New foundations in Japan and recent pile researches in ...
Transcript of New foundations in Japan and recent pile researches in ...
New foundations in Japan and
recent pile researches
in Kyoto University
Kyoto University Makoto Kimura
Contents
・ Japanese design ideas of road
bridge foundations
・ New pile foundation in Japan
・ Investigation of mechanical
behavior of pile group
Seismic design for pier and foundation
橋脚
フーチング
杭
軟弱地盤
硬い地盤
路線直角方向から見た図 路線方向から見た図
No foundation
failure
(杭)基礎
earthquake force for design
Horizontal bearing capacity on pier
Horizontal bearing capacity on foundation
<
Earthquake force for design<Basic idea
for seismic designearthquake force for design
橋脚の水平耐力
基礎の水平耐力
設計想定地震力
Needs of seismic reinforcement for existing foundations
Stiffness of pier
Reinforcement for existing foundations
Horizontal bearing capacity on foundation
<
Earthquake force for design< Increase
After Kobe earthquake
Reinforcement of pier
Reinforcement of foundation
Pandora’s box
Advancement of numerical methodCombined calculation for upper structure and foundation
0
10
20
30
40
50
0 1 2 3 4 5 6 7 8
ボアホールカメラ調査による杭損傷の累積点数
橋脚基数
Damage to the pile in
the soft ground and
liquefied ground
Needs of seismic reinforcement
for existing foundationsPlastic deformation caused by the earthquake disaster
The Southern Hyogo prefecture EQ in 1995
The 2011 off the Pacific coast of Tohoku EQ
Cracks generated in piles
No
. o
f b
rid
ge p
ier
Cumulative No. of pile damage found
by the bore-hole camera investigation
Based on the reports of restoration for foundation
structures of Kobe line #3 by Hanshin Expressway
e
HV
M
M
H
RM
H
RM
H
R
HV
M
M
H
RM
H
RM
H
R
?
Why do we design a footing?
Pile
? ?
Footing
JACKET FOUNDATION WITH INCLINED PILES
Jacket structure
Pier
Steel pile
Stuff substratum
Soft soil layer
Offshore pile foundations for roads
Not so heavy
Jacket steel pile
foundation
with inclined piles
Jacket leg
Steel pile
Ballast tank
AXIAL LOAD DISTRIBUTION(STATIC)
-6
-4
-2
0
2
4
6
No.1 No.2 No.3 No.4
Ax
ial
forc
e (M
N)
TypeA : Analysis (at 6.61s)
TypeA : Test (at 6.30s)
TypeB : Analysis (at 6.59s)
TypeB : Test (at 6.17s)
Inertial force
1 2 3 4
Inertial force
1 2 3 4
Type A
Type B
Inertial force of a superstructure
Com
pre
ssio
n
(+)
Ten
sion
(-)
PILE FOUNDATION AND CAISSON FOUNDATION
(Unit:m)
<Remarks> C.G.:Center of gravity
Pile foundation
Elastic beam Plastic beam
C.G. of superstructure
Rubber bearing
Pier
Superstructure
33
.38
.0
0.9
Elastic beam
5.0
G.L.-39.4
25
Caisson
C.G. of superstructure
18
.8
Rubber bearing
14
.58
.0
2.2
59
.4C.G. of jacket structure
C.G. of tank
Pier
A A0.4
20° 20°
Inclined pile Vertical pile
Superstructure
Substructure
Elastic solid elementAc
Asc
AsDS1
Ds2
Caisson foundation
RESPONSE FOR ACCELERATION AND DISPLACEMENT
-8.0
-4.0
0.0
4.0
8.0
0 2 4 6 8 10 12
Time (sec)
Acc
eler
atio
n (
m/s
2) Pile foundation
Caisson foundation
-2.0
-1.0
0.0
1.0
2.0
0 2 4 6 8 10 12
Time (sec)
Dis
pla
cem
ent
(m) Pile foundation
Caisson foundation
-8.0
-4.0
0.0
4.0
8.0
0 2 4 6 8 10 12
Time (sec)
Acc
eler
atio
n (
m/s
2)
Acceleration Displacement
-0.2
-0.1
0.0
0.1
0.2
0 2 4 6 8 10 12
Time (sec)
Dis
pla
cem
ent
(m)
Upper structure
Foundation
Upper structure
Foundation
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Shaking table test and numerical simulation on seismic performance of a bridge column integrated by multiple steel pipes with directly-connected piles
Koichi Isobe (Hokkaido University) H. Sugiyama, M. Shinohara, H. Kobayashi (Hanshin Expressway)
Y. Sawamura, Y. Mitsuyoshi, M. Kimura (Kyoto University)
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Development of “Integrated column by multiple steel pipes” (2004)
⚫ A bridge column integrated by 4 steel pipes and multiple shear panels interconnecting the pipes has been proposed.
⚫ It is designed based on damage control concept, in which the vertical load is supported by the steel pipes and the lateral load is adjunctively supported by shear links.
⚫ Shear panels are made of low yield stress steel and have hysteretic energy dissipation properties.
⚫ It intends to lead seismic damage into shear panels and enables early recovery by replacing only panels.
Introduction
12
Steel pipe
Shear panel
made of
low yield
steel
Shear link
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Development of “Integrated column by multiple steel pipes” (2004)
⚫ Budget-pleasing prefabricated material (ready-made spiral steel pipes) are used.
⚫ Anchor frame is NOT necessary unlike a conventional steel pier structure.
⚫ Reduce 30% of construction cost
⚫ Reduce construction time
⚫ Rapid transportation open
Introduction
13
NO Anchor frame
Cost analysis
Pile group Integrated column by multiple steel pipes
1.00 1.18 0.82 1.00 0.65
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IntroductionProposal of “Steel pipe pile foundation” for integrated column
⚫ Each pipe of the column is supported by a directly connected steel pile without a footing
⚫ Maybe rational & reasonable foundation structure for “A bridge column integrated column by multiple steel pipes”
⚫ Not impair the ability of the integrated column structure
⚫ Reduce inertia force and sectional force at the connected area between piles and column
⚫ Reduce the cost of footing and the number of piles
⚫ Can employ the pile foundation in narrow construction conditions
ConventionalGP foundationwith Footing
Way-outDirectly connected
without Footing
Energydissipation
Footing
3 x 3piles
2 x 2piles
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Purpose of Study
Shaking table test and Numerical simulation
⚫ To compare the both seismic performance (footing type vs footing-less type) ➢ Axial force acting at pile heads➢ Lateral displacement at a pier top and pile heads➢ Cross sectional force acting in a bridge column and
piles⚫ To confirm the yield order of the member for the
proposed structure⚫ To check the behavior of the proposed structure in
liquefiable sand⚫ To identify the structural issues of the proposed type⚫ To cross-check analytical model by simulating the model
tests
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Outline of Shaking table testShaking table and Large-scale rigid box with tempered glass
⚫ Public Works Research Institute in Tsukuba⚫ Large-scale 3-dimensional shaking table⚫ Table size: 8m x 8m⚫ Box size: 4m (W) x 1m (L) x 2m (H)⚫ See the ground through the tempered glass
4m 2m
1m
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Outline of Shaking table testDetail of the model used in the tests
welded
659.5
474
338
338
338
89.5
1577
.5
34
1765
.5
32
Dp 8
9.1
560
2.5Dp
2.5Dp
3409
Dc
76.3
680
474
338
338
376.5
1579
34
1764
32
Dp 8
9.1
560
2.5Dp
Dc
76.3
680
Member MaterialSteel pipe
Shear panel
Underground
beam
STK400LY225
SS400
223.7
5
223.75
94
76.3
Unit : mm
welded
Shear panel
Underground
beam
223.75 223.75
223.7
5223.7
5
659.5
659.5
Footing
147.45
9177
Underground beam
76.3 94
61106.2
61
147.45Shear panel
Strain gauge
Triaxial Strain
gauge
F-type S-type
2.5Dp
Shear panels
Underground beamFooting type Footing-less
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Outline of Shaking table test
Footing type Footing-less type
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-6
-4
-2
0
2
4
6
-60 -40 -20 0 20 40 60
Res
po
nse
acce
lera
tio
n a
t p
ier
top [
m/s
ec2]
Lateral displacement at pier top [mm]
Case-1-F
Case-1-S
Step 8Step 3
Step 3
Step 1
Pier top
20
Results of Shaking table test Dry sand
Response acceleration vs lateral displacement @ pier top
Lateral disp. @ pier top (mm)
Input wave acc.(1) 0.5 m/s2
(2) 1.0 m/s2
(3) 1.5 m/s2
(4) 2.0 m/s2
(5) 2.5 m/s2
(6) 3.0 m/s2
(7) 3.5 m/s2
(8) 5.0 m/s2
Resp
onse
acc
. @
pie
r to
p (g
al)
⚫ The stiffness of Case-1-F (D-F) is bigger than that of Case-1-S (D-S).
⚫ Case-1-F yields at earlier stage than Case-1-S.⚫ Response acceleration and lateral displacement for Case-1-
F increase rapidly and brittle deformation is observed.
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Shaking direction
Shaking direction
Shaking direction
-3000 -2000 -1000 0 1000 2000 3000-2
-1.5
-1
-0.5
0
0.5
1
1.5
Heig
ht
[m]
Strain (×10-6)
G.L.
Yield strain
-2
-1.5
-1
-0.5
0
0.5
1
1.5
-3000 -2000 -1000 0 1000 2000 3000
Heig
ht
[m]
Strain (×10-6)
Shaking direction
Shaking direction
Shaking direction
G.L.
Yield strain
Results of Shaking table testStrain on the structure at Step 3
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Results of Shaking table testDamage process of the member
22
⚫ The proposed substructure (Case-1-S) have advantages of strain reduction of column by strain descentralization at footing point.
⚫ It has high seismic performance and high toughness if the conditions are right in view of the fact that the main member (columns and piles) holds a large residual strength after yielding of the shear panels.
加振No. (最大入力加速度) 上段 中段 下段 柱 杭 上段 中段 下段 柱 杭
第1加振 (0.5 m/sec2)
第2加振 (1.0 m/sec2)
第3加振 (1.5 m/sec2)
第4加振 (2.0 m/sec2)
第5加振 (2.5 m/sec2)
第6加振 (3.0 m/sec2)
第7加振 (3.5 m/sec2)
第8加振 (5.0 m/sec2)
フーチングを有する杭基礎 (Case-1-F) 杭基礎一体型 (Case-1-S)
せん断パネル 鋼管 せん断パネル地中梁
鋼管
塑性
面外変形
弾性 弾性
塑性
塑性の可能性あり
せん断パネル 柱・杭 (鋼管)
(a)
(b)
(c)
(a)
(b)
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Summary for model tests
⚫ Based on the fact that the main members such as the columns and piles yield after the shear panels (secondary member) yield, the proposed structure has a damage control performance by energy absorption due to plastic deformation of the shear panels.
⚫ In particular, S-type has high seismic performance because the main member (columns and piles) holds a large residual strength even after yielding of the shear panels.
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My new pile foundations
24
25/23
5.2 LNG receiving terminal and LNG tank
45,000 m3
48 m2
5 m
反力体直列3本群杭試験体
9×7群杭試験体
単杭試験体
直列2本群杭試験体
500 t ジャッキ
変位計,ひずみ計設置点
傾斜計設置点
25
.5
支持層φ 0.4
G.L.
14.0
Unit : m
14 m
18
m
柱状
図
N値
0 20 40
Colu-mnar sec-tion
N value
Double-walled metal tank
Group pile foundation
(496 of steel pipe pile)
LNG tank
LNG receiving terminal
⇒demolished after 40 years service
⇒can be used for loading test
LNG tank need enough stability even if earthquake
5.3 Experimental condition
反力体3 × 1 group pile specimen Reaction piles
7 × 9 group
pile specimen
14 m
Strain gauge,Displacement transducer
Inclinometer
Loading
direction1
8 m
5,000 kN jack
496 of steel pipe pile
demolished after
40 years service
LNG tank
48 m Reaction
piles
7×9 group pile
5000 kN jack
040008000
1200016000
240002800032000
20000
0 1 2 3 4 5 6
36000
Lo
ad
(kN
)
Time (Hour)
Capacity of jack
GL
Slab
6000
Steel pipe pile
f 406.4
Thickness 12.7
800
Protective
concrete
Unit
(mm)
800
⇒Prediction FEM analysis
to decide max. load
5.3 Experimental conditions
27/19
0
4000
8000
12000
16000
24000
28000
32000
20000
0 1 2 3 4 5 6
36000
Lo
ad
(kN
)
Time (Hour)
Capacity of jack
Unidirectional multiple-cycle
multiple-step loading (6 cycle)
Max. load is decided to 30,000 kN
⇒ How to decide max. load?
It is very difficult
to calculate the load
to see ultimate behavior of
63 of group pile foundation
3D elasto-plastic FEM analysis
= Simulating group pile effect
elast-plastic approximate solution
⇒ Conducted prediction analysis
to decide max. load
5.4 Prediction analysis condition
28/19
Prediction analysis by 3 dimensional elasto-plastic FEM1
8 m
14 m
Loading
direction
Reaction
piles
5,000 kN jack
7 × 9
group pile
Analysis area
25
m
7 × 9
group pile
14 m
9 m
32
m
54 m
Elevation View
C L
Ground
improvement
Circumference
of tank
foundation
Top View
Pile : Hybrid model (Bilinear) Ground : Subloading tij model
Beam (Bilinear)
Solid element1/10 EI of real pile
Practical pile
(steel pile pile)
Beam element
(Biliear model)
1/10 stiffness of
solid element
is arranged around
beam element Hybrid element
40cm
40cm40
cm
90
cm
80
cm
40 cmPrediction analysis Analysis of after test
Hy
bri
d e
lem
ent
Hy
bri
d e
lem
ent
Bea
m
Slab (elastic) Slab (elastic)
Ground
surface
Ground
surface
5.4 Prediction analysis model
29/23
CL
The front of
anchor piles
14 m2 m = 5d (d : pile diameter)
2 m
9 × 7 group pileRemaining pile aroundX
Y
Loading direction
Pile group effect depend on L/d
Only beam element model overestimate pile spacing L
and pile group effect is misesteemed
5.5 Results ~Load-displacement~
30/19
0
4000
8000
12000
16000
20000
24000
28000
32000
36000
40000
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280
Literal displacement at loading point(mm)
Pre
diction
analys
is
Ap
plie
d lo
ad(
kN)
0
4000
8000
12000
16000
20000
24000
28000
32000
36000
40000
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280
Literal displacement at loading point(mm)
Pre
diction
analys
is
Test
Ap
plie
d lo
ad(
kN)
0
4000
8000
12000
16000
20000
24000
28000
32000
36000
40000
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280
Literal displacement at loading point(mm)
Pre
diction
analys
is
Analysis after th
e test
Test
Ap
plie
d lo
ad(
kN)
Even high load, remain stiffness ⇒not reasonable
Actually, ultimate load was lower (25400 kN)
Maximum load
Simulate accurately at initial phase but not after yield
Practical pile
(steel pile pile)
Beam element
(Biliear model)
1/10 stiffness of
solid element
is arranged around
beam element Hybrid element
40cm
40cm40
cm
90 c
m80 c
m
40 cmPrediction analysis Analysis of after test
Hybri
d e
lem
ent
Hybri
d e
lem
ent
Bea
m
Slab (elastic) Slab (elastic)
Ground
surface
Ground
surface
Practical pile
(steel pile pile)
Beam element
(Biliear model)
1/10 stiffness of
solid element
is arranged around
beam element Hybrid element
40cm
40cm40
cm
90 c
m80 c
m
40 cmPrediction analysis Analysis of after test
Hybri
d e
lem
ent
Hybri
d e
lem
ent
Bea
m
Slab (elastic) Slab (elastic)
Ground
surface
Ground
surface
Solid element of pile head share
high load at large deformation
Plastic
behavior
simulated
Yield load in design
(Chang’s formula)
Ultimate load
⇒ductile deformation over yield load in design
5.5 Results ~deformation of group pile~
The front pile
Loading direction
The second pile
Loading direction
The front pile
2.2° 1.8° 1.7° 1.6°
Front Back
-1.4 m
-2.4 m
-2.9 m-3.4 m -3.6 m -3.8 m -3.9 m
Position of the maximum bending moment from FEM result
3.0°4.1° 3.0°1.5°1.5°1.5°
25,400 kN applied
Loading direction
0.25° 0.26°0.27°0.30° 0.24°0.25°
-2.1 m-2.5 m
-2.8 m-3.2 m-3.2 m-3.1 m-3.0 m
Front Back
Incline
FEM
Test0.24°
0.19°0.22° 0.16°
8,000 kN applied
Loading direction
Position of the maximum bending moment from FEM result
5.5 Results ~Load share of each pile~
32/19
Lo
ad
sh
are
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
① ② ③ ④ ⑤ ⑥ ⑦
Front Back
FEM
Test
16,000 kN
FEM
Test
12,000 kN
FEM
Test
8,000 kN
FEM
Test
4,000 kN
Middle or back pile
share small load
According to
increase of load
load share decrease
Large group pile
effect generate
in spite of L/d = 5
⇒ over 0.9 load share
3×1 group pile L/d = 5
Specific to
large scale group pile