needs and challeenges on large today’s topics …€¦ · “very large-scale (or...

1

NEEDS AND CHALLEENGES ON LARGE STRUCTURAL TESTING

FOR THE ADAVANCEMENT OF EARTHQUAKE ENGINEERING

by

Masayoshi Nakashima

Disaster Prevention Research Institute (DPRI)Kyoto University

E-DefenseNational Research Center for

Earth Science and Disaster Prevention (NIED)

Today’s Topics

IntroductionEarthquake disasters in JapanLessons learned from the 1995 Hyogoken-Nanbu (Kobe) and Engineering Needs

Needs for Large-Scale Structural TestingMember behavior versus System behaviorQuasi-static loading versus dynamic loading

Development of E-Defense and Large TestsDevelopment and early testsNew challenges – reproduction of unknown behaviorPerformance of retrofit

Collaboration with Numerical SimulationDevelopment of “numerical shaking table”

What is Masayoshi Nakashima

He is Professor at Disaster Prevention Research Institute (DPRI), Kyoto Univ.He is Director of E-Defense, National Research Institute for Earth Science and Disaster Prevention (NIED).He serves as Editor of Earthquake Engineering and Structural Dynamics (EESD), the official journal of International Association for Earthquake Engineering q g g(IAEE), published by Wiley.He serves as Vice-President of Architectural Institute of Japan (AIJ) (2007 – 2009) and Vice-President of Japan Society for Earthquake Engineering (JAEE) (2009 –present).

1995 Hyogoken-Nanbu Earthquake

Great damage to our buildings and civil infrastructures

2004Niigata-Chuetsu

2003Mi i H k b

Damaging Earthquake After 1995 Kobe

2003Tokachioki

2007Niigata-Chuetsuoki

2005Fukuoka-Seihouoki

2001Geiyo

Miyagi-Hokubu

2000Tottori-Seibu

2007Notohanto

gata C uetsuo

Tokai, Tonankai, and Nankai Earthquakes– Hitting us periodically –

Tokyo

KyotoKobe

Tokai

Tonankai

Nankai

500 km

2

Tokai, Tonankai, and Nankai Earthquakes– Hitting us periodically –

Year Earthquake Tokai Tonankai Nankai1605 Keicho ○ ○1707 Hoei ○ ○ ○0 oe ○ ○ ○1854 Ansei ○ ○ ○1944 Tonankai ○1946 Nankai ○20XX Next ? ? ?

Expected Damage and Loss of Next Tokai, Tonankai, and Nankai Earthquakes

Tokai Tonankai Tokai+TonankaiKobe+ Nankai + Nankai

Collapse 460 629 940 105(x 1,000)Death 9,200 17,800 24,700 6,400Loss ($) 260 380 530 100(x billion) - 370 - 570 - 810

Notable lessons learned from the 1995 Hyogoken-Nanbu earthquake

(1) Cities and towns throughout Japan have large stocks of old buildings and infrastructural systems that are not sufficient in seismic capacity. To prepare for future large earthquakes, it is crucial to accurately evaluate their existing seismic capacities and then to retrofit and rehabilitate accordingly.

Assessment of Existing Seismic Capacity d A di R t fitand According Retrofit

(2) Much larger shaking than that contemplated in the current seismic design is known to be possible. Evaluation of the reserved seismic capacity of existing buildings and infrastructural systems, development of design and construction technologies to enhance the seismic capacity, and implementation of these technologies for real design and construction are critical.

Development and Application of Technologies to Ensure Higher Seismic Capacity

Critical Needs

(1) Characterization of Complete Collapse (the instant of inability to sustain vertical load) and Collapse Margin (distance between damage considered in design and complete collapse)

(2) Verification of Actual Performance of New Technologies developed for enhanced seismic capacity

Resistance

Incipient damage Ultimate

collapse

Damage

Resistance

Incipient damageIncipient damage Ultimate

collapseUltimate collapse

DamageDamage

Critical Needs

Collapse Margin

Enhancement of Safety & Functionality

Loss of Properties(Economic Issue)

DeformationLife Safety(Societal Issue)

Loss of Properties(Economic Issue)

DeformationLife Safety(Societal Issue)

Small Quake Medium/Large Quake Extreme Quake

Critical Needs

(1) Characterization of Complete Collapse (the instant of inability to sustain vertical load) and Collapse Margin (distance between damage considered in design and complete collapse)considered in design and complete collapse)

(2) Verification of Actual Performance of New Technologies developed for enhanced seismic capacity

3

Critical Needs

Devices and Elements

Developed for Passive Damping

Systems

Critical Needs(1) Characterization of Complete Collapse (the

instant of inability to sustain vertical load) and Collapse Margin (distance between damage considered in design and complete collapse)

(2) Verification of Actual Performance of New Technologies developed for enhanced seismic capacitycapacity

Need of Real Experimental Data

Need of Real Experimental DataRealistic Data on Complete Collapse, Complete Failure, Actual Performance Still limited.

Critical NeedsNeed of Real Experimental Data

Equip Sensors in Structures and Wait for a Large Shaking, and Measure.

Test in Laboratory.

Collapse (mild inelasticity vs. complete failure)Size (full-scale vs. miniature)Time (dynamic vs. quasi-static)Redundancy (member vs. system)

Collapse Characterization Performance Verification

Today’s Topics





Is “Full-Scale” Needed?Difficulties in Scaling Down DetailsDifficulties in Duplicating Details

RC Column

Buiding

Weld

Sorry, I cannot scale down.

Steel Connection

Big Specimen Small Specimen

0.8 m4 m

Is “Full-Scale” Needed?Difficulties in Scaling Down DetailsDifficulties in Duplicating Details

Ductile, but failed after so so deformation

-2

-1

0

1

2

-0.5 0 0.5

M/Mp

θx (rad)

Infinitely Ductile?Dynamic Test Video

4

Rate-of-Loading Effect?“Dynamic” sometimes increase ductility.

Effect of strain rate on stress-strain behavior

quasi-static dynamicDynamic Test Video

3.5m

1.5m

Test of Full-Scale Steel Frame to Failure in Cyclic Loading

3.5m

1.5m

6.0m6.0m

8.25m

Test Structure

South

North

1.5m

8.25m

Oil Jacks

South North

6.0m 6.0m

1.5m

1.5m3.5m

3.5m

Oil Jacks

Force (kN)

500

Fracture

Element Failure versus Frame BehaviorBeam bottom-flange fracture cause drop of 15%

but resistance remained stable

Beam

Column

Fracture

Story DriftAngle(rad)

0.04-0.04

-500Force (kN)

1/20rad

Final Failure

1000

Force (kN)Force (kN)

1000

Column bases are the potential weak spot, ultimately being the source of collapse.

Story Drift Angle(rad)

-1000

-0.1 0.1

Story DriftAngle(rad)

0. 1-0. 1 -1000

d

H

Step-1:Beam Collapse

Mechanism formed

Step-2:Beam Collapse

Mechanism progressed

Step-3:Story Collapse

Mechanism formed

Change in Collapse Mechanism

Column base crash

Column local buckling

5

Critical NeedsNeed of Real Experimental Data

Collapse (mild inelasticity vs. complete failure)Size (full-scale vs. miniature)Time (dynamic vs. quasi-static)Redundancy (member vs. system)

Collapse Characterization

Performance Verification

It may make sense to test in “Full-Scale” (instead of miniatures), for “System” (instead of member),

Dynamically (instead of quasi-statically), till Collapse (instead of mild inelasticity).

Today’s Topics





What is E-Defense?

It is a jumbo shaking table of 20 m by 15 m in plan, activated in 3D

Owned by National Research Institute for Earth Science and Disaster Prevention

Lessons from 1995 Hyogoken-Nanbu Earthquake

It may make sense to test in “Full-Scale” (instead of miniatures), for “System” (instead of member),

Dynamically (instead of quasi-statically), till Collapse (instead of mild inelasticity).

Mission of E-DefenseE-Defense has the unique capacity to experiment with life-size buildings and infrastructural systems in real earthquake conditions. It (I hope) stands as a tool of ultimate verification.

Shaking table and actuator system Shaking Table at InstallationTwo Crane: 400 metric ton each

Weight: 700 metric ton

6

3D Full-Scale Earthquake Testing FacilityPayloadSizeDriving Type

Sh ki Di ti

12 MN (1,200 tonf)20 m x 15 m

Accumulator ChargeElectro-Hydraulic Servo ControlX & Y H i t l Z V ti l

Specifications of Shaking System

Shaking DirectionMax. Acceleration(at Max. Loading)Max. VelocityMax. DisplacementMax. Allowable Moment

X & Y Horizontal>9 m/s/s

2 m/s1 m

OverturningMoment

150 MN x m

Z Vertical>1.5 m/s/s

0.7 m/s0.5 m

YawingMoment

40 MN x m

Three Major Tests at E-Defense TestIn Fiscal 2005 to 2006

RC Wood

Soils/Foundation

Two nearly identical houses built in 1974, one unretrofitted the other retrofitted; actual houses were transported.

First – Wood Test

Test click here

Six-story RC building with shearwall, designed in accordance with 1970s practice

Second – RC Building Test

RC clickColumn click

Reproduction of Liquefaction and Lateral Spreading of Quay side with Sheet Piles and Structures with Pile Foundations

Third – Soil Test Using Rigid Sand Box

Box global click

Box local click

NEES – E-Defense Collaboration

NEESReady in October, 2004

E-DefenseReady in April, 2005

7

Complete Collapse Test of FourComplete Collapse Test of Four--Story Story Steel Moment FrameSteel Moment Frame

E-Defense Steel Collapse

Investigation Investigation –– Anatomy of Specimen Anatomy of Specimen Collective Effort by six researchers headed Collective Effort by six researchers headed

and twenty studentsand twenty studentsDamage of

Interior Partition

Damage of Cladding

Overall Dynamic Response

Structural Health

Connection Behavior

Column Base Behavior

Correlation with Design Behavior

Column Local Buckling

Composite Action

CladdingMonitoring

Calibration of Numerical Analysis

Blind Analysis CompetitionParticipants from all over the world.Application through website.Competition for accurate simulation of collapse testCategory :

(1) 3D Analysis, Researcher (2) 3D Analysis, Practicing Engineer( ) l i h(3) 2D Analysis, Researcher (4) 2D Analysis, Practicing Engineer

Registration：115 teams（US:44, Japan:37, others:34）

Final submission : 47 teams（Japan:17, US:15, others:15）

Please, predict my collapse!

Blind Analysis Competition – Examples (for JR Takatori 60%)

200%

300%

400%

500%

600%

700%

ysis

/ M

easu

red

) rat

io_ Analysis results of participants Measured

-0.01

0

0.01

0.02

0.03

t ang

le o

f 1st

stor

y

Analysis(Y) Measured

0%

100%

200%

0 5 10 15 20 25 30 35 40 45Teams

( Ana

ly

Statistics: Maximum drift angle of first story

(Y-direction)

-0.03

-0.02

0 5 10 15 20sec

Drif

t

A good example: Time history of first story drift

(Y-direction)

Our modern cities have changed very significantly for the past forty years. For example, In Tokyo of late 1960s, there was no high-rise office in downtown Tokyo, the metropolitan subway had far less commercial lines, waterfronts remained sparse, neither PC nor Internet was existent, very few people who did not speak Japanese lived in Japan, or the word “globalization” was not invented yet

Change of our Society

not invented yet.

Earthquake engineering has a long history of “learning from actual earthquakes and earthquake damages.” That is, we first understand problems by actual damage; then develop engineering to patch them.

Progress of R&D based on “Learning from Earthquakes”

1964 Niigata 1968 Tokachi-oki 1995 Kobeg

Liquefaction RC Shear Failure

Seismic Retrofit

8

Attitude toward “learning from actual damage,” seems to make sense, because civil/building engineering traditionally places much emphasis on “experiences” compared to other engineering disciplines

Changes in Life and Society

BUT --- Our society has changed significantly for recent decades. We have to deal with urbanized cities like below. “Life safety”, of course, but “quality of life” and “security of life” become very important.

Shall this approach be successful, we would be able to predict our current problems, take action to solve or resolve them, and prepare for the future, all achieved before a real big one would hit us.

Change from “Learning from actual earthquake damage” to “learning from

quasi-actual earthquake damage”

How are we able to produce quasi-actual damage? –“very large-scale (or realistic-scale) tests,” “tests using actual ground motions,” and “tests on the entire structure (rather than members and elements)” is a solution.

Solution Today’s Topics





Never ceasing urban society, characterized by “high performance”, “density”, and “globalization.

Rapidly Grown Megacities

22% of companies whose stock are open to the Tokyo stock market has their headquarter offices in high-rises in downtown Tokyo. Their sales amass to about 30% of Japan’s total sale (1.0 trillion US $$).

Prediction of Un-experienced Behavior and Proposal for Necessary Measures

Performance of High-Rise Buildings Subjected to Long-Period Ground Motion

Response

Tokai

TonankaiNankai

Nankai1995 Kobe

Ground Motion

9

Prototype and Test Structure

PrototypeHigh-rise building

Me1

Me1Ke2

Ke3DamperRubberBearing

Concrete Mass

Substructure Model forHigh-Rise Steel Building

3 8

1.5m×3

50Mass Stiffness

Ke1Me1

Me2

Specimen

8m12m

4.5m

3.8m×3

21.6

m

Rubber Bearings Steel Damper

Construction of SpecimenConstruction of Specimen

Piping Partition Wall

Specimen

High-Rise

Fracture Local BuccklingCracks

Column

Damage to Beam-to-Column Connections

Column

ColumnColumn

1000

2000M (kN-m)

-2000

-1000

0

1000

2000

-0.02 -0.01 0 0.01 0.02

M (kN-m)

Rotation (rad)

-2000

-1000

0

1000

2000

-0.02 -0.01 0 0.01 0.02

M (kN-m)

Rotation (rad)

0

1000

2000M (kN-m)

-2000

-1000

0

1000

2000

-0.02 -0.01 0 0.01 0.02

M (kN-m)

Rotation (rad)

Moment-Rotation Relationships of Beam-to-Column Connections in Third Story

-2000

-1000

0

1000

2000

-0.02 -0.01 0 0.01 0.02

M (kN-m)

Rotation (rad)

-2000

-1000

0

-0.02 -0.01 0 0.01 0.02Rotation (rad)

-2000

-1000

0

1000

2000

-0.02 -0.01 0 0.01 0.02

M (kN-m)

Rotation (rad) -2000

-1000

0

1000

2000

-0.03 -0.02 -0.01 0 0.01 0.02 0.03

M (kN-m)

Rotation (rad)

-2000

-1000

-0.02 -0.01 0 0.01 0.02Rotation (rad)

Protection of Megacities- Safety of Course, Maintenance of

Functionality and Operability Required

Response

Nankai1995 Kobe

Ground Motion

Tokai

TonankaiNankai

10

Reproduction of Top Story ResponseCapacity Demand

Acceleration 9 m/s2 4.20 m/s2

Velocity 2 m/s 2.15 m/sDisplacement 1 m 1.24 m

Oil amount 20 kl 306 klr(t)Shaking table

Substructure

Direct Way Table LimitationDirect Way Table Limitation

Rubber-mass system

u(t):

ye(t))

Special input wave

Invention

Reproduction of Floor Response of Top Story of High-Rise Building

①

56

22m

xy

z Shaking Table

②

①Steel Frame(Rigid Body)

②Rubber-and-Mass system

Input-A Simulation result

3

0

3

6

cc. [

m/s

2 ]

X-direction

SpecimenTarget

-1 50

1.53

X-direction

cc. [

m/s

2 ]

Selection of Input WaveUse of “Inverse Dynamic Compensation via Simulation” Technique to Choose Best Input for Reproduction of Expected Floor Response

0 50 100 150 200 250-6

-3

Ac

0 50 100 150 200 250-6

-3

0

3

6

time [s]

Acc

. [m

/s2 ]

Y-direction

SpecimenTarget

0 50 100 150 200 250-31.5

Ac

0 50 100 150 200 250-3-1.5

01.5

3Y-direction

Acc

. [m

/s2 ]

time [s]

oil(kl)

X Y X Y X YTarget 0.93 1.50 3.31 5.43 20

Simulation 0.85 1.47 2.83 4.76 37

AMax Disp.(m) Max Acc.（m/s2) Error

3.55% 6.23%

Reproducibility

Furniture Behavior in Top Floors

BedroomOverall Office Living

WithoutWith Countermeasure

Motion in Office Floors

With Video Without Video

Base-Isolation as Solution for Better “Quality of Life”

200

250

Construction of Base-Isolated Buildings in Japan(by courtesy of JSSI)

0

50

100

150

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

11

X-ray Operation

Operability and Functionality of Medical Facilities – Test on Four-Story RC Hospital

y p

Surgery Bed

Four Story RC Hospital(Height: 17 m, Plan Dimension: 10 by 8 m)

SpecimenConventional RC FrameBase-Isolated RC Frame

Type I: Natural Rubbers and Steel DamperspType II: High Damping RubbersMeasurement• Sensor Channels• Structures: 160 chs.• Machines/Equipment: 540 chs.• Video : 50 chs.

Four Story RC HospitalBase-Isolation Systems

Type I: Natural Rubbers and Steel Dampers (Clearance: 500 mm)Ts=2.56s (30cm), 2.70s (50cm)

Fixed Base

Type II: High Damping Rubbers(Clearance: 300 mm)Ts=2.41s(30cm), 2.52s(50cm)

Types of Ground MotionType Input Motion Direction Amplitude

Fixed-Base Sannomaru X and Y 100 %

Yokohama X and Y 100 %El Centro X and Y 0.5 m/s (max Vel)

JMA Kobe X, Y, and Z 80 %Base-I l ti

El Centro X and Y 0.5 m/s (max vel)Isolation(Type I)

JMA Kobe X, Y, and Z 80 % (*1)Sannomaru X and Y 100 %

Base-Isolation(Type II)

El Centro X and Y 0.5 m/s (max vel)JMA Kobe X and Y 80 %

JMA Kobe X, Y, and Z 80% (*1)Sannnomaru X and Y 100 % (*2)

Sannnomaru: Synthesized long period motion

(*1) Effect of Vertical Motion; (*2) Collision with Retaining Wall

Four Story RC HospitalBase-Isolation Systems

Type I: Natural Rubbers and Steel Dampers (Clearance: 500 mm)Ts=2.56s (30cm), 2.70s (50cm)

Fixed Base

Type II: High Damping Rubbers(Clearance: 300 mm)Ts=2.41s(30cm), 2.52s(50cm)

Overall Sloshing

JMA Sannomaru

Today’s Topics





12

Passage to Seismic Retrofit ---Evolution of Mind in Emphasis on “Stocks”

Year：1974Floor Area：69m2

Retrofit of Wood HouseTransportation

Floor Area：69m2

Decomposition

Seismic Diagnosis：A (unretrofit): 0.43B (retrofit):

0.31 → 1.57Cost: 1.2 million yen

Wood Brace

Wood Plank

Beam

Foundation

Connection Plate (25kN)Connection Plate (15kN)Connection Plate (8.5kN)Connection Plate (5.1kN)

Referred

Outline of Retrofit

Referred Guideline

First Floor

Direction of Primary Motion

Second Floor

Adopted Retrofit Techniques

Braces Wood PanelAddition of Beam

Metal Connectors

Test on Retrofit Performance

1 2

Test click here

1 23 4

A (Unretrofit) and B (Retrofit)with Unreduced JR Takatori Motion

Restoring Force Behavior

100

200

300

rce P

(kN

)

Max Force = 241 kN

-300

-200

-100

0

-400 -200 0 200 400Displacement δ (mm)

Sto

ry s

har

e f

or

Max Force = 163 kN

13

Retrofit Performance of RC School Building Validation of retrofit by exterior steel braces Examination into correlation between type of foundation and damage to superstructure

Strength = 0.7

Strength = 1.3Plan of Specimen

Retrofit by Exterior Steel Braces

Test on Retrofit RC School Building

RC Comparison

Restoring Force Behavior (JMA Kobe)

Retrofit (JMA 100%)

Retrofit (JMA 130%)

Unretrofit (JMA 100%)

Story Shear Coefficient

1.0

Unretrofit (JMA 130%)

Drift Angle

0.04-0.04 0

0

-1.0

Retrofit of Steel High-Rise BuildingRetrofit by Buckling Restrained BracesRetrofit by Oil DampersRetrofit by Strengthening Beam-Column Connections

Long Period Ground Motion

Steel Damper

Test on Retrofit High-Rise Building

Strengthening of

ConnectionsSpecimen

High-Rise Strengthened

14

10

15

20

10

15

20

E = 637kNmE = 5487kNmE = 627kNmE = 5871kNm

Retrofitted

Story Story El Centro_0.5 m/s Sannomaru

fi d

Comparison in Response between Unretrofitted and Retrofit by BRBs

0

5

10

0 0.005 0.01 0.015 0.020

5

10

0 0.005 0.01 0.015 0.02

UnretrofittedRetrofitted

IDRmax (rad) IDRmax (rad)

Unretrofitted

Energy Dissipation: by 10 timesReduction of Max. Story Drift Angle: by 50%

s7

A

s780

12 169

162

80

50

50

690

s7

A

s780

12 169

162

80

50

50

690

R25

R25 25 83

607

150

2G3 / Hc -800 ~199 ~10 ~15 (ハニカム)

12

16

R25

R25 25 83

607

150

2G3 / Hc -800 ~199 ~10 ~15 (ハニカム)

12

16

Quest of “Handy” Retrofit Solution

Retrofit Alternatives

Supplemental Weld

80

B

1050

80

110

25

80

B

1050

80

110

25

7 193200

30 170

200

8515

100

R25

7 193200

30 170

200

8515

100

R25

400

35 415

450

125

150

125

34 50 158 158 50

450

125 150 125

400

400

35 415

450

125

150

125

34 50 158 158 50

450

125 150 125

400

Vertical Haunch

Wing Plates

Associated Member test

Wing plate

Presence of RC slabLong-period ground motion

Wing Plates

HaunchweldSupplemental

Tube or box section column

Increase in Cumulative Ductility

Before RetrofitAfter Retrofit Retrofit

Increase in Performance

More than 6 Times

After Retrofit

Seismic Retrofit to High-Rises

Downtown Tokyo – Shinjuku Area

Retrofit using “special oil dampers” completed for a high-rise built in 1975

Today’s Topics





15

Collaboration with Numerical SimulationUNDERSTANDING: “Large Scale Test” and “Numerical Simulation” shall

go side by side for advancement of Earthquake Engineering.

“Large Scale Test” provides data for calibration and enhancement of accuracy of “Numerical Simulation”, while “Numerical Simulation”Simulation , while Numerical Simulation suggests future test targets.

“Analysis only attitude” or “Test (Experience) only attitude should be avoided.

ACTION and POLICYE-Defense “Numerical Shaking Table “Project is

ongoing for development of collapse simulation.Development is being made while watching E-

Defense shaking.

E-Defense “Numerical Shaking Table” Project

Simulation – 3D solid elements

needs and challeenges on large today’s topics …€¦ · “very large-scale (or...

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