Park Japan Presentation Final

7/31/2019 Park Japan Presentation Final

1/25

Analytical and Experimental Study onAnalytical and Experimental Study onAnalytical and Experimental Study onAnalytical and Experimental Study onAnalytical and Experimental Study onAnalytical and Experimental Study onAnalytical and Experimental Study onAnalytical and Experimental Study on

R/C Exterior BeamR/C Exterior BeamR/C Exterior BeamR/C Exterior BeamR/C Exterior BeamR/C Exterior BeamR/C Exterior BeamR/C Exterior Beam--------Column JointsColumn JointsColumn JointsColumn JointsColumn JointsColumn JointsColumn JointsColumn Joints

without Transverse Reinforcementwithout Transverse Reinforcementwithout Transverse Reinforcementwithout Transverse Reinforcementwithout Transverse Reinforcementwithout Transverse Reinforcementwithout Transverse Reinforcementwithout Transverse Reinforcement

Sangjoon Park, Ph.D Candidate

Khalid Mosalam, Prof. & Vice Chair

UC Berkeley

5th ICEE, Tokyo, Japan, March 3-5, 2010


2/25

MotivationMotivation

Seismic performance of old existing RC building joints

- No seismic design code prior to 1970s

- No transverse reinforcement in the joint region

Brittle failure and collapse

Lateral displacement

Lateralf

orce

Beam flexural failure

Joint shear failure


3/25

MotivationMotivation

Existing joint strength models and suggestions

- Inappropriate application from reinforcedjoints to unreinforcedjoints

- Overly simplified failure mechanism

- Underestimation of shear strength (ASCE41)

'

c

proposed,j

f

v

'

c

test,j

f

v

0

2

4

6

8

10

12

14

16

0 2 4 6 8 10 12 14 16

)psi('

ccjjj fhbVv ==

joint

geometry

4

6

8


4/25

Unreinforced exterior joint tests w/o or w/ one lateral beam

Anchorage details of selected specimens

Column width (bc) beam width (b

b)

62 test data are collected

Failure mode: J (joint shear failure without beam yielding)

BJ (joint shear failure with beam yielding)

Database of Previous TestsDatabase of Previous Tests

Type A Type B Type C Type D

(a) (b) (c)

or


5/25

Developed SemiDeveloped Semi--Empirical ModelEmpirical Model

0

0.2

0.4

0.6

0.8

1

1.2

0.8 1 1.2 1.4 1.6 1.8 2 2.2

H

h

f

f

hb

A b

c

y

cj

s 85.01'

low aspect ratio,

high aspect ratio,

0

0.2

0.4

0.6

0.8

1

1.2

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

Joint aspect ratio, hb/hc

c

b'

ccj

jh

h

h

a

fhbV

085.031.1

cos2+

=

Beam reinforcement index

H

h

fhb

fAb

ccj

ys85.01

'

=

H

hfA

fhb

Vb

ys

ccj

jh85.01

'

25.11.0factorthoverstreng:

'

ccj

jh

fhb

V

Ymax=X2

Ymin=1.25X1

X1

X2

Proposed

Model


6/25

Developed Analytical ModelDeveloped Analytical Model

21 STjh,STjh,jh VVV += ( )==h

l

ssjhjh,ST1 dxfnfAVV0

bs

( )c

l

sjhjh,ST2 VdxfnVVh

== 0b)1(

)( sf

ST1ST2

Asfs

1jh,STV

fy fpfs : tensile stress of beam reinforcement

: Bond strength

E

Y

R

Lehman & Moehle (2000)

CEB-FIP (1990)

]psi[12'

cf

]psi[6'

cf

]psi[8.1'

cf

Vc

( )

=

s

l

s

b f

df

h.H

Hh

0

b

x41

850


7/25

Developed Analytical ModelDeveloped Analytical Model

No

Input:

hsbc

cbbyc

lAHh

bhbff

,,,,

,,,,,'

Calculate: fo ,fp ,fr,

1 , 2 , Vjh,ST1,max

Assume:fs,i

Determine: i

Calculate: Vjh,i , Vjh,ST1,i

Check: Vjh,ST1,iVjh,ST1,maxCheck: fs,i < foYes

Define: Vjh,i =Asfo(1-0.85hb/H)

Yes

NoDefine: Vjh = Vjh,i

End


8/25

Predictions by Proposed ModelsPredictions by Proposed Models

0

50

100

150

200

250

300

0 50 100 150 200 250 300

(a) Semi-Empirical

Vjh,test

[kip]

MEAN = 0.98

COV = 0.15

0

50

100

150

200

250

300

0 50 100 150 200 250 300

(b) Analytical

Vjh,test

[kip]

MEAN = 0.97

COV = 0.16


9/25

For More DetailsFor More Details

PEER Report 2009/106

http://peer.berkeley.edu/publications/peer_reports/reports_2009/web_PEER9106_PARK_Mosalam.pdf


10/25

Experimental ProgramExperimental Program

For All Specimens:

Target concrete strength: f'c = 24 MPa (3.5 ksi)

Reinforcing bars nominal yield strength: fy = 414 MPa (Grade 60)

1. Test matrix Beam Section (A-A)

Column Section (B-B)

SP1&2 SP3&4

18"

18"

8-#8

hoop #3@3''

8-D25

D10@76mm457

457

18"

18"

8-#8

hoop #3@3''

8-D32

D10@76mm457

457

AspectRatio

SP1 SP2

SP3

18"

16"

4-#8

4-#7

stirrup

#3@3''

18"

16"

4-#6

4-#6

stirrup

#3@3''

4-D19

4-D19D10@76mm

4-D25

4-D22D10@76mm

457 457

406 406

Reinforcement Ratio

30"

16"

4-#6

4-#6#3

stirrup

#3@3''30"

16"

4-#8

4-#7#3

stirrup

#3@3''

4-D19

4-D19

D10@76mm

4-D25

4-D22

D10@76mm762

406 406

762

top and bottom slab reinforcement : D10@305mm

B B

A

A

L=2.44m

H=3.6

8m

SP4 (in progress)


11/25


2. Construction

EW direction

76.2mm

38.1mm

NS direction

50.8mm

63.5mm


12/25


3. Loading Control beam tip displacementControl beam tip displacement

+

-EW

+

-NS

+

-

+

-

40

y=

y

y 5.1

y 25.2

Papplied

SP1&2 : Papplied=-95 + 4Vb,x + 4Vb,y

SP3&4 : Papplied=-95 + 2Vb,x + 2Vb,y

- Simulate variation of column axial loading

previouse3

1

Group 1

Group 2

Group 3

Group 4

Group 5

Group 6Group 7

P/(f'cA

g)

Testing time (sec)0 0.5 1 1.5 2 2.5 3 3.5

x 104

-0.25

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

SP1SP2


13/25


14/25

Test ResultsTest Results

-8 -6 -4 -2 0 2 4 6 8-150

-100

-50

0

50

100

150

Drift (%)

-8 -6 -4 -2 0 2 4 6 8-150

-100

-50

0

50

100

150

Drift (%)

Beam

shear(kN) EW direction NS direction

Yielding

Peak

Yielding

Peak

SP1

SP1- Load vs. Drift

8

7

6 54

4

56

7

84

5 6

7

7

65

4


15/25


Drift (%)-8 -6 -4 -2 0 2 4 6 8

-200

-150

-100

-50

0

50

100

150

-8 -6 -4 -2 0 2 4 6 8-200

-150

-100

-50

0

50

100

150

Drift (%)

Yielding

Peak

Yielding

Peak

Beam


SP2

SP2- Load vs. Drift

8

7

65

4

8

7

65 4

4

56

7

84

5 6

7

8


16/25


-8 -6 -4 -2 0 2 4 6 8-200

-150

-100

-50

0

50

100

150

200

-8 -6 -4 -2 0 2 4 6 8-200

-150

-100

-50

0

50

100

150

200

Drift (%) Drift (%)

Yielding

Peak

Beam


Beam

shear(kN)

SP3- Load vs. Drift

Yielding

Peak

8

7

65

4

4

56

7

8

4

56

7

8

8

7

6

54


17/25

-0.02-0.015-0.01-0.005 0 0.005 0.01 0.015 0.02

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

-0.015 -0.01 -0.005 0 0.005 0.01 0.015 0.02

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8


Normalized joint shear vs. Joint distortion

-0.01 -0.005 0 0.005 0.01

-1

-0.8

-0.6

-0.4-0.2

0

0.2

0.4

0.6

0.8

Joint shear strain

(

MPa)

-0.01 -0.005 0 0.005 0.01

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

Joint shear strain

EW direction

NS direction

Joint distortion (rad)


-0.01 -0.005 0 0.005 0.01

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.60.8

Joint shear strain

-0.01 -0.005 0 0.005 0.01

-1

-0.8

-0.6

-0.4-0.2

0

0.2

0.4

0.6

0.8

Joint shear strain

(

MPa)

EW direction

NS direction



EW direction

NS direction



ASCE 41

ASCE 41

SP1 SP2 SP3

- Normalized joint shear stress ASCE41

- Joint distortion: upward loading, i.e. slab in compression > downward loading, i.e. slab in tension


18/25


Joint Shear Strength

Joint aspect ratio, hb/hc

0

0.2

0.4

0.6

0.8

1

1.2

0.8 1 1.2 1.4 1.6 1.8 2 2.2

SP2

SP1

SP3

LoadingTest

[MPa0.5]

Semi-

empirical

[MPa0.5]

SP1

EWUp 0.71 0.64 (0.90)*

Down 0.71 0.71 (1.00)

NSUp 0.67 0.64 (0.96)

Down 0.66 0.71 (1.08)

SP2

EWUp 0.80 0.79 (0.99)

Down 1.09 0.97 (0.89)

NS

Up 0.81 0.79 (0.98)

Down 1.10 0.97 (0.88)

SP3

EWUp 0.52 0.57(1.10)

Down 0.59 0.61(1.03)

NSUp 0.47 0.57(1.21)

Down 0.51 0.61(1.20)

( )*: vj_model/ vj_test


19/25

Intermediate Column Bar

-1

-0.5

0

0.5

1

1.5

2

2.5

-5 -4 -3 -2 -1 0 1 2 3 4

Drift (%)

Strain(10-3)

top

middle

bottom

-1

-0.5

0

0.5

1

1.5

2

2.5

3

-5 -4 -3 -2 -1 0 1 2 3 4

Drift (%)

top

middle

bottom

topmiddle

bottom

topmiddle

bottom

(a) EW direction (b) NS direction


Tension Tie ?

Not likely

SP2


20/25


Effect of Slab

Loading group

6543

1 2 3 41

2

3

4

1 2 3 4

Bottom gages only @1,2

Top gages @1 to 4

Stra

in(

)y

/

0

0.2

0.4

0.6

0.8

1

1 2

Bar number

0

1

2

3

4

5

1 2 3 4

Bar number

457

152 top

bot

slip

0

1

2

3

4

5

1 2 3 4

0

0.2

0.4

0.6

0.8

1

1 2

S

tra

in(

)y

/

Bar numberBar number

EW-Top EW-Bottom

slip

0

1

2

3

4

5

1 2 3 4

0

0.2

0.4

0.6

0.8

1

1 2

Bar number Bar number

SP1

NS-Top NS-Bottomslip

Stra

in

(

)y

/

SP2

0

1

2

3

4

5

1 2 3 4

0

0.2

0.4

0.6

0.8

1

1 2


Strain

(

)y

/

NS-Bottomslip

EW-Top

NS-Top

EW-Bottom

Beam reinforcement

low high


21/25

Test ResultsTest ResultsEffect of Slab

Loading group

6543

1 2 3 41

2

3

4

1 2 3 4

Bottom gages only @1,2

Top gages @1 to 4

457(SP1)

152

0

1

2

3

4

5

1 2 3 4

0

0.2

0.4

0.6

0.8

1

1 2

S

tra

in(

)y

/

Bar numberBar number

EW-Top EW-Bottom

slip

0

1

2

3

4

5

1 2 3 4

0

0.2

0.4

0.6

0.8

1

1 2


SP1

NS-Top NS-Bottomslip

762(SP3)

0

1

2

3

4

5

1 2 3 4

0

1

2

3

4

5

1 2 3 4

0

0.2

0.4

0.6

0.8

1

1.2

1 2

0

0.2

0.4

0.6

0.8

1

1 2

EW-TopEW-Bottom

slip

NS-Top NS-Bottom

slip

SP3

S

tra

in(

)y

/

Strain(

)y

/

Strain

(

)y

/

Beam depth

small large


22/25


23/25

SummarySummary

Joint aspect ratio (hb/ h

c)

Beam reinforcement index

1. Main parameters

= 0.5~1.1 from tests vs. = 0.5 from ASCE 41

Accurate prediction by proposed models

2. Shear strength of unreinforced exterior joints

3. Intermediate column bars

Contribution of slab reinforcement

Torsional effect

Different joint shear distortion when slab in tension or in compression

4. Effect of slab

No function as a tension tie


24/25

Further verification of proposed models

Extension to unreinforced interior joints

Progressive collapse analysis using developed joint element

Collapse fragility curve of old existing R/C prototype buildings

Future ResearchFuture Research

Pro

ba

bilityo

fco

llapse

Hazard level (PGA)

Complete collapse

Partial collapse by column axial failure

Partial collapse by joint shear failure


25/25

Thank You!

Test results are uploaded at

http://research.eerc.berkeley.edu/projects/cornerbeamcolumnjoints/

Thomas(Oct.,2009) Gordon(Dec.,2009) James(Jan.,2010) Percy(Next week)

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Park Japan Presentation Final

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