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Chapter 1
DEFINITIONS AND GENERAL EQUIREMENTS1.1 INTRODUCTION1.1.1 SCOPEThe definitions providing meanings of different terms and general requirements for the structural design of
buildings,structures,andcomponents thereofarespecified in this chapter.Theserequirementsshall applytoall
buildings and structuresor their componentsregulated bythis code. All anticipated loadsrequired for structural
design shall be determined in accordance with the provisions of Chapter 2. Design parameters required for the
structuraldesignoffoundationelementsshallconformtotheprovisionsofChapter3.Designofstructuralmembers
usingvariousconstructionmaterialsshall comply withthe relevantprovisionsof Chapters 4through13.The FPS
equivalentsoftheempiricalexpressionsusedthroughoutPart6arelistedinAppendixA.
ThisCodeshallgoverninallmatterspertainingtodesign,construction,andmaterialpropertieswhereverthisCode
is in conflict with requirements contained in other standards referenced in this Code. However, in special cases
wherethedesignofastructureoritscomponentscannotbecoveredbytheprovisionsofthiscode,otherrelevant
internationallyacceptedcodesreferredinthiscodemaybeused.
1.1.2 DEFINITIONSThefollowingdefinitionsshallprovidethemeaningofcertaintermsusedinthischapter.
BASESHEAR:Totaldesignlateralforceorshearatthebaseofastructure.
BASIC WIND SPEED : Threesecond gust speed at 10 metres above the mean ground level in terrain ExposureB
definedinSec2.4.8andassociatedwithanannualprobabilityofoccurrenceof0.02.
BEARINGWALLSYSTEM:Astructuralsystemwithoutacompleteverticalloadcarryingspaceframe.
BRACEDFRAME:Anessentiallyverticaltrusssystemoftheconcentricoreccentrictypewhichisprovidedtoresist
lateralforces.
BUILDINGFRAMESYSTEM:Anessentiallycompletespaceframewhichprovidessupportforloads.
CONCENTRICBRACEDFRAME(CBF):AsteelbracedframedesignedinconformancewithSec10.20.13.or10.20.14.
COLLECTOR : A member or element used to transfer lateral forces from a portion of a structure to the vertical
elementsofthelateralforceresistingelements.
BUILDINGS:Structuresthatencloseaspaceandareusedforvariousoccupancies.
DEADLOAD:Theloadduetotheweightofallpermanentstructuralandnonstructuralcomponentsofabuildingor
astructure,suchaswalls,floors,roofsandfixedserviceequipment.
DIAPHRAGM : A horizontal or nearly horizontal system acting to transmit lateral forces to the vertical resisting
elements.Theterm"diaphragm"includeshorizontal bracingsystems.
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DUALSYSTEM:AcombinationofMomentResistingFramesandShearWallsorBracedFramestoresistlateralloads
designedinaccordancewiththecriteriaofSec1.3.2.
ECCENTRICBRACEDFRAME(EBF):AsteelbracedframedesignedinconformancewithSec10.20.15.
HORIZONTAL BRACING SYSTEM : A horizontal truss system that serves the same function as a floor or roof
diaphragm.
INTERMEDIATE MOMENT RESISTINGFRAME (IMRF) :A concrete momentresisting frame designed in accordance
withSec8.3.10.
LIVELOAD:Theloadsuperimposedbytheuseandoccupancyofabuilding.
MOMENT RESISTING FRAME : A frame in which members andjoints are capable of resisting forces primarily by
flexure.
ORDINARY MOMENT RESISTING FRAME (OMRF) : A moment resisting frame not meeting special detailing
requirementsforductilebehaviour.
PRIMARYFRAMINGSYSTEM:Thatpartofthestructuralsystemassignedtoresistlateralforces.
SHEARWALL:Awalldesignedtoresist lateralforcesparalleltotheplaneofthewall(sometimesreferredtoasa
verticaldiaphragmorastructuralwall).
SLENDER BUILDINGS AND STRUCTURES : Buildings and structures having a height exceeding five times the least
horizontal dimension, or having a fundamental natural frequency less than 1 Hz. For those cases where the
horizontaldimensionsvarywithheight,theleasthorizontaldimensionatmidheightshallbeused.
SOFTSTOREY:Storeyinwhichthelateralstiffnessislessthan70 percentofthestiffnessofthestoreyabove.
SPACEFRAME:Athreedimensionalstructuralsystemwithoutbearingwallscomposedofmembersinterconnected
soastofunctionasacompleteselfcontainedunitwithorwithouttheaidofhorizontaldiaphragmsorfloorbracing
systems.
SPECIAL MOMENT RESISTING FRAME (SMRF) : A moment resisting frame specially detailed to provide ductile
behaviourcomplyingwiththerequirementsofChapter8or10forconcreteorsteelframesrespectively.
SPECIAL STRUCTURAL SYSTEM : A structural system not listed in Table 1.3.1 and specially designed to carry the
lateralloads.SeeSec1.3.2.5.
STOREY:Thespacebetweenanytwofloorlevelsincludingtheroofofabuilding.Storeyxisthestoreybelowlevel
x.
STOREYSHEAR,Vx :Thesummationofdesignlateralforcesabovethestoreyunderconsideration.
STRENGTH:Theusablecapacityofanelementoramembertoresisttheloadasprescribedintheseprovisions.
TERRAIN:Thegroundsurfaceroughnessconditionwhenconsideringthesizeandarrangementofobstructionsto
thewind.
THREESECONDGUSTSPEED: Thehighestaveragewindspeedovera3seconddurationataheightof10m.The
threesecondgustspeedisderivedusingDurst'smodelintermsofthemeanwindspeedandturbulenceintensity.
TOWER:Atall,slimverticalstructure.
VERTICALLOADCARRYINGFRAME: Aspaceframedesignedtocarryallverticalgravityloads.
WEAKSTOREY: Storeyinwhichthelateralstrengthislessthan80percentofthatofthestoreyabove.
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1.1.3 SYMBOLSANDNOTATIONThe following symbols and notation shall apply to the provisions of this chapter:D =dead load on a member including self weight and weight of components, materials andpermanent equipments supported by the memberE
=earthquake loadFi =lateral force applied at leveliof a buildingh =height of a building or a structure above ground level in metreshi,hn,hx =height in metres above ground level to leveli, nor xrespectivelyleveli = ith level of a structure above the base; i=1 designates the first level above
the baseleveln =upper most level of a structurelevelx =xth level of a structure above the base;x=1 designates the first level above the base.L
=live load due to intended use or occupancyl =span of a member or component.Mx =overturning moment at levelxV =the total design lateral force or shear at the baseVx =the storey shear at storey levelxR =response modification or reduction coefficient for structural system given in Table 2.5.7 for
seismic design.S =Snow loadT = Fundamental period of vibration in secondsW = Load due to wind pressure.W = Weight of an element or componentZ = Seismic zone coefficient given in Fig 2.5.1 or Tables 2.5.2 or 2.5.3 = Storey lateral drift.
1.2 BASIC CONSIDERATIONS1.2.1 GENERALAllbuildingsandstructuresshallbedesignedandconstructed inconformancewiththeprovisionsofthissection.
Thebuildingsandportionsthereofshallsupportallloadsincludingdeadloadspecifiedinthischapterandelsewhere
inthisCode.Impact,fatigueandselfstrainingforcesshallbeconsideredwheretheseforcesoccur.
1.2.2 BUILDINGSANDSTRUCTURESA structure shall ordinarily be described as an assemblage of framing members and components arranged to
support both gravity and lateral forces. Structures may be classified as building and nonbuilding structures.
Structuresthatencloseaspaceandareusedforvariousoccupanciesshallbecalledbuildingsorbuildingstructures.
Structuresotherthanbuildings,suchaswatertanks,bridges,communication towers,chimneysetc.,shallbecalled
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nonbuildingstructures.Whenusedinconjunctionwiththewordbuilding(s),thewordstructure(s)shallmeannon
buildingstructures,e.g.'buildingsandstructures'or'buildingsorstructures'.Otherwisetheword'structures'shall
includebothbuildingsandnonbuildingstructures.
1.2.3 BUILDINGANDSTRUCTUREOCCUPANCYCATEGORIESBuildingsandotherstructuresshallbeclassified,basedonthenatureofoccupancy,accordingtoTable1.2.1forthe
purposes ofapplying flood, surge,windandearthquakeprovisions.Theoccupancy categories range from Ito IV,
whereOccupancyCategoryIrepresentsbuildingsandotherstructureswithalowhazardtohumanlifeintheevent
of failure and Occupancy Category IV represents essential facilities. Each building or other structure shall be
assignedtothehighestapplicableoccupancycategoryorcategories.Assignmentofthesamestructuretomultiple
occupancycategoriesbasedonuseandthetypeofloadconditionbeingevaluated(e.g.,windorseismic)shallbe
permissible.
Whenbuildingsorotherstructureshavemultipleuses(occupancies),therelationshipbetweentheusesofvarious
partsofthebuildingorotherstructureandtheindependence ofthestructuralsystemsforthosevariouspartsshall
beexamined.Theclassificationforeachindependentstructuralsystemofamultipleusebuildingorotherstructure
shallbethatofthehighestusagegroupinanypartofthebuildingorotherstructurethatisdependentonthatbasic
structuralsystem.
1.2.4 SAFETYBuildings, structures and components thereof, shall be designed and constructed to support all loads, including
deadloads,withoutexceedingtheallowablestressesorspecifiedstrengths(underapplicablefactoredloads)forthe
materialsofconstructioninthestructuralmembersandconnections.
1.2.5 SERVICEABILITYStructuralframingsystemsandcomponentsshallbedesignedwithadequatestiffnesstohavedeflections,vibration,
or any other deformations within the serviceability limit of building or structure. The deflections of structural
members shall not exceed the more restrictive of the limitations provided in Chapters 2 through 13 or that
permittedbyTable1.2.2orthenotesthatfollow.Forwindandearthquake loading,storydriftandswayshallbe
limitedinaccordancewiththeprovisionsofSec1.5.6.
1.2.6 RATIONALITYStructuralsystemsandcomponentsthereofshallbeanalyzed,designedandconstructedbasedonrationalmethods
whichshallinclude,butnotbelimitedto,theprovisionsofSec1.2.7
1.2.7 ANALYSISAnalysis of the structural systems shall be made for determining the load effects on the resisting elements and
connections, basedonwellestablishedprinciplesofmechanicstakingequilibrium,geometriccompatibilityandboth
shortandlongtermpropertiesoftheconstruction materialsintoaccountandincorporatingthefollowing:
1.2.7.1 MATHEMATICALMODELA mathematical model of the physical structure shall represent the spatial distribution of stiffness and other
propertiesofthestructurewhichisadequatetoprovideacompleteloadpathcapableoftransferringallloadsand
forces from their points of origin to the loadresisting elements for obtaining various load effects. For dynamic
analysis,mathematical modelshallalso incorporatetheappropriatelydistributedmassanddampingpropertiesof
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thestructureadequateforthedeterminationofthesignificantfeaturesof itsdynamicresponse.Allbuildingsand
structures shall be thus ananlyzed preferably using a threedimensional computerizedmodel incorporating these
featuresofmathematicalmodel.It isessentialtousethreedimensionalcomputermodeltorepresentastructure
havingirregularplanconfigurationsuchasthoselistedinTables1.3.2and1.3.3andhavingrigidorsemirigidfloor
and roof diaphragms. Requirements for twodimensional model and three dimensional models for earthquake
analysisaredescribedinSec.2.5.11to2.5.14.
Table1.2.1 OccupancyCategoryofBuildingsandOtherStructuresforFlood,Surge,WindandEarthquakeLoadsNatureofOccupancy OccupancyCategoryBuildingsandotherstructuresthatrepresentalowhazardtohumanlifeintheeventoffailure,including,butnotlimited
to:
Agriculturalfacilities Certaintemporaryfacilities Minorstoragefacilities
I
AllbuildingsandotherstructuresexceptthoselistedinOccupancyCategoriesI,III,andIV II
Buildingsandotherstructuresthatrepresentasubstantialhazardtohumanlifeintheeventoffailure,including,butnot
limitedto:
Buildingsandotherstructureswheremorethan300peoplecongregateinonearea Buildingsandotherstructureswithdaycarefacilitieswithacapacitygreaterthan150 Buildingsandotherstructureswithelementaryschoolorsecondaryschoolfacilitieswithacapacitygreaterthan250 Buildingsandotherstructureswithacapacitygreaterthan500forcollegesoradulteducationfacilities
Healthcare
facilities
with
a
capacity
of
50
or
more
resident
patients,
but
not
having
surgery
or
emergency
treatmentfacilities Jailsanddetentionfacilities
Buildingsandotherstructures,notincludedinOccupancyCategoryIV,withpotentialtocauseasubstantialeconomicimpactand/ormassdisruptionofdaytodaycivilianlifeintheeventoffailure,including,butnotlimitedto:
Powergeneratingstationsa Watertreatmentfacilities Sewagetreatmentfacilities Telecommunicationcenters
BuildingsandotherstructuresnotincludedinOccupancyCategoryIV(including,butnotlimitedto,facilitiesthatmanufacture,process,handle,store,use,ordisposeofsuchsubstancesashazardousfuels,hazardouschemicals,hazardouswaste,orexplosives)containingsufficientquantitiesoftoxicorexplosivesubstancestobedangeroustothepublicifreleased.
III
Buildingsandotherstructuresdesignatedasessentialfacilities,including,butnotlimitedto:
Hospitalsandotherhealthcarefacilitieshavingsurgeryoremergencytreatmentfacilities Fire,rescue,ambulance,andpolicestationsandemergencyvehiclegarages Designatedearthquake,hurricane,orotheremergencyshelters
Designatedemergency
preparedness,
communication,
and
operation
centers
and
other
facilities
required
for
emergencyresponse Powergeneratingstationsandotherpublicutilityfacilitiesrequiredinanemergency Ancillarystructures(including,butnotlimitedto,communicationtowers,fuelstoragetanks,coolingtowers,
electricalsubstationstructures,firewaterstoragetanksorotherstructureshousingorsupportingwater,orotherfiresuppressionmaterialorequipment)requiredforoperationofOccupancyCategoryIVstructuresduringanemergency
Aviationcontroltowers,airtrafficcontrolcenters,andemergencyaircrafthangars Waterstoragefacilitiesandpumpstructuresrequiredtomaintainwaterpressureforfiresuppression Buildingsandotherstructureshavingcriticalnationaldefensefunctions
Buildingsandotherstructures(including,butnotlimitedto,facilitiesthatmanufacture,process,handle,store,use,ordispose of such substances as hazardous fuels, hazardous chemicals, or hazardous waste) containing highly toxicsubstances where the quantity of the material exceeds a threshold quantity established by the authority havingjurisdiction.
IV
aCogenerationpowerplantsthatdonotsupplypoweronthenationalgridshallbedesignatedOccupancyCategoryII.
1.2.7.2 LOADSANDFORCESAllprescribed loadsandforcestobesupportedbythestructuralsystemsshallbedetermined inaccordancewith
theapplicable provisionsofthischapterandChapter2.Loadsshallbeappliedonthemathematicalmodelspecified
inSec.1.2.7.1atappropriatespatiallocationsandalongdesireddirections.
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Table1.2.2DeflectionLimits(Exceptearthquakeload)
In the above table lstands for span of the member under consideration; Lstands for live load, Wstands forwind load andDstands for dead load.Notes:
a. For structural roofing and siding made of formed metal sheets, the total load deflection shall not exceed l/60. For secondary roofstructural members supporting formed metal roofing, the live load deflection shall not exceed l/150. For secondary wall memberssupporting formed metal siding, the design wind load deflection shall not exceed l/90. For roofs, this exception only applies when themetal sheets have no roof covering.b. Interior partitions not exceeding 2m in height and flexible, folding and portable partitions are not governed by the provisions of thissection.c. For cantilever members, lshall be taken as twice the length of the cantilever.d. For wood structural members having a moisture content of less than 16 percent at time of installation and used under dry conditions,the deflection resulting from L + 0.5D is permitted to be substituted for the deflection resulting from L + D.e. The above deflections do not ensure against ponding. Roofs that do not have sufficient slope or camber to assure adequate drainage shallbe investigated for ponding. See Section 1.6.5 for rain and ponding requirements.f. The wind load is permitted to be taken as 0.7 times the component and cladding loads for the purpose of determining deflection limitsherein.g. For steel structural members, the dead load shall be taken as zero.h. For aluminum structural members or aluminum panels used in skylights and sloped glazing framing, roofs or walls of sunroomadditions or patio covers, not supporting edge of glass or aluminum sandwich panels, the total load deflection shall not exceed l/60. Forcontinuous aluminum structural members supporting edge of glass, the total load deflection shall not exceed l/175 for each glass lite orl/60 for the entire length of the member, whichever is more stringent. For aluminum sandwich panels used in roofs or walls of sunroomadditions or patio covers, the total load deflection shall not exceed l/120.
1.2.7.3 SOIL-STRUCTUREINTERACTIONSoilstructure interaction effects,where required, shall be included in the analysis by appropriately including the
properlysubstantiatedpropertiesofsoilintothemathematicalmodelspecifiedinSec.1.2.7.1above.
1.2.8 DISTRIBUTIONOFHORIZONTALSHEARThetotallateralforceshallbedistributedtothevariouselementsofthelateralforceresistingsysteminproportion
totheirrigiditiesconsideringtherigidityofthehorizontalbracingsystemsordiaphragms.
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1.2.9 HORIZONTALTORSIONALMOMENTSStructural systems and components shall be designed to sustain additional forces resulting from torsion due to
eccentricity between the centre of application of the lateral forces and the centre of rigidity of the lateral force
resisting system. Forces shall notbe decreaseddue to torsional effects. For accidental torsion effects on seismic
forces,requirementsshallconformtoSec2.5.9.6
1.2.10 STABILITYAGAINSTOVERTURNINGANDSLIDINGEverybuildingorstructureshallbedesignedtoresisttheoverturningandslidingeffectscausedbythelateralforces
specifiedinthischapter.
1.2.11 ANCHORAGEAnchorageoftherooftowallandcolumns,andofwallsandcolumnstofoundations,shallbeprovidedtoresistthe
upliftandslidingforcesresultingfromtheapplicationoftheprescribedloads.Additionalrequirementsformasonry
orconcretewallsshallbethosegiveninSec1.7.3.6.
1.2.12 GENERALSTRUCTURALINTEGRITYBuildingsandstructuralsystemsshallpossessgeneralstructuralintegrity,that istheabilitytosustainlocaldamage
caused due to misuse or accidental overloading, with the structure as a whole remaining stable and not being
damagedtoanextentdisproportionatetotheoriginallocaldamage.
1.2.13 PROPORTIONINGOFSTRUCTURALELEMENTSStructuralelements,componentsandconnectionsshallbeproportionedanddetailedbasedonthedesignmethods
provided inthesubsequent chapters forvariousmaterialsofconstruction,suchasreinforcedconcrete,masonry,
steeletc.toresistvariousloadeffectsobtainedfromarationalanalysisofthestructuralsystem.
1.2.14 WALLSANDFRAMINGWalls and structural framing shall be erected true and plumb in accordance with the design. Interior walls,
permanent partitions and temporary partitions exceeding 1.8 m of height shall be designed to resist all loads to
whichtheyaresubjected.IfnototherwisespecifiedelsewhereinthisCode,wallsshallbedesignedforaminimum
load of 0.25 kN/m2
applied perpendiculartothe wall surfaces. The deflection ofsuchwalls under a load of0.25
kN/m2
shall not exceed1/240ofthespanforwallswithbrittlefinishesand
1/120ofthespanforwallswithflexible
finishes. However, flexible, folding or portable partitions shall not be required to meet the above load and
deflectioncriteria,butshallbeanchoredtothesupportingstructure.
1.2.15 ADDITIONSTOEXISTINGSTRUCTURESWhenanexistingbuildingorstructureisextendedorotherwisealtered,allportionsthereofaffectedby suchcause
shallbestrengthened,ifnecessary,tocomplywiththesafetyandserviceabilityrequirementsprovidedinSec1.2.4and1.2.5respectively.
1.2.16 PHASEDCONSTRUCTIONWhenabuildingorstructureisplannedoranticipatedtoundergophasedconstruction,structuralmemberstherein
shallbeinvestigatedanddesignedforanyadditionalstressesarisingduetosuchconstruction.
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1.2.17 LOADCOMBINATIONSANDSTRESSINCREASEEvery building, structure, foundation or components thereof shall be designed to sustain, within the allowable
stress or specified strength (under factored load), the most unfavourable effects resulting from various
combinations ofloadsspecifiedinsection2.7.Exceptotherwisepermittedorrestrictedbyanyothersectionofthis
Code,maximumincreaseintheallowablestress shallbe33%whenallowableorworkingstressmethodofdesignis
followed.Forsoilstressesduetofoundationloads,loadcombinationsandstressincreasespecifiedinSec2.7.4for
allowablestressdesignmethodshallbeused.
1.3 STRUCTURALSYSTEMS1.3.1 GENERALEverystructureshallhaveoneofthebasicstructuralsystemsspecified inSec1.3.2oracombinationthereof.The
structuralconfigurationshallbeasspecifiedinSec1.3.4withthelimitationsimposedinSec2.5.7.4.
1.3.2 BASICSTRUCTURALSYSTEMSStructuralsystemsforbuildingsandotherstructuresshallbedesignatedasoneofthetypesAtoGlisted inTable
1.3.1. Each type is again classified as shown in the table by the types of vertical elements used to resist lateral
forces.Abriefdescriptionofdifferentstructuralsystemsarepresentedinfollowingsubsections.
Table1.3.1:BasicStructuralSystemsA.BEARINGWALLSYSTEMS(noframe)
1. Special reinforced concrete shear walls
2. Ordinary reinforced concrete shear walls
3. Ordinary reinforced masonry shear walls
4. Ordinary plain masonry shear walls
B.BUILDINGFRAMESYSTEMS (withbracingorshearwall)1. Steel eccentrically braced frames, moment resisting connections atcolumns away from links2. Steel eccentrically braced frames, non-moment-resisting, connections at
columns away from links3. Special steel concentrically braced frames
4. Ordinary steel concentrically braced frames5. Special reinforced concrete shear walls
6. Ordinary reinforced concrete shear walls
7. Ordinary reinforced masonry shear walls
8. Ordinary plain masonry shear walls
C.MOMENTRESISTINGFRAMESYSTEMS(noshearwall)1. Special steel moment frames
2. Intermediate steel moment frames
3. Ordinary steel moment frames4. Special reinforced concrete moment frames
5. Intermediate reinforced concrete moment frames
6. Ordinary reinforced concrete moment frames
D.DUALSYSTEMS:SPECIALMOMENTFRAMESCAPABLEOFRESISTINGATLEAST25%OF
PRESCRIBEDSEISMICFORCES(withbracingorshearwall)1. Steel eccentrically braced frames2. Special steel concentrically braced frames
3. Special reinforced concrete shear walls
4. Ordinary reinforced concrete shear walls
E.DUALSYSTEMS:INTERMEDIATEMOMENTFRAMESCAPABLEOFRESISTINGATLEAST25%
OFPRESCRIBEDSEISMICFORCES(withbracingorshearwall)1. Special steel concentrically braced frames
2. Special reinforced concrete shear walls
3. Ordinary reinforced masonry shear walls
4. Ordinary reinforced concrete shear walls
F.DUALSHEARWALLFRAMESYSTEM:ORDINARYREINFORCEDCONCRETEMOMENT
FRAMESANDORDINARYREINFORCEDCONCRETESHEARWALLS
G.STEELSYSTEMSNOTSPECIFICALLYDETAILEDFORSEISMICRESISTANCE
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1.3.2.1 BEARINGWALLSYSTEMA structural system having bearing walls or bracing systems without a complete vertical load carrying frame to
supportgravityloads.Resistancetolateralloadsisprovidedbyshearwallsorbracedframes.
1.3.2.2 BUILDINGFRAMESYSTEMA structural system with an essentially complete space frame providing support for gravity loads. Resistance to
lateralloadsisprovidedbyshearwallsorbracedframesseparately.
1.3.2.3 MOMENTRESISTINGFRAMESYSTEMAstructuralsystemwithanessentiallycompletespaceframeprovidingsupportforgravityloads.Momentresisting
framesalso provideresistancetolateralloadprimarilybyflexuralactionofmembers,andmaybeclassifiedasone
ofthefollowingtypes:
a) SpecialMomentResistingFrames(SMRF)b) IntermediateMomentResistingFrames(IMRF)c) OrdinaryMomentResistingFrames(OMRF).
The framing system, IMRF and SMRF shall have special detailing to provide ductile behaviour conforming to the
provisions of Sec8.3 and 10.20 forconcrete and steel structures respectively. OMRF need not conform to these
specialductilityrequirementsofChapter8or10.
1.3.2.4 DUALSYSTEMAstructuralsystemhavingacombinationofthefollowingframing systems:
a) Momentresistingframes(SMRF,IMRForsteelOMRF),andb) Shearwallsorbracedframes.
The
two
systems
specified
in
(a)
and
(b)
above
shall
be
designed
to
resist
the
total
lateral
force
in
proportion
to
their
relativerigiditiesconsideringtheinteractionofthedualsystematalllevels. However,themoment resistingframes
shallbecapableofresistingatleast25%oftheapplicabletotalseismiclateralforce,evenwhenwindoranyother
lateralforcegovernsthedesign.
1.3.2.5 SPECIALSTRUCTURALSYSTEM:AstructuralsystemnotdefinedabovenorlistedinTable1.3.1andspeciallydesignedtocarrythelateralloads,such
astubeintube,bundledtube,etc.
1.3.2.6 NON-BUILDINGSTRUCTURALSYSTEMAstructuralsystemusedforpurposesotherthaninbuildingsandconformingtoSec1.5.4.8,1.5.4.9,2.4and2.5.
1.3.3 COMBINATIONOFSTRUCTURALSYSTEMSWhendifferentstructuralsystemsofSec1.3.2arecombinedfor incorporation intothesamestructure,designof
thecombinedseismicforceresistingsystemshallconformtotheprovisionsofSec2.5.7.5.
1.3.4 STRUCTURALCONFIGURATIONSBased on the structural configuration, each structure shall be designated as a regular or irregular structure as
definedbelow:
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1.3.4.1 REGULARSTRUCTURESRegularstructureshavenosignificantphysicaldiscontinuitiesorirregularitiesinplanorverticalconfigurationorin
theirlateralforceresistingsystems.TypicalfeaturescausingirregularityaredescribedinSec1.3.4.2.
1.3.4.2 IRREGULARSTRUCTURESIrregularstructureshaveeithervertical irregularityorplan irregularityorboth intheirstructuralconfigurationsor
lateralforceresistingsystems.
1.3.4.2.1 VerticalIrregularityStructureshavingoneormoreoftheirregularfeatureslistedinTable1.3.2shallbedesignatedashavingavertical
irregularity.
Table1.3.2:VerticalIrregularitiesofStructuresVerticalIrregularity Reference*
Type Definition SectionI StiffnessIrregularity (SoftStorey):A soft storey is one in which the lateral stiffness is less than 70 per cent of that
in the storey above or less than 80 per cent of the average stiffness of thethree storeys above.
2.5.7 to 2.5.14and 2.5.19
II MassIrregularity :Mass irregularity shall be considered to exist where the effective mass of anystorey is more than 150 per cent of the effective mass of an adjacent storey. Aroof which is lighter than the floor below need not be considered.
2.5.7 to 2.5.14
III VerticalGeometricIrregularity :Vertical geometric irregularity shall be considered to exist where horizontaldimension of the lateral forceresisting system in any storey is more than 130per cent of that in an adjacent storey, onestorey penthouses need not beconsidered.
2.5.7 to 2.5.14
IV In-PlaneDiscontinuityinVerticalLateralForce-ResistingElement:An inplane offset of the lateral loadresisting elements greater than thelength of those elements.
2.5.7 to 2.5.14
VaDiscontinuityinCapacity (WeakStorey) :
A weak storey is one in which the storey strength is less than 80 per cent ofthat in the storey above. The storey strength is the total strength of allseismicresisting elements sharing the storey shear for the direction underconsideration.
2.5.7 to 2.5.14and 2.5.19
Vb ExtremeDiscontinuityinCapacity (VeryWeakStorey) :A very weak storey is one in which the storey strength is less than 65 per centof that in the storey above.
2.5.7 to 2.5.14and 2.5.19
1.3.4.2.2 PlanIrregularityStructureshavingoneormoreof the irregular features listed in Table 1.3.3shallbedesignatedas havinga plan
irregularity.
Table1.3.3:Plan Irregularities ofStructuresPlanIrregularity Reference*
Type Definition SectionI Torsional Irregularity (to be considered when diaphragms are not
flexible):
Torsional irregularity shall be considered to exist when the maximum storeydrift, computed including accidental torsion, at one end of the structure is morethan 1.2 times the average of the storey drifts at the two ends of the structure.
2.5.7 to 2.5.14
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II ReentrantCorners:Plan configurations of a structure and its lateral forceresisting system containreentrant corners, where both projections of the structure beyond a reentrantcorner are greater than 15 per cent of the plan dimension of the structure inthe given direction.
2.5.7 to 2.5.14
III DiaphragmDiscontinuity :Diaphragms with abrupt discontinuities or variations in stiffness, includingthose having cutout or open areas greater than 50 per cent of the grossenclosed area of the diaphragm, or changes in effective diaphragm stiffness ofmore than 50 per cent from one storey to the next.
2.5.7 to 2.5.14
IV Out-of-planeOffsets :Discontinuities in a lateral force path, such as outofplane offsets of thevertical elements.
2.5.7 to 2.5.14
V NonparallelSystems :The vertical lateral loadresisting elements are not parallel to or symmetricabout the major orthogonal axes of the lateral forceresisting system.
2.5.7 to 2.5.14
1.4 DESIGNFORGRAVITYLOADS1.4.1 GENERALDesign of buildings and components thereof for gravity loads shall conform to the requirements of this section.
Gravity loads, such as dead load and live loads appliedat the floors or roof of a building shall be determined in
accordancewiththeprovisionsofChapter2.
1.4.2 FLOORDESIGNFloorslabsanddecksshallbedesignedforthefulldeadandliveloadsasspecified inSec2.2and2.3respectively.
Floor supporting elements such as beams,joists, columns etc. shall be designed for the full dead load and the
appropriately reduced live loads set forth by the provisions of Sec 2.3.13. Design of floor elements shall also
conformtothefollowingprovisions:
a) UniformlyDistributedLoads: Whereuniformfloorloadsareinvolved,considerationmaybelimitedtofulldeadloadonallspansincombinationwithfullliveloadonadjacentspans and
on alternate spans to determine the most unfavourable effect of stresses in the member
concerned.
b) ConcentratedLoads : Provisionshallbemade indesigningfloorsforaconcentrated loadasset forth in Sec 2.3.5 applied at a location wherever this load acting upon an otherwise
unloaded floor would produce stresses greater than those caused by the uniform load
requiredtherefore.
c) PartitionLoads :Loads due to permanent partitions shall betreatedasa dead loadappliedoverthefloorasauniformlineloadhavinganintensityequaltotheweightpermetrerunof
thepartitionsasspecifiedinSec2.2.5.Loadsforlightmovablepartitionsshallbedetermined
inaccordancewiththeprovisionsofSec2.3.6.
d) Design of Members : Floor members, such as slabs or decks, beams,joists etc. shall bedesignedtosustaintheworsteffectofthedeadplusliveloadsoranyotherloadcombinations
asspecifiedinSec2.7.Wherefloorsareusedasdiaphragmstotransmitlateralloadsbetween
various resisting elements, those loads shall be determined following the provisions of Sec
1.7.3.8. Detailed design of the floor elements shall be performed using the procedures
providedinChapters4through13for variousconstructionmaterials.
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1.4.3 ROOFDESIGNRoofs and their supporting elements shall be designed to sustain, within their allowable stresses or specified
strengthlimits,alldead loadsand live loadsassetoutbytheprovisionsofSec2.2and2.3respectively.Designof
roofmembersshallalsoconformtothefollowingrequirements:
a) Application of Loads : When uniformly distributed loads are considered for the design ofcontinuousstructuralmembers,loadincludingfulldeadloadsonallspansincombinationwith
fullliveloadsonadjacentspansandonalternate span,shallbeinvestigatedtodeterminethe
worst effects of loading. Concentrated roof live loads and special roof live loads, where
applicable,shallalsobeconsideredindesign.
b) UnbalancedLoading:Effectsduetounbalancedloadsshallbeconsideredinthedesignofroofmembersandconnectionswheresuchloadingwillresultinmorecriticalstresses.Trussesand
archesshallbedesignedtoresistthestressescausedbyuniformliveloadsononehalfofthe
span if such loading results in reverse stresses, or stresses greater in any portion than the
stressesproducedbythisunitliveloadwhenappliedupontheentirespan.
c) RainLoads: Roofs,wherepondingofrainwaterisanticipatedduetoblockageofroofdrains,excessivedeflectionor insufficientslopes, shall bedesignedtosupportsuch loads.Loadson
roofs due to rain shall be determined in accordance with the provisions of Sec 2.6.3. In
additiontothedeadloadoftheroof,eithertheroofliveloadortherainload,whicheverisof
higherintensity,shallbeconsideredindesign.
1.4.4 REDUCTIONOFLIVELOADSThedesign live loadsspecified inSec2.3,maybereducedtoappropriatevaluesaspermittedbytheprovisionsof
Sec2.3.13.andSec.2.3.14.
1.4.5 POSTINGOFLIVELOADSIneverybuilding,ofwhichthefloorsorpartsthereofhaveadesignliveloadof3.5kN/m2ormore,andwhichare
used as library stack room, file room, parking garage, machine or plant room, or used for industrial or storage
purposes,theownerofthebuildingshallensurethatthe live loadsforwhichsuchspacehasbeendesigned,are
postedondurablemetalplatesasshowninFig1.1,securelyaffixedinaconspicuousplaceineachspacetowhich
theyrelate.Ifsuchplatesarelost,removed,ordefaced,theownershallberesponsibletohavethemreplaced.
1.4.6 RESTRICTIONSONLOADINGThe building owner shall ensure that the live load for which a floor or roof is or has been designed, will not be
exceededduringitsuse.
1.4.7 SPECIALCONSIDERATIONSIntheabsenceofactualdeadandliveloaddata,theminimumvaluesoftheseloadsshallbethosespecifiedinSec
2.2and2.3.Inaddition,specialconsiderationshallbegiventothefollowingaspectsofloadinganddueallowances
shallbemadeindesignifoccurrenceofsuchloadingisanticipatedafterconstructionofabuilding:
a) IncreaseinDeadLoad:Actualthicknessoftheconcreteslabsorothermembersmaybecomelargerthanthedesignedthicknessduetomovementsordeflectionsoftheformworkduring
construction.
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1.4.8Structural
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1.5.3.1 DIRECTIONOFWINDStructural design for wind forces shall be based on the assumption that wind may blow from any horizontal
direction.
1.5.3.2 DESIGNCONSIDERATIONSDesignwindloadontheprimaryframingsystemsandcomponentsofabuildingorstructureshallbedeterminedon
thebasisoftheproceduresprovidedinSec2.4consideringthebasicwindspeed,shapeandsizeofthebuilding,and
theterrainexposureconditionofthesite.Forslenderbuildingsandstructures,dynamicresponsecharacteristics,
such as fundamental natural frequency, shall be determined for calculating the gust response coefficient. Load
effects, such as forces, moments, deflections etc. on various components of the building due to wind shall be
determinedfromastaticanalysisofthestructureasspecifiedinSec1.2.7.1.
1.5.3.3 SHIELDINGEFFECTReductions in wind pressure on buildings and structures due to apparent direct shielding effects of the up wind
obstructions,suchasmanmadeconstructionsornaturalterrainfeatures,shallnotbepermitted.
1.5.3.4 DYNAMICEFFECTSDynamic wind forces such as that from alongwind vibrations caused by the dynamic windstructure interaction
effects, as set forth by the provisions of Sec 2.4.10, shall be considered in the design of regular shaped slender
buildings.Forotherdynamiceffectssuchascrosswindortorsionalresponsesasmaybeexperiencedbybuildings
orstructureshavingunusualgeometricalshapes(i.e.verticalorplan irregularitieslistedinTables1.3.2and1.3.3),
responsecharacteristics,orsitelocations,structuraldesignshallbemadebasedontheinformationobtainedeither
fromother reliable referencesor from windtunnel testspecified inSec 1.5.3.5below, complying withthe other
requirementsofthissection.
1.5.3.5 WINDTUNNELTESTProperlyconductedwindtunneltestsshallberequiredforthosebuildingsorstructureshavingunusualgeometric
shapes,responsecharacteristics,orsitelocationsforwhichcrosswindresponsesuchasvortexshedding,galloping
etc. warrant special consideration, and for which no reliable literature for the determination of such effects is
available. This test is also recommended for those buildings or structures for which more accurate windloading
informationisdesiredthanthosegiveninthissectionandinSec2.4.
Testsforthedeterminationofmeanandfluctuatingcomponentsofforcesandpressuresshallbeconsideredtobe
properlyconductedonlyifthefollowing requirementsaresatisfied:
a) Thenaturalwindhasbeenmodelledtoaccountforthevariationofwindspeedwithheight,b) The intensity ofthe longitudinal components of turbulence has been taken into consideration in the
model,
c) The geometricscaleofthestructuralmodel isnotmorethanthreetimesthegeometric scaleofthelongitudinal component ofturbulence,
d) Theresponsecharacteristicsofthewindtunnelinstrumentationareconsistentwiththemeasurements tobemade, and
e) The Reynolds number is taken into consideration when determining forces and pressures on thestructuralelements.
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Tests for the purpose of determining the dynamic response of a structure shall be considered to be properly
conductedonly ifrequirements (a)through (e) aboveare fulfilledand, inaddition,the structural model is scaled
withdueconsiderationtolength,distributionofmass,stiffnessanddamping ofthestructure.
1.5.3.6 WINDLOADSDURINGCONSTRUCTIONBuildings, structures and portions thereof under construction, and construction structures such as formwork,
stagingetc.shallbeprovidedwithadequatetemporarybracingsorotherlateralsupportstoresistthewindloadon
themduringtheerectionandconstructionphase.
1.5.3.7 MASONRYCONSTRUCTIONINHIGH-WINDREGIONSDesignandconstructionofmasonrystructuresinhighwindregionsshallconformtotherequirementsofrelevant
sectionsofChapter7.
1.5.3.8 HEIGHTLIMITSUnlessotherwisespecifiedelsewhereinthisCode,noheightlimitsshallbeimposed,ingeneral,onthedesignand
constructionofbuildingsorstructurestoresistwindinducedforces.
1.5.4 DESIGNFOREARTHQUAKEFORCESDesign of structures and components thereof to resist the effects of earthquake forces shall comply with the
requirementsofthissection.
1.5.4.1 BASICDESIGNCONSIDERATIONForthepurposeofearthquakeresistantdesign,eachstructureshallbeplacedinoneoftheseismiczonesasgivenin
Sec 2.5.6.2 and assigned with a structure importance category as set forth in Sec 2.5.7.1. The seismic forces on
structuresshallbedeterminedconsideringseismiczoning,sitesoilcharacteristics,structureimportance,structural
systemsandconfigurations,heightanddynamicpropertiesofthestructureasprovided inSec2.5.Thestructural
systemandconfigurationtypesforabuildingorastructureshallbedeterminedinaccordancewiththeprovisionsofSec2.5.7.4.Otherseismicdesignrequirementsshallbethosespecifiedinthissection.
1.5.4.2 REQUIREMENTSFORDIRECTIONALEFFECTSThedirectionsofapplicationofseismicforcesusedinthedesignshallbethosewhichwillproducethemostcritical
loadeffects.Earthquakeforcesactinbothprincipaldirectionsofthebuildingsimultaneously.Designprovisionsfor
consideringearthquakecomponentinorthogonaldirectionshavebeenprovidedinSec2.5.15.1.
1.5.4.3 STRUCTURALSYSTEMANDCONFIGURATIONREQUIREMENTSSeismicdesignprovisionsimposethefollowinglimitationsontheuseofstructuralsystemsandconfigurations:
a) The structural system used shall satisfy requirements of the Seismic Design Category (defined inSec.2.5.7.2)andheightlimitationsgiveninSec2.5.7.4.
b) StructuresassignedtoSeismicDesignCategoryDhavingverticalirregularityTypeVbofTable1.3.2shall not be permitted. Structures with such vertical irregularity may be permitted for Seismic
DesignCategoryBorCbutshallnotbeovertwostoriesor9minheight.
c) Structures having irregular features described in Table 1.3.2 or 1.3.3 shall be designed incompliancewiththeadditionalrequirementsofthesectionsreferencedintheseTables.
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d) Special Structural Systems defined in Sec 1.3.2.5 may be permitted if it can be demonstrated byanalytical and test data to be equivalent, with regard to dynamic characteristics, lateral force
resistance and energy absorption, to one of the structural systems listed in Table 2.5.7, for
obtaininganequivalentRandCdvalueforseismicdesign.
1.5.4.4 METHODSOFANALYSISEarthquake forces and their effects on various structural elements shall be determined by using either a static
analysismethodoradynamicanalysismethodwhicheverisapplicablebasedonthelimitationssetforthinSec2.5.7
through2.5.14andconformingtoSec1.2.7.
1.5.4.5 MINIMUMDESIGNSEISMICFORCEThe minimum design seismic forces shall be those determined in accordance with the Sec 2.5.7 through 2.5.14
whicheverisapplicable.
1.5.4.6 DISTRIBUTIONOFSEISMICFORCESThetotallateralseismicforcesandmomentsshallbedistributedamongvariousresistingelementsatanyleveland
alongtheverticaldirectionofabuildingorstructureinaccordancewiththeprovisionsofSec2.5.7through2.5.14
asappropriate.
1.5.4.7 VERTICALCOMPONENTSOFSEISMICFORCESDesignprovisionsforconsideringverticalcomponentofearthquakegroundmotionisgiveninSec2.5.15.2
1.5.4.8 HEIGHTLIMITSHeight limitationsfordifferentstructuralsystemsaregiven inTable2.5.7ofSec2.5.7.4ofPart6ofthiscodeasa
functionofseismicdesigncategory.
1.5.4.9 NON-BUILDINGSTRUCTURESSeismiclateralforceonnonbuildingstructuresshallbedeterminedinaccordancewiththeprovisionsofChapter15
ofASCE7 05.However,provisionsofChapter15ofASCE705maybesimplified,consistentwiththeprovisionsof
Section2.5ofPart6ofthiscode.Otherdesignrequirementsshallbethoseprovidedinthischapter.
1.5.5 OVERTURNINGREQUIREMENTSEverystructureshallbedesignedtoresisttheoverturningeffectscausedbywindorearthquakeforcesspecifiedin
Sec2.4and2.5respectivelyaswellotherlateralforceslikeearthpressure,tidalsurgeetc.Theoverturningmoment
Mx atanystoreylevelxofabuildingshallbedeterminedas:
1.5.1
where,
hi,hx,hn = Heightinmetresatlevel i, xor nrespectively.Fi = Lateralforceappliedatleveli,i=1ton.
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Atanylevel,theincrementofoverturningmomentshallbedistributedtothevariousresistingelementsinthesame
mannerasthedistributionofhorizontalshearprescribedinSec2.5.9.5.Overturningeffectsoneveryelementshall
becarrieddowntothefoundationlevel.
1.5.6 DRIFTANDBUILDINGSEPARATION1.5.6.1 STOREYDRIFTLIMITATIONStoreydriftisthehorizontaldisplacementofonelevelofabuildingorstructurerelativetothelevelaboveorbelow
duetothedesigngravity(deadandliveloads)orlateralforces(e.g.windandearthquakeloads).Exceptotherwise
permitted in Sec 1.3.4.2.1 calculated storey drift shall include both translational and torsional deflections and
conformtothefollowingrequirements:
1. Storeydrift, ,forloadsotherthanearthquakeloads, shallbelimitedasfollows: 0.005h for T
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1.6 DESIGNFORMISCELLANEOUSLOADS1.6.1 GENERALBuildings,structuresandcomponentsthereof,whensubjectto loadsotherthandead, live,windandearthquake
loads,shallbedesignedinaccordancewiththeprovisionsofthissection.Miscellaneousloads,suchasthosedueto
temperature,rain,floodandsurgeetc.onbuildingsorstructures,shallbedeterminedinaccordancewithSec2.6.Structural memberssubjecttomiscellaneousloads,notspecifiedinSec2.6shallbedesignedusingwellestablished
methods giveninanyreliablereferences,andcomplyingwiththeotherrequirementsofthisCode.
1.6.2 SELF-STRAININGFORCESSelfstraining forces such as those arising due to assumed differential settlements of foundations and from
restraineddimensionalchangesduetotemperature,moisture,shrinkage,creep,andsimilareffects,shallbetaken
intoconsiderationinthedesignofstructural members.
1.6.3 STRESSREVERSALANDFATIGUEStructural members andjoints shall be investigated and designedagainstpossible stressreversals caused dueto
various construction loads. Where required, allowance shall be made in the design to account for the effects of
fatigue.Theallowablestressmaybeappropriatelyreducedtoaccountforsucheffectsinthestructuralmembers.
1.6.4 FLOOD,TIDAL/STORMSURGEANDTSUNAMIBuildings, structures and components thereof shall be designed, constructed and anchored to resist flotation,
collapseoranypermanentmovementduetoloadsincludingflood,tidal/Stormsurgeandtsunami,whenapplicable.
Structuralmembersshallbedesignedtoresistbothhydrostaticandsignificanthydrodynamic loadsandeffectsof
buoyancyresultingfromfloodorsurge.Floodandsurge loadsonbuildingsandstructuresshallbedetermined in
accordance with Sec2.6.4. Loadcombination including flood and surge loads shall conform toSec2.7.Designof
foundationstosustaintheseloadeffectsshallconformtotheprovisionsofSec1.8.
Stability against overturning and sliding caused due to wind and flood or surge loads simultaneously shall be
investigated,andsucheffectsshallberesistedwithaminimumfactorofsafetyof1.5,consideringdeadloadonly.
1.6.5 RAINLOADSRoofsofthebuildingsandstructuresaswellastheirothercomponentswhichmayhavethecapabilityofretaining
rainwatershallbedesignedforadequategravityloadinducedbyponding.Roofsandsuchothercomponentsshall
beanalysedanddesignedforloadduetopondingcausedbyaccidentalblockageofdrainagesystemcomplyingwith
Sec.2.6.3.
1.6.6 OTHERLOADSBuildingsandstructuresandtheircomponentsshallbeanalyzedanddesignedforstressescausedbythefollowingeffects
a. TemparatureEffects(Sec2.6.5).b. SoilandHydrostaticPressure(Sec2.6.6).c. ImpactsandCollisionsd. Explosions(Sec2.6.7).
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e. Firef. VerticalForcesonAirRaidShelters(Sec2.6.8).g. LoadsonHelicopterLandingAreas(Sec2.6.9).h. ErectionandConstructionLoads(Sec2.6.10).i. MovingLoadsforCraneMovementsj. CreepandShrinkagek. DynamicLoadsduetoVibrationsl. ConstructionLoads
Designofbuildingsandstructuresshallincludeloadingandstressescausedbytheaboveeffectsinaccordancewith
theprovisionssetforthinChapter2.
1.7 DETAILEDDESIGNREQUIREMENTS1.7.1 GENERALAll structural framing systems shall comply with the requirements of this section. Only the elements of the
designated lateral force resisting systems can be used to resist design lateral forces specified in Chapter 2. The
individual componentsshallbedesignedtoresisttheprescribedforcesactingonthem.Designofcomponentsshall
alsocomplywiththespecificrequirementsforthematerialscontainedinChapters4through13.Inaddition,such
framingsystemsandcomponentsshallcomplywiththedesignrequirementsprovidedinthissection.
1.7.2 STRUCTURALFRAMINGSYSTEMSThebasicstructuralsystemsaredefined inSec1.3.2andshowninTable1.3.1,andeachtypeissubdividedbythe
typesofframingelementsusedtoresistthelateralforces.Thestructuralsystemusedshallsatisfyrequirementsof
seismicdesigncategoryandheight limitations indicated inTable 2.5.7.Specialframingrequirementsaregiven in
thefollowingsectionsinadditiontothoseprovidedinChapters4through13.
1.7.3 DETAILINGREQUIREMENTSFORCOMBINATIONSOF STRUCTURALSYSTEMS:
Forcomponentscommontodifferentstructuralsystems,amorerestrictivedetailingshallbeprovided.
1.7.3.1 CONNECTIONSTORESISTSEISMICFORCESConnections which resist prescribed seismic forces shall be designed in accordance with the seismic design
requirements provided in Chapters 4 through 13. Detailed sketches for these connections shall be given in the
structuraldrawings.
1.7.3.2 DEFORMATIONCOMPATIBILITYAllframingelementsnotrequiredbydesigntobepartofthelateralforceresistingsystem,shallbeinvestigatedand
showntobeadequateforverticalloadcarryingcapacitywhensubjectedtolateraldisplacementsresultingfromthe
seismic lateral forces. For designs using working stress methods, this capacity may be determined using an
allowablestressincreaseof30percent.PDeltaeffectsonsuchelementsshallbeaccountedfor.
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a. AdjoiningRigidElements : Momentresistingframesmaybeenclosedoradjoinedbymorerigidelementswhichwouldtendtoprevent aspaceframefromresistinglateralforceswhereitcanbe
shownthattheactionorfailureofthemorerigidelementswillnotimpairtheverticalandlateral
loadresistingabilityofthespaceframe.
b. ExteriorElements:Exteriornonbearing,nonshearwallpanelsorelementswhichareattachedtoorenclosetheexterior ofastructure,shallbedesignedtoresisttheforcesaccordingtoSec.2.5.17of Chapter 2, if seismic forces are present, and shall accommodate movements of the structure
resulting from lateral forces or temperature changes. Such elements shall be supported by
structural members or by mechanical connections and fasteners joining them to structural
membersinaccordancewiththefollowingprovisions:
i. Connectionsandpaneljointsshallallowforarelativemovementbetweenstoreysofnotlessthan two times the storey drift caused by wind forces or design seismic forces, or 12 mm,
whicheverisgreater.
ii. Connections to permit movement in the plane of the panel for storey drift shall be eitherslidingconnectionsusingslottedoroversizedholes,connectionswhichpermitmovementby
bendingofsteel,orotherconnectionsprovidingequivalentslidingandductilitycapacity.
iii. Bodies of connections shall have sufficient ductility and rotation capability to preclude anyfractureoftheanchoringelementsorbrittlefailuresatornearweldings.
iv. Bodies of the connection shall be designed for 1.33 times the seismic force determined bySec.2.5.17ofChapter2,orequivalent.
v. All fasteners in the connection system, such as bolts, inserts, welds, dowels etc. shall bedesignedfor4timestheforcesdeterminedbySec.2.5.17ofChapter2orequivalent.
vi. Fastenersembeddedinconcreteshallbeattachedto,orhookedaroundreinforcingsteel,orotherwiseterminatedsoastotransferforcestothereinforcingsteeleffectively.
1.7.3.3 TIESANDCONTINUITYAllpartsofastructureshallbe interconnected.Theseconnectionsshallbecapableoftransmittingtheprescribed
lateralforcetothelateralforceresistingsystem.Individualmembers,includingthosenotpartoftheseismicforce
resisting system, shall be provided with adequate strength to resist the shears, axial forces, and moments
determined in accordancewith this standard.Connectionsshall developthe strengthoftheconnectedmembers
andshallbecapableoftransmittingtheseismicforce(Fp)inducedbythepartsbeingconnected.
1.7.3.4 COLLECTORELEMENTSCollector elements shall be provided which are capable of transferring the lateral forces originating in other
portionsofthestructuretotheelementprovidingtheresistancetothoseforces.
1.7.3.5 CONCRETEFRAMESWhenconcreteframesareprovidedbydesigntobepartofthelateralforceresistingsystem,theyshallconformto
thefollowingprovisions:
a) InSeismicZones3and4theseframesshallbedesignedasspecialmomentresistingframes(SMRF).b) InSeismicZone2theyshall,asaminimum,beintermediatemomentresistingframes(IMRF).
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1.7.3.6 ANCHORAGEOFCONCRETEANDMASONRYSTRUCTURALWALLSThe concrete and masonry structural walls shall be anchored to supporting construction. The anchorage shall
provide a positive direct connection between the wall and floor or roof and shall be capable of resisting the
horizontal forces specified in Secs 2.4.13 and 2.5.17, or a minimum force of 4.09 kN/m of wall. Walls shall be
designedtoresistbendingbetweenanchorswheretheanchorspacingexceeds1.2m.Inmasonrywallsofhollow
units or cavity walls, anchors shall be embedded in a reinforced grouted structural element of the wall.Deformations ofthe floor androofdiaphragmsshallbe considered in thedesign of the supported walls and the
anchorageforcesinthediaphragmsshallbedeterminedinaccordancewithSec1.7.3.9below.
1.7.3.7 BOUNDARYMEMBERSSpecially detailed boundary members shall be considered for shearwalls and shearwall elements whenever their
designisgovernedbyflexure.
1.7.3.8 FLOORANDROOFDIAPHRAGMSDeflection in the plane of the diaphragm shall not exceed the permissible deflection of the attached elements.
Permissible deflection shall be that deflection which will permit the attached element to maintain its structural
integrityundertheindividual loadingandcontinuetosupporttheprescribedloads.Designofdiaphragmsshallalso
complywiththefollowingrequirements.
a) DiaphragmForces: Diaphragmsshallbe designedtoresist theseismicforcesgiveninSec2.5orforsimilarnonseismiclateralforces,whicheverisgreater.
b) DiaphragmTies:Diaphragmssupportingconcreteormasonrywallsshallhavecontinuousties,orstruts between the diaphragm chords to distribute the anchorage forces specified in Sec 1.7.3.6
above.Addedchordsmaybeprovidedtoformsubdiaphragmstotransmittheanchorageforcesto
themaincrossties.
c) WoodDiaphragms :Wherewooddiaphragmsareused to laterallysupport concreteormasonrywalls,theanchorageshallconformtoSec1.7.3.6 above.InseismicZones2,3and4thefollowing
requirementsshallalsoapply:
i. Anchorageshallnotbeaccomplishedbyuseoftoenailsornailssubjecttowithdrawal,norshallwoodledgersorframingbeusedincrossgrainbendingorcrossgraintension.
ii. The continuous ties required by paragraph (b) above, shall be in addition to thediaphragmsheathing.
d) Structureshavingirregularitiesi) ForstructuresassignedtoSeismicDesignCategoryDandhavingaplanirregularityofType
I,II,III,orIVinTable1.3.3oraverticalstructuralirregularityofTypeIVinTable1.3.2,the
designforcesdeterminedfromSection2.5.9shallbeincreased25percentforconnections
ofdiaphragms tovertical elementsandtocollectors and forconnectionsofcollectorsto
the vertical elements. Collectors and their connections also shall be designed for these
increased forces unless they are designed for the load combinations with overstrength
factor.
ii) For structures having a plan irregularity of Type II in Table 1.3.3, diaphragm chords andcollectorsshallbedesignedconsideringindependentmovementofanyprojectingwingsof
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thestructure.Eachofthesediaphragmelementsshallbedesignedforthemoresevereof
thefollowingcases:
1. Motionoftheprojectingwingsinthesamedirection.2. Motionoftheprojectingwingsinopposingdirections.
Exception:ThisrequirementmaybedeemedtobesatisfiediftheproceduresofSec2.5.10whenseismicforcesarepresent,in
conjunctionwithathreedimensionalmodel,havebeenusedtodeterminethelateralseismicforcesfordesign.
1.7.3.9 FRAMINGBELOWTHEBASEWhenstructuralframingscontinuebelowthebase,thefollowingrequirementsshallbesatisfied.
a. FramingbetweentheBaseandtheFoundation: Thestrengthandstiffnessoftheframingbetweenthebaseandthefoundationshallnotbelessthanthatofthesuperstructure.Thespecialdetailing
requirements of Sec 8.3 or 10.20, as appropriate for reinforced concrete or steel, shall apply to
columns supporting discontinuous lateral force resisting elements and to SMRF, IMRF, and EBF
systemelementsbelowthebasewhicharerequiredtotransmitthe forcesresulting from lateralloadstothefoundation.
b. Foundations: The foundation shall be capable of transmitting the design base shear and theoverturning forces from the superstructure into the supporting soil, but the short term dynamic
nature of the loads may be taken into account in establishing the soil properties. Sec 1.8 below
prescribestheadditionalrequirementsforspecifictypesoffoundationconstruction.
1.8 FOUNDATIONDESIGNREQUIREMENTS1.8.1 GENERALThe
design
and
construction
of
foundation,
foundation
components
and
connection
between
the
foundation
and
superstructureshallconformtotherequirementsofthissectionandapplicableprovisionsofChapter3andother
portionsofthisCode.
1.8.2 SOILCAPACITIESThe bearingcapacityofthesoil,orthecapacityofthesoilfoundationsystemincludingfooting,pile,pierorcaisson
andthesoil,shallbesufficienttosupportthestructurewithallprescribedloads,consideringthesettlementofthe
structure. For piles, this refers to pile capacity as determined by pilesoil friction and bearing which may be
determinedinaccordancewiththeprovisionsofChapter3.Fortheloadcombinationincludingearthquake,thesoil
capacity shall be sufficient to resist loads at acceptable strains considering both the short time loading and the
dynamicpropertiesofthesoil.Thestressandsettlementofsoilunderappliedloadsshallbedeterminedbasedon
establishedmethodsofSoilMechanics.
1.8.3 SUPERSTRUCTURE-TO-FOUNDATIONCONNECTIONTheconnectionofsuperstructureelementstothefoundationshallbeadequatetotransmittothefoundationthe
forcesforwhichtheelementsarerequiredtobedesigned.
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1.8.4 FOUNDATION-SOILINTERFACEFor regular buildings the base overturning moments for the entire structure or for any one of its lateral force
resisting elements, shall not exceed twothirds of the dead load resisting moment. The weight of the earth
superimposedoverfootingsmaybeusedtocalculatethedeadloadresistingmoment.
1.8.5
SPECIAL
REQUIREMENTS
FOR
FOOTINGS,
PILES
AND
CAISSONS
IN
SEISMIC
ZONES2,3AND4
1.8.5.1 PILESANDCAISSONSPiles and caissons shall be designed for flexure whenever the top of such members is anticipated to be laterally
displacedbyearthquakemotions.ThecriteriaanddetailingrequirementsofSec8.3forconcreteandSec10.20for
steelshallapplyforalengthofsuchmembersequalto120percentoftheflexurallength.
1.8.5.2 FOOTINGINTERCONNECTIONa. Footingsandpilecapsshallbecompletely interconnectedbystruttiesorotherequivalentmeans
torestraintheirlateralmovementsinanyorthogonaldirection.
b. Thestruttiesorotherequivalentmeansasspecified in(a)above,shallbecapableofresisting intensionorcompressionaforcenotlessthan10%ofthelargerfootingorcolumnloadunlessitcan
bedemonstratedthatequivalentrestraintcanbeprovidedbyfrictionalandpassivesoilresistance
orbyotherestablishedmeans.
1.8.6 RETAININGWALLDESIGNRetainingwallsshallbedesignedtoresistthelateralpressureoftheretainedmaterial,underdrainedorundrained
conditions and including surcharge, in accordance with established engineering practice. For such walls, the
minimumfactorofsafetyagainstbaseoverturningandslidingduetoappliedearthpressureshallbe1.5.
1.9 DESIGNANDCONSTRUCTIONREVIEWEverybuildingorstructuredesignedshallhaveitsdesigndocumentspreparedinaccordancewiththeprovisionsof
Sec1.9.1.Theminimumrequirementsfordesignreviewandconstructionobservationshallbethosesetforthunder
Sec1.9.2and1.9.3respectively.
1.9.1 DESIGNDOCUMENTThe designdocumentsshall be prepared andsigned by theengineer responsible for thestructural design of any
building or structure intended for construction. The design documents shall include a design report, material
specificationsandasetofstructuraldrawings,whichshallbepreparedincompliancewithSec1.9.2and1.9.3below
forsubmittaltotheconcernedauthority.Forthepurposeofthisprovision,theconcernedauthorityshallbeeither
personsfromthegovernmentapprovalagencyfortheconstruction,ortheownerofthebuildingorthestructure,or
oneofhisrepresentatives.
1.9.2 DESIGNREPORTThedesignreportshallcontainthedescriptionofthestructuraldesignwithbasicdesign informationasprovided
below,sothatanyotherstructuraldesignengineerwillbeabletoindependently verifythedesignparametersand
themembersizesusingthesebasicinformation.Thedesignreportshallinclude,butnotbelimitedto,thefollowing
:
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a) Name and governing edition of this Code and other referenced standards, and the specificportions, stating chapter, section, clause etc. of these Code and standards including any
specialistreportusedforthestructuraldesign.
b) Methodsusedforthecalculationofallapplied loadsalongwith basic loadcoefficientsandother basic information including any assumption or judgment made under special
circumstances.
c) A drawing of the complete mathematical model prepared in accordance with Sec 1.2.7.1 torepresent the structure and showing on it thevalues, locations and directions of all applied
loads,andlocationofthelateralloadresistingsystemssuchasshearwalls,bracedframesetc.
d) Methodsofstructuralanalysis,andresultsoftheanalysissuchasshear,moment,axialforceetc., used for proportioning various structural members and joints including foundation
members.
e) Methods of structural design including types and strength of the materials of constructionusedforproportioningthestructuralmembers.
f) Reference of the soil report or any other documents used in the design of the structure,foundationorcomponentsthereof.
g) Statementsupportingthevalidityoftheabovedesigndocumentswithdateandsignatureoftheengineerresponsibleforthestructuraldesign.
h) When computer programs are used, to any extent, to aid in the analysis or design of thestructure,thefollowing items,inadditiontoitems(a)through(g)above,shallberequiredto
beincludedinthedesignreport:
i. Asketchofthemathematicalmodelusedtorepresentthestructure inthecomputergeneratedanalysis.
ii. The computer output containing the date of processing, program identification,identification of structures being analysed, all input data, units and final results. The
computer input data shall be clearly distinguished from those computed in the
program.
iii. A program description containing the information necessary to verify the input dataand interpret the results to determine the nature and extent of the analysis and to
checkwhetherthecomputationscomplywiththeprovisionsofthisCode.
iv. Thefirstsheetofeachcomputerrunshallbesignedbytheengineerresponsibleforthestructuraldesign.
1.9.3 STRUCTURALDRAWINGSANDMATERIALSPECIFICATIONSThestructuraldrawingsshallinclude,butnotbelimitedto,thefollowing:
a) Thefirstsheetshallcontain:(1)identificationoftheprojecttowhichthebuildingorthestructure,orportionthereofbelongs,(2)referencetothedesignreportspecifiedinSec1.9.2above,(3)date
ofcompletionofdesign,and(4)identificationandsignaturewithdateoftheengineerresponsible
forthestructuraldesign.
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b) The second sheet shall contain detail material specifications showing : (1) Specified compressivestrength of concrete at stated ages or stages of construction for which each part of structure is
designed (2) Specified strength or grade of reinforcement (3) Specified strength of prestressing
tendonsorwires(4)Specifiedstrengthorgradeofsteel(5)Specifiedstrengthsforbolts,weldsetc.
(6) Specified strength of masonry, timber, bamboo, ferrocement (7) Minimum concrete
compressivestrengthattimeofposttensioning(8)Stressingsequenceforposttensioningtendons
(9) General notes indicating clear cover, development lengths of reinforcements, or any other
design parameter relevant to the member or connection details provided in drawings to be
followed,asapplicable,and(10)identificationandsignaturewithdateoftheengineerresponsible
forthestructuraldesign.
c) Drawing sheets, other than the first two, shall include structural details of the elements of thestructure clearly showing all sizes, crosssections and relative locations, connections,
reinforcements, laps, stiffeners, welding types, lengths and locations etc. whichever is applicable
for a particularconstruction. Floor levels, column centresand offset etc., shall be dimensioned.
Camber of trusses and beams, if required, shall be shown on drawings. For bolt connected
members,connectiontypessuchasslip,critical,tensionorbearingtype,shallbeindicatedonthe
drawing.
d) Drawingsshallbepreparedtoascalelargeenoughtoshowtheinformationclearlyandthescalesshallbemarkedonthedrawingsheets.Ifanyvariationfromthedesignspecificationsprovided in
sheettwooccurs, thedrawingsheet shallbeprovidedadditionallywiththedesignspecifications
includingmaterialtypesandstrength,clearcoveranddevelopment lengthsofreinforcements,or
anyotherdesignparameterrelevanttothememberorconnectiondetailsprovidedinthatdrawing
sheet.Eachdrawingsheetshallalsocontainthesignaturewithdateoftheengineerresponsiblefor
thestructuraldesign.
1.9.4 DESIGNREVIEWThedesigndocumentsspecifiedinSec1.9.1shallbeavailableforreviewwhenrequiredbytheconcernedauthority.
Reviewshallbeaccomplishedbyan independentstructuralengineerqualified forthistaskandappointedbythe
concernedauthority.Designreviewshallbeperformedthroughindependentcalculations,basedontheinformation
provided in the design documents prepared and signed by the original structural design engineer, to verify the
designparameters includingapplied loads,methodsofanalysisanddesign,andfinaldesigndimensionsandother
detailsofthestructuralelements.Thereviewingengineershallalsocheckthesufficiencyandappropriatenessof
thesuppliedstructuraldrawingsforconstruction.
1.9.5 CONSTRUCTIONOBSERVATIONConstruction observation shall be performed by a responsible person who will be a competent professional
appointed
by
the
owner
of
the
building
or
the
structure.
Construction
observation
shall
include,
but
not
be
limited
to,thefollowing:
a. Specificationofanappropriatetestingand inspectionschedulepreparedandsignedwithdatebytheresponsibleperson;
b. Reviewoftestingandinspectionreports;andc. Regular site visit to verify the general compliance of the construction work with the structural
drawingsandspecificationsprovidedinSec1.9.3above.