Joints - Moehle c - PEER - University of California, Berkeley

reelingripebeltΠολεοδομικά Έργα

15 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

79 εμφανίσεις

Beam
-
Column Connections

Jack Moehle

University of California, Berkeley


with contributions from

Dawn Lehman and Laura Lowes

University of Washington, Seattle

Outline

design of new joints

existing joint details

failure of existing joints in earthquakes

general response characteristics

importance of including joint deformations

stiffness

strength

deformation capacity

axial failure

Special Moment
-
Resisting Frames

-

Design intent
-

Beam

Beam Section

l
nb

V
p

w

M
pr

M
pr

V
p

M
pr

V
p

M
pr

l
c

V
col

V
col

For seismic design,
beam yielding
defines demands

Joint demands

(a) moments, shears, axial
loads acting on joint

(c) joint shear

V
col

T
s1

C
2

V
u

=V
j

=
Ts1 + C
1

-

V
col

(b) internal stress resultants
acting on joint

T
s2

=


1.25
A
s
f
y

C
2

=
T
s2

T
s1

=

1.25
A
s
f
y

C
1

=
T
s2

V
col

V
col

V
b1

V
b2

Joint geometry

(ACI Committee 352)

a)
Interior
A.1

c) Corner

A.3

b) Exterior

A.2

d) Roof


Interior B.1

e) Roof

Exterior B.2

f) Roof

Corner B.3

ACI 352



Classification

/type



interior



exterior



corner



cont. column





20



15



12



Roof



15



12



8



Values of

g

(ACI 352)

Joint shear strength

-

code
-
conforming joints
-

h
b
f
V
V
j
c
n
u
'
g





= 0.85

ACI 352

Joint Details
-

Interior

h
col



20
d
b

ACI 352

Joint Details
-

Corner



l
dh

ACI 352

Code
-
conforming joints

Older
-
type beam
-
column connections

Survey of existing buildings




Mosier

Joint failures

Studies of older
-
type joints

Lehman

-80
-60
-40
-20
0
20
40
60
80
-6
-4
-2
0
2
4
6
Drift %
Column Shear (K)
Yield of Beam
Longitudinal
Reinforcement
Spalling of
Concrete Cover
Longitudinal
Column Bar
Exposed
Measurable
residual cracks
20% Reduction
in Envelope
Damage progression

interior connections

Lehman

Effect of load history

interior connections

-
6

-
4

-
2

0

2

4

6

Story Drift

Column Shear (k)

Column Bar

Envelope for standard

cyclic history

Impulsive loading history

Lehman

Standard Loading

Impulsive Loading

Damage at 5% drift

Lehman

0
20
40
60
80
100
120
1
4
7
10
13
16
19
22
25
28
31
34
Cycle Number
Percent Contribution
Jo
int Shear
Bar Slip
Beam
Flexur
e
Column
Specimen CD15
-
14

Contributions to drift

interior connections

“Joints shall be modeled
as either stiff or rigid
components.” (FEMA 356)

Lehman

Evaluation of FEMA
-
356 Model

interior connections

0

2

4

6

8

10

12

14

16

18

0

0.005

0.01

0.015

0.02

0.025

0.03

Joint Shear Strain

Joint Shear Factor

FEMA

PEER
-
14

CD15
-
14

CD30
-
14

PADH
-
14

PEER
-
22

CD30
-
22

PADH
-
22

Lehman

Joint panel deformations

Joint Deformation

0.000

0

12

G
c
/5

G
c

Joint shear stiffness

interior connections

psi
f
c
,
20
'
0.005

0.010

0.015

0.020

0.025

0.030

Joint shear strain

Joint shear stress (MPa)

10

8

6

4

2

psi
f
c
,
20
'
psi
f
c
,
10
'
G
c
/8

Lehman

Joint strength

effect of beam yielding

Joint Stress (psi)

0

400

800

1200

1600

0

1

2

3

4

5

6

Drift (%)



Joint strength closely linked to beam flexural strength



Plastic deformation capacity higher for lower joint shear

Lehman

Yield

Yield

Joint strength

interior connections
-

lower/upper bounds

/f
c


0

0.1

0.3

0.4

0

10

20

30

40

50

60

L

0.2

v
j

Beam Hinging/

Beam Bar Slip

Failure forced into
beams between
8.5

f’
c

and
11

f’
c


Joint
Shear
Failure

Joint failure without
yielding near
25.5

f’
c


Lehman

Joint strength

interior connections

0

500

1000

1500

2000

2500

3000

3500

0

4000

8000

12000

16000

Concrete Strength (psi)

Joint Stress (psi)

Joint Failures

Beam Failures

psi
f
c
,
10
'
Lehman

Joint deformability

Joint Stress (psi)

0

400

800

1200

1600

0

1

2

3

4

5

6

v
max

Drift (%)

0.2
v
max

plastic drift capacity

envelope

Plastic drift capacity

interior connections

0

5

10

15

20

25

30

0

0.01

0.02

0.03

0.04

0.05

0.06

plastic drift angle

psi
f
v
c
jo
,
'
int
Note: the plastic drift angle includes inelastic deformations of the beams

Damage progression

exterior connections

Pantelides, 2002

Joint behavior

exterior connections

2 Clyde

6 Clyde

4 Clyde

5 Clyde


5 Pantelides


6 Pantelides


6 Hakuto


Priestley longitudinal


Priestley transverse

psi
f
v
c
jo
,
'
int
15

0

1

2

3

4

5

6

7

10

5

0

Drift, %

bidirectional
loading

Plastic drift capacity

0

5

10

15

20

25

30

0

0.01

0.02

0.03

0.04

0.05

0.06

plastic drift angle

psi
f
v
c
jo
,
'
int
Note: the plastic drift angle includes inelastic deformations of the beams

Interior

Exterior

Exterior joint

hook detail

hook bent into joint

hook bent out of joint

Interior joints with
discontinuous bars

Column
shear,
kips

40

30

20

10

0

0

1

2

3

4

5

Drift ratio, %

Beres, 1992


Assuming bars are anchored in
joint, strength limited by strength of
framing members, with upper
bound of
g



25. For 25 ≥
g

≥ 8,
joint failure may occur after
inelastic response. For
g

≤ 8, joint
unlikely to fail.

Unreinforced Joint Strength

bh
f
V
c
j
'
g

g

joint

geometry

4

6

10

8

12

FEMA 356 specifies the following:


No new data. Probably still valid.


Assuming bars are anchored in
joint, strength limited by strength of
framing members, with upper
-
bound of
g



15. For 15

g

≥ 4,
joint failure may occur after
inelastic response. For
g

≤ 4, joint
unlikely to fail.

Joint failure?

s
y

t
cr

t
cr

'
'
6
1
6
c
y
c
cr
f
f
s
t


, psi

Joint failure?

Drift at “tensile failure”

Drift at “axial failure”

Lateral Load

Lateral Deflection, mm

Drift at “lateral failure”

Priestley, 1994

0

0.02

0.04

0.06

0.08

0.1

0

0.05

0.1

0.15

0.2

0.25

0.3

Axial load ratio

Drift ratio

}

Interior

0.03
-

0.07

0.10
-

0.18

0.20
-

0.22

Range of
g

values

Joint test summary

axial failures identified

Tests with axial load failure

0.36

Exterior, hooks bent in

Exterior, hooks bent out

Corner

'
c
j
f
v
g

Suggested envelope relation

interior connections with continuous beam bars

psi
f
v
c
jo
,
'
int
25

20

15

10

5

0

0.015

0.04

0.02

8

psi
f
c
,
25
'
strength = beam strength
but not to exceed

stiffness based on effective
stiffness to yield

Note: the plastic drift angle includes inelastic deformations of the beams

axial
-
load stability unknown,
especially under high axial loads

Suggested envelope relation

exterior connections with hooked beam bars

psi
f
v
c
jo
,
'
int
25

20

15

10

5

0

0.010

0.02

0.01

strength = beam strength
but not to exceed

psi
f
c
,
12
'
stiffness based on effective
stiffness to yield

connections with demand less

than have beam
-
yield
mechanisms and do not follow
this model

'
4
c
f
Note: the plastic drift angle includes inelastic deformations of the beams

Joint panel deformations

Joint Deformation

Methods of Repair (MOR)

Method of
Repair

Activities

Damage
States

0. Cosmetic
Repair

Replace and repair finishes

0
-
2

1. Epoxy Injection

Inject cracks with epoxy and
replace finishes

3
-
5

2. Patching

Patch spalled concrete, epoxy
inject cracks and replace
finishes

6
-
8

3. Replace
concrete

Remove and replace damaged
concrete, replace finishes

9
-
11

4. Replace joint

Replace damaged reinforcing
steel, remove and replace
concrete, and replace finishes

12


Pagni

Interior joint fragility relations

0.0
1.0
2.0
3.0
4.0
5.0
6.0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Drift (%)
MOR 0
MOR 1
MOR 2
MOR 3
MOR 4
0.0
1.0
2.0
3.0
4.0
5.0
6.0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Drift (%)
MOR 0
MOR 1
MOR 2
MOR 3
MOR 4
MOR 0
MOR 1
MOR 2
MOR 3
MOR 4
MOR 0
MOR 1
MOR 2
MOR 3
MOR 4
Probability of Requiring a MOR
Cosmetic repair

Epoxy injection

Patching

Replace concrete

Replace joint

Beam
-
Column Connections

Jack Moehle

University of California, Berkeley


with contributions from

Dawn Lehman and Laura Lowes

University of Washington, Seattle

References


Clyde, C., C. Pantelides, and L. Reaveley (2000), “Performance
-
based evaluation of exterior reinforced
concrete building joints for seismic excitation,”
Report No. PEER
-
2000/05
, Pacific Earthquake
Engineering Research Center, University of California, Berkeley, 61 pp.


Pantelides, C., J. Hansen, J. Nadauld, L Reaveley (2002, “Assessment of reinforced concrete building
exterior joints with substandard details,”
Report No. PEER
-
2002/18
, Pacific Earthquake Engineering
Research Center, University of California, Berkeley, 103 pp.


Park, R. (2002), "A Summary of Results of Simulated Seismic Load Tests on Reinforced Concrete Beam
-
Column Joints, Beams and Columns with Substandard Reinforcing Details,
Journal of Earthquake
Engineering
, Vol. 6, No. 2, pp. 147
-
174.


Priestley, M., and G. Hart (1994), “Seismic Behavior of “As
-
Built” and “As
-
Designed” Corner Joints,”
SEQAD Report to Hart Consultant Group,
Report #94
-
09
, 93 pp. plus appendices.


Walker, S., C. Yeargin, D. Lehman, and J. Stanton (2002), “Influence of Joint Shear Stress Demand and
Displacement History on the Seismic Performance of Beam
-
Column Joints,”
Proceedings
, The Third US
-
Japan Workshop on Performance
-
Based Earthquake Engineering Methodology for Reinforced Concrete
Building Structures, Seattle, USA, 16
-
18 August 2001,
Report No. PEER
-
2002/02
, Pacific Earthquake
Engineering Research Center, University of California, Berkeley, pp. 349
-
362.


Hakuto, S., R. Park, and H. Tanaka, “Seismic Load Tests on Interior and Exterior Beam
-
Column Joints
with Substandard Reinforcing Details,” ACI Structural Journal, Vol. 97, No. 1, January 2000, pp. 11
-
25.


Beres, A., R.White, and P. Gergely, “Seismic Behavior of Reinforced Concrete Frame Structures with
Nonductile Details: Part I


Summary of Experimental Findings of Full Scale Beam
-
Column Joint Tests,”
Report NCEER
-
92
-
0024, NCEER, State University of New York at Buffalo, 1992.


Pessiki, S., C. Conley, P. Gergely, and R. White, “Seismic Behavior of Lightly
-
Reinforced Concrete
Column and Beam Column Joint Details,” Report NCEER
-
90
-
0014, NCEER, State University of New
York at Buffalo, 1990.


ACI
-
ASCE Committee 352, Recommendations for Design of Beam
-
Column Connections in Monolithic
Reinforced Concrete Structures,” American Concrete Institute, Farmington Hills, 2002.

References (continued)


D. Lehman, University of Washington, personal communication, based on the following resources:


Fragility functions:


Pagni, C.A. and L.N. Lowes (2006). “Empirical Models for Predicting Earthquake Damage and Repair
Requirements for Older Reinforced Concrete Beam
-
Column Joints.”
Earthquake Spectra
. In press.


Joint element:


Lowes, L.N. and A. Altoontash. “Modeling the Response of Reinforced Concrete Beam
-
Column Joints.”
Journal of Structural Engineering
,
ASCE
. 129(12) (2003):1686
-
1697.


Mitra, N. and L.N. Lowes. “Evaluation, Calibration and Verification of a Reinforced Concrete Beam
-
Column Joint Model.”
Journal of Structural Engineering
,
ASCE
. Submitted July 2005.


Anderson, M.R. (2003). “Analytical Modeling of Existing Reinforced Concrete Beam
-
Column Joints”
MSCE thesis, University of Washington, Seattle, 308 p.

Analyses using joint model:


Theiss, A.G. “Modeling the Response of Older Reinforced Concrete Building Joints.”
M.S. Thesis
.
Seattle: University of Washington (2005): 209 p.

Experimental Research


Walker, S.*, Yeargin, C.*, Lehman, D.E., and Stanton, J. Seismic Performance of Non
-
Ductile
Reinforced Concrete Beam
-
Column Joints,
Structural Journal, American Concrete Institute
, accepted
for publication.



Walker, S.G. (2001). “Seismic Performance of Existing Reinforced Concrete Beam
-
Column Joints”.
MSCE Thesis, University of Washington, Seattle. 308 p.


Alire, D.A. (2002). "Seismic Evaluation of Existing Unconfined Reinforced Concrete Beam
-
Column
Joints", MSCE thesis, University of Washington, Seattle, 250 p.


Infrastructure Review


Mosier, G. (2000). “Seismic Assessment of Reinforced Concrete Beam
-
Column Joints”. MSCE thesis,
University of Washington, Seattle. 218 p.