Joint Research of Seismic Retrofitting Technology for Existing Foundations Masahiro Ishida Public Works Research Institute JAPAN “Design and Execution Manual for Seismic Retrofitting of Existing Pile Foundations“

2 M8.0 Fri. 9/26/2003 4:50(JST) Thu. 9/25/ :50(PST) 2: Missing Over 300:Injured Ｈｏｋｋａ ｉｄｏ Tokachioki EQ 2003

3 Damaged Freeway Bridge

4 Nishinomiya Br. (Kobe EQ, 1995)

5 Damaged Piles by Kobe EQ.

6 Joint Research of Seismic Retrofitting Technology for Existing Foundations Public Works Research Institute Advanced Construction Technology Center Twelve Private Companies Three years from 1999

7 Outline of the Micropile Methods High Capacity Micropile ST MicropileMulti-Helix Micropile

8 Major Experiments in this project High Capacity Micropile ST Micropile Multi-Helix Micropile Common Tests Static Lateral Load Testing of Model Foundations with different kind of piles with different kind of piles Dynamic Lateral Load Testing of Model Foundations with different kind of piles Loading Tests in a Centrifuge Bending Tests Vertical Loading Tests Lateral Loading Tests Tests for Workability (Vertical and incline piles) Tests for the connection of Steel Piles Pull Tests for the connection of Pile Head Vertical Loading Tests Lateral Loading Tests Tests for Workability Tests for the connection of Steel Piles Skin Friction Tests Vertical Loading Tests Tests for Workability Tests for the connection of Steel Piles

9 Vertical Loading Tests

10 Vertical Loading Tests

11Results Vertical loading test Ground condition Maximum friction (N/mm 2 ) Measured value Design value* Push-in loading Hard clay layer c=0.87 N/mm Fine sand layer N-value = Pull-out loading ※ Fine sand layer Average N-value = * Ground Anchor Design and Execution Standards (JGS)

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

13 Static Horizontal Loading Tests Case Number of Piles SpacingInclination Loading Method 1 1 EP -- One Dir. 2 1 MP 1 MP-- One Dir. 3 4 EP -- One Dir. 4 4 EP 6 MP 200 mm 0 One Dir. 5 4 EP 6 MP 400 mm 0Cyclic 6 4 EP 6 MP 200 mm 10 One Dir. 7 4 EP 6 MP 200 mm 20 One Dir. 1/5 scale

14 Static Horizontal Loading Tests

15 (1) Design Model –Rigid flame structure (2) Resistance properties in axis direction –Elasto-plastic model with limit of bearing capasity Retrofitting Effects Model

16 (3) Resistance properties at right angles –Elasto-plastic model with limit of P HU –P HU is corrected by the ratio of the pile spacing and pile diameter –P HU is corrected by the ratio shown in the table Front PileOthersFront PileOthers Sand Layer MicropileExsiting Pile

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

18 Summary These results are reflected in “Design and Execution Manual for Seismic Retrofitting of Existing Pile Foundations with High Capacity Micropiles” We will distribute the English version of the manual by CD-ROM after this session Next speakers introduce further information of this manual