buckling-restrained braces and applications9 chapter 4: connection design and global stability 9...

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Chapter 1: Composition and history of Buckling‐restrained Braces

Buckling‐restrained Braces and Applications1

Buckling-Restrained Braces and Applications

座屈拘束ブレースとその応用

Toru Takeuchi, Akira Wada, Ryota Matsui, Ben Sitler, Pao-Chun Lin,

Fatih Sutcu, Hiroyasu Sakata, Zhe Qu

Japan Society of Seismic Isolation, 2017

座屈拘束ブレースは1987年に日本で実用化され、現在米国,中国,台湾,ニュージーランド,チリ等、世界の地震地域で広く規準化、適用されている耐震・制振部材である。本書は最新の知見を盛り込んだ初めての座屈拘束ブレースの専門書である。

introduction

2



目次

Chapter 1: Composition and history of buckling-restrained braces /しくみと開発の歴史

Chapter 2: Restrainer design and clearances /座屈拘束材の設計とクリアランス

Chapter 3: Local bulging failure /局部崩壊の防止

Chapter 4: Connection design and global stability /接合部設計と全体安定性の確保

Chapter 5: Cumulative deformation capacity /累積繰返し変形性能

Chapter 6: Performance test specification for BRB /性能確認試験とクライテリア

Chapter 7: BRBF Applications /座屈拘束ブレースを用いた構造デザイン

7.1 Damage tolerant concept /損傷制御設計

7.2 Response evaluation of BRBF /等価設計化手法による応答評価

7.3 Seismic retrofit with BRBs /座屈拘束ブレースによる耐震改修

7.4 Response Evaluation of BRBs Retrofit for RC Frames / RC 耐震改修時の応答評価

7.5 Direct Connections to RC Frames /RC 架構への直接接合

7.6 Applications for truss and spatial structures /空間構造への応用

7.7 Spine frame concepts /心棒構造への応用

Appendix /付録

A1 Typical BRB details /代表的な座屈拘束ブレースの標準図

A2 Rotational spring at connections /接合部回転剛性の評価

A3 BRB buckling capacity /接合部を含む弾性座屈荷重

introduction

3



Concept of Buckling-restrained Brace

Types of restrainerAppearance of typical BRB

1.1 座屈拘束ブレースの構成

Mortar

4



-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

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 開発の歴史

6

Chapter 2: Restrainer Design and Clearances


履歴特性の劣化とその要因

Inappropriate clearance

Plastic strainconcentration

Local buckling Local bulging

Uneven stiffness

Degradationin compression side

Unevenstrength

Unevenstrength Local bulging Degradation

in compression side

Bulging-induced failure

Tearing

FractureSlack

(pin connection)

Buckling

Buckling-induced failure

7

Chapter 2: Restrainer Design and Clearances


2. 座屈拘束材の設計とクリアランス

Global Stability, including:

Restrainer End

Higher Mode Buckling

Connection Strength

Fatigue Fracture

ConnectionsRestrainer

座屈拘束ブレースの崩壊形式と安定性条件

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)

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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. 局部崩壊の防止

9

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. 接合部設計と全体安定性の確保

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

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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

5. 破断までの累積繰返し変形性能

11

Chapter 6: Performance Test Specification for BRB


(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)

6. 性能確認試験とクライテリア

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Chapter 7.1: Damage Tolerant Concept


Triton Square Project

7.1 損傷制御設計

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Chapter 7.1: Damage Tolerant Concept


Grand Tokyo North Tower Election of Large BRBF

最近の損傷制御設計事例

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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 座屈拘束ブレース外郭構造

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Chapter 7.3: Seismic retrofit with BRBs

Buckling‐restrained Braces and Applications15Midorigaoka-1st Building Retrofit concept

7.3 座屈拘束ブレースによる耐震改修

Before Retrofit

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Chapter 7.3: Seismic retrofit with BRBs


After Retrofit

17

Chapter 7.5: Direct connections to RC frames


7.5 RC 架構への直接接合

2000 2000

2000

2800

2000

225

2000 kN Actuator

1000 kN Actuator

+

Bea

m

Column

For strut

Out-of-plane restrained



40.4º

+

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Chapter 7.6: Applications for truss and spatial structures


7.6 空間構造への応用a) トラス架構への応用

△ △ △ △ △ △

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

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Chapter 7.6: Applications for truss and spatial structures


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

b) ラチスシェル屋根への応用

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Chapter 7.7: Spine frame concepts


7.7 心棒構造への応用

buckling-restrained braces and applications9 chapter 4: connection design and global stability 9...

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