beam coupling

8/20/2019 Beam Coupling

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Design of Shear Wall CouplingDesign of Shear Wall Coupling

--

Fiber Fiber--Reinforced ConcreteReinforced Concrete

James K. WightJames K. Wight

. . , .. . , . ..

ofof MichiganMichigan

CoCo--Investigator: Prof. Gustavo ParraInvestigator: Prof. Gustavo Parra--MontesinosMontesinos

Graduate Students: Remy Lequesne and Monthian SetkitGraduate Students: Remy Lequesne and Monthian Setkit


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oup eoup e -- a ys emsa ys ems Coupling Beams: Design RequirementsCoupling Beams: Design Requirements

Use of diagonal reinforcementUse of diagonal reinforcement

Design, detailing and construction issuesDesign, detailing and construction issues

Design Modifications and the use ofDesign Modifications and the use of

HPFRCHPFRC

ConclusionsConclusions


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-- CoreCore--wall s stems o ular in moderate towall s stems o ular in moderate to

highhigh--rise structuresrise structures

openings from floor to flooropenings from floor to floor –– result isresult is


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--

a era s ness an s reng o sys ema era s ness an s reng o sys em

significantly influenced by design of couplingsignificantly influenced by design of coupling

eamseams

Can be designed to spread plasticity overCan be designed to spread plasticity overheight of systemheight of system

Designed/detailed to retain strength andDesigned/detailed to retain strength and

significant percentage of stiffness duringsignificant percentage of stiffness during

large deformations into plastic range oflarge deformations into plastic range of

behavior.behavior.


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BeamsBeams

Observed response of RC coupling beamsObserved response of RC coupling beams--

ductileductile


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(http://www.nisee.org)


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Proposed by Thomas Paulay and others;

Diagonals carry all shear and all flexure

A sd


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Test Usin Dia onal Reinforcement


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Construction Issues andConstruction Issues and

System Design ChangesSystem Design Changes

es gn o agona re n orcemen s easyes gn o agona re n orcemen s easy – –

construction is NOTconstruction is NOT

Trend in the USA is to use more slenderTrend in the USA is to use more slender

coupling beams, i.e. a larger length/depth ratiocoupling beams, i.e. a larger length/depth ratio Should we change our design approach?Should we change our design approach?

Dia onal reinforcement is not as efficient atDia onal reinforcement is not as efficient at

shallow angleshallow angle

Use of HPFRC can reduce need for diagonal andUse of HPFRC can reduce need for diagonal and

confinement reinforcementconfinement reinforcement


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Construction Issues


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Cou lin Beam Desi n:Mechanism Analysis of Coupling Beam

V jMpj 2

n M V

j nV

jn,

2 pj

*Assume, ( )( )s

A f jd


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Cou lin Beam Desi n:Flexural Design of Coupling Beam

assume combination of dia onal and lon itudinal steel

A A sd


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Cou lin Beam Desi n:Flexural Design of Coupling Beam

assume combination of dia onal and lon itudinal steel

cos ( )(0.9 )n s sd M A A f d

Solve for, cos p M

A A .

y

- ,


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Cou lin Beam Desi n:Shear Design of Coupling Beam

, n

where 0.85uV

V

V V V V V

For reinforced concrete, use 0cV

For fiber reinforced concrete, use 4cf c w

V f b d


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Cou lin Beam Desi n:Shear Design of Coupling Beam

contribution from dia onal reinforcement

A ssd

s nsd sd yt


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Cou lin Beam Desi n:Shear Design of Coupling Beam(contribution from vertical reinforcement)

A s

A v

s

v t A f d

s

s


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Hi h Performance Fiber Hi h Performance Fiber--Reinforced ConcretesReinforced Concretes

e n on o ge n on o g --per ormance er per ormance er--

reinforced concrete typically means thereinforced concrete typically means the

ma er a as a s ra nma er a as a s ra n-- ar en ng e av or nar en ng e av or n

tension.tension.


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Regular FRC HPFRC


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Earthquake-Resistant Design Applications

The ductility, stiffness retention andcon inement properties o HPFR

members under inelastic load reversalsma e t em an exce ent can ate oruse in earthquake-resistant design of

re n orce concre e u ngs.


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Investigate the use of precast HPFRCcoupling beams in earthquake-resistantcoupled wall systems

Reduce (eliminate) transverse anddiagonal reinforcement requirements incoupling beams

Develop information on shear strengthand damage tolerance of HPFRC members


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Cracking Pattern at Low Drift(Span/depth ratio of 1.2)

SP-1 vs. SP-4 at 1.5% Drift

SP-1 SP-4


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Shear Stress vs. Beam Drift Response

- . -10

6

8

)

0

2

t r e s s ( M P

-4

-2

S h e a r

SP-1

-10

-8

-6SP-4

-6 -4 -2 0 2 4 6

Drift(%)


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CB-2 desi n L/d = 1.75Precast – shaded region


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Component Test Setup

Actuator

Precast Coupling “Rigid” Links

a oc

Wall Block


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-


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-

3% Drift

5.5% Drift


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coupled-wall

spec men


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Precast Beam Casting


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Coupled Wall Construction


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Coupled Wall Construction


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RC Wall Behavior


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Three beams, span/depth ratio of 2.75Three beams, span/depth ratio of 2.75

arget s ear stress at m target s ear stress at m t

Specimen Diagonal Reinf.Material

2 YesHPFRC

4 Concrete Yes

No


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Specimen 6Specimen 2

. . . .


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2.0 and 4.0, the use of2.0 and 4.0, the use of onlyonly diagonal reinforcementdiagonal reinforcementis unreasonableis unreasonable – – Thus use combinationThus use combination ofof

diagonal and longitudinal steel for flexural strengthdiagonal and longitudinal steel for flexural strength..

UUsese of HPFRCof HPFRC allowedallowed elimination of transverseelimination of transversereinforcement requirements for diagonal barsreinforcement requirements for diagonal bars – –

SSignificantly simplifiedignificantly simplified the beamthe beam construction.construction.

We recommend to use a combinationWe recommend to use a combination of diagonalof diagonalreinforcement,reinforcement, verticalvertical stirrups, and HPFRCstirrups, and HPFRC forfor

s ear s rengs ear s reng ..


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superior damage tolerance at low to moderate driftsuperior damage tolerance at low to moderate driftlevel com ared to RC cou lin beams.level com ared to RC cou lin beams.

Supplemental diagonal reinforcement is required inSupplemental diagonal reinforcement is required in

short coupling beams to achieve large driftshort coupling beams to achieve large driftcapacities, stiffness retention and adequate energycapacities, stiffness retention and adequate energy

dissipation.dissipation.

UseUse of a precast coupling beam is a practicalof a precast coupling beam is a practicalalternativealternative..


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uu


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beam coupling

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