follett tech 3

8/12/2019 Follett Tech 3

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Technical WashingtonParkCondominiumsReport#3 Mt.Lebanon,PA

B.Follett Page2

TableofContents:TableofContents...2ExecutiveSummary.....3Introduction...4ExistingCompositeJoistandPrecastConcretePlankSystem...5ApplicableCodes,DesignCriteriaandLoadCases......8BuildingDesignLoadsandLateralCriteria.........9LoadDistributionandAnalysis.....12

DeterminationofRelativeStiffness(k)andCenterofRigidity....12DeterminationofDirectandTorsionalShear.... 12,13

FrameAnalysis.. 15PortalFrameAnalysis........15STAAD.Pro2006Analysis......15MemberVerificationandStrengthChecks.17

ServiceabilityCheck(DriftAnalysis)... 26OverturningMomentandUplift... 27Conclusion.......29AppendixA:BuildingLayout...30AppendixB:WindandSeismicDesignData........33AppendixC:CenterofMassandRigidity..36AppendixD:PortalFrameAnalysisCalculations....38AppendixE:TorsionalForceTables.....44


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ExecutiveSummary:WashingtonParkCondominiumsisan8storymultiuseretailandresidentialbuildinglocatedin

Mt.Lebanon,Pennsylvania. Thelateralforceresistingsystemofthebuildingwhichwillbe

studiedinthisreportisasteelmomentframesystem. Therearefourframesthatruninthe

northsouthdirectionofthebuildingwhichalsoisthelongestlengthofthebuilding.Furthermore,therearenine,3baymomentframesthatrunintheeastwestdirectionofthe

building. Theseframesareconnectedtobraceframesinthebasementandsubbasement

levelswhichhelptocarrythesoilpressureandtransferthelateralloadtothefoundations.

ThepurposeofTechnicalReport#3wastoinvestigatethelateralsystemofthebuildingandto

prepareananalysisanddesignverificationsummaryofthestructure. Theloadsfoundin

TechnicalReport#1wereusedasabaseandwereeventuallymodifiedbasedonthestiffnesss

oftheframesthatwasdeterminedduringthedesignandanalysisprocess. Theinvestigation

usedhandmethodsalongwithcomputeranalysistodetermineanddiscussthefollowing:

DirectandTorsionalShearForces

ControllingLoadCombinations

LogicalLoadPath

StoryandOverallStructureDrift

Beam,ColumnandBraceStrength

OverturningMomentsandUplift

Theanalysisshowshowthemomentframes,runninginbothdirectionsthroughthebuilding,

resistthelateralforcesthatareappliedbybothwindandseismic. Oncetheloadswereapplied

tothestructureaframeanalysiswasperformedbybothhandcalculationandcomputer

modeling. Thisallowedthestrengthofcertaincriticalmemberstobeaccessed. After

reviewingthesemembersitwasdeterminedthatthemembersizeswerechosenbasedonthe

governingdrift. Uponcompletionoftheanalysisitwasdeterminedthatinmostcasesthewind

controlsthelateraldesign. However,thisisnotapparentinthedriftcalculationswhichshow

thewinddriftsmeetingtheacceptablecodelimitswhiletheseismicdriftsfailsthelimits

deemedacceptablebycode. Thisissuewillbestudiedatlengthintheproposaltoseeifthere

isreallyanissueintermsofseismicdriftandifsohowcanthedriftbeminimizedwithout

compromisingthearchitecturalaspectsofthefloorsystemandthereforevastlyincreasing

buildingcosts.


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Introduction:

WashingtonParkCondominiumsisamultiuseretailandresidentialbuildinglocatedatthe

intersectionofBowerHillRoadandWashingtonRoadinMt.Lebanon,Pennsylvania. Sitework

andexcavationhasbegunatthesiteandconstructionshouldbeginsometimebeforetheend

ofthefall2008,withtheprojectlastinguntilfall2010. WashingtonParkCondominiumsisthe

firstoftwobuildingsproposedtobebuiltonthesite. Buildingoneisaninestory,148,000ft2

structurewhichisownedbyZamagiasPropertiesofPittsburgh,PA. Thebuildingwas

architecturallydesignedbyIndovinaAssociatesArchitectsandisbeingconstructedbyPJDick,

Inc.forapriceof$23,418,000. Thebuildingsprimaryuseisresidentialanditcontains7stories

ofcondominiumsonthe2ndthrough8

thfloors. Thefirstfloorofthebuildingisusedforretail

spaceandasalocationforextraamenitiesfortheresidentsofWashingtonPark. Thebuilding

alsocontainstwobelowgradelevelsofparking. Theenclosedparkinggaragecontains78

parkingspacesthatcanbeusedbytheresidents. Twoelevatorsandtwostairsservethe

parkingareasthatalsocontainresidentstorage,awineroomandtrashcollectionalongwith

mechanicalandelectricalrooms. Thegroundfloorservesprimarilyasretailspacewithfour

separateareasavailableforpossibletenants. Alsocontainedonthefloorarearesident

exerciseroomandaprivateentranceandlobbyfortheresidents.

Asthebuildingmovestothesecondfloor,thefunctionchangesfromprimarilyretailtooneof

solelyresidentialwithsixupscalecondominiumslocatedonthefloor. Thesecondominiums

eachhavedifferentfloorplansandlayoutswithoverallareasrangingfrom1523ft2to2288ft

2.

Eachunitcontainstwoorthreebedroomsandbathroomsdependingonsize,alongwithaliving

room,diningroom,kitchen,study,laundry,entryandinsomecasesabalcony. Thisfloorlayoutcontinuesthroughoutthenextfourfloors,withatotalof30unitsonfloors2through6. The7

th

and8thfloorsofthebuildingarethepenthouselevel. Thisfloorcontainsfivecondominiums

thatrangefrom1732ft2to2453ft

2. Theseunitscontainthesameamenitiesandspacesasthe

unitsonthebelowfloorsdo. Allofthecondominiumsfloorsareservedbytwoelevatorsand

twostairwaysthatareconnectedbyahallwaythatrunsthroughthecenterofthebuildingin

thelongdirection. Finally,theroofcontainsmechanicalspacesthatareaccessedbyusingthe

northernmoststairwayorelevator.

Thetypicalexteriorwallsystemofthebuildingconsistsmainlyof4brickveneerbackedbya2

airspaceand2ofrigidXPSinsulation,thencontaininganother2layerofrigidsprayfoam

insulationthatisfollowedbyanairspaceandthen5/8gypsumboard. Thisexteriorwall

systemistypicalforthefirst6floorsofthebuilding. The7thand8

thfloorsofthebuilding

consistofasimilarwallconstructionexceptfortheexteriorfaadewhichisa5/16layerof

paintedfibercementsiding.


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ExistingCompositeJoistandPrecastConcretePlankSystem:FoundationsThefoundationsystemcanbebestdescribedasaspreadfootingsystemwithattached

concretepiers. Thesizesforthespreadfootingsrangefromthesmallest,a40x40x20footingwith#8@12eachway,toa140x140x36footingwith#8@6eachwaywith

thedeepestofthefootingswillbe250belowgrade. Inadditiontothespreadfootings,

interiorandexteriorwallfootingswereusedandareeither20or30wideby14deep.

Thesteelreinforcinginthesewallfootingsare(3)#5continuousbarsand#5x18@16.

Theslabongradeinthissystemconsistofeithera6or8normalweightconcreteslab

reinforcedwith6x6W2.9xW2.9weldedwirefabricor6x6W4xW4weldedwirefabric.Theslab

ongradeisalsothickenedtoaminimumif10atnonloadbearingwallsand(2)#4barsare

addedfortensilestrength. Connectingthecolumnstotheslabongradeandthefootingsare

columnpiersthatrangefrom16x16with(4)#7ofverticalreinforcementto40x40w/

(12)#7ofverticalreinforcementandfc=4000psiconcreteisusedfortheentiresystem.FloorSystemsTwoseparatefloorssystemsaretypicalwithinthestructureofWashingtonPark. Thefirstisa

precastconcreteplanksystemthatisusedintheparkingareasaswellasthefirstandsecond

floorframing. Theprecastconcreteplankis8thickandalsocontainsa2thickstructural

topping. Thereinforcinginthestructuraltoppingis6x6W1.4xW1.4weldedwirefabric. The

precastconcreteplanksystembearsonWshapeswhichthencarrytheloadtothecolumns.

Thissystemwasusedintheparkingareasbecauseofthesystemsdiaphragmcapacity(abilityto

transferhorizontalloading)andbecauseofitsdurabilityandstrength.

ThesecondprimaryfloorsysteminthebuildingistheVESCOMcompositejoistfloorsystem.

Thecompositejoistsysteminterlocksthetopchordofajoistwiththeconcreteproducingless

deflection,lessvibrationandgreaterstiffness. Thefloorconstructionconsistsofa211/16

reducedweightconcreteslabthatispouredontopofthe15/16,22Gagegalvanizedfloor

decking. Thebottomchordactsasthemaintensionmember,andinthecompositestagethe

embeddedtopchordservesasacontinuousshearconnection. Theconcreteisalsoreinforced

withweldedwirefabricandcompressivestrengthoftheconcreteisfc=3500psi. Finally,the

systemwasusedasanarchitecturalelementsincetheceilingcouldbeinstalleddirectlytothe

joistbottomchordandthemechanicalsystems(HVAC,plumbing,fireprotection,electricaland

telecommunications)couldbeinstalledwiththejoistsystem,savingspaceandallowingfor

higherceilingsandfloortofloorheightwithintheapartments. AsectionoftheVESCOM

CompositefloorsystemcanbefoundinAppendixB.


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LateralSystemThelateralresistingsystemwithinthebuildingismainlymomentresistingsteelframesmade

upofwideflangebeams. Theseframesbeginonthesecondfloorandcontinueupthroughthe

topofthebuilding.TheseframesruninthenorthsouthdirectionandrunalongcolumnlinesA,

B,CandD. Rigidconnectionsalsooccuronthesefloorsalongcolumnlines1through9. Figure

1belowshowsthefourdifferenttypesofmomentframesthatexistwithinthebuilding. These

fourframesSincetheVESCOMfloorsystemisbeingusedasadiaphragmtotransfershear

loadingtheloadpathbeginsattheexteriorbeamsandthencontinueonthroughthefloor

systemtojoistgirderswhicharetobedesignedandmanufacturedbythejoistmanufacturer.

TheloadisthentransferredintothelargeW14columns,andfinallytothebraceframesandthe

foundations. Thereareatotalofelevenbracedframeslocatedinthebasementandsub

basementlevelsrunningalongcolumnlines1through11fromcolumnlinesA.1toB. Thebrace

framesare172inlengthandtheybeginatthesubbasementlevelandconnectintothe

framingforthegroundfloor. ThebracingintheframesconsistsofHSS8x8x1/2uptothe

basementlevel,andHSS6x6x3/8fromthebasementleveltothegroundfloor. Theseframes

areshowninFigure2below. Thisplandetailandthedetailofthebraceframescanbefoundin

Figures2and3.

Figure1:BracedFrameLocation

NorthSouthFrames(A&D)

NorthSouthFrames(B&C)

EastWestFrames(FthruL)

EastWestFrames(E&M)

(0,0)

Figure1:MomentFrameDiagram


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ApplicableCodes,DesignCriteriaandLoadCasesSinceanindepthlateralanalysiswasperformedthereweremanyreferencemanualsand

materialsthatwereusedtocompletethedesign,thesearelistedasfollows:

IBC2003withAmendmentsforMt.Lebanon,Pennsylvania ASCE705:MinimumDesignLoadsforBuildingsandOtherStructures

ACI31808BuildingCodeandCommentary

DesignofConcreteStructuresTextbook(AE431)

AISCSpecificationforStructuralSteelBuildings,13thEdition

RAMStructuralSystem(GravityLoads)

STAADPro2006(LateralLoadAnalysis)

DesignDeflectionCriterionThefollowingdesigncriterionwasalsousedandcanbefoundinIBC2006andASCE705:

=H/400forAllowableStoryandBuildingDriftduetoWindLoading

=0.015hsxforAllowableStoryandBuildingDriftduetoSeismicLoading

DesignLoadCombinationsThefollowingLoadandResistanceFactorDesignloadcombinationswereconsideredfor

analysis,asnotedinASCE705Chapter2:

1.4(Dead)

1.2(Dead)+1.6(Live)+0.5(RoofLive)

1.2(Dead)+1.6(RoofLive)+0.8(Wind)

1.2(Dead)+1.6(Snow)+0.8(Wind)

1.2(Dead)+1.6(Snow)+1.0(Live)

1.2(Dead)+1.6(Wind)+1.0(Live)+0.5(Snow)

1.2(Dead)+1.6(Wind)+1.0(Live)+0.5(RoofLive)

1.2(Dead)+1.0(Earthquake)+1.0(Live)+0.2(Snow)


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BuildingDesignLoadsandLateralCriteriaInordertocompleteananalysisofWashingtonParkCondominiums,thatgravityandlateral

loadsactingonthebuildingneedtobeidentified. Thedeadandliveloadsthatareusedwere

alsousedinTechnicalReport#1becauseitwasdeterminedthatthoseloadscloselymatched

thoseusedbythedesignengineer. Thelateralloadswererecalculatedbydeterminingthe

equivalentstiffnessforeachmomentframeinthebuilding. Findingthestiffnessofeachframe

allowedforthedirectshearandtorsionalshearateachleveltobecalculatedandfortheloads

tobedistributedthroughoutthebuildingaccordingtostiffness. Theseloadsandtheprocessin

whichtheyweredeterminedwillbediscussedindetailinthenextsection. Thetablesbelow

listthedeadandliveloadsforthebuildingaswellasthewindandseismicdesigncriteriaused

inthecomputationofthelateralloads.

GravityLoads

Table1:DeadLoadTables

DeadLoadTableFloorDeadLoad RoofDeadLoad

Material/System Load Material/System Load

NormalWeightConcrete 145pcf

411/16"RWCSlab

on15/16"FLR

Deck

68psf

Steel PerShape MEP 6psf

BrickVeneerw/studs 40psf Sprinklers 3psf

8"P/CPlankw/2"StructuralTopping 90psfCeiling 8psf

VESCOMJoists

4psf

MEP 6psfAsphalt

Shingles/Felts4psf

Sprinklers 3psf

1/2"Cement

BondedParticle

Board

5psf

Ceiling 5psf

LightGaugeRoof

Trusses@2'0"

O.C.

4psf

FloorFinishes 5psf

Partitions 20psf

VESCOMJoists 4psf211/16"RWCSlabon15/16"FLR

Deck43psf


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LiveLoadTableFloorLiveLoadTable RoofLiveandSnowLoadTable

Occupancy

Load

Material/System

Load

Typ.CondominiumFloor 40psf RoofLiveLoad 20psf

Stairs 100psfRoofLiveLoad

(Mechanical)150psf

FirstLevel(PlazaandTraffic/Parking

Areas250psf

GroundSnowLoad

(Pg)25psf

FirstLevel(NonPlazaAreas) 100psfFlatRoofSnow

Load(Pf)23psf

BasementLevelParkingAreas/Ramps 50psfExposureFactor

(Ce)1.2

SlabsonGrade 150psf ThermalFactor(Ct) 1

ExerciseAreaatGroundFloor 150psfImportanceFactor

(I)1.1

CorridorsOn1stFloor 100psf

CorridorsAbove1stFloor 80psf

Mech/ElecSpaces 150psf

SecondFloorTerrace 100psf

ApartmentBalconies 100psf

Table2:LiveLoadTablesWindCriteriaThewindloadsforWashingtonParkCondominiumswerecalculatedusingthedesigncriteria

foundinASCE705,Chapter6anditwasdeterminedthatitwaspermittedtouseMethod2

AnalyticalProcedureforthedesign. Thetablebelowliststheapplicablewinddesignfactors.

Basic Wind Speed (V) 90 mph

Wind Direction Factor (Kd) 0.85

Importance Factor (I) 1

Exposure Category C

Velocity Pressure Coefficient (Kz) Case 2

Topographic Factor (Kzt) 1

Enclosure Class Enclosed

Table3:WindDesignCriteria


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SeismicCriteriaTheseismicloadsforWashingtonParkCondominiumswerecalculatedusingASCE705,

Chapter12,aswellasusingtheinformationprovidedbythestructuralengineerandthe

geotechnicalengineer. Fromthegeotechnicalreport,itwasdeterminedthattheSiteClassfor

constructionwouldbeSiteClassC. Theremainderoftheinformationneededtocalculate

seismicloadingandbaseshearwasfoundinChapter12ofASCE705. Thetablebelowliststhe

applicableseismicdesignfactors.

SeismicParametersforWashingtonParkCondominiums

Ss S1 SiteClass Fa Fv Sds Sd1SeismicDesign

Category

SeismicUse

Group

0.128 0.058 C 1.6 2.4 0.137 0.093 B I

I R Cu Ta TL Ts Cs k PeriodCoefficient

1 3.5 1.7 1.082 12 0.6333 0.01706 1.291 0.80

Table4:SeismicDesignParameters


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LoadDistributionandAnalysisThedistributionoflateralforcesthroughoutthestructurecanbedeterminedusingvarying

designmethods. Forthistechnicalreportthelateralloadswereascertainedbasedonthe

relativestiffnessofeachframeinconjunctionwiththerestoftheframesinthebuilding. The

compositejoistfloorsystemisusedasasheardiaphragmanditdistributesloadtothevarious

framesbasedontheirrespectiverelativestiffness. Thisprocessallowsforamoreaccurate

distributionofloadsalongwiththeabilitytostudyhowtheframesworktogethertotransfer

theloadsfromthemomentframestothefoundations. Fortheanalysis,handcalculations,

MicrosoftExcelandSTAAD.Pro2006wereutilizedasawaytoobtainamorethorough

understandingofthedistribution.

DeterminationofRelativeStiffness(k)andCenterofRigidityThedeterminationofeachframesrelativestiffnesswasdoneusinghandcalculationsand

STAAD.Pro2006. Tobeginthefourdifferentframes(interiorandexteriorineachdirection)

wereconstructedinSTAADusingthesteelsizesandconnectionsgivenbythestructural

engineer. Nextaonekiploadwasappliedatthetopofeachmomentframetoestablishthe

amountofdeflectionthatoccursatthetopoftheframe. Fromthere,theinverseofthis

deflectionwastakenandthesevalueswereusedfork. Fromthesekvalues,thecenterof

rigidityofthebuildingwasfound. Thexandydistancevaluesusedforthecenterofrigidity

weretakenfroma(0,0)pointchosenonthebottomrightcornerofthebuildingasshownin

AppendixC. Therelativestiffnesssforeachframeareincludedinthetableforthedirectand

torsionalshearshownbelow.

DeterminationofDirectShearandTorsionalShearAfterestablishingthestiffnessvaluesforeachframe,thedirectandtorsionalshearsforeach

frameateachlevelcouldbedetermined. Forthisanalysis,itwasdecidedthatfourregular

framescouldbechosenthatwouldberepresentativeofalltheframesinthebuilding. Frames

AandEaretheexteriorframesinthenorth southandeast westdirectionsrespectively.

Also,framesCandFaretheinteriorframesinthenorth southandeast westdirections

respectively. Thecalculationforthemomentsforeachframeateachfloorusedinthetorsional

forcecanbefoundinAppendixF. Thedirectandtorsionalshearsarethenfoundbyusingthe

followingequationsandvariables. ThesevariablescanbefoundinTable5belowalongwith

thevaluesfortheforcesofthefourframesthatarebeingstudied:


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Where: K=EquivalentStiffnessofFrame

Fi=LateralStoryForce

Mi=Fix(dCMdR)

di=DistancefromCenterofRigiditytoFrame

TorsionConstants

FloorCenterofRigidity CenterofMass

IX (in4) Iy (in

4) IP (in4)

XR(ft) YR(ft) XR(ft) YR(ft)

Second 104.92 39.89 102.3 34.7 2837888.75 353494.66 3191383.41

Third 104.92 39.89 102.3 34.7 2837888.75 353494.66 3191383.41

Fourth 104.92 39.89 102.3 34.7 2837888.75 353494.66 3191383.41

Fifth

104.92

39.89

102.3

34.7

2837888.75

353494.66

3191383.41

Sixth 104.92 39.89 102.3 34.7 2837888.75 353494.66 3191383.41

Seventh 104.92 39.89 102.3 34.7 2837888.75 353494.66 3191383.41

Eighth 104.92 39.89 102.3 34.7 2837888.75 353494.66 3191383.41

Roof 104.92 39.89 102.3 34.7 2837888.75 353494.66 3191383.41

Table5:CenterofRigidityandMassalongwithCalculatedMomentofInertia

Table6:ResultantShearsDuetoWindLoading


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Table7:ResultantShearsDuetoSeismicLoadingAfterobtainingthedirectandtorsionalforcesforeachframeitisobviousthatthesevaluesare

smallerthanthatofstoryforcesthataredeterminedusingtributaryarea. Thiscouldbedueto

thefactthatusingrelativestiffnessallowsforthebuildingtobeanalyzedasanentirestructure

sincethedirectshearsaredeterminedbyusingaratioofframestiffnesstototalstiffness. The

methodoftributaryareadoesnottakeintoaccountanyotherframeorhowtheotherframes

inthebuildingmaybeworkingtogethertodistributethelateralloadthroughoutthebuilding.

Thisallowsforthecalculatedforcesusingtherelativestiffnesstobemoreaccurateand

thereforemakethesubsequentportalframe,strengthanddriftanalysesmorereliable.


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FrameAnalysisPortalFrameFollowingthedeterminationofthedirectandtorsionalforcesthroughtheestablishmentof

relativestiffness,thestoryforceswereappliedtothestructureandwereanalyzedusingPortalMethod. Inthiscase,threedifferentportalmethodanalyseswereperformed. FramesEandF

wereanalyzedusingresultantshearsduetowindsincethevaluefortotalshearduetowind

weregreaterthanthatofseismic. Next,asinglefloorofframeCwasanalyzedusingthe

resultantshearduetoseismicloadingsinceforframeCtheshearforseismicwasgreaterthan

theshearduetowind. Themomentsinthebeamsandcolumnsthatwereobtainedfromthe

portalframeanalysiswereusedinthebeamandcolumnstrengthchecks. Theresultsofthe

portalframeanalysiscanbefoundinAppendixD.

STAADAnalysisInconjunctionwiththeportalframeanalysis,aframeanalysisusingSTAAD.Pro2006was

performed. Thisanalysiswasusefulinprovidinginformationconcerningstoryandoverall

buildingdriftaswellasdeterminingwhetherornotthesteelmemberschoseninthedesign

wereadequatetocarrytheloads. Figures4and5belowshowthetwoframeconstructions

thatwereanalyzedusingSTAAD. Foreaseofanalysisalongwithaconservativedesign,frames

AandCwereanalyzedasiftheywerestraightmomentframes. Thiswasdonebecausethe

entireframeworkstogetherandacontinuousframewouldbemoreconservativeintermsof

windloadsaddedtothebuilding. Furthermore,bothtypesofframeswereanalyzedtwicefor

exteriorandinteriormomentframeconditions. Ineachcase,thelateralforcesthatwereaddedtotheframewerechangedbasedonthevaluesthatweredeterminedfortotalstory

shearinTables2and3onthepreviouspages. Usingtheseloadsthatstorydriftsandoverall

driftofthebuildingwasdeterminedandwasusedinthecomparisonwiththeallowabledrift

valuesdeterminedinTables4and5. STAADwasalsousedtodeterminethecontrollingload

combinationsineachdirection. Thefollowingloadcombinationscontrolinthegivendirection.

Finally,theSTAADmodelwasoneofthewaysthatsteelmembersusedinthebuildingsdesign

wereverified. Thesesteelshapeswerealsodesignedinthememberandstrengthchecks

beginningonthenextpage. Overall,usingSTAADallowedforasimplifiedmethodofmember

verificationanddriftanalysis,aswellasamethodofcomparisontothehandcalculationsperformedforbothmemberandframechecks.


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Bythecomputeranalysisitwasdeterminedthatthecontrollingloadcombinationsforeach

directionwereasfollows:

NorthSouthDirection(FramesAthruD):1.2(Dead)+1.0(Earthquake)+1.0(Live)+0.2(Snow)

EastWestDirection(FramesEthruM):1.2(Dead)+1.6(Wind)+1.0(Live)+0.5(Snow)

Thesecombinationsmakessensesincetheshorterofthemomentsframeswouldbecontrolled

bythewindloadssincethestoryshearsontheframewouldbearesultofthewindpressures

onthelongsideofthebuilding. Theseloadcombinationswereusedtoverifymembersizes

andstrengthsinthenextsection.

Figure4:FramesEandF(EastWestDirection)

Figure5:FramesAandC(NorthSouthDirection)


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MemberVerificationandStrengthChecksUponcompletionoftheportalmethod,themomentsfromtheanalysiswereusedin

conjunctionwithmomentsandforcesfoundintheSTAADanalysistoverifybeam,columnand

braceframemembersthroughoutthebuilding. Membersinframesrunningbothnorthsouth

andeastwestwereanalyzedusingthecontrollingloadcombinationandaredenotedonthe

calculations. AlthoughthemembersweredesignedandcheckedusingSTAAD,itisstill

necessarytocheckthecomputeroutputsothatacompetentunderstandingofmember

strengthcanbeachieved. ThemembersthatwerechosenareshowninFigure6. Boththeblue

andredhighlightedmembersarethelongestspanningbeamsintheirrespectivemoment

framesandthereforewerechosenforanalysis. Thecolumns,denotedbycircles,werechosen

basedbecauseintheportalanalysistheinteriorcolumnscarrytwicetheshearwhenthelateral

loadsaredistributedthroughouttheframe. Finally,abraceineachofthebracedframeswas

designedfortheaxialloadcausedbydead,wind,liveandsoilpressure.

Figure6:MembersusedforVerification(FramesCandF)W18x97(FrameF)

W18x97(FrameC)

W14x90(FrameF)

W14x90(FrameC)


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FrameF:BeamandColumnStrengthChecks(RedonPlan)


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FrameC:BeamandColumnStrengthChecks(BlueonPlan)


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BracedFrameStrengthChecks


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ServiceabilityCheck(DriftAnalysis)Thedriftofastructureisextremelyimportanttotheoverallperformanceofthebuilding. Too

muchstorydriftortotaldriftinastructurecouldresultindamagetothebuildingexteriorand

othersystemscausingrepairsandobviouslyaddedcostsduetomaintenance. Becauseofthis

theIBCandASCE705havelaidoutparametersfordriftcontrolbasedonoccupancycategory,

buildingheightandstructuretype. InthecaseofWashingtonParkCondominiumsthewind

driftdeterminedinSTAADwascomparedtow=H/400fortheentirebuilding. Theseismic

drift,alsodeterminedinSTAAD,wascomparedtoS=0.015hsxwherehsxisthestoryheightof

thebuildingatacertainlevel. TheallowablewinddriftcanbefoundonTable1604.3oftheIBC

andtheallowabledriftduetoseismicisfoundonTable12.121inASCE705. Thetablesbelow

displaythecomparisonbetweenactualandallowabledriftforbothwindandseismic.

Table8:ActualWindDriftComparedtoAllowableDriftControllingSeismicDrift

Floor

Story

Height

(ft)

Total

Height

(ft)

Story

Drift

(in)

AllowableStory

Drift(in)

seismic=0.020hsx

Acceptable?

Total

Drift

(in)

AllowableStory

Drift(in)

seismic=0.020hsx

Acceptable?

Second 14.333 14.33 0.232


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Asdisplayedintheabovetablesthecontrollingwinddriftinthebuildingisacceptableatboth

individualfloorsandfortheoverallheightofthebuildingwhencomparedtothecode

allowabledriftofw=H/400. However,thecontrollingseismicdriftinthebuildingisgreater

thanthecodeallowablevalueofS=0.020hsx. Apossiblereasonforthiscouldbethefactthat

theindividualmomentframeswereanalyzedindividuallyinSTAAD. Anotherreasoncouldbe

thefactthatwithintheanalysisthatbracedframeslocatedonthebasementandsubbasement

levelswerenotincludedinthecalculationsincetheyareconsideredtobebelowgrade. These

bracedframesprimarilyservetoresistthesoilpressurewhichcanbeseeninthebracedframe

strengthchecks. Anotherpossibilityisthefactthatthestiffnessofthecompositejoistfloor

systemwasnottakenintoaccount. Since,thefloorsystemservesasadiaphragm,itcanalso

beassumedthatitalsohassomelevelofstiffnessandthereforewouldhelptoresistand

transfersomeamountoflateralloadingtothecolumnsandultimatelythefoundations. Many

solutionstotheproblemcouldbeusedincluding,increasecolumnandbeamsizesandpossibly

addedsomebracedframesthroughoutthebuilding. Regardlessofthesolutionthatisused,the

issueofmorethanallowablestoryandoveralldriftinthestructurecouldbestudiedinmore

depthintheproposalandresearchlater.

OverturningMomentandUpliftOneoftheissuesthatarerarelyconsideredwhencompletinglateralanalysisonastructureis

howthelateralloadsandensuingtransferofthoselateralloadstothefoundationswillimpact

theirsize. Theimpactofthefoundationsthatneedstobeconsiderediscausedbywindand

seismicforcesproducinganoverturningmomentforthebuilding. Inturn,theoverturning

moment,

may

cause

uplift

within

the

exterior

columns

and

foundations

of

the

building

because

thereisnotenoughdeadweightonthecolumnsandfoundationstoresisttheoverturning

moment. Tables6and7listtheupliftfoundduetowindandseismicloadinginbothdirections.

UpliftDuetoWindLoading

Moment

(kft)

UpliftForce

(kips)

DeadLoad

Resistance(kips)UpliftProblem?

East West

Direction24400.21 389.36 271.24 Yes

North SouthDirection

6606.64 32.67 463.79 No

Table10:UpliftduetoWindLoading


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B.Follett Page28

UpliftDuetoSeismicLoading

Moment

(kft)

UpliftForce

(kips)

DeadLoad

Resistance(kips)UpliftProblem?

East West

Direction15850.95 252.94 271.24 No

North South

Direction15850.95 78.38 463.79 No

Table11:UpliftduetoSeismicLoadingTheresultsoftheupliftcalculationshowthattherewouldbenetupliftforcesintheeastwest

directionduetowindloads. Becauseofthisthefoundationswouldneedtobedesignedto

resistanetupliftof118.12kips. Currentlythefoundationsontheexteriorofthebuildingrange

from8.5

x8.5

to

13

x13

and

are

placed

25

below

grade.

This

gives

the

foundations

the

abilitytoresistthenetupliftforcesappliedbytheoverturningmoment. Asaresultofthe2

storybasementandnetupliftthefloorsystembelowgradeaswellastheslabongradeisused

tohelptiethevariousfoundationstogether. Thisalsohelpedresistslidingandoverturning

forcescausedbytheimbalanceofsoilpressureaswellastheuplift. Finally,someofthe

foundationswereinserteddirectlyintotherockandutilizedrockskinfrictiontoresistupliftas

wellasincreasingtheslidingresistanceofthefoundationsystem. Overall,itseemsthatthe

presentfoundationsareadequateinresistingthenetuplift.


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B.Follett Page29

ConclusionThelateralanalysisanddesignofthemomentframestructureforWashingtonPark

Condominiumswasdiscussedindetailedthroughoutthistechnicalreport. Thereportexamines

theprocesswhichwastakentoarriveatdesignoflateralmemberswithintheframesthrough

bothhandcalculationsandcomputermodeling. Bothhandcalculationsandcomputer

modelingwereusedtodeterminetherelativestiffnessfactorsforeachframe. Fromthere,the

directandtorsionalshearforcesoneachlevelofeachframewerecalculatedsothattheycould

appliedtotheframeandcomparedtotheresultsfoundinTechnicalReport#1. After

determiningtheforcestobeappliedtotheseparateframes,itwasnecessarytocompletea

portalframeanalysisalongwithacomputeranalysis. Theportalframeanalysisrenderedshear

andmomentsinthebeamsandcolumnsoftheframes. Thecomputermodelanalyzedin

STAADallowedforacomparisonandcheckoftheportalframeanalysis. TheSTAADmodelwas

alsousedtodeterminethecontrollingloadcasesforeachframeanddeterminethedriftof

bothintheindividualstoriesandtheentireframe. Afterobtainingthevaluesfordriftfrom

STAADtheywerecomparedtotheallowabledriftlimitsforbothwindandseismicgiveninthe

InternationalBuildingCodeandASCE705. Thecontrollingwinddriftwasdeemedacceptable

bycode,howeverthestorydriftandoverallstructuredriftduetoseismicloadswerefoundto

beabovetheacceptablecodelimits. Althoughthevaluesdidnotmeettheacceptablelimits

foundinthecode,itisbelievedthatthereasonforthiscouldbecontributedtothefactthatthe

stiffnessofthecompositejoistfloorsystemwasnottakenintoaccount. Since,thefloorsystem

servesasadiaphragm,itcanalsobeassumedthatitalsohassomelevelofstiffnessand

thereforewouldhelptoresistandtransfersomeamountoflateralloadingtothecolumnsand

ultimatelythefoundations.

Alongwiththedriftcalculations,thedesignstrengthofseveralcriticalmembersofthedifferent

frameswereanalyzedbasedontheloadsandmomentsfoundintheSTAADanalysis. All

membersthatwerelookedatwerewellwithintheirultimatecapacitygivenbytheAISC

SpecificationforStructuralSteelBuildings,13thEdition. Finally,anoverturningmomentand

upliftcheckwasdonetoseeifthiswouldbeanissueforthefoundations. Itwasdetermined

thatintheeastwestdirectiontheremaybeanissuewithuplift. Thiswillbefurtherexamined

intheproposalandcouldleadtofurtherdiscussionofthefoundationsystemusedonthe

project.

Ultimately,itwasconcludedthatthelateralsystemissufficientlydesignedtocarrythelateral

loadingofthebuilding. Thedriftissueswillbediscussedandexaminedingreaterdetail

throughtheproposalandfollowingresearch.


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B.Follett Page30

AppendixA:BuildingLayout


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TypicalFloorLayout


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CompositeJoistSystemIsometricSection


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AppendixB:WindandSeismicData


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B.Follett Page34

WindLoadingCoefficientsandStoryResultsFloor Kz Kzt Kd Kh V (mph) I qh (lb/ft

2) qz (lb/ft

2)

2nd 0.849 1.0 0.85 1.253 90.0 1.0 22.085 14.964

3rd 0.948 1.0 0.85 1.253 90.0 1.0 22.085 16.709

4th 1.023 1.0 0.85 1.253 90.0 1.0 22.085 18.031

5th 1.081 1.0 0.85 1.253 90.0 1.0 22.085 19.053

6th 1.13 1.0 0.85 1.253 90.0 1.0 22.085 19.917

7th 1.172 1.0 0.85 1.253 90.0 1.0 22.085 20.657

8th 1.216 1.0 0.85 1.253 90.0 1.0 22.085 21.433

Roof 1.256 1.0 0.85 1.253 90.0 1.0 22.085 22.138

qz=0.00256KzKztKdV2I(lb/ft

2) qh=0.00256KhKztKdV

2I(lb/ft

2)

Wind (North - South Direction)

Floor Height(ft)

TributaryHeight(ft)

Kz qz

(psf)Windward

(psf)Leeward

(psf)Total(psf)

StoryForce(kips)

StoryShear(kips)

OverturningMoment (ft-k)

Ground 0.00 0.00 0.849 0.00 0.00 0.00 0.00 0.00 128.694 6487.847

Second 14.33 13.667 0.849 14.964 10.403 -5.758 16.161 15.166 128.694 6487.847

Third 25.33 11.000 0.948 16.709 11.616 -5.758 17.374 13.123 113.528 4905.356

Fourth 36.33 11.000 1.023 18.031 12.535 -5.758 18.293 13.817 100.405 3728.723

Fifth 47.33 11.000 1.081 19.053 13.246 -5.758 19.003 14.354 86.588 2076.624

Sixth 58.33 11.000 1.130 19.917 13.846 -5.758 19.604 14.807 72.235 1826.709

Seventh 69.33 13.167 1.172 20.657 14.361 -5.758 20.118 18.190 57.427 1113.563

Eighth 82.67 13.500 1.216 21.433 14.900 -5.758 20.658 19.150 39.237 536.123

Roof 96.33 13.833 1.256 22.138 15.390 -5.758 21.148 20.088 20.088 277.877

Wind (East - West Direction)

FloorHeight

(ft)

TributaryHeight

(ft)Kz

qz(psf)

Windward(psf)

Leeward(psf)

Total(psf)

StoryForce(kips)

StoryShear(kips)

OverturningMoment (ft-

k)

Ground 0.00 0.00 0.849 0.00 0.00 0.00 0.00 0.000 474.909 23767.869

Second 14.33 13.667 0.849 14.964 10.140 -9.353 19.493 57.664 474.909 23767.869

Third 25.33 11.000 0.948 16.709 11.322 -9.353 20.675 49.228 417.245 17927.222

Fourth 36.33 11.000 1.023 18.031 12.218 -9.353 21.571 51.361 368.017 13608.280

Fifth 47.33 11.000 1.081 19.053 12.910 -9.353 22.263 53.010 316.656 9889.078

Sixth 58.33 11.000 1.130 19.917 13.496 -9.353 22.849 54.404 263.646 6650.892

Seventh 69.33 13.167 1.172 20.657 13.997 -9.353 23.350 66.551 209.242 4050.000

Eighth 82.67 13.500 1.216 21.433 14.523 -9.353 23.876 69.770 142.692 1947.879

Roof 96.33 13.833 1.256 22.138 15.001 -9.353 24.354 72.922 72.922 1008.730


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B.Follett Page35

SeismicLoadingCoefficientsandStoryResults

SeismicParametersforWashingtonParkCondominiums

Ss S1 SiteClass Fa Fv Sds Sd1SeismicDesign

Category

SeismicUse

Group

0.128 0.058 C 1.6 2.4 0.137 0.093 B I

I R Cu Ta TL Ts Cs k V(kips)

1 3.5/5 1.7 1.082 12 0.6333 0.01706 1.291 248.3248

BaseShearCalculation

FloorHeight

(ft)

Tributary

Height

(ft)

DeadLoad

(kips)wxhx

k Cvx

Lateral

Force

(Fx)

Story

Shear

(Vx)

Overturning

Moment

(ftkips)

Ground 0.00 7.167 1939.190 0 0 248.325 248.325 15451.152

2nd 14.33 13.667 2050.530 63764.65 0.0291058 7.228 248.325 15451.152

3rd 25.33 11.000 1501.591 97419.23 0.0444676 11.042 241.097 12345.445

4th 36.33 11.000 1501.591 155186.6 0.0708359 17.590 230.055 9754.098

5th 47.33 11.000 1488.721 216478.4 0.0988129 24.538 212.464 7320.232

6th 58.33 11.000 1488.721 283517.5 0.1294133 32.137 187.927 5118.067

7th 69.33 13.167 1540.881 366773.9 0.1674162 41.574 155.790 3227.610

8th 82.67 13.500 1540.881 460325.8 0.2101186 52.178 114.217 1609.312

Roof 96.33 13.833 1503.864 547324.3 0.2498296 62.039 62.039 858.184

Total W= 14555.970 2190790


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AppendixC:CenterofMassandRigidity

Area1

Area2Area3

Area5Area4

(0,0)


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B.Follett Page37

TorsionConstants

FloorCenterofRigidity CenterofMass

IX (in4) Iy (in

4) IP (in4)

XR(ft) YR(ft) XR(ft) YR(ft)

Second 104.92 39.89 102.3 34.7 2837888.75 353494.66 3191383.41

Third

104.92

39.89

102.3

34.7

2837888.75

353494.66

3191383.41

Fourth 104.92 39.89 102.3 34.7 2837888.75 353494.66 3191383.41

Fifth 104.92 39.89 102.3 34.7 2837888.75 353494.66 3191383.41

Sixth 104.92 39.89 102.3 34.7 2837888.75 353494.66 3191383.41

Seventh 104.92 39.89 102.3 34.7 2837888.75 353494.66 3191383.41

Eighth 104.92 39.89 102.3 34.7 2837888.75 353494.66 3191383.41

Roof 104.92 39.89 102.3 34.7 2837888.75 353494.66 3191383.41


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AppendixD:PortalFrameAnalysisCalculations


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PortalFrameE


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PortalFrameF


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PartialPortalFrameA


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AppendixE:TorsionalForceTables


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WindTorsionalForces


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Technical WashingtonParkCondominiumsReport#3 Mt.Lebanon,PASeismicTorsionalForces

follett tech 3

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