New foundations in Japan and recent pile researches

in Kyoto University

Kyoto University Makoto Kimurakimura.makoto.8r@kyoto-u.ac.jp

Contents

・ Japanese design ideas of roadbridge foundations

・ New pile foundation in Japan

・ Investigation of mechanical behavior of pile group

(・ A seismic reinforcement methodfor an existing pile )

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 foundati

on 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 boxAdvancement of numerical methodCombined calculation for upper structure and foundation

e

HV

M

MH

R MＨ

R MＨ

R

HV

M

MＨ

R MＨ

R MＨ

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 foundationwith 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

Axi

al fo

rce 　

(MN

)

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

pres

sion

(+

)Te

nsio

n (-

)

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

33.3

8.0

0.9

Elastic beam 5.0

G.L.-39.4

25

Caisson

C.G. of superstructure

18.8

Rubber bearing

14.5

8.0

2.25

9.4C.G. of jacket structure

C.G. of tank

Pier

A A0.4

20° 20°

Inclined pile Vertical pile

Superstructure

Substructure

Elastic solid elementAc

AscAsDS1

Ds2

Caisson foundation

RESPONSE FOR ACCELERATION AND DISPLACEMENT

-8.0

-4.0

0.0

4.0

8.0

0 2 4 6 8 10 12Time (sec)

Acc

eler

atio

n (m

/s2 ) Pile foundationCaisson foundation

-2.0

-1.0

0.0

1.0

2.0

0 2 4 6 8 10 12Time (sec)

Disp

lace

men

t (m

) Pile foundationCaisson foundation

-8.0

-4.0

0.0

4.0

8.0

0 2 4 6 8 10 12Time (sec)

Acc

eler

atio

n (m

/s2 )

Acceleration Displacement

-0.2

-0.1

0.0

0.1

0.2

0 2 4 6 8 10 12Time (sec)

Disp

lace

men

t (m

)

Upper structure

Foundation

Upper structure

Foundation

My new pile foundations

10

NEW STRUCTUREHanshin Expressway

Cost analysis

Pile group Integrated column by multiple steel pipes

1.00 1.18 0.82 1.00 0.65

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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

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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

16

NO Anchor frame

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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

Footing3 x 3piles

2 x 2piles

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Purpose of StudyShaking 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

Shear panels

Underground beamFooting type Footing-less

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Outline of Shaking table testFooting type (conventional) Footing-less type (way-out)

Natural periodIn air: 0.236(sec)In sand: 0.361(sec)

Natural periodIn air: 0.578(sec)In sand: 0.544(sec)

long-period structure

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Outline of Shaking table testDry sand (Case-1-S) Liquefiable sand (Case-2-S)

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Outline of Shaking table testTest cases

Footing type Footing-less typeDry sand Case-1F (D-F) Case-1S (D-S)Liquefiable sand Case-2F (L-F) Case-2S (L-S)

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Outline of Shaking table test

Footing type Footing-less type

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目標値 計測値

Step 1 1.92 m/sec2 2.0 m/sec2

ステップ最大入力加速度

Case-2 (Liquefiable sand)Case-1 (Dry sand)

Case-2

-6-4-20246

0 5 10 15 20Acc

eler

atio

n [m

/sec

2 ]

Time [sec]-6-4-20246

0 5 10 15 20Acc

eler

atio

n [m

/sec2 ]

Time [sec]

Case-1 Step8

Outline of Shaking table test

目標値 計測値

Step 1 0.5 m/sec2 0.62 m/sec2

Step 2 1.0 m/sec2 0.94 m/sec2

Step 3 1.5 m/sec2 1.45 m/sec2

Step 4 2.0 m/sec2 2.01 m/sec2

Step 5 2.5 m/sec2 2.47 m/sec2

Step 6 3.0 m/sec2 3.07 m/sec2

Step 7 3.5 m/sec2 3.63 m/sec2

Step 8 5.0 m/sec2 5.25 m/sec2

加振ステップ最大入力加速度

Loading step Loading stepInput accelerationInput acceleration

Obs.Target Obs. Target

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(1) Dry sand

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-6

-4

-2

0

2

4

6

-60 -40 -20 0 20 40 60

Res

pons

e ac

cele

ratio

n at

pie

r top

[m/s

ec2 ]

Lateral displacement at pier top [mm]

27

Results of Shaking table test Dry sandResponse 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

. @ p

ier

top

(gal

)

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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Results of Shaking table testStrain on the structure at Step 2

-3000 -2000 -1000 0 1000 2000 3000-2

-1.5

-1

-0.5

0

0.5

1

1.5

Hei

ght [

m]

-2

-1.5

-1

-0.5

0

0.5

1

1.5

-3000 -2000 -1000 0 1000 2000 3000

Hei

ght [

m]

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-3000 -2000 -1000 0 1000 2000 3000-2

-1.5

-1

-0.5

0

0.5

1

1.5

Hei

ght [

m]

-2

-1.5

-1

-0.5

0

0.5

1

1.5

-3000 -2000 -1000 0 1000 2000 3000

Hei

ght [

m]

Results of Shaking table testStrain on the structure at Step 3

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Results of Shaking table testDamage process of the member

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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

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(2) Liquefiable sand

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Results of Shaking table testExcess pore water pressure

0.00.20.40.60.81.01.2

0 5 10 15 20 25

PS-0.2PS-1.0

Time (sec)EP

WP

ratio

0.00.20.40.60.81.01.2

0 5 10 15 20 25

PF-0.2PF-1.0

Time (sec)

EPW

P ra

tio

Case-2F (Ｌ-F) Case-2S (Ｌ-S)

The excess pore water pressure ratio of PF-0.2 & PS-0.2 sharply increasesafter the shaking and reaches 1 at around 5 seconds. This indicates that theground is fully liquefied.

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-60-40-20

0204060

0 5 10 15 20 25

L-FL-S

Late

ral d

ispl

acem

ent (

mm

)

Time (sec)

-60-40-20

0204060

0 5 10 15 20 25

L-FL-S

Late

ral d

ispl

acem

ent (

mm

)

Time (sec)

-8-6-4-202468

0 5 10 15 20 25

L-FL-S

Resp

onse

acc

eler

atio

n (m

/s2 )

Time (sec)Pier top Pile head

Pier top

Ｌ-F Ｌ-S

Meanwhile, the same inversion phenomenon is confirmed even in the pile head,almost the same amount of displacement is finally obtained.

This is worthy of special mention because L-F has twice the pile number of L-Sand a footing with a large resistance area and mass.

Results of Shaking table testTime history of lateral displacement @ pier top and pile head

Results of Shaking table testStrain of the structure

36

Case-2F (Ｌ-F) Case-2S (Ｌ-S)

The maximum strain in the whole structure generates at the column base for L-Fand on the pile for L-S.

The max. strain in column base for L-F has been over yield strain (2000 µ). The max. strain in the pile for L-S has not exceeded the yield strain.

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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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Numerical simulationFE mesh

5.1 Objectives of lateral loading test

1. To investigate bearing capacity and failure level of practical LNG tank foundation

⇒ No one check the practical LNG tank foundation after long time service

2. To investigate mechanical behavior ofthe largest scale group pile foundation

⇒ Pile group efficiency e = f( pile spacing L / d, number of pile, etc.)

The largest in-situ ultimate lateral loading test in Japan 3×3

L

~ In-situ lateral loading test of 63 group pile foundation ~

41/23

5.2 LNG receiving terminal and LNG tank

5.3 Experimental condition

496 of steel pipe pile

demolished after40 years service

LNG tank

48 m Reaction piles

7×9 group pile

5000 kN jack

Slab

6000

Steel pipe pileφ 406.4Thickness 12.7

800

Protective concrete

Unit (mm)

800

⇒Prediction FEM analysisto decide max. load

5.3 Experimental conditions

43/19

5.4 Prediction analysis condition

44/19

Prediction analysis by 3 dimensional elasto-plastic FEM

Analysis area

Pile : Hybrid model (Bilinear) Ground : Subloading tij model

5.4 Prediction analysis model

45/23

5.5 Results ~Load-displacement~

46/19

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

5.5 Results ~deformation of group pile~

5.5 Results ~Load share of each pile~

49/19

The Composite-Pile Method (Patent No.5077857 )

Should not be fundamentally reinforced even if seismic piles in soft ground and liquefied ground .Development of new technologies improve the unsuitable soil .Cost reduction, Workability is good. Pile format does not change

Liquefaction phenomena is nationwide challengesAn urgent measures are necessary.

Collapse of the buildingdue to liquefaction

The 2011 off the Pacific coast of Tohoku EQ

Liquefaction phenomena: 9700 places in Tohoku andCapital Area

Needs of seismic reinforcement for existing foundations

Design criteria revision, liquefaction phenomenon

Assuming a large-scale earthquake, improvement of design seismic force and anti-seismic strength for new bridges is required

Niigata EQ of 1964

例 )RC巻立て

P

δO

基礎の荷重変位関係

×

×

PyP

PyF

×

補強後の橋脚躯体の荷重変位関係

FPy ：橋脚基礎の降伏耐力PPy ：橋脚躯体の降伏耐力

Even if the super- and sub-structure were reinforced, thereis a possibility that the entire bridge would collapse in casethe whole seismic energy affects on the existing foundation.

Needs of seismic reinforcement for existing foundationsAn increase in the seismic load to the foundation due to seismic reinforcement for the superstructure of bridges

Bridge pier reinforcement works and collapse-prevention devices are designed on thepremise that the pile foundation satisfies a certain horizontal load bearing capacity.

Concrete jacketing method

Seismic reinforced bridge pier

Original foundation

Lateral load

Lateral disp.

FPy: Yield resistance of foundationPPy: Yield resistance of bridge pier

Proposition:How to deal with the existing pile foundation of bridges?

As-needed repairs and seismic reinforcement

1. Frequent occurrence of large-scale earthquake (twice in a quarter of acentury)

*The Southern Hyogo prefecture EQ in 1995*The 2011 off the Pacific coast of Tohoku EQ*Occurrence of Nankai Trough EQ is assumed

2. Aging bridges that have been cross-linked during the high-growth periodin Japan >> It is important to prolong their life. The total number is700,000 bridges.

3. Basic Act for National Resilience Contributing to Preventing andMitigating Disasters for Developing Resilience in the Lives of the Citizenry.Disaster Prevention and Mitigation is a national policy.

A seismic reinforcement method for an existing pile foundation in soft ground and liquefiable ground

Procedure for evaluating the seismic safety of existing bridge foundations

The Composite-Pile Method (Patent No.5077857 )

Should not be fundamentally reinforced even if seismic piles in soft ground and liquefied ground .Development of new technologies improve the unsuitable soil .Cost reduction, Workability is good. Pile format does not change

56/16

57/16

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 foundations

Plastic deformation caused by the earthquake disaster

The Southern Hyogo prefecture EQ in 1995The 2011 off the Pacific coast of Tohoku EQ

Cracks generated in piles

No.

of b

ridge

pie

r

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