4_award_002_E.pdf

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Chapter 1: Composition and history of Buckling‐restrained Braces
Buckling‐restrained Braces and Applications
1
Buckling-Restrained Braces and
Applications
Toru Takeuchi, Akira Wada,
Ryota Matsui, Ben Sitler, Pao-Chun Lin,
Fatih Sutcu, Hiroyasu Sakata, Zhe Qu
Japan Society of Seismic Isolation, 2017
30-years from the first application, BRBs are still actively researched and
expanding in applications. This book is the first devoted specifically to BRBs.
introduction

2
2
Contents
Chapter 1: Composition and history of buckling-restrained braces
Chapter 2: Restrainer design and clearances
Chapter 3: Local bulging failure
Chapter 4: Connection design and global stability
Chapter 5: Cumulative deformation capacity
Chapter 6: Performance test specification for BRB
Chapter 7: BRBF Applications
7.1 Damage tolerant concept
7.2 Response evaluation of BRBF
7.3 Seismic retrofit with BRBs
7.4 Response Evaluation of BRBs Retrofit for RC Frames
7.5 Direct Connections to RC Frames
7.6 Applications for truss and spatial structures
7.7 Spine frame concepts
Appendix
A1 Typical BRB details
A2 Rotational spring at connections
A3 BRB buckling capacity
introduction

3
3
Concept of Buckling-restrained Brace
Types of restrainer
Appearance of typical BRB
1.1 Composition of
buckling-restrained Braces (BRB)
Mortar

4
4
-600
-400
-200
0
200
400
600
-40 -20 0 20 40
Axial deformation (mm)
Axial
force
(kN)
Hysteresis of well‐designed BRB
Clearance and eccentricity
Development of
higher buckling mode
Restrainer
Core plate

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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

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Chapter 2: Restrainer Design and Clearances
6
Quality Requirement for Hysteresis models
Inappropriate
clearance
Plastic strain
concentration
Local buckling Local bulging
Uneven stiffness
Degradation
in compression side
Uneven
strength
Uneven
strength
Local bulging Degradation
in compression side
Bulging-induced failure
Tearing
Fracture
Slack
(pin connection)
Buckling
Buckling-induced failure

7
Chapter 2: Restrainer Design and Clearances
7
2. Restrainer Design and Clearance
Global Stability,
including:
Restrainer End
Higher Mode
Buckling
Connection
Strength
Fatigue Fracture
Connections
Restrainer
Failure pattern and stability conditions
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)

8
Chapter 3: Local Bulging Failure
8
in‐plane local bulging failure
out‐of‐plane local bulging failure
(Tokyo Institute of Technology)
(National Center for Research on Earthquake Engineering)
3. Local Bulging Failure

9
Chapter 4: Connection Design and Global Stability
9
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. Connection design and global stability

Moment transfer
capacity is lost at the
end of restrainer
EIB
JEIB
JEIB
L0
L0
lB L0
Connection
zone
Connection
zone
Restrained
zone
=Plastic
zone
EIB
>
Bending
moment
transfer
Gusset plate
JEIB EIB
>
JEIB EIB
KRg
KRg
Restrainer-end
zone
Connection
zone
Connection
zone
Restrainer-end
zone
Plastic
zone
Restrained
zone
1: Cantilevered gusset 2: Restrainer end continuity

10
Chapter 5: Cumulative Deformation Capacity until Fracture
10
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. Cumulative deformation capacity

11
Chapter 6: Performance Test Specification for BRB
11
(a) ANSI/AISC 341-05 and US practice
Cycle 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 practice
Cycle 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. Performance test specification for BRB

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Chapter 7.1: Damage Tolerant Concept
12
Triton Square Project
7.1 Damage tolerant concept

13
Chapter 7.1: Damage Tolerant Concept
13
Grand Tokyo North Tower Election of Large BRBF
Following Damage Tolerant Projects

14
Solar-panel Envelope Structure
Flexible and Lightweight structure over the main frame
Main Frame
Spiral Layout of Energy-dissipation
Fuses around Perimeter zones
Open Space
Energy Dissipation Brace
Energy-dissipation Skins with Solar Cells
2. Disaster Prevention and Environmental Sustainability
Grid skin structures

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Chapter 7.3: Seismic retrofit with BRBs
15
Midorigaoka-1st Building Retrofit concept
7.3 Seismic retrofit with BRBs
Before Retrofit

16
Chapter 7.3: Seismic retrofit with BRBs
16
After Retrofit

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Chapter 7.5: Direct connections to RC frames
17
7.5 Direct connections to RC frames
2000 2000
2000
2800
2000
225
2000 kN Actuator
1000 kN Actuator
+
Beam
Column
For strut
Out-of-plane
restrained
Out-of-plane
restrained
Out-of-plane
restrained
40.4º
+

18
Chapter 7.6: Applications for truss and spatial structures
18
7.6 Applications for truss and spatial structures
a) 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 [%]
Force
Limiting
Function
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
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Horizontal Acceleration
Vertical Acceleration
Horizontal Input
(R‐1) Roof with Dampers (R‐2) Base Isolated
Roof
(R‐3) Substructure with Dampers (R‐4) Entire Base Isolation
Seismic Response of Raised Roof
Device Layout for Response-controlled Roof Structures
b) Roof structures

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Chapter 7.7: Spine frame concepts
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7.7 Spine frame concepts

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