Behavior and Design of Concrete-Filled Beam-Columns Webinar Slides

8/11/2019 Behavior and Design of Concrete-Filled Beam-Columns Webinar Slides

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BehaviorandDesignof

ConcreteFilledComposite

Columns

RobertoT.Leon

VirginiaTech,Blacksburg,VA

JeromeF.Hajjar

NortheasternUniversity,Boston,MA

LarryGriffis

WalterP.Moore,Austin,TX

Scope Briefintroductiontocompositecolumns(LG)

Researchmotivationandexperimentalresults(RL)

Analyticalmodelingandsystemstudies(JH)

Conclusionsanddesignrecommendations(LG)

Workisbasedonthedissertationsof:

TizianoPerea,UAM,MexicoCity(MX) GeorgiaTech

MarkDenavit,SDL,Atlanta(GA) UIUC

InKind:


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Compositeorhybridsystem(concrete&steel)

Systemwhichcombinestheadvantagesofconcreteandstructuralsteel

Concrete*Rigid *Economic

*Fireresistant *Durable

Structuralsteel*Highstrength *Ductile

*Easytoassembly *Fasttoerect

Frames with CFT columns Steel tubeconfines concrete

Concreterestrictsthebucklingofthesteeltube

Increaseinstrength&deformationoftheconcrete

Delayinthebuckling ofthesteeltube

Frames with SRC columnsSteelelementsupportstheconstructionloads

Theconcrete givesfinalstiffnessandfireresistant

ShearconnectionsbecomeFRonceconcreteiscast

Systemfasttoerect&build(redundancy)

UsesforCompositeColumns

Extracapacityinconcretecolumnfornoincreaseindimension

Largeunbracedlengthsintallopenspaces Lowerstoryinhighrisebuildings

Airportterminals,conventioncenters

Corrosion,fireproofprotectioninsteelbuildings

Compositeframe highriseconstruction

Transitioncolumn

between

steel,

concrete

systems Toughness,redundancyasforblast,impact


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CompositeSystems Perimetermomentframesfor

stiffnessinhurricanezones.

Extensiontoseismicbasedon

Japaneseexperience.

Distributedsystemsvs.

supercolumns

BuildingswithSRCColumns (MartinezRomero,1999&2003)


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Composite Braced Frame

Bank of ChinaHong Kong

Composite Column

Bank of ChinaHong Kong


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Composite Moment FrameTube Design

3 Houston CenterHouston, Texas

CompositeColumnForming


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Tree ColumnsComposite Columns

3 Houston CenterHouston, Texas

CompositeErectionColumns


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Composite ColumnsReinforcement Cage

CompositeShearWalls


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Composite Braced Frame

2 Union SquareSeattle, Washington

Composite Frame Construction

Dallas, Texas


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CompositeFrameConstruction

Possibleconfigurationsincompositecolumns

a) SRC b) Circular and Rectangular CFT

c) Combinations between SRC and CFT


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Flexibility

SizesandShapes

FilledCompositeColumn

(CoveredinthisWebinar)

Round HSS Square or Rectangular HSS


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EncasedCompositeColumn

MotivationforResearch Lackofdesigninformationforthestiffnessof

columnstobeusedforbucklingandlateralrigiditycalculations

Lackofknowledgeontheinteractionbetweenaxialloadandbendingatultimate(2Dand3D)

Lackofknowledgeonsystemfactors(forcereductionanddeflectionamplificationforseismic

design) Gapsindataforslendercolumns(localand

overallbuckling)


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(1)Flexuralrigidityforlateralforces

Advancedcomputationalanalysis:

eff s s s c c cEI EI EI

HSS

Section

t

D

Fiberelement

analysis

Finiteelement

analysis

Semiempirical :

ConcreteonlyorSteelonly forcalculatingcolumncapacity,not

forlateral

analysis

SelectedSystems R

Cd

SSMF (SteelSpecialMomentFrames): 8.0 3.0 5.5

CSMF (CompositeSpecialMomentFrames): 8.0 3.0 5.5

SIMF (SteelIntermediateMomentFrames;SDCB,C,D): 4.5 3.0 4.0

CIMF (CompositeIntermediateMomentFrames;SDCB,C): 5.0 3.0 4.5

SOMF (SteelOrdinaryMomentFrames;SDCB,C,D): 3.5 3.0 3.0

COMF (CompositeOrdinaryMomentFrames;SDCB!!): 3.0 3.0 2.5

SCBF (SteelConcentricallyBracedFrames): 6.0 2.0 5.0

CSBF (CompositeSpecialBracedFrames): 5.0 2.0 4.5

OCBF (CompositeOrdinaryConc.BracedFrames;SDCBF): 3.25 2.0 3.25

COBF (CompositeOrdinaryBracedFrames;SDCB,C!!): 3.0 2.0 3.0

(2)Behaviorfactorsforseismicdesign?

ASCE/SEI710,Table1221


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0.0

0.5

1.0

1.5

2.0

2.5

0.00 0.50 1.00 1.50 2.00 2.50 3.00

Pexp/Po

Pn/Po

AISC

P/P

o

CCFTcolumnsdatabase

(3)LackofSlenderExperimentalTests

DatabasescompiledbyLenetal.,2005andGoodeetal.,2007

1375CircularCFT

912columns

463beamcolumns

798RectangularCFT

524columns

274beamcolumns

267EncasedSRC

119columns

148beam

column

(4)InteractionEquations

Howdowegetasimplifiedexpression

thatisclosetothedesignstrength?


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ProjectObjectives Obtainandevaluateexperimentalresponse:

Criticalload(Pcr)

PMinteractiondiagram(uniaxialandbiaxialbending)

Cycliclateralforce(uniaxialandbiaxialbending)

Torsion(torsionalstrengthandrigidity)

Wetconcretepressureduetothepouring

Flexuralrigidity(EIeff)

Steellocalbucklingandconcreteconfinement

Developnewcomputationalformulationsfor

completeframeanalysisofcompositesystems Providerecommendations onconstruction,analysis,

anddesignofCFTs.

NEES UMNMASTLabMASTcapabilities:

6DOFs

Pz=1320kip

Px,Py=880kips

Ux=Uy=+/16

14


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Specimen L Steel section Fy fc D/

name (ft) HSS D x t (ksi) (ksi)

1-C5-18-5 18 HSS5.563x0.134 42 5 45

2-C12-18-5 18 HSS12.75X0.25 42 5 55

3-C20-18-5 18 HSS20x0.25 42 5 86

4-Rw-18-5 18 HSS20x12x0.25 46 5 67

5-Rs-18-5 18 HSS20x12x0.25 46 5 67

6-C12-18-12 18 HSS12.75X0.25 42 12 55

7-C20-18-12 18 HSS20x0.25 42 12 86

8-Rw-18-12 18 HSS20x12x0.25 46 12 67

9-Rs-18-12 18 HSS20x12x0.25 46 12 67

CFTTest Matrix(18specimens)

Similarforspecimens1018butat26ft.

CCFT

103

52(S)

RCFT

5634(S)

Setup

and

Instrumentation

VideoandStillImagesFourtowersforimagesofwhole

specimenaswellasbase

KryptonCoordinate

MeasurementMachine

StringPotsDistributedalongheight

LVDTsSetsofthreeforbiaxialcurvature

measurement

StrainGagesUniaxialandrosettesdistributed

alongheight

Measurementsduringconcrete

pouringandtesting


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HydrostaticPressuresonSlenderRCFT

FEAnalysis:max max 36.1ksimax in

2

Stiffenerstoreduceexpansioninthe

RCFTsduringtheconcretepouring

Surveyed

Initial

Imperfections Length (ft) Length (ft)

Initial imperfection Initial imperfectionCCFTs, L=26ft RCFTs, L=26ft

0 0.5 1 1.5 20

5

10

15

20

25 10

11

14 1518

o

=L/50

0=

0.6

3

0 0.5 1 1.50

5

10

15

20

2512 13

16

17

o

=L/50

0=

0.6

3


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LC1

Loadprotocol

Pcr

0,

PA

ME,PE

MB,0

MB,PC

MD,

PC

/2

0,PAPA,PA

LC1

StabilityEffects

LC1 Axialloadonly

Loadprotocol0

,P

A

ME,PE

MB,0

MB,PC

MD,

PC

/2

0,PAPA,PA

LC1

MLC2a,2PALC2a

unidirectional

MLC2b,PALC2bunidirectional

Fmax

P

LC2

StabilityEffects

LC2 AxialloadpluslateraldisplacementalongX

attwodifferentaxialloadlevels


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LC3

y

x

Loadprotocol

0,

PA

ME,PE

MB,0

MB,PC

MD,

PC

/2

0,PAPA,PA

LC1

MLC2a,2PALC2a

unidirectional


LC3a

bidirectional

LC3b

bidirectional

LC3c

bidirectional

Fmax

P StabilityEffects

LC3A Axialloadatthreelevelspluslateraldisplacement

alongbothXandyinadiamondspikeconfiguration

LC3

Loadprotocol0

,P

A

ME,PE

MB,0

MB,PC

MD,

PC

/2

0,PAPA,PA

LC1

MLC2a,2PALC2a

unidirectional


LC3a

bidirectional

LC3b

bidirectional

LC3c

bidirectional

Fmax

P

-10 -5 0 5 10

-30

-20

-10

0

10

20

30

Lateral Displacement (in)

LateralForce(kip)

-6 -4 -2 0 2 4 6

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

Lateral Drift (%)

Crackingofconcrete

Steelyieldingincompression

Steelyieldingintension

Crushing ofconcrete

Steellocalbuckling

y

x

LC3B Axialloadatthreelevelspluslateraldisplacement

alongbothXandyinafigureeightconfiguration


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Loadprotocol

LC4

T

Pcr

0,

PA

ME,PE

MB,0

MB,PC

MD,

PC

/2

0,PAPA,PA

LC1

MLC2a,2PALC2a

unidirectional


LC3a

bidirectional

LC3b

bidirectional

LC3c

bidirectional

T

-10 -5 0 5 10

-30

-20

-10

0

10

20

30

Lateral Displacement (in)

LateralForce(kip)

-6 -4 -2 0 2 4 6

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

Lateral Drift (%)

Crackingofconcrete

Steelyieldingincompression

Steelyieldingintension

Crushing ofconcrete

Steellocalbuckling

-600

-400

-200

0

200

400

600

-10 -5 0 5 10

P=0

P=0.2Po

Angleoftwist(deg)

Tors

iona

lMoment

(kip

ft)

CCFT20x0.2518ft5ksi

LC4 Torsionattwolevelsofaxialload


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Loadprotocol:LC1 Purecompression

0 200 400 600 800 10000

500

1000

1500

2000

2500

3000

Cross-section

Beam-column

Experimental

P(kip)

M(kipft)

Stability

Effects

Specimen17Rs2612

P

M

Loadprotocol:LC2 Uniaxialbending

Specimen3C20185


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Probe

-5000

500 -5000

5000

500

1000

1500

Y Moment (k-ft)X Moment (k-ft)

ZF

orce

(k)

AISC Beam Column Strength (K=2)

All Load Cases

Experimental Interaction Points

Loadprotocol:LC3 Biaxialbending

CCFT Specimen20x0.25

Fy = 42 ksi

fc = 5 ksi

L = 18 feet

KL = 36 feet

CorrectedColumnStrengths(LC1)

MASTcapacityreached:3,5,7,9

Largeimperfection:1,8,11,17


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LocalBuckling 2010

Composite Members Subject to Axial Compression

Description of

Element

Width-

Thickness

Ratio

pCompact/

Noncompact

rNoncompact/

Slender

Max.

Permitted

Sides of rectangular

box and hollow

structural sections

of uniform thickness

b/t 2.26 3.00 5.00

Round filled sectionsD/t 0.15 E/Fy 0.19E/Fy 0.35 E/Fy

yF

E

yF

E

yF

E


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ExtractionofEI fromtheexperimentalM curves

M (kip-ft)

(10-4/in)

Specimen 4-Rw-18-5

0 1 2 3 4 50

100

200

300

400

500

600EI

eff=21081046 kip-i n2

EIexpL

=21865004 k ip -in2

EIexpL

/EIeff

=1.0372

EIexpU

=21868261 ki p-in2

EIexpU

/EIeff

=1.0373

Specimen13Rs265,LC2

M(kipft)

(1/in)

Loadprotocol:LC4Torsion

PT

Specimen3C20185

-600

-400

-200

0

200

400

600

-10 -5 0 5 10

P=0

P=0.2Po

T(

kip-ft)

z(deg)


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Analysis of Composite Frames:

Mixed BeamColumn Element

Mixedbeamfiniteelementformulationwasdevelopedusingbothdisplacementandforceshapefunctions

Distributedplasticityfiberformulation: stressandstrainmodeledexplicitlyateachfiberofcrosssection

Perfectcompositeactionassumed(i.e.,slipneglected)

TotalLagrangian corotationalformulation

ImplementedintheOpenSeesframework

0 L

0

1Shape Functions

Transverse

Disp

lacemen

t

0 L0

1

Ben

ding

Momen

t

Constitutive Relations Constitutiveformulations,calibration, andvalidationdevelopedforfive

separatesteelandsteelconcretecompositecrosssectionsplusconnections CCFT,RCFT,andSRCbeamcolumns

WFbeams

WFandRect.HSSbraces

Momentframeandbracedframeconnections

ProposedforBehaviorconstitutivemodel Aimstocapturethebehaviorasaccuratelyaspossible

ProposedforDesignconstitutivemodel Followstypicalassumptionscommoninthedevelopmentofdesign

recommendations(e.g.,nosteelstrainhardening,noconcretetension)

Calibratedandvalidatedagainstdetailedresultsofover100monotonicallyandcyclicallyloadedexperimentsofcompositebeamcolumns,connections,andframes


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Uniaxial Cyclic Concrete Constitutive

Relations for CFTs and SRCs ProposedforBehaviorconstitutive relation: BasedontherulebasedmodelofChangandMander(1994)

BackbonestressstraincurvefortheconcreteisbasedonTsaisEquation,whichisdefinedby:

InitialstiffnessEc Peakcoordinate(cc,fcc)

r,whichactsasashapefactorforTsaisequationandenablescalibrationforconfinementinCFTs,betweentheflangesinSRCs,etc.

ProposedforDesignconstitutiverelation:simplifiedversionofPB

-10 00 0 -90 00 -80 00 -70 00 -60 00 -50 00 -40 00 -30 00 -20 00 -10 00 0 1 00 0-5

-4

-3

-2

-1

0

1

Strain (strain)

Stress(

ks

i)

-10 00 0 -90 00 -80 00 -70 00 -60 00 -50 00 -40 00 -30 00 -20 00 -10 00 0 1 00 0-5

-4

-3

-2

-1

0

1

Strain (strain)

Stress(

ks

i)

Uniaxial Cyclic Steel ConstitutiveRelations for CFTs, SRCs, WFs, Rebar FortheProposedfor

Behaviormodel,basedontheboundingsurfaceplasticitymodelofShen etal.(1995).

Modificationsfortheanalysisofcompositemembers Localbuckling

Residualstressdefinedwithinitialplasticstrain

FortheProposedforDesignmodel,eitherelasticperfectlyplastic(SRCWFs;rebar)orbasedonthemodelofAbdelRahman &Sivakumaran 1997(CFTs)

0 2 4 6 8 100

0.2

0.4

0.6

0.8

1

1.2

1.4

Normalized Strain (/y,flat

)

Norma

lize

dStress

(/F

y,f

lat)

Et1 = Es/2

Et2 = Es/10

Et3 = Es/200

Et1

Et2Et3

Flat

Corner

Elastic Unloading

Es

Fp = 0.75 Fy

Fym = 0.875 Fy

Et3

Et1

Et2

Fp

Fym

Fy


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SRC BeamColumn ValidationRicles and Paboojian 1994

-150 -100 -50 0 50 100 150-400

-300

-200

-100

0

100

200

300

400

Lateral Displacement (mm)

Test #4: 4 (Ricles and Paboojian 1994)

La

tera

lLoa

d(kN)

Expt.

PfB

-150 -100 -50 0 50 100 150-500

-400

-300

-200

-100

0

100

200

300

400

500

Lateral Displacement (mm)

Test #8: 8 (Ricles and Paboojian 1994)

La

tera

lLoa

d(kN)

Expt.

PfB

H=406mm;B=406mm

W8x40Fy=372MPa

4#9;Fyr=448MPa

fc=31MPa

P/Pno=0.19

L/H= 4.8

H=406mm;B=406mm

W8x40Fy=372MPa

12#7;Fyr=434MPa

fc=63MPa

P/Pno=0.11

L/H= 4.8

RCFT BeamColumn ValidationVarma 2000

-100 -80 -60 -40 -20 0 20 40 60 80 100-500

-400

-300

-200

-100

0

100

200

300

400

500

Lateral Displacement (mm)Test #5: CBC-32-46-10 (Varma 2000)

La

tera

lLoa

d(kN)

Expt.

PfB

-80 -60 -40 -20 0 20 40 60 80-500

-400

-300

-200

-100

0

100

200

300

400

500

Lateral Displacement (mm)Test #8: CBC-48-46-20 (Varma 2000)

La

tera

lLoa

d(kN)

Expt.

PfB

H/t=B/t=35

Fy=269MPa

fc=110MPa

P/Pno=0.11

L/H=4.9

H/t=B/t=53

Fy=471MPa

fc=110MPa

P/Pno=0.18

L/H=4.9


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CCFT BeamColumn Validation

Specimen 11 Load Case 3a

L=7.9m;D=508mm.;t=5.9mm.;D/t=85.8;Fy=305MPa; fc=55.9MPa

Benchmark Frame Studies forComposite Frames: Schematic

L =oe1g EIgross

Pno,gross

ktop =6 EIgrossGg,topL

kbot =

6 EIgross

Gg,botL

P P P

HM

M

EIelasticEIelastic

x

EIgross = EsIs + EsIsr + EcIcPno,gross = AsFy + AsrFysr + Acfc

Initial Imperfections:

Out-of-plumbness o = L/500Out-of-straightness o = L/1000 (sinusoidal)


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AISC 36010 Section I2: Calculation

of Axial Compressive Strength: EIeff10.5 (SRC)eff s s s sr c cEI E I E I C E I

1 0.1 2 0.3s

c s

AC

A A

3 (CFT)eff s s s sr c cEI E I E I C E I

3 0.6 2 0.9s

c s

AC

A A

/ 2

0/

Composite Axial Compressive Strength

from Benchmark Study

CCFT RCFT

SRC(strongaxis)

SRC(weakaxis)


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Proposed Formula for Axial

Compressive Strength of SRCs, 1, (SRC)eff proposed s s s sr proposed c cEI E I E I C E I

1,

20.60 0.75sproposed

g

AC

A

SRC(strongaxis) SRC(weakaxis)

Axial Compressive Strength of SRCColumns: Experimental Validation

, 1, (SRC)eff proposed s s s sr proposed c cEI E I E I C E I

1,

20.60 0.75sproposed

g

AC

A

0 0.5 1 1.50

0.5

1

1.5

oe,proposed

Pexp

/Pno,p

ropose

d

Column Curv e

Anslijn & Janss 1974

Chen, Astaneh-Asl, & Moehle 1992

Han & Kim 1995

Han, Kim, & Kim 1992

Roderick & Loke 1975


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Benchmark Study Results:

Secant Values of EIelastic for Elastic Analysis

0 0.5 1 1.50

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Normalized Bending Moment (M/Mn)

Section 13: RCFT-E-4, Frame 37: UA-67-g1

Norma

lize

dAx

ialCompress

ion

(P/P

no

)

0.4

0.6

0.8

1

elastic

s s c c

EI

E I E I

Serviceability Level

Strength/1.6

0 0.5 1 1.50

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Normalized Bending Moment (M/Mn)

Section 4: RCFT-B-4, Frame 37: UA-67-g1

Norma

lize

dAx

ialCompress

ion

(P/P

no

)

0.4

0.5

0.6

0.7

0.8

0.9

1First-OrderApplied Load

Interaction

elastic

s s c c

EI

E I E I

EIelasticvalue provides comparable deflection to fully nonlinear

analysis for forces shown

CalculationofRequiredStrengthsAnalysisRequirements

SecondOrderElastic Analysis

ConsiderationofInitialImperfections

AdjustmentstoStiffness

CalculationofAvailableStrengthsChaptersDthoughKwithoutfurther

considerationofoverallstructurestability

0.8

0.8

DA b elastic

DA elastic

EI EI

EA EA

0.002i i

N Y

AISC 36010 Direct Analysis MethodChapter C

1K

Mr

Pr

cPn,K=1

cPn,K=K

EffectiveLength

FactorMethod

DirectAnalysis

Method

Distributed

Plasticity

Analysis


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Direct Analysis

Fromapracticalstandpointitisbestto

maintainastiffnessreductionof0.8b

Thus,differencesbetweencompositeand

steelmaybeembodiedinproposedEIelastic:

0.8DA b elasticEI EI

1.0 for 0.5

4 1 for 0.5

r no

b

r no r no r no

P P

P P P P P P

10.75 (SRC)elastic s s s sr c cEI E I E I C E I

30.75 (CFT)elastic s s c cEI E I C E I

Composite Interaction StrengthP

M

(PA,0)

(PA,0)

(PC,MC)

(PC,MC)

(0,MB)

Nominal

Section

Strength

Nominal

Beam-Column

Strength

= Pn/Pno

(PA,0)

(PA,0)

(PC,MC)

(CPA,0.9BMB)

(0,BMB) (0,MB)

Nominal

Beam-Column

Strength

P

M

= Pn/PnoNominal

Section

Strength

for 0.5

0.2 0.5 for 0.5 1.5

0.2 for 1.5

C A oe

C C A C A oe oe

oe

P P

P P P P

1 for 1

1 0.2 1 for 1 2

0.8 for 2

oe

B oe oe

oe

AISC2010 Proposed


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Variation of the Composite Interaction

Diagram with Slenderness

0

1

2

30 0.5 1 1.5

0

0.2

0.4

0.6

0.8

1

1.2

NormalizedBendingMoment(M/Mn)

No

rmalizedAxialLoad(P/P

no

)

CFTBondProvisionsinAISC36010

ForCCFT:

Rn=0.25D2CinFin

ForRCFT:

Rn=B2CinFin

where,

Rn =nominalbondstrength,kips

Cin =2iftheCFTextendstoonesideofthepointofforcetransfer

=4iftheCFTextendstobothsidesofthepointofforcetransfer

Fin =nominalbondstress=60psi

B =overallwidthofrectangularsteelsectionalongfacetransferringload,in.

D =outsidediameteroftheroundsteelsection,in.

=0.45=3.33


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ExperimentalSetupsfor

AssessingBondStrength

(a) Push-off test(b) Push-out test

without shear tabs

(c) Push-out test

with shear tabs

(d) Typical CFT

connection

Air Gap

Air Gap

ProposedDesignProvisionsForCCFT:

Rn=DLbondFin

Lbond=CinD

Fin=30.9(t/D2)0.2

ForRCFT:

Rn=2(B+H)LbondFin

Lbond=CinH

Fin=12.8(t/H2)0.1

where,

Rn =nominalbondstrength,kipsFin =nominalbondstress,ksi

t =designwallthicknessofsteelsection,in.

B =overallwidthofrectangularsteelsection(B H),in.

H =overallheightofrectangularsteelsection(H B),in.

D =outsidediameterofroundsteelsection,in.

Lbond =lengthofthebondregion(thebondregionofadjacentconnectionsshallnotoverlap),in.

Cin =4ifloadisappliedtothesteeltubeandtheCFTextendstobothsidesofthepointofforcetransfer

=2otherwise

ForRCFT:BothLbondandFinarebased

onthelargerlateraldimensionofthetube(H B)

=0.50,=3.00


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Seismic Performance Factors:

FEMA P695 Archetype Frame Study:

Selection and Design of Archetype Frames

= Location of Braced Frame= Fully Restrained Connections

= Shear Connections

MomentFrames BracedFrames

Selected Composite Archetype FramesDesign

Gravity

Load

Bay

Width

Design

Seismic

Load

Conc.

Strength

(fc)

Index

MomentFrames BracedFrames

RCFT RCFT SRC RCFTCd CCFT CCFT

3Stories 9Stories 3Stories 3Stories 3Stories 9Stories

High 20 Dmax 4 ksi 1

High 20 Dmax 12ksi 2

High 20 Dmin 4 ksi 3

High 20 Dmin 12ksi 4

High 30 Dmax 4 ksi 5

High 30 Dmax 12ksi 6

High 30 Dmin 4 ksi 7

High 30 Dmin 12ksi 8

Low 20 Dmax 4 ksi 9

Low 20 Dmax 12ksi 10

Low 20 Dmin 4 ksi 11

Low 20 Dmin 12ksi 12

Low 30 Dmax 4 ksi 13

Low 30 Dmax 12ksi 14

Low 30 Dmin 4 ksi 15

Low 30 Dmin 12ksi 16


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Typical Composite Connection Region Modeling:

Validated Against Tests

Rigid Links

Zero Length Spring

Representing the

Panel Zone Shear

Behavior

Nonlinear

Column

Element

Nonlinear

Beam

Element

Elastic

Beam

Element

Nonlinearstressresultantspacemultisurface

kinematichardeningmodelusedforrotational

springformulation(afterMuhummud 2003)

Rigid

Links

Nonlinear

Column

Element

Nonlinear

Beam

Element

Nonlinear

Brace

Element

Moment

Release

Modelingassumptionsestablished

byHsiaoetal.(2012)

Evaluation ofSeismic Performance Factors

Archetypeframesarecategorizedintoperformance

groupsbasedonbasicstructuralcharacteristics

Group

Number

Design

GravityLoad

Level

Design

SeismicLoad

Level

Period

Domain

Numberof

CSMFs

Number of

CSCBFs

PG1 High Dmax Short 6 4

PG2 High Dmax Long 2 2

PG3 High Dmin Short 6 4

PG4 High Dmin Long 2 2

PG5 Low Dmax Short 6 4

PG6 Low Dmax Long 2 2

PG7 Low Dmin Short 6 4

PG8 Low Dmin Long 2 2


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Typical Static Pushover Analysis

0 10 20 30 40 50 600

100

200

300

400

500

600

700

800

900

1000

Roof Displacement (in)

Base

Shear

(kips

)

Vmax

= 879.3 kips

V80

= 703.4 kips

V = 153.9 kips

u

=50

.8in

SFRS: C-SMF, Frame: RCFT-3-1

System Overstrength Factor, o

BytheFEMAP695methodology,oshouldbetakenasthelargestaveragevalueoffromanyperformancegroup Roundedtonearest0.5

Upperlimitsof1.5Rand3.0

HighoverstrengthforCSMFs Displacementcontrolleddesign

Currentvalue(o=3.0)isupperlimitandisacceptable

OverstrengthforCSCBFsnearcurrentvalue(o=2.0) HigherforPG3andPG4(Highgravity

load,SDCDmin)

Group

Number

Average

CSMF CSCBF

PG1 5.9 2.1

PG2 5.3 1.9

PG3 7.6 2.8

PG4 9.9 2.7

PG5 6.2 1.8

PG6 5.5 1.7

PG7 7.5 2.3

PG8 6.5 2.2


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Typical Dynamic Time History Analyses:

Incremental Dynamic Analysis

0% 5% 10% 15%0

2

4

6

8

10

12

14

16

18

Maximum Story Drift

ST

=S

MT

SF

2(g)

SFRS: C-SMF, Frame: RCFT-3-1

5.72CTS g

1.50MTS g

Response Modification Factor, R ACMR10%=AcceptablevalueoftheAdjusted

CollapseMarginRatiofor10%collapse

probability

ACMR10%=1.96forbothCSMFandCSCBF

andarelessthantheACMRshownforeach

performancegroupinthetable

SimilarlypositiveresultsforACMR20%per

frame

ACMRvaluesshowcorrelationwiththe

overstrength

CSMFs

Currentvalue(R=8.0)isacceptable

CSCBFs

Currentvalue(R=5.0)isacceptable

Group

Number

ACMR

CSMF CSCBF

PG1 4.8 3.3

PG2 3.7 2.3

PG3 7.5 5.1

PG4 8.5 5.4

PG5 4.9 2.6

PG6 3.9 2.9

PG7 7.1 3.8

PG8 6.9 3.7


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Deflection Amplification Factor, Cd

BytheFEMAP695methodology,Cd=Rforthesesystems

WouldrepresentaminorchangeforCSCBF Currentvalues:Cd=4.5,R=5.0

Typicallystrengthcontrolleddesign

WouldrepresentasignificantchangeforCSMF Currentvalues:Cd=5.5,R=8.0

Typicallyalreadydisplacementcontrolleddesign

FourCSMFarchetypeframesdesignedwiththecurrentC

dvalue

LoweroverstrengthwithcurrentCd(average4.9vs.6.4withCd=R)

AcceptableperformancewithcurrentCd

KeyConclusionsfromtheResearch

ExperimentalResearch

Acomprehensiveanduniquedatasetforaxialstrengthandbeamcolumn

strengthhasbeengeneratedforslenderCCFTsandRCFTs.

CFTsdemonstratedgreattoughnessundercomplexcyclicloadings.

Localbucklingdidnotleadtosubstantialstrengthorstiffnesslosses.

ComputationalResearch

Newmixedelementanalysisformulationdevelopedforcompositebeam

columns Compositebeamcolumnsexhibitrobustperformanceunderseverecyclic

loading

Analysisformulationenablesbenchmarkstudiesofstabilityandstrength

ofcompositeframes(nonseismicandseismic)


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ProposalsforAISC36016(2016)

SpecificationforStructuralSteelBuildings

Newcommentaryonaddressingwetweightofconcreteduringconcrete

pourforCFTs

NewEIeffvalueforcalculatingcolumnstrengthofSRCstobetterreflect

computationaldata

Newrecommendations forEIelastic valuetouseforcalculatingelastic

stiffnessofCFTsandSRCsforuseinelasticanalysisanduseinDirect

Analysis

Newinteractionequationthataddressespossibleunconservative errors

forveryslendercompositemembers

NewCFTbondprovisionsthatmoreaccuratelyreflectthechangeinbond

strengthwithCFTdiameterandthatclarifyhowtocomputebondstrength

inloadtransferregions

ValidationofcurrentseismicperformancefactorsinASCE710and

recommendationtoconsiderincreasingthedeflectioncriteriaforCSMFs

ifCd=R

FutureWork

FinalizerecommendationsforAISC36016

Prequalifiedcompositeconnections

Incorporatecreepandshrinkageeffectsintodesignof

compositesystems

Effectsofelevatedtemperatureincompositesystems,and

effectsofinternalreinforcement

Innovativecompositeframingsystems:

Prefabricatedcompositeconstructionsystems Integrationofnewmaterials,includinghigherstrength

materials

Etc.


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ThankYouNEESProjectWarehouse:https://nees.org/warehouse/project/440

440 SystemBehaviorFactorsforCompositeandMixedStructuralSystem

RobertoT.Leon,JeromeF.Hajjar,Nakin Suksawang

ReferencesandalistofpapersandpublicationsforthisworkareavailableattheNEES

siteforthiswebinar: https://nees.org/events/details/190

TheworkdescribedhereispartofaNEESRprojectsupportedbytheNationalScienceFoundationunderGrantNo.CMMI0619047,theAmericanInstituteofSteel

Construction,theGeorgiaInstituteofTechnology,andtheUniversityofIllinoisat

UrbanaChampaign. TheseexperimentswereconductedattheMultiaxial

Subassemablage TestingSystem(MAST)attheUniversityofMinnesota.

InKind:

Documents

Behavior and Design of Concrete-Filled Beam-Columns Webinar Slides