Musashi Institute of Technology IWM ’03 Seattle Application of High-capacity Micro-piles for Seismic Retrofitting of Existing Water Service Tower in Japan Sep.25th 2003 Yoshinori Otani Hirose & Co., Ltd. Masaru Hoshiya Musashi Institute of Technology

Contents HMP Okazaki Example ( RC Water Service Tower ) Preliminary　Survey Design Construction Evaluation of Earthquake Performance of HMP by Acceleration Seismograph’s Measuring　　　　　　　　　　　　　　　　　　　　　　　　　　　

Location Location of the Site Rokku Water Purification Plant Tokai Plate Boundary Type Earthquake

Water Service Tower Constructed in 1933 70 years old Historic Significance　　　　　　　　 Urban Landscape and Environment Prize Functioning for water supply

Section Planning S

Design Flow Chart Preliminary survey Verification of existing tower Selection of retrofitting method Seismic design (level 1) Level 1:earthquake motion of high occurrence probability Seismic design (level 2) Level 2:earthquake motion with the strong 　　intensity of low occurrence probability type Ⅰ:Plate boundary type large-scale earthquake type Ⅱ:Inland direct strike type earthquake

Preliminary Survey Schmidt Hammer Test for Existing Concrete Material Stress strength 24 kN/m2　　　　　 Degree Investigation of Visual Observation Corrosion of the steel reinforcement bars , Cracking Water leakage, Surface deterioration Diagnosis Conducted to Classify Deterioration

Design（１） Verification of existing tower Selection of retrofitting method Micro pile 　 Construction limit (Root pile) Small boring machine　　　　　 HMP Satisfaction of allowable displacement (Level 2 earthquake motion) High-capacity

Seismic Design Design of pile Verification of pile foundation Response displacement method Verification　of pile foundation Level１：Allowable bearing capacity Allowable stress Level 2： Allowable ductility factor Allowable response displacement Strength Design Coefficient Yield of foundation Yield Coefficient Response displacement

Protection of vegetation Construction(1) Protection of vegetation Excavation of the base Placing of HMP Placing of HMP

Reinforcing bar arrangement of new footing Construction(2) Attachment of steel pile head Reinforcing bar arrangement Reinforcing bar arrangement of new footing Pile Head

Completed work

Disaster Prevention Plan The central disaster prevention conference Basic disaster plan Regional disaster plan Prime Minister Koizumi Tokai Earthquake High probability of occurrence Large scale earthquake

Disaster Strengthening Area Earthquake Motion of Seismic Intensity low 6 Tsunami Disaster Strengthening Area HMP Examples in Disaster Strengthening Area for Tokai Earthquake

Measurement Plan Bisyamon bridge Acceleration　Seismographs

Purpose of Measurement Expected vibration behavior of non-reinforced abutment Seismograph on the ground surface Comparison The actual measured values of reinforced abutment Seismograph on the abutment Seismic performance of HMP

Summary and future plans HMP Method ( for reinforcing of the existing structures) respond ・to revisions in the seismic design standard ・to changes in the demands of society by way of non-detrimental to the landscape In the future, confirm ・the actual seismic performance of HMP by seismograph measurement