workingworking stressstress isis usuallyusually calledcalled factorfactor ofof
safety,safety, whichwhich isis actuallyactually aa stressstress factorfactor ofof safetysafety..

8. 4/28/2018 HDBRTS CO. LTD.
DesignDesign::
22.. UltimateUltimate loadload methodmethod oror loadload factorfactor methodmethod ofof
designdesign::
TheThe ratioratio ofof collapsecollapse loadload toto thethe workingworking loadload knownknown
asas loadload factorfactor whichwhich givesgives exactexact marginmargin ofof safetysafety
againstagainst collapsecollapse.. SinceSince methodmethod usesuses largelarge reservereserve
strengthstrength inin plasticplastic regionregion && ofof ultimateultimate strengthstrength ofof
membermember resultingresulting inin veryvery thinthin andand slenderslender sectionsection..
ThisThis givesgives riserise toto excessiveexcessive deformationsdeformations andand
crackingcracking.. ThisThis methodmethod alsoalso doesdoes notnot taketake intointo
considerationconsideration ofof effectseffects ofof creepcreep andand shrinkageshrinkage andand
doesdoes notnot taketake intointo considerationconsideration ofof serviceabilityserviceability &&
avoidanceavoidance ofof excessiveexcessive deflectiondeflection && crackingcracking..

9. 4/28/2018 HDBRTS CO. LTD.
DesignDesign::
33.. LimitLimit statestate methodmethod ofof designdesign::
 WorkingWorking stressstress methodmethod isis unrealisticunrealistic atat ultimateultimate
statestate ofof collapsecollapse....
 UltimateUltimate loadload methodmethod doesdoes notnot guaranteeguarantee thethe
satisfactorysatisfactory serviceabilityserviceability requirementsrequirements atat serviceservice
loadload..
ThereforeTherefore LimitLimit statestate methodmethod designdesign makesmakes judiciousjudicious
combinationcombination ofof bothboth workingworking stressstress andand ultimateultimate
loadload philosophyphilosophy andand thusthus avoidsavoids aboveabove demeritsdemerits..
TheThe acceptableacceptable limitlimit ofof safetysafety andand serviceabilityserviceability
requirementsrequirements beforebefore failurefailure occursoccurs isis calledcalled “limit“limit
statestate::””

10. 4/28/2018 HDBRTS CO. LTD.
DesignDesign::
33.. LimitLimit statestate methodmethod ofof designdesign::
ThreeThree typestypes ofof limitlimit statesstates areare therethere..
1.1. StrengthStrength limitlimit statestate
2.2. ServiceabilityServiceability limitlimit statestate &&
3.3. DurabilityDurability limitlimit statestate..

11. 4/28/2018 HDBRTS CO. LTD.
BasicBasic requirementsrequirements forfor structuralstructural AnalysisAnalysis::
1)1) TheThe typetype ofof structurestructure..
a.a. BuildingBuilding:: ResidentialResidential // Commercial/PublicCommercial/Public
b.b. BridgeBridge:: CC..D/Minor/MajorD/Minor/Major..
c.c. RoadRoad:: Flexible/Rigid/WhiteFlexible/Rigid/White toppingtopping..
22)) TheThe purposepurpose ofof useuse ofof structurestructure..
a.a. ResidentialResidential-- Individual/Flat/RowIndividual/Flat/Row houseshouses
b.b. CommercialCommercial-- TypeType Business/StorageBusiness/Storage
c.c. Hospital/EducationalHospital/Educational..
d.d. IndustrialIndustrial
e.e. TallTall buildingsbuildings

12. 4/28/2018 HDBRTS CO. LTD.
33)) MaterialsMaterials toto bebe usedused forfor structurestructure..
a.a. ConcreteConcrete..
b.b. SteelSteel..
c.c. WoodWood..
d.d. FibreFibre
e.e. PlasticPlastic etcetc..,,
44)) LocationLocation ofof thethe structurestructure..
a.a. SeismicSeismic zonezone..
b.b. CostalCostal areaarea..
c.c. OtherOther areasareas..--WindWind velocityvelocity..

13. 4/28/2018 HDBRTS CO. LTD.
55)) SoilSoil explorationexploration::
a.a. FoundingFounding stratastrata-- NatureNature andand typetype ofof soilsoil..
b.b. SS..BB..CC withwith respectrespect toto depthdepth..
c.c. TopographyTopography ofof groundground..
d.d. LocationLocation ofof lowlow lyinglying areaarea andand itsits WaterWater tabletable..
Let me emphasize on Structural Analysis &Let me emphasize on Structural Analysis &
Design of Buildings.Design of Buildings.

14. ISIS codescodes::
1)1) ISIS::456456--20002000.. (Plain(Plain && ReinforcedReinforced ConcreteConcrete
CodeCode ofof Practice)Practice)
2)2) ISIS:: 875875--19871987 ,,
PartPart--11––DD..L/StoredL/Stored materialsmaterials unitunit wtwt..
PartPart--22-- ImposedImposed loadsloads..
PartPart--33--WindWind loadsloads..
PartPart--44-- SnowSnow loadsloads..
PartPart--55--SpecialSpecial loadsloads && LoadsLoads combinationscombinations
1)1) ISIS::17861786--19851985--SpecificationSpecification forfor highhigh strengthstrength
deformeddeformed steelsteel barsbars andand wireswires forfor RCCRCC

15. ISIS::43264326-- 19931993-- CodeCode ofof practicepractice forfor EQEQ resistantresistant
designdesign andand constructionconstruction..
ISIS::18931893--20022002-- CriteriaCriteria forfor EQEQ resistantresistant designdesign ofof
structurestructure..
ISIS::1392013920--19931993--DuctileDuctile detailingdetailing ofof RCCRCC StrStr..
SubjectedSubjected toto SeismicSeismic forcesforces.. CodeCode ofof PracticePractice..
ISIS::29502950--(Part(Part--I)I)--19811981--CodeCode ofof PracticePractice forfor DgnDgn &&
ConCon.. OfOf RaftRaft FoundationFoundation..
ISIS::94179417--19891989-- RecommendationsRecommendations forfor weldingwelding coldcold
workedworked barsbars forfor RCCRCC..

16. ISIS::1026210262--20092009-- ConcreteConcrete MixMix ProportioningProportioning ––
GuidelinesGuidelines.. (First(First revision)revision)..
ISIS::29112911 –– 19641964-- DesignDesign ofof PilePile foundationfoundation..
ISIS::800800--19621962-- CodeCode ofof practicepractice forfor useuse ofof StructuralStructural
steelsteel inin generalgeneral buildingbuilding constructionconstruction..
SPSP::3838(S&T)(S&T)--19871987--HandHand bookbook ofof TypifiedTypified designsdesigns forfor
StructuresStructures withwith SteelSteel roofroof TrussesTrusses (With(With andand
withoutwithout cranescranes basedbased onon ISIS Codes)Codes)
ISIS::961961--19621962--HighHigh TensileTensile StructuralStructural SteelSteel
ISIS::20622062--19621962--StructuralStructural Steel(FusionSteel(Fusion weldingwelding
Quality)Quality)..

17. SI UnitsSI Units ((IRC:71IRC:71--1977)1977)
StructuralStructural engineerengineer shouldshould knowknow aboutabout SISI unitsunits..
AsAs aa uniformuniform measurementmeasurement systemsystem allall overover thethe worldworld
SystemeSysteme InternationaleInternationale Units)Units) commonlycommonly calledcalled SISI
unitsunits areare usedused..
ItIt isis easyeasy toto switchswitch overover fromfrom MKSMKS toto SISI unitsunits ratherrather
thanthan FPSFPS toto MKSMKS..
TheThe basebase unitunit ofof lengthlength isis mm whichwhich togethertogether withwith thethe
millimetremillimetre (mm)(mm) isis extensivelyextensively usedused inin geometricalgeometrical
quantitiesquantities..

18. 28/04/2018
SI UnitsSI Units –– ComtiComti................
TheThe basicbasic unitunit ofof massmass isis thethe kilogramkilogram (kg)(kg) shouldshould
notnot bebe confusedconfused withwith oldold metricmetric forceforce kgfkgf..
MaterialMaterial quantitiesquantities areare measuredmeasured inin massmass unitsunits
ratherrather thanthan inin weightweight oror forceforce unitsunits.. ThusThus
MassMass /length/length forfor steelsteel beambeam isis kg/mkg/m..
GravityGravity floorfloor loadingloading isis kg/mkg/m22..
MassMass ofof anan objectobject isis kgkg..
MassMass densitydensity isis kg/mkg/m33
InIn contrastcontrast toto weightweight units,units, thesethese quantitiesquantities dodo notnot

19. 4/28/2018 HDBRTS CO. LTD.
SI UnitsSI Units-- Conti.......Conti.......
DependDepend uponupon accelerationacceleration duedue toto gravitygravity.. WeightWeight isis
notnot directlydirectly usedused inin SISI system,system, butbut forceforce isis
obviouslyobviously causedcaused byby gravitygravity onon massmass..
OnOn earthearth weightweight isis aa forceforce measuredmeasured inin NewtonNewton..
ObjectObject withwith massmass ofof 11 kgkg isis measuredmeasured asas 1010 NN..
11 NN isis forceforce requiredrequired toto givegive 11kgkg ofof massmass 11m/sm/s22
accelerationacceleration..
ThusThus 11NN isis 11kgkg..m/sm/s22.. NewtonNewton isis derivedderived unitunit andand
independentindependent ofof accelerationacceleration duedue toto gravitygravity

20. 4/28/2018 HDBRTS CO. LTD.
SI UnitsSI Units--Conti......Conti......
AA kilokilo NewtonNewton ((10001000N)N) oror kNkN isis aboutabout 100100kgfkgf..
ApproximatingApproximating thethe accelerationacceleration duedue toto gravitygravity
((99..8066580665m/sm/s22)) toto 99..8181m/sm/s22,, aa kgkg ofof massmass exertsexerts aa
forceforce ofof 99..8181NN onon itsits supportsupport pointpoint..
TheThe stressstress unitunit isis N/mN/m22 calledcalled PaPa.. (Pascal)(Pascal)
ThusThus 11kg/cmkg/cm22approximatesapproximates toto 9810098100PaPa
ForFor practicalpractical inin SISI unitunit withwith prefixprefix (k(k oror M)M) isis usedused..
ForFor convenientconvenient 10000001000000 PaPa oror MPaMPa isis usedused whichwhich
isis identicalidentical toto ==11 N/mmN/mm22

21. 4/28/2018 HDBRTS CO. LTD.
SI UnitsSI Units--Conti........Conti........
For example :
D.L of slab with unit wt. (density) of 2500kg/m3
Th. Of slab = 0.15 m
D.L of slab /m2 = 0.15 x 2500 = 375 kg/m2
= 375x10 N/m
= 3750 N/m2
= (3750/1000 )kN/m2
= 3.75 kN/m2
Simple form is 0.15 x 25.00 = 3.75kN/m2

22. SI UnitsSI Units--Conti.......Conti.......
SurfaceSurface loadingsloadings andand SoilSoil pressurepressure areare measuredmeasured inin
termsterms ofof kNkN/m/m22
MomentMoment isis expressedexpressed inin NN..mm oror kNkN..mm
TempTemp.. InIn SISI unitunit isis KelvinKelvin (K)(K) degree,degree, CelsiusCelsius isis
alsoalso usedused asas theythey areare equalequal inin temptemp.. ChnagesChnages..
IncrementIncrement ofof 11ooCC isis equalequal toto 11 KK
EnergyEnergy isis expressedexpressed asas JoulesJoules.. EqualEqual toto NN..mm &&
PowerPower isis expressedexpressed inin wattswatts (W)(W) equalequal toto
11Jouel/secJouel/sec (J/s)(J/s)..

23. SI UnitsSI Units--Conti........Conti........
Force/Load/WeightForce/Load/Weight 11 kgfkgf ==99..8066580665NN
Force/Load/Weight/unitForce/Load/Weight/unit lengthlength 11kgf/m=kgf/m=99..8066580665N/mN/m
Force/Load/WeightForce/Load/Weight 11tf/mtf/m == 99..8066580665 xx 1000010000 NN
oror 99..8066580665x(x(1000010000//1000010000)) kNkN
UnitUnit weightweight kgfkgf/m/m33 == 99..8065580655N/mN/m33
Stress/Pressure/Modulus ofStress/Pressure/Modulus of
elasticity=1kgf/melasticity=1kgf/m22=9.81N/m=9.81N/m22=9.81 Pa=9.81 Pa
Moment of force 1kgf.m = 9.81Moment of force 1kgf.m = 9.81 N.mN.m

24. 28/04/2018
What is characteristic strength of concrete?What is characteristic strength of concrete?
It is defined as the strength of material below which notIt is defined as the strength of material below which not
more than 5% of test results are expected to fall.more than 5% of test results are expected to fall.
What is “characteristic load”What is “characteristic load” –– It means the value of loadIt means the value of load
which has 95% probability of not exceeding during thewhich has 95% probability of not exceeding during the
life of structure.life of structure.
D.L Shall be calculated based on unit wt. Of materials:D.L Shall be calculated based on unit wt. Of materials:
For Plain concrete as 24kN/mFor Plain concrete as 24kN/m33 and R.C.C =25kN/mand R.C.C =25kN/m33

25. 28/04/2018
We should know the characteristic strength of concreteWe should know the characteristic strength of concrete
Group Grade designation Specified Ch.Compressive strength of
150 mm cube at
28 days.
N/mm2 or MPa
Ordinary Concrete
M10 10
M15 15
M20 20
Standard Concrete
M25 25
M30 30
M35 35
M40 40
M45 45
M50 50
M55 55
High Strength
Concrete
M60 60
M65 65
M70 70
M75 75
M80 80

26. 28/04/2018
What is Yield stress and Ultimate tensile strength.?What is Yield stress and Ultimate tensile strength.?
Yield strength is, by definition, the point after whichYield strength is, by definition, the point after which
the material begins to deform plastically,the material begins to deform plastically,
whereas the tensile strength is the short for ultimatewhereas the tensile strength is the short for ultimate
tensile strength (UTS) that is the maximum stresstensile strength (UTS) that is the maximum stress
that the material can withstand.that the material can withstand.
These are denoted by following stressThese are denoted by following stress--strain diagram.strain diagram.

27. 28/04/2018

28. 28/04/2018
What isWhat is Stress, Strain & Modulus of elasticity or elasticStress, Strain & Modulus of elasticity or elastic
modulus?modulus?
Stress is the internal force per unit area or Load/Area,Stress is the internal force per unit area or Load/Area,
Strain is the relative change in shape / sizeStrain is the relative change in shape / size
(Volume/Length) to its original shape and has no(Volume/Length) to its original shape and has no
unit. (unit. (L1/Lo orL1/Lo or V1/Vo)V1/Vo)
Modulus of elasticity is Stress/Strain.Modulus of elasticity is Stress/Strain.

29. 28/04/2018
PARTPART --66 StructuralStructural DesignDesign (NBC)(NBC)
DD..LL-- ShallShall comprisecomprise thethe wtwt.. ofof allall walls,walls, portions,portions,
floors,floors, roofsroofs andand shallshall includeinclude wtwt.. ofof allall permanentpermanent
structuresstructures inin aa buildingbuilding..
ImposedImposed (Live)(Live) LoadsLoads:: AssumedAssumed loadsloads producedproduced byby
intendedintended useuse oror occupancyoccupancy ofof aa buildingbuilding includingincluding
thethe wtwt.. ofof movablemovable partitions,partitions, distributeddistributed andand
concentrated,concentrated, loadsloads duedue toto impactimpact andand vibrations,vibrations,
andand dustdust loadsloads butbut excludingexcluding wind,wind, seismic,seismic, snow,snow,
andand otherother loadsloads duedue toto temptemp.. changes,changes, creep,creep, shrinkage,shrinkage,
differentialdifferential settlementsettlement..

30. 28/04/2018
PARTPART --6 Structural Design (NBC)6 Structural Design (NBC)
As per Table 1. LL for diff. occupancy: Some majorAs per Table 1. LL for diff. occupancy: Some major
cases.cases.
Occupancy U.D.LOccupancy U.D.L kNkN/m2 Concentrated/m2 Concentrated kNkN/m2/m2
ResiResi-- Rooms 2 .00 1.80Rooms 2 .00 1.80
Corridor/Corridor/ BalconotyBalconoty 3.00 4.503.00 4.50
Store room (Comm.) 5.00 4.50Store room (Comm.) 5.00 4.50
Restaurant 4.00 2.70Restaurant 4.00 2.70
Garage(up to 40t) 5.00 9.00Garage(up to 40t) 5.00 9.00
Libraries (2.20m ht.) 6.00 4.50Libraries (2.20m ht.) 6.00 4.50
2kN/m2 for every 1m above 2.20m2kN/m2 for every 1m above 2.20m
Whole sale shop 6.00 4.50Whole sale shop 6.00 4.50

31. 28/04/2018
PARTPART --6 Structural Design (NBC)6 Structural Design (NBC)
L.L shall be increased for Impact loads:L.L shall be increased for Impact loads:
For frames supporting Lifts and HoistsFor frames supporting Lifts and Hoists –– 100%100%
ForFor foundnfoundn, footings & piers, footings & piers ––dodo-- -- 40%40%
For supportingFor supporting StrStr && FoundnFoundn
for light machinery or motor unitsfor light machinery or motor units -- --
20%20%
For supportingFor supporting StrStr && FoundnFoundn
for reciprocating machinery or power unitsfor reciprocating machinery or power units ––
50%50%
Allowance for Crane GirdersAllowance for Crane Girders –– Clause 3.6.3Clause 3.6.3

32. 28/04/2018
PARTPART --6 Structural Design (NBC)6 Structural Design (NBC)
Wind load:Wind load:
BijapurBijapur, Belgaum,, Belgaum, BangaluruBangaluru & Mysore& Mysore-- 33m/sec.33m/sec.
JamJam nagarnagar ,, BhujBhuj, Chennai,, Chennai, BhuvaneshwarBhuvaneshwar –– 50m/sec50m/sec
AgartalaAgartala,, AizawlAizawl SilcharSilchar (attached to Bangladesh)(attached to Bangladesh)55m/sec55m/sec
Centre of India , Kashmir,Centre of India , Kashmir, RameshwaramRameshwaram, Madurai, Madurai-- 39m/sec39m/sec
Strong wind >Strong wind > 80km/h80km/h –– Cyclonic stormsCyclonic storms..
Depending on ht. ofDepending on ht. of BldBld and class of building, wind speedand class of building, wind speed
variation is considered as pervariation is considered as per TableTable--5 of NBC Part5 of NBC Part--66
SuctionSuction means pressure less than atmospheric (static) and ismeans pressure less than atmospheric (static) and is
taken away from the str.taken away from the str.

33. 28/04/2018
PARTPART --6 Structural Design (NBC)6 Structural Design (NBC)
SeismeicSeismeic Zones: Based on this Zone factor (Z) is consideredZones: Based on this Zone factor (Z) is considered
for design.for design.
India is divided in to 5 Seismic zones namelyIndia is divided in to 5 Seismic zones namely
ZoneZone--IIII -- BangaluruBangaluru,, ChitradurgaChitradurga,,
Kalaburgi,Kalaburgi,Hydrabad,Hydrabad,MangaloreMangalore,, Mysore,Mysore,
ZoneZone--IIIIII -- BijapuBijapurr,, Agra,AhemdabadAgra,Ahemdabad,, BelgaumBelgaum, Chennai,, Chennai,
DharwadDharwad,, Goa,Goa, KanchipurumKanchipurum, Kanpur,, Kanpur, KarwarKarwar, Mumbai, Mumbai
PunePune,, SolapurSolapur,,
ZoneZone--IVIV -- AmbalaAmbala, Chandigarh, Darjeeling, Delhi,, Chandigarh, Darjeeling, Delhi,
Moradabad,PatnaMoradabad,Patna,, RoorkeeRoorkee,, SimlaSimla,,
ZoneZone--VV --BhujBhuj,, DarbhangaDarbhanga,, GuwahatiGuwahati,, ImphalImphal,, KohimaKohima,,
MandiMandi, Srinagar,, Srinagar, TezpurTezpur,, SadiyaSadiya..

34. 28/04/2018
Deflection criteria.Deflection criteria.
Deflection of a str. Or part thereof shall not beDeflection of a str. Or part thereof shall not be
adversely affect the appearance or efficiency, oradversely affect the appearance or efficiency, or
finishes or partitions. Therefore the deflection shallfinishes or partitions. Therefore the deflection shall
be limited to the following.be limited to the following.
a.a. The final deflection due to all loads, effect of temp.The final deflection due to all loads, effect of temp.
creep, shrinkage measured from as cast level shallcreep, shrinkage measured from as cast level shall
not be more than Span/250.not be more than Span/250.
b.b. The deflection due to temp. creep & shrinkageThe deflection due to temp. creep & shrinkage
occurring after erection of partitions & applicationoccurring after erection of partitions & application
of finishes should not exceed Span/350 or 20mmof finishes should not exceed Span/350 or 20mm
whichever is less.whichever is less.

35. 28/04/2018
Deflection criteria.Deflection criteria.
Basic criteria for vertical deflection by ratio of span to depth shall notBasic criteria for vertical deflection by ratio of span to depth shall not
exceed the following.exceed the following.
a.a. Basic value of span toBasic value of span to effeeffe. depth ratio for spans up to 10m. depth ratio for spans up to 10m
CantileverCantilever –– 77
Simply supportedSimply supported –– 2020
ContinuousContinuous ------2626
b For spans >10m Above to be multiplied by 10/b For spans >10m Above to be multiplied by 10/SapnSapn in m except forin m except for
cantilever (which is to be calculated).cantilever (which is to be calculated).
Depending upon the area and stress of steel the values at a & b shallDepending upon the area and stress of steel the values at a & b shall
be modified by multiplying with modification factor (figbe modified by multiplying with modification factor (fig--4 IS456)4 IS456)
Depending upon the area of compression reinforcement the values atDepending upon the area of compression reinforcement the values at
a & b shall be modified by multiplying with modification factora & b shall be modified by multiplying with modification factor
(fig(fig--5 IS456)5 IS456)

36. 28/04/2018
Design should be done for.Design should be done for.
1)1) D.LD.L
2)2) L.LL.L
3)3) Finishing loads,Finishing loads,
4)4) Wind loadsWind loads
5)5) EQ (Seismic loads/forces)EQ (Seismic loads/forces)
6)6) Effects of shrinkage, creep and temp. shall be takenEffects of shrinkage, creep and temp. shall be taken
in to account as per IS 875 (Partin to account as per IS 875 (Part--5) In ordinary bld.5) In ordinary bld.
Not exceeding 45m laterally these can be ignored.Not exceeding 45m laterally these can be ignored.

37. 28/04/2018
77)) EffectsEffects ofof shrinkage,shrinkage, creepcreep andand temptemp..
shallshall bebe takentaken inin toto accountaccount asas perper ISIS 875875
(Part(Part--55)) InIn ordinaryordinary bldbld.. NotNot exceedingexceeding
4545mm laterallylaterally thesethese cancan bebe ignoredignored..
88)) FoundationFoundation movementsmovements
99)) ElasticElastic axialaxial shorteningshortening..
1010)) SoilSoil andand fluidfluid pressurespressures..
1111)) Vibrations,Vibrations,

38. 28/04/2018
11) Fatigue.11) Fatigue.
12) Impact .12) Impact .
13) Erection loads .13) Erection loads .
14) Stress concentration due to point load14) Stress concentration due to point load
like.like.
15)15)Loads imposed by Rains.Loads imposed by Rains.

39. 28/04/2018
D.L: Wt. of all permanent components of str.D.L: Wt. of all permanent components of str.
Such as beam, column, floors and roof slabs ,Such as beam, column, floors and roof slabs ,
any other loads which have constantany other loads which have constant
magnitude and attached to the str. It canmagnitude and attached to the str. It can
easily be computed.easily be computed.
Imposed loads and forces: These act on aImposed loads and forces: These act on a str.bystr.by
character use of the building. These arecharacter use of the building. These are
a)a) L.L b) Wind load, c) seismic load, d) snowL.L b) Wind load, c) seismic load, d) snow
load, e) loads imposed by rains, f) Soil &load, e) loads imposed by rains, f) Soil &
hydrostatic forces, g) erection loads & h)hydrostatic forces, g) erection loads & h)
Other loads. L.L onOther loads. L.L on bldsblds. And. And brgsbrgs..

40. 28/04/2018
L.L on bridges:L.L on bridges: Class AA, Class A & Class BClass AA, Class A & Class B
Rules of the Ministry of Railways G.O.I. TheRules of the Ministry of Railways G.O.I. The
critical position of moving vehicles or wheelcritical position of moving vehicles or wheel
loadsloads that produce max. forces at various pointsthat produce max. forces at various points
of str.of str.
Wind loadsWind loads: VIP in case of tall: VIP in case of tall strsstrs. & also low. & also low
level lightlevel light strsstrs on costal region. Depends onon costal region. Depends on
shape ofshape of bldbld (Aerodynamic) . Code(Aerodynamic) . Code
recommends same wind pressure up to 10m ht.recommends same wind pressure up to 10m ht.
and then every 5m ht up to 150m. Allowableand then every 5m ht up to 150m. Allowable
stress can be increased by 33 to 50% dependingstress can be increased by 33 to 50% depending
up on the ratio of map values and anyup on the ratio of map values and any
particular area.particular area.

41. 28/04/2018
EarthquakeEarthquake loadsloads:: ItIt isis highlyhighly irregularirregular andand transmitstransmits
randomrandom accelerationacceleration toto strstr.. AndAnd thethe massmass ofof thethe
strstr resistsresists thethe motionmotion duedue toto nertianertia..
TheThe totaltotal inertiainertia ii..ee..,, horizontalhorizontal shearshear atat thethe basebase ofof
thethe strstr rangesranges fromfrom 00..0202 toto 00..1212 WW.. WhileWhile
designingdesigning thethe strstr.. ForFor emergencyemergency reliefrelief stores,stores,
foodfood grasingrasin storage,storage, waerwaer works,works, powerpower stationsstations
“importance“importance factor”factor” shallshall bebe takentaken inin toto accountaccount..
SnowSnow andand RainfallRainfall:: HighestHighest accumulationaccumulation ofof snowsnow
cancan bebe hadhad fromfrom ISIS::875875--19641964.. DueDue toto
accumulationaccumulation waterwater forfor notnot drainingdraining thethe stormstorm
waterwater willwill leadlead toto strstr deflectiondeflection // collapsecollapse

42. 28/04/2018
SoilSoil && HydrostaticHydrostatic forcesforces:: StrStr.. BelowBelow groundground
like,like, foundationfoundation wallwall andand retainingretaining wallswalls
willwill bebe subjectedsubjected toto earthearth pressurepressure andand
hydrostatichydrostatic pressurepressure.. P=P= gg..hh ((gg== unitunit wtwt.. ofof
fluidfluid andand h=hth=ht.. ofof fluidfluid retained)retained)

43. 28/04/2018
WhatWhat isis designdesign loadload::
DesignDesign loadload isis thethe loadload toto bebe takentaken forfor useuse ,, inin
thethe appropriateappropriate methodmethod ofof designdesign.. ItIt isis thethe
characteristiccharacteristic loadload inin casecase workingworking stressstress
methodmethod andand CharacteristicCharacteristic loadload withwith
appropriateappropriate partialpartial safetysafety factorfactor forfor limitlimit
statestate methodmethod ofof deisgndeisgn..

44. 28/04/2018
Slab 15 mm
Walls 15 mm
Beams (main bars) 25mm/dia
Stirrups in beams 15 mm
At end of main bar 25 mm
Columns D up to 200
D > 200
25mm
40 mm /dia
Ties in columns 15 mm
Let us look at some basic aspects.
Minimum Cover to concretete.(For general structures)
( Referance Clause 25 I.S 456 - 2000)

45. 28/04/2018
Mats in footing 50 mm
On prepared earth 75 mm
Chemical industries As above +15 mm > 75 mm
Water retaining structure As above Min 25 mm
Sea shore structures As above + 40 mm > 75
On C.C bed
For easy way of adopting the covers recommended ,
use readily available Cover Blocksreadily available Cover Blocks as U can see
some of the models now.
Contact No., for cover blocks : 94483724699448372469 MrMr PramodPramod ZalakikarZalakikar

46. 28/04/2018 46
Nominal Cover, to meet Durability Requirements based on exposureNominal Cover, to meet Durability Requirements based on exposure
conditionsconditions
Exposure Min. Nominal concrete cover in mm
Mild
Moderate
Sever
Very sever
Extreme
20
30
45
50
75

47. 28/04/2018 47
Min. and Max. reinforcement
Tension Ast.
Compression Asc.
Side reinforcement where web
>750mm
Min &Max. spacing of stirrups
Slab Main
Distribution
Max.&Min dia. of bars
AS
bd
=
0.85
fy
MIN. MAX.
0.04bD
(4%)
0.04bD0.33 Ast
0.1% web
area
0.75 de or
450 mm
0.15% M..S. &
0.12 Tor
1/8th total th. slab8 mm main
To design
2%
80 mm

48. 28/04/2018 48
Minimum thickness of member for fire resistance str.Minimum thickness of member for fire resistance str.
FigFig--1 of IS 4561 of IS 456--20002000
For resistanceFor resistance –– h =0.5 (Expressed in timeh =0.5 (Expressed in time –– hours)hours)
Min beam widthMin beam width --200mm200mm
Min RibMin Rib ---- 125 mm125 mm
MinMin th.ofth.of floor 75 mmfloor 75 mm
Column b or DColumn b or D –– fully exposedfully exposed –– 150 mm150 mm
50% exposed50% exposed –– 125 mm125 mm
One faceOne face esposedesposed-- 100 mm100 mm
Min WallMin Wall thth. 150 p<0.4%, 100mm p=0.4%to1%. 150 p<0.4%, 100mm p=0.4%to1%
100mm p>1%100mm p>1%

49. 28/04/2018 49
SlendernessSlenderness ofof columncolumn::
DefinitionDefinition ofof columncolumn oror strutstrut:: ItIt isis thethe
compressioncompression membermember whosewhose effectiveeffective lengthlength isis
moremore thanthan 33xx leastleast laterallateral dimensiondimension..
SlendernessSlenderness:: TheThe columncolumn isis saidsaid toto bebe slenderslender oror
shortshort columncolumn whenwhen bothboth
lexlex/D/D <<1212
leyley/b</b< 1212

50. 28/04/2018 5050
Development length (Ld) of bars
Ld =
O σs
4 Tcbd
O = Nominal dia of bar
σs = Stress in bar at the section in design
Tc bd = Design bond stress given table 26.2.1.1
of IS 456 - 2000

51. 28/04/2018 5151
Anchorage length of bars
The anchorage length of straight bar in compression shall
be equal to the development length of the bars in
compression
al al
al

52. 28/04/2018 5252
Anchorage length
M15 M20 M25
Tension 50 x d 45 x d 40 x d
Compression 45 x d 40 x d 35 x d
Where d = diameter of the bar

53. 28/04/2018 53
Development length (Ld) of bars (Tor 40) values in
cms
Tension Compression
O in mms M15 M20 M25 M30 M15 M20 M25 M30
6 34 29 25 23 28 24 20 19
8 46 38 33 30 37 31 27 24
10 57 47 41 38 46 38 33 31
12 68 57 49 46 55 46 40 37
16 91 76 65 61 73 61 52 49
20 113 94 81 76 91 76 65 61
25 141 118 101 94 113 95 81 76

54. 28/04/2018 54
SideSide reinforcementreinforcement:: WhenWhen depthdepth ofof webweb
ofof aa beambeam exceedsexceeds 750750 mm,mm, thenthen itit isis
calledcalled deepdeep beambeam.. SoSo sideside
reinforcementreinforcement isis toto bebe providedprovided forfor bothboth
thethe facesfaces ..TheThe totaltotal areaarea ofof whichwhich shallshall
notnot bebe lessless thanthan 00..1010%% ofof thethe webweb areaarea
andand shallshall bebe equallyequally distributeddistributed onon bothboth
thethe sidessides atat spacingspacing notnot exceedingexceeding
300300mmmm oror WebWeb thicknessthickness whicheverwhichever isis
lessless..

55. 28/04/2018 55
LongitudinalLongitudinal reinforcementreinforcement:: TheThe crosscross sectionalsectional
areaarea ofof whichwhich shallshall notnot bebe lessless thanthan
00..88%% oror moremore thanthan 66%% ofof grossgross crosscross sectionsection
areaarea ofof columncolumn..
MinMin barsbars:: forfor rectangularrectangular columncolumn 1212 TorTor 44 NoNo..ss
ForFor roundround columncolumn –– 66 NoNo..ss equallyequally placedplaced alongalong
thethe peripheryperiphery ofof columncolumn..
SpacingSpacing ofof barsbars alongalong peripheryperiphery ofof columncolumn << 300300
InIn casecase ofof pedestalspedestals longlong.. ReinforcementReinforcement shallshall notnot
bebe lessless thanthan 00..1515%% ofof c/sc/s areaarea..

56. 28/04/2018 56
ExpansionExpansion jointsjoints::
1.1. TheThe strstr.. InIn whichwhich abruptabrupt changeschanges inin
dimensionsdimensions shallshall bebe providedprovided withwith expnexpn jointjoint..
2.2. TheThe strstr.. AdjancentAdjancent toto expnexpn.. JointJoint shallshall bebe
preferablypreferably supportedsupported onon separateseparate colncoln.. OrOr
wallwall..
3.3. ReinforcementReinforcement shallshall notnot extendextend acrossacross jointjoint..
4.4. NormallyNormally strstr.. ExceedingExceeding 4545mm lengthlength areare
designeddesigned withwith oneone oror moremore expnexpn.. JointJoint..
5.5. ISIS;;34143414 givesgives dgndgn dertailsdertails ofof expnexpn..jointjoint..

57. 28/04/2018 57
InIn casecase ofof designdesign ofof aa simplysimply supportedsupported beambeam::
66..0000 mm spanspan.. WithWith UDLUDL ofof 2020kN/m,kN/m,
GradeGrade ofof concreteconcrete-- MM2020 && SteelSteel gradegrade FeFe 415415
WorkingWorking StressStress MethodMethod:: ExampleExample
BB..MM == WlWl22//88 ==9090kNkN--mm
σσstst==230230N/mmN/mm22 ((00..5555xx415415==228228..2525 SaySay 230230))
6.00 m
20kN/m m

58. 28/04/2018 58
WorkingWorking StressStress MethodMethod:: ExampleExample
σσ cbccbc == 77N/mmN/mm22
mm == 280280//33xx σσ cbccbc ==11..3333
k=mk=m σσ cbccbc // ((σσ cbccbc ++σσstst)) == 22..2929
j=j=11--k/k/33 == 00..99
Q=Q=11//22xx σσ cbccbc xx kxjkxj ==00..9191
EffectiveEffective depthdepth dd == √M/√M/QbQb ==655655..7474 mmmm
SaySay D=D=700700mmmm usingusing 1616 TorTor
d=d=700700--2525--1616//22==667667mmmm
AstAst=M/=M/σσstst xx jj xx dd ==651651..88 mmmm22 ii..ee,, 1616Tor/Tor/44 No,sNo,s

59. 28/04/2018 59
LimitLimit StateState MethodMethod:: SameSame exampleexample::
M=M=9090 kNkN--mm MuMu == 9090 xx 11..5050==135135 kNkN--mm
(M=(M=00..138138 xx ffckck xx bb dd22))
d=d= √√ M/M/00..138138 xx ffckck xx bb == 461461..1515 mmmm
SaySay D=D=500500mmmm usingusing 1616Tor/Tor/44 NoNo..
d=d=500500--2525--((1616//22)) == 467467 mmmm
AstAst == 00..55 xx ffckck//ffyy 11--√√11--((44..66Mu/(Mu/(ffckck xx bb xx d))d)) bb xx dd
== 990990 mmmm22 ii..ee..,, 1616 Tor/Tor/55 NoNo..

60. Thank You
Er.V.H.Jadhav
28/04/2018