buckling-restrained braces and applications1 chapter 1: composition and history of...
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Chapter 1: Composition and history of Buckling‐restrained Braces
Buckling‐restrained Braces and Applications1
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 andexpanding in applications. This book is the first devoted specifically to BRBs.
introduction
2
Chapter 1: Composition and history of Buckling‐restrained Braces
Buckling‐restrained Braces and Applications2
Contents Chapter 1: Composition and history of buckling-restrained braces Chapter 2: Restrainer design and clearancesChapter 3: Local bulging failureChapter 4: Connection design and global stabilityChapter 5: Cumulative deformation capacityChapter 6: Performance test specification for BRB Chapter 7: BRBF Applications
7.1 Damage tolerant concept7.2 Response evaluation of BRBF 7.3 Seismic retrofit with BRBs7.4 Response Evaluation of BRBs Retrofit for RC Frames7.5 Direct Connections to RC Frames 7.6 Applications for truss and spatial structures7.7 Spine frame concepts
AppendixA1 Typical BRB detailsA2 Rotational spring at connections A3 BRB buckling capacity
introduction
3
Chapter 1: Composition and history of Buckling‐restrained Braces
Buckling‐restrained Braces and Applications3
Concept of Buckling-restrained Brace
Types of restrainerAppearance of typical BRB
1.1 Composition of buckling-restrained Braces (BRB)
Mortar
4
Chapter 1: Composition and history of Buckling‐restrained Braces
Buckling‐restrained Braces and Applications4
-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
Chapter 1: Composition and history of Buckling‐restrained Braces
Buckling‐restrained Braces and Applications5
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
Buckling‐restrained Braces and Applications6
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 side
Bulging-induced failure
Tearing
FractureSlack
(pin connection)
Buckling
Buckling-induced failure
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Chapter 2: Restrainer Design and Clearances
Buckling‐restrained Braces and Applications7
2. Restrainer Design and Clearance
Global Stability, including:
Restrainer End
Higher Mode Buckling
Connection Strength
Fatigue Fracture
ConnectionsRestrainer
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)
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Chapter 3: Local Bulging Failure
Buckling‐restrained Braces and Applications8
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
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Chapter 4: Connection Design and Global Stability
Buckling‐restrained Braces and Applications9
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 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
Buckling‐restrained Braces and Applications10
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
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Chapter 6: Performance Test Specification for BRB
Buckling‐restrained Braces and Applications11
(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. Performance test specification for BRB
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Chapter 7.1: Damage Tolerant Concept
Buckling‐restrained Braces and Applications12
Triton Square Project
7.1 Damage tolerant concept
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Chapter 7.1: Damage Tolerant Concept
Buckling‐restrained Braces and Applications13
Grand Tokyo North Tower Election of Large BRBF
Following Damage Tolerant Projects
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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 Grid skin structures
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Chapter 7.3: Seismic retrofit with BRBs
Buckling‐restrained Braces and Applications15Midorigaoka-1st Building Retrofit concept
7.3 Seismic retrofit with BRBs
Before Retrofit
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Chapter 7.3: Seismic retrofit with BRBs
Buckling‐restrained Braces and Applications16
After Retrofit
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Chapter 7.5: Direct connections to RC frames
Buckling‐restrained Braces and Applications17
7.5 Direct connections to RC frames
2000 2000
2000
2800
2000
225
2000 kN Actuator
1000 kN Actuator
+
Bea
m
Column
For strut
Out-of-plane restrained
Out-of-plane restrained
Out-of-plane restrained
40.4º
+
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Chapter 7.6: Applications for truss and spatial structures
Buckling‐restrained Braces and Applications18
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 [%]
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
Buckling‐restrained Braces and Applications19
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) Roof structures
20
Chapter 7.7: Spine frame concepts
Buckling‐restrained Braces and Applications20
7.7 Spine frame concepts