Joint Research of Joint Research of Seismic Retrofitting Technology forSeismic Retrofitting Technology for

Existing Foundations Existing Foundations

Masahiro IshidaMasahiro Ishida

Public Works Research InstitutePublic Works Research Institute

JAPANJAPAN

“Design and Execution Manual for Seismic Retrofitting of Existing Pile Foundations“

22

M8.0Fri. 9/26/2003 4:50(JST)Thu. 9/25/2003 11:50(PST)

2: Missing

Over 300:Injured

ＨｏｋｋａＨｏｋｋａｉｄｏｉｄｏTokachioki EQ 2003Tokachioki EQ 2003

33

Damaged Freeway Bridge

44

Nishinomiya Br.Nishinomiya Br. 　　(Kobe EQ, 1995)(Kobe EQ, 1995)

55

Damaged Piles by Kobe EQ.Damaged Piles by Kobe EQ.

66

Joint Research of Joint Research of Seismic Retrofitting Technology forSeismic Retrofitting Technology for

Existing Foundations Existing Foundations

Public Works Research Institute

Advanced Construction Technology Center

Twelve Private Companies

Three years from 1999

77

Outline of the Micropile MethodsOutline of the Micropile Methods

Bearinglayer

Anchoringby grout

Deformed bar

Steel pipe

Pile head

Bearinglayer

Anchoringby grout

Deformed bar

Steel pipe

Pile head

Partitionedsteel pipe

Soil-cementcolumn

Partitionedsteel pipe

Soil-cementcolumn

Wings

Rotary penetration

Steel pile

Wings

Rotary penetration

Steel pile

High Capacity Micropile

ST Micropile Multi-Helix Micropile

88

Major Experiments in this projectMajor Experiments in this project

　　High Capacity High Capacity

MicropileMicropileST MicropileST Micropile

Multi-Helix Multi-Helix MicropileMicropile

CommoCommon Testsn Tests

Static Lateral Load Testing of Model Static Lateral Load Testing of Model FoundationsFoundations

with different kind of pileswith different kind of piles

Dynamic Lateral Load Testing of ModelDynamic Lateral Load Testing of Model 　　Foundations with different kind of pilesFoundations with different kind of piles

Loading Tests in a CentrifugeLoading Tests in a Centrifuge

Bending TestsBending TestsVertical Loading TestsVertical Loading TestsLateral Loading TestsLateral Loading TestsTests for Workability Tests for Workability (Vertical and incline (Vertical and incline

piles)piles)Tests for the Tests for the

connection of Steel connection of Steel PilesPiles

Pull Tests for the Pull Tests for the connection of Pile connection of Pile

HeadHead

  Vertical Loading TestsVertical Loading TestsLateral Loading TestsLateral Loading TestsTests for WorkabilityTests for Workability

Tests for the Tests for the connection of Steel connection of Steel

PilesPilesSkin Friction TestsSkin Friction Tests

  Vertical Loading Vertical Loading

TestsTests  

Tests for Tests for WorkabilityWorkability

Tests for the Tests for the connection of Steel connection of Steel

PilesPiles

99

Vertical Loading TestsVertical Loading Tests

- 16

- 15

- 14

- 13

- 12

- 11

- 10

- 9

- 8

- 7

- 6

- 5

- 4

- 3

- 2

- 1

00 10 20 30 40 50

Dep

th

(m)

0m

- 2.9m

- 4.0m

- 6.2m

- 10.5m

N Value

- 7.7m

- 8.9mSilt(M)

Soilfilling(FI)

Loam

Finesand(FS)

Clay(CL)

Finesand

Finesand

(FS)

850

300

1200

7150

1000

1500

1500

1500

500

2500

2500

9650

1465

0

Strain Gauges： Inside steel pipe 3 points： On steel bar 6 points：

Displacement seismograph : 1 point Displacement seismograph in hole : 1 point

Anchoring by grout

①

②

③

④

⑤

⑥

⑦

⑧

Steel pipe (diameter : 177.8mm)

Deformed steel bar (D51)

Anchorage zone

Effective anchoringdiameter =200mm

Anc

horing

leng

th=5

.0mSte

el p

ipes

sec

tion

Non

-ste

el p

ipes

sec

tion

Ground during loading test

1010

Vertical Loading TestsVertical Loading Tests

- 1200

- 1000

- 800

- 600

- 400

- 200

0

200

400

600

800

1000

- 150 - 120 - 90 - 60 - 30 0 30

Displacement of pile head （ｍｍ）

Load

（ｋＮ

）

Pus

h -i

n Lo

adin

gP

ull-

out

Load

ing

1111

ResultsResults

Vertical Vertical loading testloading test

Ground Ground conditioncondition

Maximum friction (N/mmMaximum friction (N/mm22))

Measured valueMeasured value Design value*Design value*

Push-in loadingPush-in loading

Hard clay layerHard clay layercc=0.87 N/mm=0.87 N/mm22 1.001.00 0.870.87

Fine sand layerFine sand layerNN-value =20-value =20

0.250.25 0.210.21

Pull-out Pull-out loadingloading※※

Fine sand layerFine sand layerAverageAverage

NN-value =40-value =400.320.32 0.320.32

* Ground Anchor Design and Execution Standards (JGS)

1212

Static Horizontal Loading Tests of Model Static Horizontal Loading Tests of Model Foundations with Piles of Different Foundations with Piles of Different

DiametersDiameters

1313

Static Horizontal Loading TestsStatic Horizontal Loading Tests

CaseCase Number of PilesNumber of Piles SpacingSpacing InclinationInclination Loading Loading MethodMethod

11 1 EP1 EP -- -- One Dir.One Dir.

22 1 MP1 MP -- -- One Dir.One Dir.

33 4 EP4 EP -- -- One Dir.One Dir.

44 4 EP 6 MP4 EP 6 MP 200 mm200 mm 00 One Dir.One Dir.

55 4 EP 6 MP4 EP 6 MP 400 mm400 mm 00 CyclicCyclic

66 4 EP 6 MP4 EP 6 MP 200 mm200 mm 1010 One Dir.One Dir.

77 4 EP 6 MP4 EP 6 MP 200 mm200 mm 2020 One Dir.One Dir.

1/5 scale

1414

Static Horizontal Loading TestsStatic Horizontal Loading Tests

0

30

60

90

120

150

180

210

0 20 40 60 80 100

Displacement of footing mm（ ）

Load

kN（）

Case1Case2Case3Case4Case5Case6Case7

1515

(1) Design Model(1) Design Model– Rigid flame structureRigid flame structure

(2) Resistance properties in axis direction(2) Resistance properties in axis direction– Elasto-plastic model with limit of bearing capaElasto-plastic model with limit of bearing capa

sitysity

Retrofitting Effects ModelRetrofitting Effects Model

1616

(3) Resistance properties at right angles(3) Resistance properties at right angles– Elasto-plastic model with limit of PElasto-plastic model with limit of PHUHU

– PPHU HU is corrected by the ratio of the pile spacinis corrected by the ratio of the pile spacin

g and pile diameterg and pile diameter

– PPHUHU is corrected by the ratio shown in the table is corrected by the ratio shown in the table

Front Pile Others Front Pile Others

Sand Layer 1.00 0.50 1.00 0.50

Micropile Exsiting Pile

1717

(4) Bending moment – curvature relationship (4) Bending moment – curvature relationship of micropilesof micropiles– elasto-plastic modelelasto-plastic model

1818

SummarySummary

These results are reflected in These results are reflected in “Design and “Design and Execution Manual for Seismic Retrofitting Execution Manual for Seismic Retrofitting of Existing Pile Foundations with High Capof Existing Pile Foundations with High Capacity Micropiles”acity Micropiles”

We will distribute the English version of thWe will distribute the English version of the manual by CD-ROM after this session e manual by CD-ROM after this session

Next speakers introduce further informatioNext speakers introduce further information of this manualn of this manual