USE OF HEADED REINFORCEMENT IN BEAM - COLUMN JOINTS

plantcitybusinessΠολεοδομικά Έργα

26 Νοε 2013 (πριν από 3 χρόνια και 10 μήνες)

74 εμφανίσεις

USE OF HEADED REINFORCEMENT

IN BEAM
-

COLUMN JOINTS

John W. Wallace, Ph.D., P.E.

Associate Professor, UCLA

Scott W. McConnell, M.S., P.E.

Structural Engineer, Schoor
-
DePalma, NJ



National Science


Foundation



Headed Reinforcement


Corporation



ERICO Incorporation

HEADED

REINFORCEMENT ?





Plate Anchor


Rectangular/Round



Threaded/Friction Weld



Area = 5 to 10 Bar Area



Beam
-
Column Joints


Standard Hooks



Ease of Fabrication &


Placement

WHY HEADED REINFORCEMENT ?

Congestion/Fabrication/Placement



AVAILABLE INFORMATION

Anchorage/Beam
-
Column Joints


UCLA & Clarkson University

Wallace, McConnell, Gupta


Reports/ACI Papers (1994, 1997, 1998)


Also Yu (2001)


University of Texas, Austin

Jirsa, Devries, Bashandy

Ph.D. Dissertations (1996), ACI Paper (1999)


University of Kansas

McCabe, Wright, Wu (Reports, 1997)

PROJECT OVERVIEW



EXTERIOR ROOF

& CORNER JOINTS



EXTERIOR INTER
-

STORY JOINTS



HYDRAULIC ACTUATOR
LOAD CELL
CLEVIS
52"
HEAVY LINK
SPECIMEN
LVDT FOR DISPL.
CONTROL
RIGID REFERENCE
FRAME
36"
TIE DOWN
REACTION WALL
STRONG FLOOR
TEST SETUP

Exterior Roof Connections

SPECIMEN DETAILS

Exterior Roof Connections

#5 GR60 US REBAR
(16 mm)
#3 STIRRUP
(9.5 mm)
14.5"
9.5"
0.75"
BEAM CROSS SECTION
11" x 16"
280 mm x 406 mm
COLUMN CROSS SECTION
16" x 16"
406 mm x 406 mm
#6 (20mm)
14.5"
14.5"
0.75"
#3 HOOP &
CROSSTIES
(368 mm)
(241 mm)
DESIGN REQUIREMENTS

Exterior Roof Connections


Strong Column
-

Weak Beam (352
-
01)









Joint Confinement Reinforcement (352
-
01)





Joint Shear Stress Limits (352
-
91)







2 (1.1 Test)

.

1



/

beam

column

M

M

(test)



51

.

1

/



f

/

f



)

1

/

(

3

.

0

'

,

,

y

'

c

=

-

=

d

req

sh

provided

sh

ch

g

c

sh

A

A

A

A

sh

A

0

.

1



to



5

.

0



/

kips



140



to



75

P





)



60

)(

25

.

1

)(



(

kips



140

)

"

5

.

13

)(

"

16

(

(psi)



4000



)

12

)(

85

.

0

(

2

=

=



=

=

=

n

u

beam

s

u

n

V

V

ksi

in

A

V

V

f

f

DESIGN REQUIREMENTS

Exterior Roof Connections


Anchorage Requirements


Tension
(318 Eq. 21
-
5, 352
-
91)





Compression
(318 S12.3)




1.55



to



25

.

1

22)/14.23



to



(18



/

23

.

14

(psi)



f

/



900



(0.75)



(psi)



f

/



1200





(psi)



f

/

f





02

.

0

'

c

'

c

'

c

y

=

=

=

=

=

=

=

d

provided

b

d

db

d

d

b

db

l

l

d

d

l

l

d

d

l

1.5



to



23

.

1

6

.

14

/

22)



to



18

(



/



14.6



(psi)



f

/

925





(psi)



f



65

/



f



'

c

'

c

=

=

=

=

=

b

b

dh

provided

b

b

b

y

dh

d

d

l

l

d

d

d

l

LOAD HISTORY

Exterior Roof/Inter
-
Story Connections

0
2
0
0
4
0
0
6
0
0
8
0
0
C
o
u
n
t
e
r

N
u
m
b
e
r
-
6
-
4
-
2
0
2
4
6
D
r
i
f
t

L
e
v
e
l

(
%
)
B
C
E
J
-
1
Specimen Damage

Exterior Roof Connections

KJ16
-

Top Bar Pull
-
out

REINFORCING DETAILS

Exterior Roof Connections

Top View


Side View


Restraint Bars

Restraint Bars

Moment
-
Rotation Response

Exterior Roof Connections

-
0
.
0
6
-
0
.
0
4
-
0
.
0
2
0
.
0
0
0
.
0
2
0
.
0
4
0
.
0
6
S
p
e
c
i
m
e
n

R
o
t
a
t
i
o
n
-
2
5
0
0
-
2
0
0
0
-
1
5
0
0
-
1
0
0
0
-
5
0
0
0
5
0
0
1
0
0
0
1
5
0
0
2
0
0
0
M
o
m
e
n
t

(
i
n
-
k
i
p
s
)
-
2
5
0
-
2
0
0
-
1
5
0
-
1
0
0
-
5
0
0
5
0
1
0
0
1
5
0
2
0
0
M
o
m
e
n
t

(
k
N
-
m
)
K
n
e
e

J
o
i
n
t

#
1
7
4
.
0
%
3
.
0
%
2
.
0
%
1
.
5
%
1
.
0
%
M
n
=
1
5
0
8

i
n
-
k
i
p
s

(
P
=
4
9
.
5

k
i
p
s
)
C
l
o
s
i
n
g
O
p
e
n
i
n
g
M
n
=
1
0
1
1

i
n
-
k
i
p
s

(
P
=
-
3
3

k
i
p
s
)
6
.
0
%
0
.
5
%
MEASURED REBAR STRAINS

Beam Top Bars Within the Joint

-
2
0
0
0
0
2
0
0
0
4
0
0
0
6
0
0
0
M
I
C
R
O
S
T
R
A
I
N
T
B
1
-
F
A
C
E
T
B
1
-
M
I
D
1.0%
2.0%
4.0%
1.0%
2.0%
4.0%
0
1
0
0
2
0
0
3
0
0
4
0
0
5
0
0
D
A
T
A

P
O
I
N
T
-
2
0
0
0
0
2
0
0
0
4
0
0
0
6
0
0
0
M
I
C
R
O
S
T
R
A
I
N
T
B
2
-
F
A
C
E
T
B
2
-
E
N
D
TEST SETUP

Exterior Inter
-
Story Connections

12.75 ft (3.89 m)
10 ft
(3.05m)
SPECIMEN GEOMETRY

Exterior Inter
-
Story Connections

BEAM CROSS SECTION
18" x 24"
457 mm x 610 mm
COLUMN CROSS SECTION
18" x 18"
457 mm x 457 mm
DESIGN REQUIREMENTS

Exterior Inter
-
Story Connections


Strong Column
-

Weak Beam (352
-
01)









Joint Confinement Reinforcement (352
-
01)





Joint Shear Stress Limits (352
-
91)







2 (1.7 Test)

.

1



/

beam

column

M

M

(test)



17

.

1

/



f

/

f



)

1

/

(

3

.

0

'

,

,

y

'

c

=

-

=

d

req

sh

provided

sh

ch

g

c

sh

A

A

A

A

sh

A

80

.

0

/

kips



207





)



60

)(

25

.

1

)(



79

.

0

4

(

kips



260

)

"

18

)(

"

18

(

(psi)



4000



)

15

)(

85

.

0

(

2

=

=

-

=

=

=

n

u

column

u

n

V

V

V

ksi

in

x

V

V

f

f

DESIGN REQUIREMENTS

Exterior Inter
-
Story Connections


Anchorage Requirements


Tension
(318 Eq. 21
-
5, 352
-
91)





Compression
(318 S12.3)




352)

per



(0.82



9

.

0

6

.

14

/

13



/



14.6



(psi)



f

/

925





(psi)



f



65

/



f



'

c

'

c

=

=

=

=

=

b

b

dh

provided

b

b

b

y

dh

d

d

l

l

d

d

d

l

0.91

13/14.23



/

23

.

14

(psi)



f

/



900



(0.75)



(psi)



f

/



1200





(psi)



f

/

f





02

.

0

'

c

'

c

'

c

y

=

=

=

=

=

=

=

d

provided

b

d

db

d

d

b

db

l

l

d

d

l

l

d

d

l

Beam End Rotation

Exterior Interstory Connections

BCEJ1
-

Drift Level 6%


Potentiometer

Potentiometer

MOMENT
-
ROTATION

Exterior Inter
-
Story Connections

-
0
.
0
6
-
0
.
0
4
-
0
.
0
2
0
.
0
0
0
.
0
2
0
.
0
4
0
.
0
6
J
O
I
N
T

R
O
T
A
T
I
O
N

2
4
"

F
R
O
M

T
H
E

C
O
L
U
M
N

F
A
C
E
-
6
0
0
0
-
4
0
0
0
-
2
0
0
0
0
2
0
0
0
4
0
0
0
6
0
0
0
M
O
M
E
N
T

(
k
i
p
-
i
n
)
6

%
4

%
2

%
3

b
e
a
m

b
a
r
s

i
n

t
e
n
s
i
o
n
4

b
e
a
m

b
a
r
s

i
n

t
e
n
s
i
o
n
M
n
=

2
8
6
0
M
n
=

3
7
6
0
Specimen Damage

Exterior Interstory Connections

BCEJ1
-

Drift Level 6%

Bottom Bar Push
-
Out @ 6%


Compression Bar Push
-
Out

Exterior Inter
-
Story Connections



Beam Moment Capacity


Compression Steel



Slight Pushout Occurs


Redistribution From


Steel to Concrete



Minor Reduction in


Beam Moment Capacity



Note
-

Compression l
d



Satisfied by Checking


Tension l
d

Summary Observations

Headed Bars in Beam
-
Column Joints



Required Embedment Length


Kansas Study:

l
d

=

0.60 l
dh



Texas Study:

l
d

=

(
0.60
-

0.70) l
dh



UCLA/Clarkson Large
-
Scale Study:
l
d

=

0.82 l
dh




Other Design Requirements


Flexural Strength Ratio: M
column

/M
beam

> 1.2


Joint Shear


Emdedded Bars Must Be Shoved To Back of Joint



Practical Recommendation for Emdedment


l
d

=

0.75 l
dh


CONCLUSIONS


Beam
-
Column Joint Tests


Six Specimens (3 Exterior, 3 Roof)


Small Cover/Need for Transverse Steel


Push
-
Out of Compression Bars


ACI Committee 352 Draft Report


Modified to Allow Use of Headed Bars


Research Needs
-

Cyclic Loading


Cover/Transverse Reinforcement


Multiple Layers of Reinforcement