Buckling‐restrained Braces and Applications · Toru Takeuchi, Akira Wada RyotaMatsui, Ben Sitler,...

1

Chapter 1: Composition and history of Buckling‐restrained Braces

Buckling‐restrained Braces and Applications1

BUCKLING-RESTRAINED BRACEHISTORY, DESIGN and APPLICATIONS

Toru Takeuchi, Akira WadaRyota Matsui, Ben Sitler, Pao-Chun Lin,

Fatih Sutcu, Hiroyasu Sakata, Zhe Qu

2



Concept of Buckling-restrained Brace

Types of restrainerAppearance of typical BRB

1.1 Composition of buckling‐restrained Braces (BRB)

Mortar

3



-600-400-200

0200400600

-40 -20 0 20 40Axial deformation (mm)

Axi

al fo

rce

(kN

)

Hysteresis of well‐designed BRB

Clearance and eccentricity

Development of higher buckling mode

RestrainerCore plate

4



1972: Takeda et al. tried to improve the post-buckling behaviour ofH-section braces by encasing the steel section in reinforcedconcrete. However, because no debonding mechanism wasprovided, the restrainer received a significant compressiveforce, cracked and ultimately experienced overall buckling.

1979: Motizuki et al. proposed introducing a debonding layerbetween the core plate and reinforced concrete restrainer.However, the system tended to buckle at the unrestrained coreextension

1988: The first practical buckling-restrained brace was achieved bySaeki, Wada, et al. employed rectangular steel tubes with in-filled mortar for the restrainer, and determined the optimaldebonding material specifications to obtain stable andsymmetric hysteresis behaviour.

1.2 History of Development

5



The first application of Buckling‐restrained Brace (Unbonded Brace, 1987)

Nippon Steel Headquarter No.2 (Tokyo) BRB installation

BRB experiment 1987

M Fujimoto, A Wada, E Saeki, T Takeuchi, A Watanabe: Development of Unbonded Braces, Quarterly Column, No.115, pp.91‐96, 1990.1

1.2 History of Development

6



Plant & Environmental Sciences, UC Davis Bennett Federal BuildingRetrofit/ Salt Lake City

Early US applications in 2000’s

7



1.3 BRB TYPES (Mortar in‐filled type)

Restrainer

Core Plate

Spacer

Slit

Connection

RestrainerRestrainer

Core Plate

8



1.3 BRB TYPES (Dry type)

Restrainer Tube

Core Tube

Pin End

Solid End

Bolt End Restrainer Tube

Core Tube

Restrainer TubeCore Tube

Core Tube

Restrainer Tube

Core Plate

RestrainerUnbonded Sheet

Slit

Core Plate

Core Plate

Bolt

Restrainer Bolt

9

Chapter 2: Restrainer Design and Clearances


Quality Requirement for Hysteresis models

Inappropriate clearance

Plastic strainconcentration

Local buckling Local bulging

Uneven stiffness

Degradationin compression side

Unevenstrength

Unevenstrength Local bulging Degradation

in compression sideBulging-induced failure

Tearing

FractureSlack

(pin connection)

Buckling

Buckling-induced failure

10



2.1 Restrainer Design

Global Stability, including:

Restrainer End

Higher Mode Buckling

Connection Strength

Fatigue Fracture

ConnectionsRestrainer

BRB Stability and Strength

1.Restrainer successfully suppresses core first‐mode buckling (Chapter 2)2.Debonding mechanism decouples axial demands and allows for Poisson effects (Chapter 2)3.Restrainer wall bulging due to higher mode buckling is suppressed (Chapter 3)4.Global out‐of‐plane stability is ensured, including connection (Chapter 4)5.Low‐cycle fatigue capacity is sufficient for expected demands (Chapter 5)

11



Ecr c

c c Ecr cu

N aa yN N

2( )

1 1cuB Bcu c

cu c c yB Bcu cr cu cr

N a s eN aM N a y MN N N N

a: Fabrication tolerances of core and/or brace s：Clearance or thickness of debonding material (per face)e：Eccentricity of the axial forceMB

y：flexural strength of the restrainerNcu= da Ny：core yield force amplified by overstrength and strain hardening

da =1.4~1.5NB

cr ：Euler buckling strength of the restrainer, given by:2

2B Bcr

B

EINl

Where initial imperfections ec/lB ≤ 1/500, a relatively slender restrainerwith lB/Dr > 20 and with an overall safety factor of eα ≥ 1.5;

2

2B Bcr e cu

B

EIN Nl

12

Chapter 3: Local Bulging Failure


in‐plane local bulging failure

out‐of‐plane local bulging failure

(Tokyo Institute of Technology)

(National Center for Research on Earthquake Engineering)

3.1 Failure Caused by High Mode Buckling

13




core strain

axial force

Compression

Tension

mortarsteel core steeltube wall

section s‐s

Bc

section w‐w

srs

srwtc

debondinglayer

Bc Br

Dr

BrBc

tc

Dr

srw

srs

ww

s

s

14




core strain

axial force

Compression

Tension

ww

s

s

section s‐s

section w‐w

N N

N N

Compression is initially applied

Flexural buckling waves form in both the in‐plane and out‐of‐plane directions

15



srs+0.5γp Bc ɛt

srw+0.5 γp tc ɛt

core strain

axial force

Compression

Tension

ww

s

s

Bc

tc

srw

srs

ɛt

section s‐s

section w‐w

Maximum tensile strain is applied

γp =0.5, Poisson ratio of steel inelastic deformation Clearances increase because of the Poisson effect


16



lp,s

lp,w

Bc

tc

core strain

axial force

Compression

Tension

ww

s

s

Ny

Ny

Ny

Ny

Ny

2srs+γp Bc ɛt

2srw+ γp tc ɛt

section s‐s

section w‐w

Compression reaches yield strength Ny

High mode buckling waves form and generating the outward forces.

outward force

outward force


17



Pd,s

Pd,w Pd,w

Pd,w Pd,w

core strain

axial force

Compression

Tension

ww

s

s

Ncu

lp,w

core strain

axial force

Compression

Tension

Ncu

Ncu

Ncu

Ncu

2srs+γp Bc ɛt

2srw+ γp tc ɛt

section s‐s

section w‐w

lp,s

Compression reaches maximum compressive capacity Ncu

High mode buckling wavelengths remain, the maximum outwards are fully developed.


18



ww

s

s

out‐of‐plane local bulging failure

in‐plane local bulging failure

in‐plane bulging

out‐of‐plane bulging

section s‐s

section w‐w

core strain

axial force

Compression

Tension

Ncu

Local bulging failure when restrainer is too weak in sustaining outward forces


19



3.2 Estimation on Outward Force (demand)

0.5Pd,s

0.5Pd,s0.5lp,s

Bc

,

,

4 2cu rs p c td s

p s

N s ν B εP

l

,

,

4 2cu rw p c td w

p w

N s ν t εP

l

In‐plane outward force Pd,s

Out‐of‐plane outward force Pd,w

Ncu

Ncu

2srs+γp Bc ɛt

0.5Pd,w

Ncu

0.5Pd,w

0.5lp,w

tc

2srw+ γp tc ɛtNcu

Apply moment equilibrium condition on the free body,

20



B

A’

B’

Bc

D

D’

x

Pc,w

Pc,w

Ab

b

x

External work = Pc,wδw

t

w

section w‐w

section t‐ta

Br

δw

3.4 Estimation on Steel Tube Resistance (capacity)out‐of‐plane bulging failure

Bc

A

D

B

B’

A’

D’

2x

3‐D view

Bc

t

w

δw

21



small deformation curvature

3.4 Estimation on Steel Tube ResistanceYield line patterns

B

A’

B’

D’

A

α

D

B

A’

B’

D’

A D

45。

B

A’

B’

D’

A D

45。

B

A’

B’

D’

A D

Condition 1

Yield lines AD and A’D’ ignored residual stress at tube corners

Condition 2 Condition 3 Condition 4

α

(Yoshida et al. 2010) (Lin et al. 2010)

Internal energy: E9(9 yield lines)α = 45°

Internal energy: E9(9 yield lines)α: minimizing E9

Internal energy: E5(5 yield lines)α = 45°

Internal energy: E5(5 yield lines)α: minimizing E5

2,

2,

41

41

c w r ry

c r

c s r ry

c r

P t σB B

P t σt D

2,

2,

4 214 21

c rc w r ry

c r

c rc s r ry

c r

B BP t σ

B Bt D

P t σt D

2,

2,

21

21

c w r ry

c r

c s r ry

c r

P t σB B

P t σt D

2,

2,

2121

c rc w r ry

c r

c rc s r ry

c r

B BP t σ

B Bt D

P t σt D

A D

(resistance factor) (resistance factor) (resistance factor) (resistance factor)

22



3.5 Test Results and Evaluations

,exp2

,

,exp2

,

4 2out‐of‐plane:

4 2in‐plane:

cu rw p c t

p w r ry

cu rs p c t

p s r ry

N s ν t ε

l t σ

N s ν B ε

l t σ

Experimental resistance factor

● 15 specimens without bulging× 14 out‐of‐plane bulged specimens ▲ 5 in‐plane in‐plane bulged specimens

resistan

ce fa

ctor

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Bc/Br or tc/Dr

0

2

4

6

8

10

12

14

Condition 2Condition 1

Condition 3

Condition 4

resis

tance factor

Bc/Br or tc/Dr

example:●

●

× ▲

× ▲

Appropriate: bulging did not occur in test and was not in expectation

Conservative: bulging is in expectation but did not occur in test

Appropriate: bulging occurred in test and was in expectation

Dangerous: bulging occurred in test but was not in expectation

(9 dangerous estimation)

(9 dangerous estimation)

(over‐conservative)

(recommended)

23



3.5 Test Results and EvaluationsProposed design method:

0

2

4

6

8

10

12

14

resistan

ce fa

ctor

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Bc/Br or tc/Dr

,2

, ,

,2

, ,

4 21.0

2

4 21.0

2

cu rw p c td w r cw

c w r c r ry p w

cu rs p c td s r cs

c s r c r ry p s

N s ν t εP B BDCR

P B B t σ l

N s ν B εP D tDCR

P D t t σ l

0.85

7.7

in‐plane bulgingtcDr

BrBc

0.85c

r

BB

0.85c

r

tD

● 15 specimens without bulging× 14 out‐of‐plane bulged specimens ▲ 5 in‐plane in‐plane bulged specimens

out‐of‐plane bulging

24



3.6 Required Mortar Strength for Local Pressure

3.7 Local Bulging Criteria for Circular Restrainer

Bc

lc

Pd,wcontact surface

steel core

restrainer

, 'd wc

c c

Pf

l B

,

, ,

4 221.0cu rs p c td s r r

scc s m m c r r ry p s

N s ν B εP B tDCR

P c t t πt B σ l

25

Chapter 4: Connection Design and Global Stability


The AIJ Recommendations provide rigorous evaluation methods for BRB connection out‐of‐plane buckling. Two concepts below are presented:

AIJ (2009) Recommendations for stability design of steel structures. Architectural Institute of Japan.

4.2 Design Concepts

Moment transfercapacity is lost at the

end of restrainer

EIB

JEIB

JEIB

L0

L0

lB L0

Connectionzone

Connectionzone

Restrainedzone

=Plasticzone

EIB

>

Bendingmomenttransfer

Gusset plate

JEIB EIB

>JEIB EIB

KRg

KRg

Restrainer-endzone

Connectionzone

Connectionzone

Restrainer-endzone

Plasticzone

Restrainedzone

1: Cantilevered gusset 2: Restrainer end continuity

26



Type A Type B Type C(a) low stiffness

(US/NZ detailes)(b) high stiffness

(JP details)

(a) One-way (b) ChevronBRB configurations in frame

BRB configurations

Not rotationallybraced

27


Buckling‐restrained Braces and Applications27 Toru Takeuchi, Tokyo Institute of Technology

Tsai and Nakamura’s proposal (2002) Koetaka and Inoue’s proposal (2008)

2

20

(1 2 )(2 )

J Bcr

r EINL

* *

(1 2 )( )( )

Ncr R

N N

lN Kl d l d l

1 2

1 2 0

1(1 )cr RN K

L

Stability assessment

0r

c

Li

28



Hikino and Okazaki’s proposal (2013)*

1 1 2*

1 1 2 1 2 0

11 21 (1 )

R Rcr R

K L K dN KL L L l d L

Takeuchi’s proposal (2013)0

10

( )( ) ( ) 1

r r rp r cr

lim cur r Bp r cr

M M a NN N

M M a N

2

2 20

(1 2 )(2 ) 24 /

Rgr J Bcr

Rg

EIN

L

0Rg

RgJ B

K LEI

20 24 /2

(1 2 )Rg

rc Rg

Li

point of rotation

LinDneck

a) mortar‐filled BRB

yielding

b) steel tube‐in‐tube BRB

Lin

29



Takeuchi’s proposal (cont’d)

0 02

0 0

(1 2 )

(1 2 ) ( ) 1

g r r rp p r

lim cug r r r Bp p r cr

M M M M aN N

M M M M a N

In case of plastic hinges produced at joint ends

Stable Unstable

30



4.6 In‐plane pinching

(a) Frame pinching (b) Frame opening

horizontal stiffener

verticalstiffener

Expected Failure Recommended Proposal

31

Chapter 5: Cumulative Deformation Capacity until Fracture


Expected Plastic Zone

Plastic Zone

(a) Ordinary Tube Brace

(b) Incomplete Buckling-restrained Brace

(c) Complete Buckling-restrained Brace

Local Buckling Mechanism

Plastic stress concentration

Mild local buckling and averaged strain distribution along plastic zone

Friction

Local buckling distribution until fracture

Cumulative energy‐dissipation capacity

32



1 21 2

m mt f fC N C N

0.1

1

10

100

0.01 1 10 100 100

01000

010000

0

LY100SS400LY235

Steel material fatigue performance4)

Cycle Number Nf

Stra

in Am

pilitu

deΔε

eq(%

)

BRB < Steel Material

BRB fatigue performance6),7)

Exp. Data5)

4) Saeki, E et al. 1995. A Study on Low Cycle Fatigue Characteristics of Low Yield Strength Steel, J. Struct. Constr. Eng., AIJ, No. 472, 139‐1475) Nakamura, H., Takeuchi, T., et al. 2000. Fatigue Properties of Practical Scale Unbonded Braces, Nippon Steel Technical Report, Nippon Steel Corporation, No. 82, 51‐576) Takeuchi, T. et al. 2008. A. Estimation of Cumulative Deformation Capacity of Buckling Restrained Braces, J. Struct. Eng., ASCE, Vol. 134, No. 5, 822‐8317) Takeuchi, T. et al. 2006. Cumulative Deformation Capacity and Damage Evaluation for Elasto‐plastic Dampers at Beam Ends, J. Struct. Constr. Eng., AIJ, No. 600, 115‐122

Elastic region

Plastic region

Manson‐CoffinFatigue Formula

Steel material fatigue performance4)

BRB Fatigue Performance under Cyclic Loading

33



s0=1.0mm, tc=25mm

s0=2.0mm, tc=25mm

s0=5.0mm, tc=25mm

s0=0mm (Steel material)

1 10 100 1000 10000

Strain amplitu

de Δε n

(%)

0.1

1

10

100

0.01Fracture cycle Nf

s0=2.0mm, tc=12mm

5) Nakamura, H., Takeuchi, T., et al. 2000. Fatigue Properties of Practical Scale Unbonded Braces, Nippon Steel Technical Report, Nippon Steel Corporation, No. 82, 51‐579) Takeuchi, T., Ohyama, T., and Ishihara, T. 2010. Cumulative Cyclic Deformation Capacity of High Strength Steel Frames with Energy Dissipation Braces (Part 1), Journal of Structural and Constructional Engineering, Architectural Institute of Japan, Vol. 75, No. 655, 1671‐1679 (in Japanese)

Experiment s0=1mm, tc=25mm5)

Experiment s0=2mm, tc=12mm9)

SN400B

Fatigue performance of BRBdecreases as clearance between core plate and restrainer increases

Fatigue Performance of BRB using Plastic Strain Concentration Mechanism

34



0 0.5 1 1.5 2

Damage Index

Gradually Increasing

FatigueShaking Table

(Theory)

05

1 02 04 06 08 0

1 0 01 2 0

0.52

5

1.22

5

1.92

5

2.62

5

3.32

5

4.02

5

4.72

5

5.42

5

6.12

5

6.82

5

7.52

5

8.22

5

8.92

5

9.62

5

10.3

2

11.0

2

11.7

3

12.4

3

F r e q u e n c y Nfi

( c y c l e s )

S t r a i n A m p l i t u d e i ( % )

0.001

0.01

0.1

1

10

100

1 10 100 1000 104 105 106

Constant Amp.

Strain Amp. Δε (%)

Failure Cycles Nf (cycles)

εe=0.5･N

f

-0.14

εp=54.0･N

f

-0.71

Estimation by Miner’s Method

Strain Amplitude Frequency

Fatigue Curve under Constant Amplitude

Accuracy by Miner’s Method

35

Chapter 6: Performance Test Specification for BRB


Single Brace test

Single Brace test with rotational deformation(ANSI/AISC 341-05)

6.1 Test Configurations1) Uniaxial test

36



2) Inclined test

Inclined layout with column

Inclined layout with initial out-of-plane drift

37



3) In‐frame test

38



(a) ANSI/AISC 341-05 and US practiceCycle Inelastic Deformation Cumulative strain Cumulative

(Story drift angle) ( bm = 4 by ) ( by =0.25%) Inelastic strain

by ×2 =2×4× by - by ) =0 by =2×4×0.25=2% =2×4×0=0%0.5 bm ×2 =2×4× by - by ) =8 by =2×4×0.5=4% =2×4×0.25=2%1.0 bm ×2 =2×4× by - by ) =24 by =2×4×1.0=8% =2×4×0.75=6%1.5 bm ×2 =2×4× by - by ) =40 by =2×4×1.5=12% =2×4×1.25=10%

.0 bm ×2 =2×4× by - by ) =56 by =2×4×2.0=16% =2×4×1.75=14%1.5 bm ×4 =4×4× by - by ) =80 by =4×4×1.5=24% =4×4×1.25=20%

Total =208 by =56% =52%

(b) BCJ and Japanese practiceCycle Inelastic Deformation Cumulative strain Cumulative

(Plastic length strain) ( by =0.25%) ( by =0.25%) Inelastic strain

by ×3 =3×4× by - by ) =0 by =3×4×0.25=3% =3×4×0=0%0.5%×3 =3×4× by - by ) =8 by =3×4×0.5=6% =3×4×0.25=3%1.0% ×3 =3×4× by - by ) =36 by =3×4×1.0=12% =3×4×0.75=9%

.0% ×3 =3×4× by - by ) =84 by =3×4×2.0=24% =3×4×1.75=21%

×3 =3×4× by - by ) =132 by =3×4×3.0=36% =3×4×2.75=33%

Total =264 by =81% =66%

(1.5 bm until fracture)

(3.0% until fracture)

Example BRB testing protocol

39



6.4 Post Earthquake InspectionKoriyama Big-Eye, a 24-story, 133m building complete in 1998 in Fukushima experienced

Tohku Earthquake 2011 at 234km from epicenter. The cumulative deformationmeasurements and earthquake record were used to calibrate a finite element model,indicated a peak ductility demand of µ ≈ 4 and a cumulative plastic strain of ∑εp ≈ 20%(∑δp/δy ≈ 100) in the Y direction, still 6% of their capacity.

cumulative def. meter

max def. meterFukushima Koriyama Big-EyeInaba Y, Morimoto S, Tsuruta S, Takeuchi T, Matsui R. Damage record of buckling restrained braces that received actual ground motion. AIJ Kanto Branch Research Report Collection 2017

40

Chapter 7.1: Damage Tolerant Concept


7.1.1 Damage Tolerant Concepts

Damage Tolerant StructureEarthquake Ground Motion and Seismic Design in Japan

Wada A, Connor J, Kawai H, Iwata M, Watanabe A: Damage Tolerant Structure, ATC-15-4, Proc. 5th

US-Japan WS on the Imprement of Building Structural Design and Construction Practices, 1992.9

41



0.005(1/200)

0.00125(1/800)

0.01(1/100)

0.00125(1/800)

0.01(1/100)

BRB EnergyDissipationZone

Main FrameDamage Zone

BRB EnergyDissipationZone

Main Frame(Normal Steel)

BRB

Main Frame(High-strengthSteel)

BRB

Max Response Max Response

Story DriftAngle

Story DriftAngle

ShearForce

ShearForce

System of Main Structure and DamperStrain Distribution along the beam

(a) Ordinary Concept (b) Damage Tolerant ConceptShear force-Story Drift Relationship of Damage Tolerant Structure

42



Triton Square Project

43



Grand Tokyo North Tower Election of Large BRBF

Following Damage Tolerant Projects

44 Toru Takeuchi Tokyo Tech

Grid-skin structures with BRBs

BRB is suitable for Grid-skin structures

Ductile elements, Less bending loss, Free internal space, Design with facades

45

Cg南側

Toru Takeuchi Tokyo Tech

Energy-dissipation Skins with Solar Cells2. Disaster Prevention and Environmental Sustainability

46

Solar-panel Envelope StructureFlexible and Lightweight structure over the main frame

Main FrameSpiral Layout of Energy-dissipation Fuses around Perimeter zones

Open Space

Energy Dissipation Brace

Energy-dissipation Skins with Solar Cells2. Disaster Prevention and Environmental Sustainability

47

Chapter 7.3: Seismic retrofit with BRBs


Midorigaoka-1st Building Retrofit concept

48



-800

-600

-400

-200

0

200

400

600

800

-30 -20 -10 0 10 20 30

Experiment

(kN

)

(mm)

Calculation -800

-600

-400

-200

0

200

400

600

800

-30 -20 -10 0 10 20 30

Experiment

(kN

)

(mm)

Calculation

(a) Before retrofit (b) After RetrofitReduced mock-up test for 2nd floor frame

49



Detail for the connections between frame and BRB

Maximum story drift obtained by time‐history analyses

50



summer spring/fall winter

Environmental effect of outer skins

51



Perimeter work process

Carbon fiber reinforcement BRB Attachment

52



53



(a) Exterior appearance (b) Interior viewApplication for Seismic retrofit (Administer Build. Tokyo Tech)

Retrofit with Diagonal BRB Louver

Takeuchi T, Yasuda K, Iwata M: Seismic Retrofitting using Energy Dissipation Façades, ATC-SEI09(San Francisco), 2009.12

54



7.4.1 BRB application on RC frame with elastic steel frame

55



A

B

C

D

E

F

1 2 3 4 5 6 8 9 107 12 1311

A

B

C

D

E

F

Typical RC school building in Turkey

56



‐80

‐40

0

40

80

120

160

0 20 40 60 80 100 120

Inter‐story displacemen

t (mm)

Time (sec)

RC onlyRC+BRBRC+BRB+SF

≈1/1000 story drift≈1/3000 story drift

≈1/30 story drift

Residual displacement

RC only

RC + BRB

RC + BRB + SF

57



0

0.5

1

1.5

2

0.000 0.005 0.010 0.015 0.020 0.025

"First M

ode" Spe

ctral A

cceleration S A

(T1, 5%

) (g)

Maximum inter‐story drift (rad)

RC onlyRC+CB+SFRC+BRB+SFtarget drift (1/150)

(a)

0

0.5

1

1.5

0 0.00025 0.0005 0.00075 0.001"First M

ode" Ape

ctral A

cceleration S A

(T1, 5%) (g)

Maximum Residual Drift (rad)

RC+CB+SFRC+BRBRC+BRB+SF

(b)

Increment Dynamic Analyses curves

58



Cyclic Loading Test for RC retrofit with BRB+SF(Istanbul Technological University)

59

Chapter 7.6: Applications for truss and spatial structures


7.5.2 Types of Spatial Structure Applicationsa) Truss structures

△ △ △ △ △ △

Buckling BRB -2

-1.5

-1

-0.5

0

0.5

1

1.5

2

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

y

軸歪み [%]

ForceLimitingFunction

Devices

Response Control for Truss Structures

Device Layout Types for Response-controlled Truss Structures

60



Horizontal Acceleration

Vertical Acceleration

Horizontal Input

(R‐1) Roof with Dampers (R‐2) Base IsolatedRoof

(R‐3) Substructure with Dampers (R‐4) Entire Base Isolation

Seismic Response of Raised Roof

Device Layout for Response-controlled Roof Structures

61



Seismic retrofit of communication towers

62



Deck

Horizontal Tie

Thrust Brace

Vibration Control Brace (Deck)

Main Arch

Horizontal Brace

Vibration Control Brace (Roof)

5.7

5.7

108.

3m

5.7

5.7

Toyota Stadium

Shimokita Dome

63



BRBs

Buckling‐restrained Braces

Retrofit of Hanshin highway bridge

Bridge girder with BRBs on RC peer

7.5.3 Applications to Bridge Structures

Seismic retrofit of steel arch bridge with BRBs

Celik O, Bruneau M: Skewed Slab‐on‐Girder Steel Bridge Superstructures with Bidirectional‐Ductile End Diaphragms, ASCE Journal of Bridge Engineering, Vol.16, No.2, pp.207‐218, 2011

64

Chapter 7.7: Spine frame concepts


7.6.2. Dual spine systemBRB or Damper

BRB or Damper(a) Conventional BRB distribution (b) Dual spine concept

ElasticBrace

Taga K, Koto M, Tokuda Y, Tsuruta J, Wada A. Hints on how to design passive control structure whose damper efficiency is enhanced, and practicality of this structure, Proc. Passive Control Symposium 2004, 105‐112, Tokyo Tech, 2004.11

65



Retrofit of Suzukake G3 Tokyo Tech 2010Akira Wada, Qu Zhe et al.

Qu Z, Wada A, Motoyui S, Sakata H, Kishiki S: Pin-supported walls for enhancing the seismic performance of building structures. Earthquake Engineering and Structural Dynamics 2012

66



7.6.4. Non-uplifting Hinged Spine Frame System (Material Research Building)

67



(a) Conventional BRBF (SD)

(b) Lift‐up Rocking Frame (LU)

(c) Non‐uplifting Spine Frame (NL)

7.6.5. Comparison of Spine Frame Systems

Takeuchi T, Chen X, Matsui R. Seismic performance of controlled spine frames with energy‐dissipating members, Journal of Constructional Steel Research, Vol.115, 51‐65, 2015.11

68



BRC

PT wire

BRC BRC

1

2

3

4

5

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

1

2

3

4

5

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

1

2

3

4

5

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

1

2

3

4

5

0 0.03 0.06 0.09 0.12 0.15

1

2

3

4

5

0 0.03 0.06 0.09 0.12 0.15

1

2

3

4

5

0 0.03 0.06 0.09 0.12 0.15

Residual Story Drift Angle (%)Max. Story Drift Angle (%)

0.8% rad.(1/125)

0.8% rad.(1/125)

0.8% rad.(1/125)

0.05% rad.(1/2000)

0.05% rad.(1/2000)

0.05% rad.(1/2000)

Shear DamperSystem

Lift-upSpine

System

Non Lift-upSpine

System

69



680 Folsom Street, SF, US

7.6.7 Application ExamplesRetrofit of Steel Frame with RC core wall spine

Janhunen B., Tipping S., Wolfe J., Mar T. Seismic Retrofit of a 1960s steel moment-frame highrise using a pivoting spine, SEAOC 2013 Convention Proceedings

70



BRBs

RC core

Wilshire Grand Tower, LA, US

Damped Outrigger concept

Joseph LM, Gulec C, Schwaiger K Justin M: Wilshire Grand: Outrigger Designs and Details for a Highly Seismic Site, International Journal of High‐Rise Buildings, Vol.5, Issue 1, 2016, pp.1‐12

71



atR

Optimization Method

2 2 2

2 2 2

3.28 0.75 (1 ) 0.57(1 )6.75 1.81 (1 ) 0.63(1 )

tr at tr at at at

tr at tr at at topt

a

S R S R R RS R S R R R

,, ,

2

4 2 2

0.20 0.59 0.61 ,2.01 ( 2)

b

t

at optat opt d op

r trtS

R ck R

S

Exclusive Optimization

Res

pons

e

Outrigger position

Dam

per

B.Huang, T.Takeuchi: Dynamic Response Evaluation of Damped-Outrigger Systems with Various Heights, Earthquake Spectra, Vol.33, No.2, pp.665-685, 2017.5

72



The latest knowledge is overviewed in

Buckling-Restrained Braces and Applications

T. Takeuchi and A. Wada, Japan Society of Seismic Isolation, 2017

mail to [email protected]

30-years from the first application, BRBs are still actively researched andexpanding applications. I am looking forward to further development inthe future.

73

Thank you very much for your kind attention

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