april 2016 structural design... · 2016-10-26 · nepal: structural design criteria for school...
TRANSCRIPT
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 1 of 46
DepartmentofEducation(DOE)MinistryofEducationGovernmentofNepal
April2016
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 2 of 46
Acknowledgement
This document has been prepared by the Asian Development Bank (ADB) and Japan International Cooperation Agency (JICA).
The document is intended to be the official guidelines to the Department of Education (DOE), for structural aspects of planning and design of new schools consistent with the Design Guidelines for Type Design of School Buildings which sets out architectural and planning requirements.
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 3 of 46
ListofFigures...................................................................................................................................6
ListofTables....................................................................................................................................7
Chapter 1Introduction................................................................................................................9
1.1 Introduction...................................................................................................................9
1.2 ScopeandPurpose.........................................................................................................9
1.3 StructuralSystem...........................................................................................................9
1.4 StructuralComponents................................................................................................10
1.5 Codes,StandardsandReferences................................................................................12
Chapter 2DesignPhilosophyandApproach..............................................................................14
2.1 Introduction.................................................................................................................14
2.2 Definitions....................................................................................................................14
2.3 OverallDesignProcedure.............................................................................................14
2.3.1 DesignProcedure1....................................................................................................14
2.3.2 DesignProcedure2....................................................................................................16
Chapter 3BasicMaterials..........................................................................................................17
3.1 Introduction.................................................................................................................17
3.2 Concrete.......................................................................................................................17
3.3 ReinforcingSteel..........................................................................................................17
3.4 StructuralSteel.............................................................................................................17
3.5 Cold-formedSteel........................................................................................................17
3.6 Masonry.......................................................................................................................18
3.7 Timber..........................................................................................................................18
Chapter 4Loads.........................................................................................................................19
4.1 Introduction.................................................................................................................19
4.2 GravityLoad.................................................................................................................19
4.3 WindLoad....................................................................................................................19
4.4 SeismicLoad.................................................................................................................19
4.5 LoadCombinations.......................................................................................................21
Contents
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 4 of 46
4.5.1 Code-basedDesign....................................................................................................21
4.5.2 PerformanceEvaluation............................................................................................22
Chapter 5StructuralSystems....................................................................................................23
5.1 Introduction.................................................................................................................23
5.2 DifferentStructuralSystems........................................................................................23
5.2.1 OrdinaryReinforcedConcreteMomentResistingFramesandMasonryInfillWalls23
5.2.2 SpecialSteelMomentResistingFrames....................................................................24
5.2.3 ReinforcedInterlockingBearingWalls.......................................................................25
5.2.4 SpecialReinforcedConcreteMomentResistingFrame............................................26
5.2.5 Cold-FormedSteelOrdinaryMomentFrame............................................................27
5.2.6 Hot-RolledSteelOrdinaryMomentFrame................................................................27
5.2.7 TimberStructure........................................................................................................27
Chapter 6Code-basedDesign....................................................................................................28
6.1 Introduction.................................................................................................................28
6.2 ModelingofStructuralSystem.....................................................................................28
6.2.1 Beams........................................................................................................................30
6.2.2 RoofTruss..................................................................................................................30
6.2.3 Columns.....................................................................................................................30
6.2.4 Footings.....................................................................................................................30
6.2.5 MasonryInfillWalls...................................................................................................31
6.2.6 ReinforcedInterlockingBearingWalls.......................................................................31
6.2.7 Damping....................................................................................................................31
6.3 AnalysisProcedures.....................................................................................................31
6.3.1 ModalAnalysis...........................................................................................................32
6.3.2 LinearStaticProcedure(LSP).....................................................................................32
6.3.3 ResponseSpectrumAnalysis(RS)..............................................................................32
6.4 ComponentandMemberDesign.................................................................................32
Chapter 7SeismicPerformance-basedEvaluation....................................................................36
7.1 Introduction.................................................................................................................36
7.2 ModelingofStructuralSystem.....................................................................................36
7.2.1 Beams........................................................................................................................38
7.2.2 Columns.....................................................................................................................38
7.2.3 MasonryInfillWallsandReinforcedInterlockingBearingWalls...............................38
7.2.4 Damping....................................................................................................................38
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 5 of 46
7.3 AnalysisProcedures.....................................................................................................39
7.3.1 NonlinearStaticProcedureforGravityLoad(NSP)...................................................39
7.3.2 NonlinearTimeHistoryAnalysis(NLTHA)..................................................................39
7.3.3 PushoverAnalysis......................................................................................................39
7.4 PerformanceCriteria....................................................................................................40
7.4.1 ExpectedandLower-BoundStrengthusedinPerformanceEvaluation....................40
7.4.2 PerformanceCriteriaforDesignProcedure1............................................................40
7.4.3 PerformanceCriteriaforDesignProcedure2............................................................45
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 6 of 46
ListofFigures
Figure2-1:OverallDesignProcedure1..........................................................................................15
Figure2-2:OverallDesignProcedure2..........................................................................................16
Figure4-1:ResponseSpectraforEarthquakeswithDifferentReturnPeriodsforSoilTypeII(MediumSoilSites)(Ref:Figure7.1b,HazardSpectraforKathmandu(KawashimaAttenuationModel,GC2,5%Damping,NBC400V2.RV8-1994)........................................................................21
Figure5-1:DesignProcedureforOrdinaryReinforcedConcreteMomentResistingFrameswithMasonryInfillWalls.........................................................................................................................24
Figure5-2:DesignProcedureforSpecialSteelMomentResistingFrames....................................25
Figure5-3:DesignProcedureforReinforcedInterlockingBearingWalls.......................................26
Figure5-4:DesignProcedureforReinforcedConcreteSpecialMomentResistingFrame............27
Figure7-1:CapacityCurvefromPushoverAnalysis.......................................................................45
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 7 of 46
ListofTables
Table1-1:TypicalStructuralMemberandComponents 10
Table3-1:CompressiveStrengthofconcrete 17
Table3-2:YieldStrengthofReinforcingsteel 17
Table3-3:YieldStrengthofStructuralSteel 17
Table3-4:YieldStrengthofCold-formedSteel 18
Table3-5:StrengthofMasonryPrism 18
Table4-1:LiveLoadandSuperimposedDeadLoad 19
Table4-2:ParametersforWindLoading 19
Table4-3:ParametersforSeismicLoading 20
Table4-4:UltimateStrengthDesignLoadCombinationsusedinCode-basedDesign 21
Table4-5:AllowableStressDesignLoadCombinationsusedinCode-basedDesign 22
Table6-1:ModelingofStructuralSystemforCode-basedDesign 28
Table6-2:AnalysisProceduresusedinCode-basedDesign 31
Table6-3:ComponentandMemberDesign 32
Table7-1:ModelingofStructuralSystemforPerformance-basedEvaluation 36
Table7-2:DampingRatios 39
Table7-3:AnalysisProceduresusedinPerformance-basedEvaluation 39
Table7-4:FactorstoTranslateLower-BoundMaterialPropertiestoExpectedStrengthMaterialProperties 40
Table7-5:AcceptanceCriteriaforGlobalResponseofSchoolBuildings 41
Table7-6:ClassificationofActionsandAcceptanceCriteria 42
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 8 of 46
ListofAbbreviations
ACI AmericanConcreteInstitute
ADB AsianDevelopmentBank
ASCE AmericanSocietyofCivilEngineers
DBE DesignBasisEarthquake
DOE DepartmentofEducation
DUDBC DepartmentofUrbanDevelopmentandBuildingConstruction
GON GovernmentofNepal
IBC InternationalBuildingCodes
IS IndianStandard
MCE MaximumConsideredEarthquake
NBC NepalNationalBuildingCode
NEHRP NationalEarthquakeHazardsReductionProgram
NIST NationalInstituteofStandardsandTechnology
NLTHA NonlinearTimeHistoryAnalysis
PDNA PostDisasterNeedsAssessments
PEER PacificEarthquakeEngineeringResearchCenter
PGMD PEERGroundMotionDatabase
RC ReinforcedConcrete
RS ResponseSpectrumAnalysis
UBC UniformBuildingCode
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 9 of 46
Chapter 1 Introduction
1.1 IntroductionAmajorearthquakeofshallowdepthmeasuring7.6ontheRichterscalestruckcentralNepalonApril 25th causingwidespread destruction. There have been several aftershocks, including a bigonemeasuring6.8onMay12causingfurthercausalitiesanddamage
The Government of Nepal (GON), and several development partners have developed acomprehensivePostDisasterNeedAssessment(PDNA)document.OneofthesectorconsideredintheoverallPDNAisEducation,whichidentitiestheneedsforrehabilitationandreconstructionofeffected infrastructure foreducation sector, including the schoolbuildingsand facilities. Adraftstrategywaspreparedforreconstructionafterthisdisaster,addressingbothshorttermandlong-termreconstruction,inlinewiththeoverallframeworkof“BuildBackBetter”.
Aspartoftherebuildingstrategy,guidelineshavebeendevelopedforthedesignofnewschools1.Thisdocumentisdevelopedtosupportthestructuraldesignoftheschoolbuildingstobedesignedbasedontheguidelines.Itisimportanttocarryoutproperstructuraldesignofthetypedesignforvarioushazards,aswellasforcosteffectiveness.
Thisdocumentpresents thedesigncriteriaandoverallmethodology tobeused in thestructuraldesignofnewschoolbuildingsinNepal.Thecriteriapresentedincludesspecificinformationonthedescription of the building and its structural system, codes, standards and references, loadingcriteria,materials,modeling,andtheproposedanalysisanddesignprocedures.ThisdocumentwillbeconsideredasanInterimGuidelines,untiltheNBCisrevisedoradditionalhazardmappingandassessmentisavailable.
1.2 ScopeandPurposeThisdocument is intended toprovideaunifiedandconsistent criterion for carryingoutdetailedstructuraldesignofschoolbuildingsinNepal,forresistancetotheeffectsofearthquakesandothernaturalhazards.ThedocumentisparticularlyapplicabletotheTypeDesignofnewschoolbuildingsforthepost-earthquakereconstructioninthe14mosteffecteddistricts.
However,thedocumentmayalsobeusedforstructuraldesignofschoolbuildingsingeneralintheentirecountryonceapprovedandadoptedby theDepartmentofEducation inconsultationwithandagreementofDUDBC.Schoolbuildingscoveredbythedocumentmaybesingleormulti-storybuildings2.ThebuildingsmaybelocatedanywhereinNepal,eitherinmountains,hillsorplains.
1.3 StructuralSystemFivetypesofbasicstructuralsystemsconsideredinthisdocumentwithanobjectivetoachievethegoodperformanceandcosteffectiveness.Thestructuralsystemstobedevelopedareasbelow.
1) Sys-1:Ordinaryreinforcedconcretemomentframewithunreinforcedmasonryinfillwalls
2) Sys-2:Specialsteelmomentresistingframe
1GuidelinesforDevelopingTypeDesignsforSchoolBuildingsinNepal,February2016.
2Foralltypedesign,itshouldbeapprovedbyDOEandDUDBC,andalsomeetcodeprovisionslikefireexitandlift.
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 10 of 46
3) Sys-3:Reinforcedinterlockingblockbearingwallsystem(forexample,Habitechsystem)
4) Sys-4:Specialreinforcedconcretemomentframe
5) Sys-5:Cold-formedsteelordinarymomentframe
6) Sys-6:Hold-rolledsteelordinarymomentframe
7) Sys-7:Timberstructure
Isolated and strip footings may be used to transfer the load of the building to supporting soil,dependingon the soil conditionsat site. Steel trussorRC slabmaybeused to support the roofsystem,whereas intermediate floorsmayeitherbeofRCslabonRCframeorcompositeslabonsteelframe.
1.4 StructuralComponentsThecomponentsofstructuralsystemsaresummarizedinthefollowingtable.
Table 1-1 : Typical Structural Member and Components
StructuralSystem Element TypicalComponentTypes
Sys-1:OrdinaryRCmomentframewithmasonryinfillwalls
Foundation RCisolatedfootingforcolumnorRCstripfootingforcolumnandwall
Column RCcolumn
Masonrywall Burnt-brick in c/s mortar (1:6), tied to RCframe
Beam RCbeam
Slabongrade Generallynotrequired
Plinthbeams RCbeam
Lintels RCbeam
Intermediatefloors RCslab
Walls Unreinforcedmasonrywallsfullcontactwithboundingframes
Roofsystem SteeltrussorRCslab
Sys-2:Specialsteelmomentresistingframe
Foundation RCisolatedfootingforcolumnRCstripfootingforcolumn
Column SteelhollowboxorH,IorWshapes,orbuiltupsections
Beam Steel hollow box or I sections, or built upsections
Slabongrade Generallynotrequired
Plinthbeams RCbeam
Lintels RCbeam
Intermediatefloors Compositeslab
Walls Unreinforced masonry walls, Light weightpartitions(non-loadbearingwalls)
Roofsystem Steeltrussorcompositeslab
Sys-3:Reinforcedinterlockingbearingwall(Habitechsystem)
FoundationBrickorstoneRC strip footing for wall reinforced stonemasonryinC/Cmortar
Bearingwall Compressed interlocking blocks, reinforcedwithrebars
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 11 of 46
StructuralSystem Element TypicalComponentTypes
Slabongrade Generallynotrequired
Plinthbeams RCbeam,blocksreinforcedwithrebars
Lintels RCbeam,blocksreinforcedwithrebars
Intermediatefloors RCslab,Habitechwaistslaborsimilar
Roofsystem SteeltrussorRCslab
Sys-4:Specialreinforcedconcretemomentframe
Foundation RCisolatedfootingforcolumnRCstripfootingforcolumn
Column RCcolumn
Beam RCbeam
Slabongrade Generallynotrequired
Plinthbeams RCbeam
Lintels RCbeam
Intermediatefloors RCslab
Walls Unreinforced masonry walls, Light weightpartitions(non-loadbearingwalls)
Roofsystem SteeltrussorRCslab
Sys-5:Cold-formedsteelordinarymomentframe
Foundation RCisolatedfootingforcolumnRCstripfootingforcolumn
Column Cold-formedchannelsections
Beam Cold-formedchannelsections
Slabongrade Generallynotrequired
Plinthbeams RCbeam
Lintels RCbeam
Intermediatefloors Notpermitted.
Walls Unreinforced masonry walls, Light weightpartitions(non-loadbearingwalls)
Roofsystem Cold-formedsteelchanneltruss
Sys-6: Hot-rolled steel ordinarymomentframe
Foundation RCisolatedfootingforcolumnRCstripfootingforcolumn
Column SteelhollowboxorH,IorWshapessections
Beam SteelhollowboxorIsections
Slabongrade Generallynotrequired
Plinthbeams RCbeam
Lintels RCbeam
Intermediatefloors Compositeslab
Walls Unreinforced masonry walls, Light weightpartitions(non-loadbearingwalls)
Roofsystem Steeltrussorcompositeslab
Sys-7:Timberstructure
Foundation RCisolatedfootingforcolumnRCstripfootingforcolumn
Column Timbercolumn
Beam Timberbeam
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 12 of 46
StructuralSystem Element TypicalComponentTypes
Slabongrade Generallynotrequired
Plinthbeams RCbeam
Intermediatefloors Timberfloor
Roofsystem Timbertruss
1.5 Codes,StandardsandReferencesThebasicbuilding codes tobe referredare listedbelow.However, specific applicationsof thosecodeprovisionsarediscussedinthecorrespondingsections.
BuildingCodes
• Seismic Design of Buildings in Nepal, Nepal National Building Code, NBC 105: 1994, orlatereditions,asapplicable
• WindLoad,NepalNationalBuildingCode,NBC104:1994,orlatereditions,asapplicable
• CriteriaforEarthquakeResistantDesignofStructures,IndianStandard,IS:1893(Part1)-2002
• InternationalBuildingCode,IBC2012,InternationalCodeCouncil,Inc.
• UniformBuildingCode,UBC97,InternationalCodeCouncil,Inc.
MaterialCodes
• Steel:NepalNationalBuildingCode,NBC111:1994,orequivalent
• Plain and Reinforced Concrete: Nepal National Building Code, NBC 110: 1994, orequivalent
• Masonry:Unreinforced:NepalNationalBuildingCode,NBC109:1994,orequivalent
• Mandatory Rules of Thumb Concrete Buildings with Masonry Infill, Nepal NationalBuildingCode,NBC201:1994
• MandatoryRulesofThumbReinforcedConcreteBuildingswithoutMasonry Infill,NepalNationalBuildingCode,NBC205:1994
• Timber,NepalNationalBuildingCode,NBC112:1994
• ColdFormedLightGaugeStructuralSteelSection,IS811(1987),orequivalent
• DesignofStructuralTimberinBuilding-CodeofPractice,IS883(1994),orequivalent
• CodeofPracticeforUseofColdFormedLightGaugeSteelStructuralMembersinGeneralBuildingConstruction,IS801(1975),orequivalent
• Reinforced Concrete: Building Code Requirements for Structural Concrete andCommentary,ACI318M-08,AmericanConcreteInstitute
• Building CodeRequirements and Specification forMasonry Structures, TMS 402-13/ACI530-13/ASCE5-13,AmericanConcreteInstitute
• Special Design Provisions for Wind and Seismic - 2015, ANSI / AWC SDPWS-2015,AmericanWoodCouncil
• MandatoryRulesofThumbReinforcedConcreteBuildingswithoutMasonry Infill,NepalNationalBuildingCode,NBC205:1994
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 13 of 46
• StructuralSteel:SpecificationforStructuralSteelBuildings,ANSI/AISC360-10,AmericanInstituteofSteelConstruction
• SeismicProvisionsforStructuralSteelBuildings,ANSI/AISC341-10,AmericanInstituteofSteelConstruction
• North American Specification for the Design of Cold-formed Steel StructuralMembers,AISIStandard
OtherReferences
• SeismicEvaluationandRetrofitofExistingBuildings,ASCE/SEI41-13,AmericanSocietyofCivilEngineers
• Minimum Design Loads for Buildings and Other Structures, ASCE/SEI 7-10, AmericanSocietyofCivilEngineers
• Assessment of First Generation Performance-based Seismic Design Methods for NewSteelBuildings,Volume1:SpecialMomentFrames,NISTTechnicalNote1863-1,NationalInstituteofStandardsandTechnology
• NEHRP Seismic Design Technical Brief No. 1, Seismic Design of Reinforced ConcreteSpecial Moment Frames, NIST GCR 8-917-1, National Institute of Standards andTechnology
• NEHRP Seismic Design Technical Brief No. 2, Seismic Design of Steel Special MomentFrames,NISTGCR09-917-3,NationalInstituteofStandardsandTechnology
• NEHRP Seismic Design Technical Brief No. 9, Seismic Design of Special ReinforcedMasonry Shear Walls, NIST GCR 14-917-31, National Institute of Standards andTechnology
• Seismic Hazard Mapping and Risk Assessment for Nepal 1994, NBC 400-V2. RV8, 18November1994
• Relatedresearchpapersandreports
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 14 of 46
Chapter 2 DesignPhilosophyandApproach
2.1 IntroductionThischapterpresentsthedesignphilosophyandapproachestobeusedinstructuraldesignofnewschoolbuildings.
2.2 DefinitionsThissectiondescribesthedefinitionsofthetermsusedineachbuilding.
Remain elastic:Responseofstructuralcomponentupto firstyield.Whenthe force isapplied tothecomponentitstoresstrainenergy,andwhentheforceisremovedthisenergyisrecovered.
Gravity loads:Weightof structuralcomponents,partition, floor finishing, serviceequipmentandliveload.
Inelastic behavior: Response of structural component, in which some of thework done on thecomponent as it deforms is dissipated, as plasticwork, friction, facture energy, etc. An inelasticbehaviorwillalwaysbenonlinear.
DBE: Design Basis Earthquake. This earthquake is generally used in design, based on codeprocedures.
MCE:MaximumConsideredEarthquake
Capacity design: A design process in which it is decided which components within a structuralsystemwillbepermittedtoyield(ductilecomponents)andwhichcomponentswillremainelastic(brittlecomponents).Thecomponentsaredesignedinsuchawaythatplastichingescanformonlyin predetermined positions and in predetermined sequences. The concept of this method is toavoidbrittlemodeoffailure.
Responsespectrum:Spectrumpresentsthemaximumaccelerationresponseofthebuildingduetogroundshakingwithrespecttonaturalperiods.
2.3 OverallDesignProcedureTwo methods are mentioned that the structural designer would select in consultation withDoE/DUDBC.
2.3.1 DesignProcedure1
Analysisanddesignoftheschoolbuildingsshallbeperformedaccordingtothefollowingstepsforeachstructuralsystem.
1) Develop the structural system/concept for each structural system. Use the basicstructuralsystemsdescribedinTable1.1asaguideline.
2) Create the finite element model with varying complexity and refinement suitable fordeveloping understanding the response. Carry out different types of analysis todeterminetheresponseofthebuildingundergravityandlateralloadings.
3) Design the structural components to remain elastic under gravity and wind loads andprovidewell-definedinelasticbehaviorwherenonlinearresponseoccursunderDBElevelearthquake, as appropriate. Capacity design approachwill be used for the response ofmemberstoremainelasticunderDBElevelearthquake,asappropriate.Linear,responsespectrumanalysisshouldbeconductedforDBElevelearthquakewithresponsereduction
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 15 of 46
factortodeterminetheresponseofthebuilding.Designiscarriedoutinaccordancewiththerelevantprovisionsofthelatestnationalbuildingcodeprovisions.
4) As design would be typical schools which will be replicated for several sites, theperformanceofthebuildingshouldbeevaluatedaftersubstantialcompletionofdesigninaccordancewithcodeproceduresmentionedinstep3.PerformanceofthebuildingshallbeevaluatedwithanobjectivetoprovideLifeSafetyperformancelevelunder1000-yearreturn period earthquakes. Optionally, Collapse Prevention performance level under2000-year return period earthquake may be checked. Pushover analysis shall beconductedasminimumrequirements.Overallresponse,suchastransientdrifts,residualdrifts,anddeformationandstrengthcapacityrequirementsofcomponentsarechecked.
5) If the performance based on global building and local component responses does notmeettheacceptancecriteria,carryoutstep1to4toenhancethestructuralperformanceofthebuilding.
6) If the performance based on global building and local component responsesmeet theacceptancecriteria,structuraldesigndrawingsshallbepreparedforconstruction.
Regarding“DesignProcedure1”, to refer to theChapter3,4,5,6, and7.1 to7.4.2 isrequired.
Architectural design
Step 1: Structural system development
Step 2: Modeling and analysis
Step 3: Structural design in accordance with
building codes
Step 5: Is performance acceptable?
Step 4: Verification of design using
performance-based approaches for seismic
loading
Step 6: Preparation of structural drawings
YES
NO
Figure 2-1 : Overall Design Procedure 1
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 16 of 46
2.3.2 DesignProcedure2
Analysisanddesignoftheschoolbuildingsshallbeperformedaccordingtothefollowingstepsforeachstructuralsystem.
1) Develop the structural system/concept for each structural system. Use the basicstructuralsystemsdescribedinTable1.1asaguideline.
2) Create the finite element model with varying complexity and refinement suitable fordeveloping understanding the response. Carry out different types of analysis todeterminetheresponseofthebuildingundergravityandlateralloadings.
3) Design the structural components under gravity, seismic loads and wind loads. Designshall be carried out in accordance with both Nepal National Building Code (NBC) andlatestIndianStandards(IS),andshallsatisfybothcodes.
4) After designing in accordance with NBC and IS, it is preferable to evaluate theperformanceofthebuildingbypushoveranalysis.Pushoveranalysiswillbeconductedtodetermine the displacement ductility factor “µ”. Response reduction factor, R will becalculatedbasedonductility factor “µ”.HereR factor basedon IS (code-baseddesign)canbedefinedas“Rc”andalsobasedonperformance-basedcanbedefinedas“Rp”.
5) IftheresultofRandKare
Rc>Rp,calculatecode-baseddesignagainbyusingRp.
Incase,Rc≤Rp,itisnotnecessarytoredothecode-baseddesign.
6) Structuraldesigndrawingsshallbepreparedforconstruction.
Regarding“DesignProcedure2”,it’snecessarytorefertotheChapter7.4.3.Inaddition,thesentence relating to theoriginalNBCand IS inChapter3,4,5,and6needs tobetakenintoaccount.
Figure 2-2 : Overall Design Procedure 2
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 17 of 46
Chapter 3 BasicMaterials
3.1 IntroductionThischapterpresentsthestrengthofmaterialsusedinthedesignofstructuralcomponents.
3.2 ConcreteThe minimum compressive strength measured at 28 days, for the cylinder specimen used indifferent typesof structuralcomponentsareshown in the following table.Highervaluesmaybeusedbasedonthediscretionoftheengineer.
Table 3-1 : Compressive Strength of concrete
Standard Member f'c(Nominal)(MPa)
f'c(Expected)(MPa)
NBC205:1994 Footings 16 20.8
NBC205:1994 Beams 16 20.8
NBC205:1994 Columns 16 20.8
3.3 ReinforcingSteelMinimum yield strength of reinforcing steel to be used in the design is shown in the followingtable.
Table 3-2 : Yield Strength of Reinforcing steel
Standard Diameter fy(Nominal)(MPa)
fy(Expected)(MPa)
NBC205:1994 12mmandabove 415 518
NBC205:1994 10mmandbelow 250 313
3.4 StructuralSteelYieldstrengthofstructuralsteelusedinthedesignisshowninthefollowingtable.
Table 3-3 : Yield Strength of Structural Steel
Standard SectionFy
(Nominal)(MPa)
Fu(Nominal)(MPa)
Fy(Expected)(MPa)
Fu(Expected)(MPa)
IS800:1984 Wideflangeshapes
250 410 275 451
IS800:1984 Angleandchannelsections
250 410 275 451
IS800:1984 Miscellaneousplatesandconnectionmaterials
250 410 275 451
3.5 Cold-formedSteelMinimumyieldstrengthofcold-formedsteelusedinthedesignisshowninthefollowingtable.
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 18 of 46
Table 3-4 : Yield Strength of Cold-formed Steel
Standard SectionFy
(Nominal)(MPa)
Fu(Nominal)(MPa)
Fy(Expected)(MPa)
Fu(Expected)(MPa)
IS:801-1975 Channel 250 410 275 451
3.6 MasonryMinimumstrengthofmasonryusedinthedesignisshowninthefollowingtable.
Table 3-5 : Strength of Masonry Prism
Element StrengthNominal(MPa)
Expected(MPa)
Burntclaybricks Compressivestrength 2.07 2.7
Compressedsoilcementblocks
Compressivestrength 2.71 2.71
3.7 TimberMaterialpropertiesshallbeinaccordancewithNBC112:1994orIS883-1994.
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 19 of 46
Chapter 4 Loads
4.1 IntroductionThischapterpresentsthedesignloadsconsideredinthestructuraldesign,includinggravityloads,seismicloadsandwindloads.
4.2 GravityLoadSelf-weightofthestructureisconsideredasdeadloadandfinishesandpartitionsareconsideredas superimposed dead load. Live load is determined in accordance with occupancy or use. Thefollowing loads are in addition to the self-weight of the structure. The minimum loadingrequirementsshallbetakenfromIS875(Part2)-1987orequivalent.
Table 4-1 : Live Load and Superimposed Dead Load
OccupancyorUse LiveLoad SuperimposedDeadLoad
Classrooms 3.0kPa Tobecomputedforactualfinishesandpartitions
Corridors 4.0kPa Tobecomputedforactualfinishesandpartitions
Roof 0.75kPa
4.3 WindLoadWindspeedshallbedeterminedinaccordancewithNBC104-1994.Thecountryisdividedintotworegions:a) the lowerplainsandhillsand,b) themountains.The firstzonegenerally includesthesouthern plains of the Terai, the Kathmandu Valley and those regions of the country generallybelowanelevationof3000meters.Thesecondzonecoversallareasabove3000meters.FortheNepaleseplainscontinuouswiththeIndianplanes,abasicvelocityof47m/sshallbeused.Inthehigherhills,abasicwindvelocityof55meterspersecondshallbeused.
Table 4-2 : Parameters for Wind Loading
Parameter Value
Basicwindspeed Tobedeterminedbasedonbuildinglocation
Terraincategory Tobedeterminedbasedonbuildinglocation
4.4 SeismicLoadFor design procedure 1, the basic seismic input shall be determined fromNBC. 500-year returnperiod earthquake shall be used as Design Basis Earthquake in code-based design. Theperformance shall be checked for Life Safety performance level under 1000-year return periodearthquake,andoptionallyCollapsePreventionperformancelevelunder2000-yearreturnperiodearthquake.
For design procedure 2, the seismic input used in code-based design shall be Design BasisEarthquakementionedinlatestNBCandIS.
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 20 of 46
Table 4-3 : Parameters for Seismic Loading
Parameter Value
Zonefactor,Z(NBC105-1994)Zonefactor,Z(IS1893-2002)
10.36
Importancefactor 1.5
Soiltype II(Needstobedeterminedbasedonbuildinglocation)
Structuralperformancefactor,K • System1=2• System2=1• System3=4• System4=1• System5=4• System6=4• System7=4
Responsereductionfactor,R • System1=1.5**• System2=5• System3=3• System4=5• System5=3**• System6=3**• System7=1.5**
Ca* • 500-yr=0.36• 1000-yr=0.46• 2000-yr=0.58
Cv* • 500-yr=0.45• 1000-yr=0.58• 2000-yr=0.73
*Usedindesignprocedure1.
**AssumedRvaluesincethevaluesarenotavailableinIS1893-2002.
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 21 of 46
Figure 4-1 : Response Spectra for Earthquakes with Different Return Periods for Soil Type II (Medium Soil Sites) (Ref: Figure 7.1b, Hazard Spectra for Kathmandu (Kawashima
Attenuation Model, GC 2, 5% Damping, NBC 400 V2.RV8-1994)
Note:Importancefactorof1isusedinthefigureforcomparison.
ResponsespectrumcurveforNBC105-1994isbasedonK=4.
4.5 LoadCombinations
4.5.1 Code-basedDesign
4.5.1.1 UltimateStrengthDesign
Ultimatestrengthdesignloadcombinationsusedincode-baseddesignareshowninthefollowingtable.(Ref:NBC105:1994,NBC110:1994,IS875-1987)
Table 4-4 : Ultimate Strength Design Load Combinations used in Code-based Design
No. LoadCombination
1 1.4D+1.5L
2 1.0D+1.25W
3 1.0D+1.3L+1.25W
4 1.0D+1.25W
5 1.0D+1.3L+1.25E
6 0.9D+1.25E
Where: D=Deadload
L=Liveload
E=EffectsofforcesatDBElevel
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
0 0.5 1 1.5 2 2.5 3
SpectralAcceleral
on(Sa)
NaturalPeriod(sec)
ElaslcResponseSpectra-5%ofcrilcaldamping
500-yr
1000-yr
2000-yr
NBC105-1994
IS1893-2002
2.5Ca
Ca
Cv/T
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 22 of 46
W=Windload
Liveloadisnotincludedinthemasscalculations.
Verticalseismic loadeffectshallbeconsidered,takenastwo-thirdsofdesignhorizontalresponsespectrum.
4.5.1.2 AllowableStressDesign
Allowablestressdesign loadcombinationsused incode-baseddesignareshown in the followingtable.(Ref:NBC105:1994,NBC110:1994,IS875-1987)
Table 4-5 : Allowable Stress Design Load Combinations used in Code-based Design
No. LoadCombination
1 D
2 D+L
3 D+L+W
4 0.7D+W
5 D+L+E
6 0.7D+E
4.5.2 PerformanceEvaluation
Loadcombinationsusedinperformanceevaluationareshowninthefollowingtable.
No. LoadCombination
1 1.0D+0.25L±1.0E
Where: D=Deadload
L=Liveload
E=Earthquakeload
Liveloadisnotincludedinthemasscalculations.
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 23 of 46
Chapter 5 StructuralSystems
5.1 IntroductionThischapterpresentsthebasicstructuralsystemstobeusedindesignofschoolbuildings.
5.2 DifferentStructuralSystems
5.2.1 OrdinaryReinforcedConcreteMomentResistingFramesandMasonryInfillWalls
Masonry infill walls shall be considered as primary seismic force resisting system and momentframewill be act as backup system for ductility. The frames and infillwalls shall resist the totallateralforceinaccordancewiththeirrelativerigidities,consideringtheinteractionoftheinfillwallsand frames. Referring to Table 16-N, UBC-97, overstrength factor, R for ordinary reinforcedconcretemomentresistingframeis3.5,inwhicheffectofmasonryinfillwallsarenotconsidered.InNBC-105, structural performance factor, K for ductilemoment resisting frame is 1 and framewithmasonryinfills is2.Responsereductionfactor is2timesdifferencebetweenmomentframewithmasonry infillsandmoment framewithoutmasonry infills.Hence,overstrength factor,Rof1.5wouldbeusedforordinaryreinforcedconcretemomentresistingframewithmasonryinfillsforseismicloadinginaccordancewithUBC-97.
Unreinforcedmasonry infill walls shall be designed as shear infill panels to act as seismic forceresisting system. Shear infill panels shall be in full contact with the frame elements on all foursides.RefertoTMS402-13/ACI530-13/ASCE5-13,AppendixB,theinfillwallshallbedesignedasparticipating infills. The infills shall be supported out-of-plane by connectors attached to thebounding frame. Infills shall be designed for in-plane shear forces and out-of-plane flexuraldemand.
Eachboundingcolumnshallbedesignedtoresisttheshearandmomentdemandequalnottolessthan1.1multipliedbytheresultsfromtheequivalentstrutframeanalysis,andforaxialforcenotless than the results from thatanalysis. Inaddition, thedesign shearateachendof the columnshall be increasedby thehorizontal componentof the equivalent strut force actingon that endunderdesignloads.Eachboundbeamshallbedesignedtoresisttheshearandmomentequaltoatleast1.1multipliedby theresults fromtheequivalentstrut frameanalysisand foranaxial forcenotlessthantheresultsfromthatanalysis.Inadditionalthedesignshearateachendofthebeamshallbeincreasedbytheverticalcomponentoftheequivalentstrutforceactingonthatendunderdesignloads.
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 24 of 46
Determine member demand forces
Design beams for flexural demand and columns for
axial and flexural demands
Design beam and column shear to resist the shear demand from analysis
Reinforcement detailing
Determine out-of-plane and in-plane demand
forces
Design mechanical connections between infill
and bounding frame
Design for out-of-plane flexural and in-plane shear
demand
Design check for bounding columns and
beams (moment and shear)
Figure 5-1 : Design Procedure for Ordinary Reinforced Concrete Moment Resisting Frames with Masonry Infill Walls
5.2.2 SpecialSteelMomentResistingFrames
Beams,columns,andbeam-columnconnectionsinspecialsteelmomentframesareproportionedanddetailed to resist flexural,axial,andshearingactions that resultasabuildingsways throughmultiple inelastic displacement cycles during strong earthquake ground shaking. Specialproportioning and detailing requirements are therefore essential in resisting strong earthquakeshakingwithsubstantialinelasticbehavior.Threemainobjectivesofspecialsteelmomentresistingframeare:
1) Toachieveastrong-column/weak-beamconditionthatdistributesinelasticresponseoverseveralstories
2) ToavoidP-deltainstabilityundergravityloadsandanticipatedlateralseismicdrifts
3) Toincorporatedetailsthatenableductileflexuralresponseinyieldingregions.
It is importanttoavoidearlyformationof inelasticresponsewhich isdominatedbyformationofplastic hinges at the tops and bottoms of columns within a single story. When such storymechanisms form, itwould result very largeP-delta effects at those locations. Inorder to avoidthis,formationofsideswaymechanismsdominatedbyhingingofbeamsispreferable,asopposedtocolumnhinging.
Inasevereearthquake,framestructureshavethepotentialtocollapseinasideswaymodeduetoP-delta effects. These effects are caused by vertical gravity loads acting on the deformedconfigurationofthestructure.SecondorderanalysisshallbeconductedtoconsiderP-deltaeffects.
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 25 of 46
Determine member demand forces
Capacity design for members and panel zones
Verify design story drift
Analyze the model considering P-delta effects
Figure 5-2 : Design Procedure for Special Steel Moment Resisting Frames
5.2.3 ReinforcedInterlockingBearingWalls
Reinforced interlocking bearing wall system shall be designed to resist the lateral loading andgravityloads.Areinforcedinterlockingbearingwallsystemiscomposedofwallsegments,eachofwhich can be categorized as either flexure-dominated or shear-dominated. A flexure-dominatedwall segment is one whose inelastic response is dominated by deformations resulting from thetensile yielding of flexural reinforcement. A shear-dominated segment is one whose inelasticresponse is dominated by diagonal shear (tension) cracks. It can be checked whether a wallsegmentisflexure-dominatedorshear-dominatedbycomparingitsflexuralcapacitywithitsshearcapacity. A flexure-dominated segment has a lower flexural capacity than shear capacity; for ashear-dominatedsegment,theoppositeistrue.
The ductility capacity of flexure-dominated walls depends on the aspect ratio, the flexuralreinforcementpercentage,and theaxial load. Flexure-dominatedelementsaregenerallyductile.Shear-dominated elements are generally brittle, with failure characterized by diagonal shearcracks.
When a reinforced interlockingwall has a shear-span-to-depth ratioMu/(Vudv) greater than onewith a well-designed plastic hinge zone, these requirements plus the required capacity-baseddesign for shear generally result in flexure-dominated, ductile behavior. However, when areinforcedinterlockingwallhasashear-span-to-depthratiolessthanoneorahighaxialload,thesamecombinationofprescriptive requirementsmaystill result inawall that is shear-dominatedandbrittle.
To protect a reinforced interlocking wall against shear failure caused by possible flexural overstrength, the design shear strength, ΦVn , should exceed the shear corresponding to thedevelopmentofthenominalmomentcapacitybyafactorofatleast1.25.
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 26 of 46
Determine out-of-plane and in-plane demand
forces
Design for out-of-plane flexural and axial demand
forces
Design for in-plane flexural and axial demand forces
Design for in-plane shear forces
(capacity-based design)
Check for sliding shear
Figure 5-3 : Design Procedure for Reinforced Interlocking Bearing Walls
5.2.4 SpecialReinforcedConcreteMomentResistingFrame
Specialreinforcedconcretemomentresistingframesshallbeproportionedanddetailedinsuchaway that the frame undergo safely extensive inelastic deformations that are anticipated underearthquakes.
Threemainobjectivesofspecialreinforcedconcretemomentresistingframeare:
1) To achieve a strong-column/weak-beam design that spreads inelastic response overseveralstories
2) Toavoidshearfailure
3) Toprovidedetailsthatenableductileflexuralresponseinyieldingregions.
Whenthebuildingswaysduringanearthquake,thedistributionofdamageoverheightdependsonthedistributionoflateraldrift.Ifthebuildinghasweakcolumns,drifttendstoconcentrateinoneorafewstories,andmayexceedthedriftcapacityofcolumns.Additionally,thecolumnsinagivenstory support the weight of the entire building above those columns, whereas the beams onlysupportthegravityloadsofthefloorofwhichtheyformapart;therefore,failureofacolumnisofgreaterconsequencethanfailureofabeam.
Ductileresponserequiresthatmembersyield inflexure,andthatshearfailurebeavoided.Shearfailure,especiallyincolumns,isrelativelybrittleandcanleadtorapidlossoflateralstrengthandaxial load-carryingcapacity.Flexuralyieldingregionsshallbedesignedforcode-requiredmomentstrengths, and then calculate design shears based on equilibrium assuming the flexural yieldingregionsdevelopprobablemomentstrengths.Hoopstypicallyareprovidedattheendsofcolumns,
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 27 of 46
aswellasthroughbeam-columnjoints,andattheendsofbeamsinordertoimprovetheductilebehavior.
Determine member demand forces
Design beams for flexural demand and columns for
axial and flexural demands
Design beam and column shear based on capacity based design procedures
Check for joint shear
Check strong column/weak beam requirements
Reinforcement detailing
Figure 5-4 : Design Procedure for Reinforced Concrete Special Moment Resisting Frame
5.2.5 Cold-FormedSteelOrdinaryMomentFrame
Cold-formedsteelordinarymomentresistingframesshallbeproportionedanddetailedinsuchawaythattheframewillremainessentiallyelasticordesignthehigherstrengthtoreducethehighductilitydemandsunderearthquakes.Asthemassofstructuralsystemissmall,thedesignwillbeprimarilygovernedbywindloading.
5.2.6 Hot-RolledSteelOrdinaryMomentFrame
Hot-rolled steel ordinary moment resisting frames shall be designed and detailed for higherstrengthtoreducethehighductilitydemands.
5.2.7 TimberStructure
Wood-frameshearwallssheathedwithshearpanelsofparticleboard,structuralfiberboard,andgypsumwall boardareused to resist the seismic forces.Bearingwall systemcategorywouldbeapplicablebecause shearwalls used for seismic force resistance also function to support gravityloadsofabuilding.
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 28 of 46
Chapter 6 Code-basedDesign
6.1 IntroductionThis chapterpresents the finiteelementmodeling, analysisanddesignprocedures tobeused inthecode-baseddesignofschoolbuildings.
6.2 ModelingofStructuralSystemA complete, three-dimensional elastic models are created, representing the structure’s spatialdistribution of the mass and stiffness to an extent that is adequate for the calculation of thesignificantfeaturesofthebuilding’selasticresponse.SAP2000isusedasanalysistool.Theelasticmodelsareusedforgravity,windandDBElevelearthquakeanalysis.Nominalmaterialpropertiesare used in modeling of structural components. The models include footings, columns, beams,walls, and roof truss. Recommended element types and stiffness modifiers to be used in themodelingofdifferenttypesofcomponentsaresummarizedinthefollowingtable.
Table 6-1 : Modeling of Structural System for Code-based Design
StructuralSystem Component
ElementtobeUsed Wind DBE
System1
RCbeams FrameFlexural–1.0IgShear–1.0Ag
Flexural–0.35IgShear–1.0Ag
RCcolumns Frame Flexural–1.0IgShear–1.0Ag
Flexural–0.7IgShear–1.0Ag
Masonryinfillwalls
Shellorframe(tomodelstrut)
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
In-planeFlexural–0.15IgShear–0.35AgOut-of-planeFlexural–0.1IgShear–0.2Ag
Footing Shell
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
Rooftruss FrameAxial–1.0AgFlexural–1.0IgShear–1.0Ag
Axial–1.0AgFlexural–1.0IgShear–1.0Ag
System2
Steelbeams Frame Flexural–1.0IgShear–1.0Ag
Flexural–1.0IgShear–1.0Ag
Steelcolumns Frame Flexural–1.0IgShear–1.0Ag
Flexural–1.0IgShear–1.0Ag
Footing Shell
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
Rooftruss FrameAxial–1.0AgFlexural–1.0IgShear–1.0Ag
Axial–1.0AgFlexural–1.0IgShear–1.0Ag
System3 Reinforcedinterlocking Layeredshell In-plane
Flexural–1.0IgIn-planeFlexural–0.15Ig
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 29 of 46
StructuralSystem Component
ElementtobeUsed Wind DBE
bearingwalls Shear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
Shear–0.35AgOut-of-planeFlexural–0.1IgShear–0.2Ag
Footing Shell
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
Rooftruss FrameAxial–1.0AgFlexural–1.0IgShear–1.0Ag
Axial–1.0AgFlexural–1.0IgShear–1.0Ag
System4
RCbeams Frame Flexural–1.0IgShear–1.0Ag
Flexural–0.35IgShear–1.0Ag
RCcolumns FrameFlexural–1.0IgShear–1.0Ag
Flexural–0.7IgShear–1.0Ag
Footing Shell
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
Rooftruss FrameAxial–1.0AgFlexural–1.0IgShear–1.0Ag
Axial–1.0AgFlexural–1.0IgShear–1.0Ag
System5
Cold-formedsteelbeams Frame
Flexural–1.0IgShear–1.0Ag
Flexural–1.0IgShear–1.0Ag
Cold-formedsteelcolumns
Frame Flexural–1.0IgShear–1.0Ag
Flexural–1.0IgShear–1.0Ag
Footing Shell
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
Rooftruss FrameAxial–1.0AgFlexural–1.0IgShear–1.0Ag
Axial–1.0AgFlexural–1.0IgShear–1.0Ag
System6
Hot-rolledsteelbeams Frame Flexural–1.0Ig
Shear–1.0AgFlexural–1.0IgShear–1.0Ag
Hot-rolledsteelcolumns Frame
Flexural–1.0IgShear–1.0Ag
Flexural–1.0IgShear–1.0Ag
Footing Shell
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
Rooftruss FrameAxial–1.0AgFlexural–1.0IgShear–1.0Ag
Axial–1.0AgFlexural–1.0IgShear–1.0Ag
System7 Timberbeams FrameFlexural–1.0IgShear–1.0Ag
Flexural–1.0IgShear–1.0Ag
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 30 of 46
StructuralSystem Component
ElementtobeUsed Wind DBE
Timbercolumns Frame Flexural–1.0IgShear–1.0Ag
Flexural–1.0IgShear–1.0Ag
Shearpanels Shell
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
Footing Shell
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
Rooftruss FrameAxial–1.0AgFlexural–1.0IgShear–1.0Ag
Axial–1.0AgFlexural–1.0IgShear–1.0Ag
6.2.1 Beams
Frame elements are used inmodeling of beams,which includes the effects of bending, torsion,axialdeformation,andsheardeformations.Insertionpointsandendoffsetsareappliedtoaccountfor the finite size of beam and column intersections, if required. The end offsetsmay bemadepartiallyorfullyrigidbasedonengineeringjudgmenttomodelthestiffeningeffectthatcanoccurwhentheendsofanelementareembeddedinbeamandcolumnintersections.Endreleasesareappliedtomodeldifferentfixityconditionsattheendsoftheelementinaccordancewiththetypeofdetailing.
6.2.2 RoofTruss
Frameelementsareused inmodelingof truss.End releasesareapplied tomodeldifferent fixityconditionsattheendsoftheelementinaccordancewiththetypeofdetailing.
6.2.3 Columns
Frameelements areused inmodelingof columns,which includes the effects of biaxial bending,torsion, axial deformation, and biaxial shear deformations. Insertion points and end offsets areappliedtoaccountforthefinitesizeofbeamandcolumnintersections,ifrequired.Theendoffsetsmaybemadepartiallyorfullyrigidbasedonengineeringjudgmenttomodelthestiffeningeffectthatcanoccurwhentheendsofanelementareembeddedinbeamandcolumnintersections.Endreleasesareappliedtomodeldifferentfixityconditionsattheendsoftheelementinaccordancewiththetypeofdetailing.
6.2.4 Footings
Shell elements are used in modeling of footings. The effect of soil structure interaction isconsidered for the buildings inwhich an increase in fundamental period due to soil effectswillresult in an increase in spectral accelerations. Vertical springs and lateral springs are assignedrespectively in order to consider the interaction effect of soil. The spring stiffness values arecalculated based on the sub-grade modulus values from geotechnical report if available.Approximate sub-grade modulus values can be estimated based on the empirical formulasmentionedbelow.
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 31 of 46
K=3Es forcohesionlesssoil
K=1.6Es forcohesivesoil
Vertical spring stiffness may be determined based on the allowable bearing capacity as below.Horizontalspringstiffnessmaybeassumed50%ofverticalspringstiffness.
Kv=AllowablebearingcapacityxSafetyfactorx40
6.2.5 MasonryInfillWalls
Masonryinfillwallscanbemodeledintwooptionsasbelow.
1) UsingShellElement
Shell elements shall be used inmodeling of unreinforcedmasonry infillwalls,which include themembraneandplatebendingbehavior.Thewallelementsaremeshedhorizontallyandverticallyinadequatenumbers.Theorientationoflocalaxisoftheshearwallelementsshallbeconsistentinentirewall. Unreinforcedmasonrywallsmay be checked to resist out-of-plane inertial forces asisolated components spanning between floor levels, and/or spanning horizontally betweencolumnsandpilasters.
2) UsingStrutElement
Equivalent strutmodel, capable of resisting compression only, can be used. The section size ofequivalent strut shall be determined in accordance with TMS 402-13/ACI 530-13/ASCE 5-13,Section B.3.4.1. Strut element shall be released at each end for moments about 2 and 3 axes.Tension limitshallbesettozeroforthestrutelements.Nonlinearanalysisshallbeconductedtoconsiderthecompressiononlystrut.
6.2.6 ReinforcedInterlockingBearingWalls
Layered shell elements areused inmodelingof reinforced interlockingbearingwalls. The entirecrosssectionofthewallisdiscretizedintoindividuallayers.Theselayersarelocatedbyaspecificdistance from the reference surfaceandwith the specified thickness. Thematerial propertiesofeachlayerarespecifiedbythepropertiesofeachmaterial.Theelementsaremeshedhorizontallyandverticallyinadequatenumbers.Theorientationoflocalaxisoftheshearwallelementsshallbeconsistent inentirewall. In layeredelement,massandweightarecomputed formembraneandshelllayers,notforplatelayers.
6.2.7 Damping
5%constantmodaldampingisusedinseismicanalysisatDBElevel.
6.3 AnalysisProceduresAnalysisprocedurestobeusedforcode-baseddesignarepresentedinthefollowingsections.
Table 6-2 : Analysis Procedures used in Code-based Design
LoadCase Analysis
Gravityandwind Linearstaticanalysis
Earthquake Responsespectrumanalysis
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 32 of 46
6.3.1 ModalAnalysis
Modalanalysisiscarriedouttodeterminethemodalpropertiesofthebuilding.100%ofdeadload,superimposed dead load and 25%of live load are considered asmass source inmodal analysis.EitherEigenanalysisorRitzanalysisshallbeused.Sufficientnumberofvibrationmodesshallbeconsideredtoachieveatleast90%ofparticipatingmassofthebuilding.
6.3.2 LinearStaticProcedure(LSP)
Linearstaticanalysisiscarriedoutforgravityandwindloadings.Windloadmaybeappliedtotheexposurefromwallsandroofsintheanalysismodel.
6.3.3 ResponseSpectrumAnalysis(RS)
Responsespectrumanalysis iscarriedoutusing linearlyelastic responsespectra.At least90%oftheparticipatingmassofthebuildingisconsideredineachoftwoorthogonalprincipaldirectionsofthebuilding.CompleteQuadraticCombination(CQC)ruleisusedforcombinationofresponsesfromeachmode.Orthogonaleffectsareconsideredbydesigningelementsfor100percentoftheprescribeddesignseismicforcesinonedirectionplus30percentoftheprescribeddesignseismicforcesintheperpendiculardirection.5%constantmodaldampingisconsideredintheanalysis.
6.4 ComponentandMemberDesignThe structural components are designed to satisfy the strength and ductility requirements.Strength capacity for different types of actions considered in the design are summarized in thetablebelow.
Table 6-3 : Component and Member Design
StructuralSystem
Component DesignApproach/Consideration CodeReference
System1 RCbeams Flexural,Shear ACI318-08
Chapter10,11and21
RCcolumns PMM,Shear ACI318-08
Chapter10,11and21
Masonryinfillwalls Out-of-planeflexuralandin-planeshear
ACI530-13,AppendixB
Footings Bearingcapacityofsoil
Flexural,shear
ACI318-08
Chapter15
Steeltruss AISC360-10
ChapterDandE
Steelconnections AISC360-10
ChapterJ
System2 Steelbeams Flexuralresponse
• Flexuralyielding
• Lateral-torsionalbuckling
• Flangelocalbuckling
• Weblocalbuckling
AISC360-10
ChapterFandG
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 33 of 46
StructuralSystem
Component DesignApproach/Consideration CodeReference
Shear
Steelcolumns Compression
• Flexuralbuckling
• Torsionalandflexural-torsionalbuckling
Flexure
• Flexuralyielding
• Lateral-torsionalbuckling
• Flangelocalbuckling
• Weblocalbuckling
Shear
AISC360-10
ChapterEandH
Footings Bearingcapacityofsoil
Flexural,shear
ACI318-08
Chapter15
Steeltruss Compression
• Flexuralbuckling
• Torsionalandflexural-torsionalbuckling
Tension
AISC360-10
ChapterDandE
Steelconnections Momentconnections
Shearconnections
AISC360-10
ChapterJ
System3 Reinforcedinterlockingbearingwalls
Bearing,axialcompression
In-planeflexuralandshear
Out-of-planeflexural
ACI530-13asappropriateandtestresults
Footings Bearingcapacityofsoil
Flexural,shear
ACI318-08
Chapter15
Steeltruss Compression
• Flexuralbuckling
• Torsionalandflexural-torsionalbuckling
Tension
AISC360-10
ChapterDandE
Steelconnections Momentconnections
Shearconnections
AISC360-10
ChapterJ
System4 RCbeams Flexural,Shear ACI318-08
Chapter10,11and21
RCcolumns PMM,Shear ACI318-08
Chapter10,11and21
Footings Bearingcapacityofsoil
Flexural,shear
ACI318-08
Chapter15
Steeltruss Compression AISC360-10
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 34 of 46
StructuralSystem
Component DesignApproach/Consideration CodeReference
• Flexuralbuckling
• Torsionalandflexural-torsionalbuckling
Tension
ChapterDandE
Steelconnections Momentconnections
Shearconnections
AISC360-10
ChapterJ
System5 Cold-formedsteelbeams
Flexuralresponse
Shear
AISI-Commentary
ChapterC
Cold-formedsteelcolumns
Compression
Flexure
Shear
AISI-Commentary
ChapterC
Footings Bearingcapacityofsoil
Flexural,shear
ACI318-08
Chapter15
Steeltruss Compression
Tension
AISI-Commentary
ChapterC
Steelconnections Momentconnections
Shearconnections
AISC360-10
ChapterJ
System6 Steelbeams Flexuralresponse
• Flexuralyielding
• Lateral-torsionalbuckling
• Flangelocalbuckling
• Weblocalbuckling
Shear
AISC360-10
ChapterFandG
Steelcolumns Compression
• Flexuralbuckling
• Torsionalandflexural-torsionalbuckling
Flexure
• Flexuralyielding
• Lateral-torsionalbuckling
• Flangelocalbuckling
• Weblocalbuckling
Shear
AISC360-10
ChapterEandH
Footings Bearingcapacityofsoil
Flexural,shear
ACI318-08
Chapter15
Steeltruss Compression
• Flexuralbuckling
• Torsionalandflexural-torsionalbuckling
AISC360-10
ChapterDandE
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 35 of 46
StructuralSystem
Component DesignApproach/Consideration CodeReference
Tension
Steelconnections Momentconnections
Shearconnections
AISC360-10
ChapterJ
System7 Timberbeams Flexural,Shear ANSI/AWCSDPWS-2015,NBC112:1994,IS-883:1994
Timbercolumns PMM,Shear ANSI/AWCSDPWS-2015,NBC112:1994,IS-883:1994
Shearpanels Out-of-planeflexuralandin-planeshear
ANSI/AWCSDPWS-2015,NBC112:1994,IS-883:1994
Footings Bearingcapacityofsoil
Flexural,shear
ACI318-08
Chapter15
Timbertruss ANSI/AWCSDPWS-2015,NBC112:1994,IS-883:1994
Connections ANSI/AWCSDPWS-2015,NBC112:1994,IS-883:1994
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 36 of 46
Chapter 7 SeismicPerformance-basedEvaluation
7.1 IntroductionThis chapter presents the modeling, analysis and evaluation procedures used in seismicperformance-basedevaluationofschoolbuildings.Fordesignprocedure1,structuralperformanceof the building shall be evaluated under 1000-year return period and 2000-year return period(optional) earthquakes. For design procedure 2, response reduction factor, R factor will bedeterminedbasedonthefunctionofductilityfactor,µ,regardlessofseismicdemandlevel.
7.2 ModelingofStructuralSystemFor seismic performance-based evaluation, nonlinear verification models are used, in whichdeformation-controlled actions are modeled as nonlinear while force-controlled actions aremodeledaslinear.
Themodelincludesinelasticpropertiesforcomponentsthatareanticipatedtobeloadedbeyondtheir elastic limits. These include flexural response of beams, columns, in-plane response ofunreinforced masonry infills and reinforced interlocking walls. Elements that are assumed toremain elastic are modeled with elastic member properties. These include shear response ofbeamsandcolumns,flexuralandshearresponseoffootings.
In design procedure 2, it is important to note that all force-controlled actions shall bemodeledwith force-controlled hinges. Force-controlled hinges shall lose the load carrying capacity whenmaximumforce is reached. Indeformation-controlledhinges,post-yieldingstiffnessandstrengthlossshallbeproperlydefined.
Table 7-1 : Modeling of Structural System for Performance-based Evaluation
StructuralSystem Component
ElementtobeUsed 1000-year 2000-year
System1 RCbeams Framewithflexuralhinges
Flexural–0.35IgShear–1.0Ag
Flexural–0.3IgShear–1.0Ag
RCcolumns FramewithPMMhinges
Flexural–0.7IgShear–1.0Ag
Flexural–0.3IgShear–1.0Ag
Masonryinfillwalls
Nonlinearlayeredshell
In-planeFlexural–0.15IgShear–0.35AgOut-of-planeFlexural–0.1IgShear–0.2Ag
In-planeFlexural–0.15IgShear–0.25AgOut-of-planeFlexural–0.1IgShear–0.2Ag
Footing Shell In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
Rooftruss Frame Axial–1.0AgFlexural–1.0IgShear–1.0Ag
Axial–1.0AgFlexural–1.0IgShear–1.0Ag
System2 Steelbeams Framewithflexuralhinges
Flexural–1.0IgShear–1.0Ag
Flexural–1.0IgShear–1.0Ag
Steelcolumns FramewithPMMhinges
Flexural–1.0IgShear–1.0Ag
Flexural–1.0IgShear–1.0Ag
Footing Shell In-plane In-plane
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 37 of 46
StructuralSystem Component
ElementtobeUsed 1000-year 2000-year
Flexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
Flexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
Rooftruss Frame Axial–1.0AgFlexural–1.0IgShear–1.0Ag
Axial–1.0AgFlexural–1.0IgShear–1.0Ag
System3 Reinforcedinterlockingbearingwalls
Nonlinearlayeredshell
In-planeFlexural–0.15IgShear–0.35AgOut-of-planeFlexural–0.1IgShear–0.2Ag
In-planeFlexural–0.15IgShear–0.25AgOut-of-planeFlexural–0.1IgShear–0.2Ag
Footing Shell In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
Rooftruss Frame Axial–1.0AgFlexural–1.0IgShear–1.0Ag
Axial–1.0AgFlexural–1.0IgShear–1.0Ag
System4 RCbeams Framewithflexuralhinges
Flexural–0.35IgShear–1.0Ag
Flexural–0.3IgShear–1.0Ag
RCcolumns FramewithPMMhinges
Flexural–0.7IgShear–1.0Ag
Flexural–0.3IgShear–1.0Ag
Footing Shell In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
Rooftruss Frame Axial–1.0AgFlexural–1.0IgShear–1.0Ag
Axial–1.0AgFlexural–1.0IgShear–1.0Ag
System5 Cold-formedsteelbeams
Framewithflexuralhinges
Flexural–1.0IgShear–1.0Ag
Flexural–1.0IgShear–1.0Ag
Cold-formedsteelcolumns
FramewithPMMhinges
Flexural–1.0IgShear–1.0Ag
Flexural–1.0IgShear–1.0Ag
Footing Shell In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
Rooftruss Frame Axial–1.0AgFlexural–1.0IgShear–1.0Ag
Axial–1.0AgFlexural–1.0IgShear–1.0Ag
System6 Hot-rolledbeams
Framewithflexuralhinges
Flexural–1.0IgShear–1.0Ag
Flexural–1.0IgShear–1.0Ag
Hot-rolledcolumns
FramewithPMMhinges
Flexural–1.0IgShear–1.0Ag
Flexural–1.0IgShear–1.0Ag
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 38 of 46
StructuralSystem Component
ElementtobeUsed 1000-year 2000-year
Footing Shell In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
In-planeFlexural–1.0IgShear–1.0AgOut-of-planeFlexural–1.0IgShear–1.0Ag
Rooftruss Frame Axial–1.0AgFlexural–1.0IgShear–1.0Ag
Axial–1.0AgFlexural–1.0IgShear–1.0Ag
7.2.1 Beams
Frame elements are used inmodeling of beams,which includes the effects of bending, torsion,axialdeformation,andsheardeformations.Nonlinear flexuralhingesareassignedat theendsofbeamstorepresentthenonlinearflexuralresponsewhileshearresponseismodeledaslinear.
7.2.2 Columns
Frameelements areused inmodelingof columns,which includes theeffects of biaxial bending,torsion, axial deformation, and biaxial shear deformations. Fiber P-M2-M3 hinges are used tomodelthenonlinearbehaviorofcoupledaxialforceandbi-axialbending.Fiberhingesareassignedbothendsofthecolumn.User-definedfiberhingesareused,bygeneratingthefiber layoutfromSection Designer. In reinforced concrete columns, rebar fibers are lumpedwhile generating thefiber layout to reduce the analysis time. Plastic hinge length of reinforced concrete columns isdeterminedbasedonthefollowingequation.
Lp=0.08L+0.022fyedbl≥0.044fyedbl(MPa)
Where
Lp =plastichingelength
H =sectiondepth
L =criticaldistancefromthecriticalsectionofplastichingetothepointofcontraflexure
fye =expectedyieldstrengthoflongitudinalreinforcement
dbl =diameteroflongitudinalreinforcement
7.2.3 MasonryInfillWallsandReinforcedInterlockingBearingWalls
Nonlinear layered shell elements are used in nonlinear modeling of masonry infill walls andreinforced interlocking bearing walls. The procedure is same as linear modeling of reinforcedinterlocking bearing walls, except for considering nonlinear material behavior for concrete andreinforcementinin-planeresponse.
7.2.4 Damping
Rayleighdampingmodelisused.Thedampingratiosareprovidedasfollows.
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 39 of 46
Table 7-2 : Damping Ratios
PeriodratioT/T1 DampingRatio
0.2 3%
0.9 2%
Where,T1isfirstmodenaturalperiod.
7.3 AnalysisProceduresAnalysis procedures to be used for seismic performance-based evaluation are presented in thefollowingsections.
Table 7-3 : Analysis Procedures used in Performance-based Evaluation
LoadCase Analysis
Gravity Nonlinearstaticanalysis
Earthquake Nonlineartimehistoryanalysis(fordesignprocedure1)
Pushoveranalysis(Nonlinearstatic,fordesignprocedure2)
7.3.1 NonlinearStaticProcedureforGravityLoad(NSP)
Nonlinearstaticanalysiswillbeconductedforgravity loading,priorto lateral loadanalysis,using“Full Load” control application. In nonlinear static procedure, monotonically increasing gravityloadingisappliedonthebuilding.P-∆effectsshallbeconsideredintheanalysis.
7.3.2 NonlinearTimeHistoryAnalysis(NLTHA)
Nonlinear time history analysis is carried out using pairs of ground motion records, analyzingsimultaneously along each principal direction of the building. If fewer than seven time historyanalyses are performed, the maximum response is used for evaluation. If seven or more timehistory analyses are performed the average value of response is used. Nonlinear time historyanalysisiscontinuedfromthestateendofgravityloadcase.Rayleighdampingmodelwith2-3%ofcriticaldampingisused(Specifydampingbyperiod).P-∆effectsareconsideredintheanalysis.
The selected ground motion records for time history analysis should have magnitude, faultdistances, and source mechanisms that are consistent with those that control the designearthquake groundmotions for each seismic demand level. For each set of groundmotion, thesquarerootofsumofthesquares(SRSS)ofthe5%-dampedresponsespectraofthescaledgroundmotioncomponent shallbeconstructed.Thesetsofgroundmotion records shallbescaledsuchthattheaveragevalueoftheSRSSspectradoesnotfallbelow1.3timesthe5%-dampedspectrumforthedesignearthquakeforperiodsbetween0.2Tand1.5T(whereTisthefundamentalperiodofthebuilding).
ThePEERGroundMotionDatabase (PGMD)web-based tool (PEER,2011)maybeused for linearscaling and selecting groundmotions tomatchwith the design response spectrum of particularseismicleveltobechecked.Thelinearscalingfactorforeachgroundmotionshouldnotbegreaterthan8.
7.3.3 PushoverAnalysis
Firstly, nonlinear static analysis shall be performed for gravity loads using “Full Load” controlapplication.Nonlinear static analysis for lateral loading shall be continued from the stateendof
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 40 of 46
gravityloadcase,usingmodaldeformationloadpattern,with“DisplacementControl”application.P-∆effectsshallbeconsideredinbothgravityandlateralloadcases.
7.4 PerformanceCriteriaThissectionpresentstheperformancecriteriatobeusedinseismicperformance-basedevaluationofschoolbuildings.
7.4.1 ExpectedandLower-BoundStrengthusedinPerformanceEvaluation
Whereevaluatingthebehaviorofdeformation-controlledactions,theexpectedstrength,QCE,shallbeused.Whereevaluatingthebehaviorofforce-controlledactions,alower-boundestimateofthecomponentstrength,QCL,shallbeused.
ExpectedStrength
Expectedmaterialpropertiesshallbeusedtocalculatethedesignstrengthsinaccordancewiththecodebasedprocedures,exceptstrengthreductionfactor,Φshallbetakenequaltounity.Expectedmaterialpropertiesmaybecalculatedbymultiplyinglower-boundvaluesbyappropriatefactors.
Table 7-4 : Factors to Translate Lower-Bound Material Properties to Expected Strength Material Properties
MaterialProperty Factor
Concretecompressivestrength 1.3
Reinforcingsteeltensileandyieldstrength 1.25
Masonrycompressivestrength 1.3
Masonryflexuraltensilestrength 1.3
Masonryshearstrength 1.3
Structuralsteelyieldstrength 1.1
Note:Factorof1.3isusedforconcretecompressivestrengthinlieuoffactorof1.5,mentionedinTable10-1,ASCE41-13.
Lower-boundStrength
Lower-boundmaterialpropertiesshallbeusedtocalculatethedesignstrengthsinaccordancewiththe code based procedures, except strength reduction factor, Φ shall be taken equal to unity.Nominalmaterialpropertiesareusedaslower-boundstrength.
7.4.2 PerformanceCriteriaforDesignProcedure1
Structural performance shall be satisfied for “Life Safety” performance level under 1000-yearreturn period earthquakes and “Collapse Prevention” performance level under 2000-year returnperiodearthquakes.
7.4.2.1 GlobalResponseAcceptanceCriteria
Inlieuofotherlimits,theacceptancecriteriaforglobalresponseofthebuildingisasbelow.
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 41 of 46
Table 7-5 : Acceptance Criteria for Global Response of School Buildings
Type SeismicLevel
DBE MCE
Storydrift• System1• System2• System3• System4• System5
0.5%1.5%0.6%1.5%1.5%
0.6%3%1.5%3%3%
Foundation• Totalsettlement• Differentialsettlementin30ft• Sliding• Overturning
6in.0.5in.FS≥1.5FS≥1.5
Majorsettlementand
tiltingFS≥1.5FS≥1.5
7.4.2.2 ComponentResponseAcceptanceCriteria
Actions in all lateral load resisting elements are categorized as either force-controlled ordeformation-controlled actions. Following table summarizes the classification of componentactions.
Deformation-ControlledActions
The response of the components under deformation-controlled actions shall be checked inaccordancewith theacceptancecriteria fornonlinearproceduresmentionedthroughChapters8through11ofASCE41-13.
Force-ControlledActions
Theresponseofthecomponentsunderforce-controlledactionsshallbecheckedusingthelower-boundstrengthswhichshallnotbe less thanmaximumdesign forcesormaximumdesign forcesdevelopedaslimitedbythenonlinearresponseofthecomponent.
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 42 of 46
Table 7-6 : Classification of Actions and Acceptance Criteria
StructuralSystem
ComponentDeformation-Controlled Force-Controlled
ReferenceAction NLResponse Action
System1 RCbeams • Moment • Hingerotation
• Shear ASCE41-13,Table10-7
RCcolumns • PMM • Hingerotation
• Axialcompression
• Shear
ASCE41-13,Table10-8
Masonryinfillwalls3
• In-planeshear
• In-planerotation(Drift)
• Columnshearadjacenttoinfillpanels
• Beamshearadjacenttoinfillpanels
ASCE41-13,Table11-9,11-10
Footing - - Bearingcapacityofsoil
Flexural,shear
ACI318-08
Chapter15
Steeltruss Compression
• Flexuralbuckling
• Torsionalandflexural-torsionalbuckling
Tension
AISC360-10
ChapterDandE
Steelconnections
Momentconnections
Shearconnections
AISC360-10
ChapterJ
System2 Steelbeams • Moment • Hingerotation
• Shear ASCE41-13,Table9-6
Steelcolumns • PMM • Hingerotation
• Shear ASCE41-13,Table9-6
Footing - - Bearingcapacityofsoil
Flexural,shear
ACI318-08
Chapter15
Steeltruss Compression AISC360-10
3Masonryinfillwallsshallbeprovidedwithhorizontalreinforcedconcrete(RC)bandsthroughthewallataboutone-thirdandtwo-thirdsoftheirheightabovethefloorineachstorey.WallopeningsshallbeframedbyRCframingcomponentsasperNBC201:1994Clause8.
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 43 of 46
StructuralSystem
ComponentDeformation-Controlled Force-Controlled
ReferenceAction NLResponse Action
• Flexuralbuckling
• Torsionalandflexural-torsionalbuckling
Tension
ChapterDandE
Steelconnections
Momentconnections
Shearconnections
AISC360-10
ChapterJ
System3 Reinforcedinterlockingbearingwalls
• In-planeflexureandshear
• Drift • Axialcompression
ASCE41-13,Table11-7asappropriateandtestresults
Footing - - Bearingcapacityofsoil
Flexural,shear
ACI318-08
Chapter15
Steeltruss Compression
• Flexuralbuckling
• Torsionalandflexural-torsionalbuckling
Tension
AISC360-10
ChapterDandE
Steelconnections
Momentconnections
Shearconnections
AISC360-10
ChapterJ
System4 RCbeams • Moment • Hingerotation
• Shear ASCE41-13,Table10-7
RCcolumns • PMM • Hingerotation
• Axialcompression
• Shear
ASCE41-13,Table10-8
Footing - - Bearingcapacityofsoil
Flexural,shear
ACI318-08
Chapter15
Steeltruss Compression
• Flexuralbuckling
• Torsionalandflexural-
AISC360-10
ChapterDandE
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 44 of 46
StructuralSystem
ComponentDeformation-Controlled Force-Controlled
ReferenceAction NLResponse Action
torsionalbuckling
Tension
Steelconnections
Momentconnections
Shearconnections
AISC360-10
ChapterJ
System5 Cold-formedSteelbeams
• Moment,Shear
AISI-Commentary
ChapterC
Cold-formedSteelcolumns
• Axial,moment,Shear
AISI-Commentary
ChapterC
Footing - - Bearingcapacityofsoil
Flexural,shear
ACI318-08
Chapter15
Cold-formedSteeltruss
Compression
Tension
AISI-Commentary
ChapterC
Steelconnections
Momentconnections
Shearconnections
AISC360-10
ChapterJ
System6 Hot-rolledsteelbeams
Moment Hingerotation
Shear ASCE41-13,Table9-6
Hot-rolledsteelcolumns
PMM Hingerotation
Shear ASCE41-13,Table9-6
Footing - - Bearingcapacityofsoil
Flexural,shear
ACI318-08
Chapter15
Steeltruss Compression
• Flexuralbuckling
• Torsionalandflexural-torsionalbuckling
Tension
AISC360-10
ChapterDandE
Steelconnections
Momentconnections
Shearconnections
AISC360-10
ChapterJ
System7 Notapplicable
Structural Design Criteria for School Buildings Nepal: Post earthquake Reconstruction of Schools
page 45 of 46
7.4.3 PerformanceCriteriaforDesignProcedure2
Theductilityfactor:“μ”, isdeterminedbytheratiobetweenthemaximumdisplacementandthedisplacementatfirstyield.
Figure 7-1 : Capacity Curve from Pushover Analysis
Responsereductionfactor,R,shallbedeterminedfromfollowingequationsasbelow.
R=μ(forstructuralperiodsgreaterthanapproximately0.7sec)
R= 2𝜇 − 1(forstructuralperiodslessthanapproximately0.3sec)
If R factor in code-based design is less than R factor determined from performance-basedevaluation, code-based design will be carried out using R factor from performance-basedevaluation.
DepartmentofEducation(DOE)MinistryofEducationGovernmentofNepal