PERFORMANCE LIMITS FOR PERFORMANCE LIMITS FOR REINFORCED CONCRETE COLUMNS REINFORCED CONCRETE COLUMNS UNDER UNDER SEVERE DISPLACEMENT CYCLES SEVERE DISPLACEMENT CYCLES

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25 Νοε 2013 (πριν από 3 χρόνια και 11 μήνες)

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PERFORMANCE LIMITS FORPERFORMANCE LIMITS FOR
REINFORCED CONCRETE COLUMNSREINFORCED CONCRETE COLUMNS
UNDER UNDER
SEVERE DISPLACEMENT CYCLES SEVERE DISPLACEMENT CYCLES
MIDDLE EAST TECHNICAL UNIVERSITY
DEPARTMENT OF CIVIL ENG., ANKARA, TURKEY
BBoraoraACUNACUN
Haluk SUCUOĞLUHaluk SUCUOĞLU
OBJECTIVESOBJECTIVES

Investigation of the effect of displacement history
on the
deformation response of concrete columns controlled by flexure.

Comparative evaluation of the limit states
proposed by;
ASCE/SEI 41-Update (2007),
Eurocode 8 (2005),
Turkish Earthquake Code,
TDY
(
2007
)
Turkish Earthquake Code,
TDY
(
2007
)

Assessment of the modeling criteria
in
ASCE/SEI 41-Update
EXPERIMENTAL STUDIESEXPERIMENTAL STUDIES
￿Six “non conforming” column specimens (Type-1)
=> Plain bars,=> Low strength concrete(∼13MPa)
=>
Inadequate detailing
(
poor confinement
)
Experimental Studies -GENERAL
=>
Inadequate detailing
(
poor confinement
)
￿Six “code conforming” column specimens (Type-2)
=> Deformed bars,=> Normal strength concrete(∼25MPa)
=> Ductile detailing(plastic hinging zone)
Experimental Studies–TEST SPECIMENS
Material properties and reinforcement ratios of test specimens

Concrete Longitudinal Reinforcement Transverse Reinforcement
Compressive
Strength
f’
c

Yield
Strength
fy
Ultimate
Strength
fu
Reinforcement
Ratio
ρ
ρρρ
l
Yield
Strength,

fyw

Ultimate
Strength,

fuw

Reinforcement
Ratio
ρ
ρρρ
t
Specimen
Type
(Mpa)

(Mpa)

(Mpa)

(A
/ b
.h)

(Mpa)

(Mpa)

(A
/ b
.s)

(Mpa)

(Mpa)

(Mpa)

(A
s
/ b
w
.h)

(Mpa)

(Mpa)

(A
sw
/ b
w
.s)

Type 1
13 315 448 0.01 368 487 0.0026
Type 2
25 454 604 0.01 469 685 0.0061

Experimental Studies–TEST SPECIMENS
630
825295
8 mm bars14 mm bars
φ8/165
φ8/50
φ
8/70
8 mm bars
φ8/165
φ8/55
14 mm bars
Type -1
Type -2
Dimensions and details of test specimens
Plan view
Elevation

8/70
φ8/70
Transverse Reinforcement
Not to scale
Longitudinal
Reinforcement
φ14
Transverse
Reinforcement
φ
14
All dimensions are in mm
Not to scale
Elevation
Plan view

8/165
φ8/165
φ
8/70
Longitudinal
Reinforcement
Experimental Studies–TEST SPECIMENS
Reinforcing cage of Type-2test specimens
500 mm stroke
300/100 kNs actuator
Reaction Wall
Hinge
Hinge
Steel Loading Beam
8φ24 connection
bolts
Load Cell
Post tensioning bars
Steel Head
Load CellsHydroulic Jacks
Experimental Studies–TEST SETUP

P

F
eff

Δ

L
meas
= L

I-Beams supporting
the lateral loading
system
Strong floor
Counter Weights
Mat Foundation
Fixing bars
Steel Support beam
Hinges
Reaction Wall
Post tensioning bars
Test Setup
Front View
P-Δcorrection
a) Case I

Side View
Experimental Studies–INSTRUMENTATION
2 LVDT's @ 2800mm level
Load Cell
Load Cell
Longitudinal
Reinforcement (Corner bars)
Transverse Reinforcement
8φ14
1 LVDT @ 2550mm level
1 LVDT @ 1800mm level
2 LVDT's @
2800mm level
Nominal locations of instruments
Dial gages
LVDT's
Not to scale
4 strain gages at each
level
2 strain gages at
stirrups
1 LVDT @ 1800mm level
1 LVDT @ 1150mm level
Strong Floor
0 Level
4 Dial gages @1150 level
1 LVDT @ 750mm level
4 Dial gages @1150 level
1 Dial Gage @ 350mm level
315 mm
Experimental Studies–INSTRUMENTATION
A ready-to-test specimen instrumented and connected to real time data
acquisition system
Experimental Studies–LOADING PROTOCOLS
Displacement protocols imposed on the test specimens

SPECIMENS
Type 1 Type 2
Cycle
No
1P2 2P3 3P3_N0.4

4P4 5P5 6PV1 1D2 2D3 3D4 4D5 5DV1 6DV2
1 35 50 50 70 105 10 35 50 70 105 10 17.5
2 35 50 50 70 105 10 35 50 70 105 10 17.5
3 35 50 50 70 105 10 35 50 70 105 10 17.5
4 35 50 50 70 105 50 35 50 70 105 50 35
5 35 50 50 70 105 50 35 50 70 105 50 35
6 35 70 70 105 70 50 35 50 105 70 50 35
7 35 70 70 105 70 35 35 50 105 70 35 50
8

70

70

70

105

70

35

70

70

105

70

35

50

Top Displacement Amp.
(mm)
8

70

70

70

105

70

35

70

70

105

70

35

50

9 70 70 70 105 70 35 70 70 70 35 50
10 70 70 70 105 70 70 70 70

70 70 70
11 70 105 70 70 70

70 70
12 70 105

70 70 70

70 70
13 105 105



35 105 105

35 105
14



35 105 105

35 105
15

35 105 105

35 105
16

105

105
17

105

105
18
Top Displacement Amp.

105

105

Experimental Studies–LOADING PROTOCOLS
-150
-100
-50
0
50
100150
0510152025303540
Top Displacement Amplitude (mm) . .
1D2
Imposed top
displacement protocols
(Constant Amp.)
-150
Half Cycle No
-150-100
-50
0
50
100150
0510152025303540
Half Cycle No
Top Displacement Amplitude (mm) . .
5DV1
Imposed top
displacement protocols
(Variable Amp.)
EVALUATION OF TEST RESULTSEVALUATION OF TEST RESULTS
“ Limit States and Modelling Parameters ”
150200
MOMENT -CHORD ROTATION RELATIONS -
Experiments
Chord rot. = Drift ratio=
Top Disp.
Specimen
Height
-200-150-100
-50
0
50
100
-0.08-0.06-0.04-0.0200.020.040.060.08
Chord Rotation (rad)
Base Moment (kN-m) .
2D3
Analy. Mom. Rot.
DEFORMATIONLIMIT STATES -
Codes
ASCE / SEI 41-Update
(2007)
Column Type
Table 6-8 of
ASCE/SEI 41
-
Update
LIMIT STATES
(Rotations
)
•Life Safety

Collapse
•Yield
Effective stiffness
)25.1(25
);01.0max(
);01.0max(
)3.0.(016.0
1
100
35.0
225.0
'
d
c
yw
sx
f
f
v
c
v
el
um
h
L
f
ρ
αρ
ω
ω
γ
θ




















=
c
ybLy
s
s
yy
f
fd
L
h
L
...13.0
5.11.0013.0
3
.
φ
φθ
+








++=
Eurocode 8
(2005)
um
θθ
4
3
=
Column Type
ASCE/SEI 41
-
Update
Condition (i)

Collapse
Prevention
No Classification
•Yield
•Ultimate
•Significant
Damage
cuMNsMN
(
ε) = 0.0035 ; (ε) = 0.0
10
cgGVssmsGV
(ε) = 0.0035 + 0.01 (ρρ) 0.0135 ; (
ε) = 0.040
/

≤≤≤
TDY
(2007)
Column Type
LIMIT STATES
(Strains
)
•Safety Limit

Collapse
•Min. Damage
(
ε) = 0.004 + 0.014 (ρρ) 0.018 ;
(
ε) = 0.060
/

≤≤≤
DEFORMATIONLIMIT STATES -
Codes

Collapse
Limit
No Classification
cgGCssmsGC
(
ε) = 0.004 + 0.014 (ρρ) 0.018 ;
(
ε) = 0.060
/

≤≤≤
DEFORMATION LIMIT STATES:
Type-1
Yield/Minimum damage
DEFORMATION LIMIT STATES:
Type-1
Life safety/Significant damage
DEFORMATION LIMIT STATES:
Type-1
Collapse prevention/Collapse limit
DEFORMATION LIMIT STATES:
Type-2
Yield/Minimum damage
50
100150200
Base Moment (kN-m) .
0.8 My
50
100150200
Base Moment (kN-m) .
0.8 My
Specimen 5DV1
-200-150-100
-50
0
-0.08-0.06-0.04-0.0200.020.040.060.08
Chord Rotation (rad)
Base Moment (kN-m) .
5DV1
Analy. Mom. Rot.
Yield Rot.(EC8)
Yield Rot.(ASCE41)
Min. Dmg.(TDY2007)
-200-150-100
-50
0
-0.08-0.06-0.04-0.0200.020.040.060.08
Chord Rotation (rad)
Base Moment (kN-m) .
3D4
Analy. Mom. Rot.
Yield Rot.(EC8)
Yield Rot.(ASCE41)
Min. Dmg. (TDY2007)
Specimen 3D4
50
100150200
Base Moment (kN-m) .
0.8 My
50
100150200
Base Moment (kN-m) .
0.8 My
DEFORMATION LIMIT STATES:
Type-2
Life safety/Significant damage
Specimen 5DV1
-200-150-100
-50
0
-0.08-0.06-0.04-0.0200.020.040.060.08
Chord Rotation (rad)
Base Moment (kN-m) .
5DV1
Analy. Mom. Rot.
Sig. Dmg.(EC8)
Rot-LS (ASCE41)
Safety L. (TDY2007)
-200-150-100
-50
0
-0.08-0.06-0.04-0.0200.020.040.060.08
Chord Rotation (rad)
Base Moment (kN-m) .
3D4
Analy. Mom. Rot.
Sig. Dmg.(EC8)
Rot-LS (ASCE41)
Safety L.(TDY2007)
Specimen 3D4
50
100150200
Base Moment (kN-m) .
0.8 My
50
100150200
Base Moment (kN-m) .
0.8 My
DEFORMATION LIMIT STATES:
Type-2
Collapse prevention/Collapse limit
Specimen 5DV1
-200-150-100
-50
0
-0.08-0.06-0.04-0.0200.020.040.060.08
Chord Rotation (rad)
Base Moment (kN-m) .
3D4
Analy. Mom. Rot.
Ult. Rot. Capac.(EC8)
Rot-CP (ASCE41)
Collapse L.(TDY2007)
-200-150-100
-50
0
-0.08-0.06-0.04-0.0200.020.040.060.08
Chord Rotation (rad)
Base Moment (kN-m) .
5DV1
Analy. Mom. Rot.
Ult. Rot. Capac.(EC8)
Rot-CP (ASCE41)
Collapse L.(TDY2007)
Specimen 3D4
Analytical Studies –MODELLING PARAMETERS
ASCE/SEI 41-Update
Modelling Parameters

plastic rotation at
significant loss of plastic
rotation capacity
,
a
rotation capacity
,
a

plastic rotation at
axial load failure, b
Generalized Load-Deformation
relationship
Analytical Studies –MODELLING PARAMETERS
ASCE/SEI 41-Update
Modelling Parameters
Type-1 Columns
75
125
Base Moment (kN-m) . .
75
125
Base Moment (kN-m) . .
Specimen 2P3
Specimen 6PV1
-125
-75-25
25
-0.06-0.04-0.0200.020.040.06
Chord Rotation (rad)
Base Moment (kN-m) . .
2P3
ASCE41
0.8*My
-125
-75-25
25
-0.06-0.04-0.0200.020.040.06
Chord Rotation (rad)
Base Moment (kN-m) . .
6PV1
ASCE41
0.8*My
Analytical Studies –MODELLING PARAMETERS
100
150200
Base Moment (kN-m) . .
ASCE/SEI 41-Update
Modelling Parameters
Type-2 Columns
100
150200
Base Moment (kN-m) .
-200-150-100
-50
0
50
100
-0.08-0.06-0.04-0.0200.020.040.060.08
Chord Rotation (rad)
Base Moment (kN-m) . .
5DV1
ASCE41
0.8*My
Specimen 3D4
Specimen 5DV1
-200-150-100
-50
0
50
100
-0.08-0.06-0.04-0.0200.020.040.060.08
Chord Rotation (rad)
Base Moment (kN-m) .
3D4
ASCE41
0.8*My

0.8*Vmax
304050607080
Base Shear (kN) .
1D2
2D3
3D4
Analytical Studies –EFFECT OF LOADING HISTORY
Envelope curves
0.8*Vmax
304050607080
Base Shear (kN) .
Type-1
Type-2
0
1020
00.010.020.030.040.050.06
Drift Ratio
3D4
4D5
5DV1
6DV2
0
1020
00.010.020.030.040.050.06
Drift Ratio
1P2
2P3
4P4
5P6
6PV1
SUMMARY and CONCLUSIONS
•Limit state predictions of TDY 2007 and Eurocode 8 are consistent
with the
experimental performance of
“code conforming”
reinforced concrete
columns
•Limit state predictions of all Codes for the “non-conforming”columns
controlled by flexuretested in this study are conservative
with respect to the
experimental performance of these columns.
experimental performance of
“code conforming”
reinforced concrete
columns
controlled by flexure,meanwhile ASCE/SEI 41 limit state definitions are
conservative for such columns.
•The modeling parameter a
of ASCE/SEI 41 seems to be conservative for
defining the rotation capacity of column plastic hinges under the axial load
ratio of 0.2.
Reference:
ACI Structural Journal,
May
-
June 2010, Vol. 107, No. 3, 364
-
371
ACI Structural Journal,
May
-
June 2010, Vol. 107, No. 3, 364
-
371
THANK YOU FOR YOUR ATTENTIONTHANK YOU FOR YOUR ATTENTION