Recent Development of
Seismic Retrofit Methods in Japan
Japan Building Disaster Prevention Association
January 2005
Preface
The Great Hanshin-Awaji Disaster (Kobe Earthquake) caused huge damages to building
structures, especially to old or non-engineered buildings. It has strongly been
recognized that the strengthening of these seismic vulnerable buildings is one of urgent
issues for the reduction of earthquake disaster. Thus, in response to the precious lessons
from the Kobe Earthquake, the Japanese government enacted "the Law for Promotion of
Seismic Retrofit of Buildings," in December 1995. In accordance with the law, existing
buildings of more than certain floor area for public use shall be retrofitted to satisfy the
seismic performance level equivalent to the current code requirement at the time of
renovation.
Practical evaluation of seismic performance and retrofit design of existing buildings has
been based on “The Standard for Seismic Evaluation of Existing Buildings,” and
“Guidelines for Seismic Retrofit Design,” before and after the enacting of the law,
which are published from the Japan Building Disaster Prevention Association.
Conventional methods for seismic retrofit of building structures are provided by the
guidelines in detail, the effectiveness of which has been verified through past
experimental research.
On the other hand, various efficient methods of seismic retrofit have been developed or
invented especially after the Kobe Earthquake. Although the effectiveness of the new
methods was verified through various performance tests by the researchers in the
developers group, neutral and standardized evaluation of the methods was necessary
information to users such as structural designers or clients.
For this purpose, the Japan Building Disaster Prevention Association (President: Tsuneo
Okada) has set up a technical committee for evaluation of methods for building disaster
prevention. The committee (Chairman: Shunsuke Otani) officially started in 1996, and
evaluated 28 methods in total until 2004. The members of the committee from 2004 are
listed below.
Most of the methods for evaluation are recently developed techniques for seismic
retrofit or strengthening of old reinforced concrete buildings in Japan. Requirements
and guidelines for design and construction by the new retrofit methods are prescribed as
a manual in practice. The validity of the manual is evaluated, such as in the viewpoints
of reliability of material properties, member performance, design equations, detailing
and construction work. The scope of the method is also clearly restricted by reviewing
background research. The details on the new methods could be available from the
manuals in Japanese. However, the comprehensive information in English on the
methods was not available.
January 17, 2005, is the tenth anniversary of the Kobe Earthquake. Commemorating the
anniversary, various international events are planned, such as the International
Symposium on Earthquake(ISEE Kobe 2005) and at United Nations World Conference
on Disaster Reduction in Awaji and Kobe, in order to reduce seismic disaster in the
future. The promotion of seismic retrofit of structures worldwide is one of the major
topics to be discussed there. To contribute to the symposium of the conference above by
introducing the seismic retrofit technologies recently developed in Japan, 22 methods
out of 28, evaluated by the JBDPA committee, are outlined in English and compiled in
this volume.
This volume is prepared voluntarily by each developers group according to the given
standard format for distribution at above meetings. Note that the views shown in this
volume do not reflect those of the committee members but those of the developers.
Also please note that some of these outlines in English introduce broader scope of
application than approved by the JBDPA evaluation procedure. The contents is to be
uploaded to the website of JBDPA (http://www.kenchiku-bosai.or.jp) soon and will be
updated periodically in the future. The sincere cooperation and efforts of the developers
for drafting the volume are gratefully acknowledged.
Editor
Toshimi Kabeyasawa
Technical Committee on Evaluation of Building Disaster Prevention Methods
(from April 2004 to present)
Shunsuke Otani (Chiba University, Chairman)
Yoshihoro Abe (Tohoku Institute of Technology)
Toshikatsu Ichinose (Nagoya Institute of Technology)
Daisuke Kato (Niigata University)
Toshimi Kabeyasawa (University of Tokyo)
Takashi Kaminosono (MLIT)
Kazuhiro Kitayama (Tokyo Metropolitan University)
Hiroshi Kuramoto (Toyohashi University of Technology)
Takeyoshi Korenaga (Taisei Corporation)
Hiroyasu Sakata (Tokyo Institute of Technology)
Osamu Joh (Hokkaido University)
Shinichi Sugawara (Science University of Tokyo)
Norio Suzuki (Kajima Corporation)
Matsutaro Seki (Ohibayashi Corporation)
Hideo Tsukagoshi (Shimizu Corporation)
Shigemitsu Hatanaka (Mie University)
Shizuo Hayashi (Tokyo Institute of Techonology)
Masaki Maeda (Tohoku University)
Fumio Watanabe (Kyoto University)
List of Seismic Retrofit Methods
1.
CRS-CL Method (Carbon fiber Retrofit System for CoLumns)
…1
2.
CRS Method (Carbon fiber Retrofit System for Chimney)
…5
3.
MARS system (Mending Application of Reinforced Sheets)
…9
4.
AF System (Aramid Fiber retrofitting system)
…13
5.
-- Not translated
6.
-- Not translated
7.
Precast Retrofit Shear Wall System (PRSW)
8.
-- Not translated
9.
-- Not translated
…19
10. CRS-BM Method (Carbon Fiber Retrofit System for BeaMs)
…23
11. Acrypair System
…27
12. SR-CF System (Seismic Retrofit by Carbon Fiber sheet)
…31
13. -- Not translated
14. CFRP Sandwich Panel Roof
…35
15. Pitacolumn Method
…39
16. Aoki Seismic Retrofit Method by means of Energy Dissipation Braces
…43
17. Seismic Retrofitting Technology of Existing RC Frame Structures
by External Steel Brace Reinforcement
…47
18. Tufnes method
…51
19. -- Not translated
20. SRF (Super retrofit with flexibility)
…57
21. -- Not translated
22. Seismic Retrofit for Existing R/C Buildings using SNE-Tru
…61
23. TARS (Taisei Anchor-less Retrofit System)
…65
24. OFB (Outer-frame brace)
…69
25. Seismic retrofit technology for steel structures using
(Tomoe Friction Damper)
…73
26. PPMG-CR (Seismic Retrofit Technology of Columns with a Special
Polymer-cement Mortar)
…75
27. PCa Brace System
…79
28. PCaPC External Frame Aseismic Strengthening System
…83
1. Title
CRS-CL Method (Carbon fiber Retrofit System for CoLumns)
2. Outline
CRS-CL Method is a seismic retrofit technique for existing reinforced concrete columns
and concrete-encased steel composite columns using carbon fiber reinforced plastic
(CFRP) sheet or strand. Shear strength, lateral deformability and axial capacity of the
column members can be improved by confining with CFRP sheet or strand.
3. Specifications for materials
CRS-CL Method uses carbon fiber (CF) sheet or strand as the reinforcing material.
Table 1 lists their design specification values.
Table 1 Specifications of the reinforcing materials
(a) carbon fiber sheet
weight
thickness
g/m2
200
300
mm
0.111
0.167
Elastic
modulus
kN/mm2
Fracture
stress
N/mm2
Stress
for design
N/mm2
230
3400
1750
(b) carbon fiber shrand
number of
filament
12000
area
mm2
0.435
Elastic
modulus
kN/mm2
230
Fracure
stress
N/mm2
3400
Stress
for design
N/mm2
1750
4. Typical construction details
The construction process of CRS-CL Method is as follows: removal of existing
finishing, rounding of corners, wrapping CF sheet or winding CF strand with
simultaneous impregnation of epoxy resin, and finishing of the retrofitted column.
Figure 1 shows cross sections according to the construction process. Figure 2 illustrates
wrapping CF sheet (Sheet Method) and winding CF strand (Strand Method).
glinding
exsiting
finishing
existing
column
mortar
CFRP
mortar
Figure 1 Typical construction details
1
finishing
existing
column
existing
column
carbon fiber
strand
carbon fiber
sheet
(a) wrapping CF sheet (Sheet Method)
(b) winding CF strand (Strand Method)
Figure 2 Two methods for providing CFRP
5. Research for verification
The effectiveness of CRS-CL Method for strengthening reinforced concrete columns
has been verified through a series of seismic tests. Static loading tests on columns or
beams were conducted for the total of 78 specimens in the first to tenth phase, which
represents reinforced concrete or concrete-encased steel composite columns in old
buildings of Japan or bridge columns of highway and railway. Many of the columns
were strengthened using carbon fiber sheet or strand. The columns strengthened by the
new method could maintain lateral and axial load capacity until more than eight percent
inter-story drift, while the bare specimens without strengthening failed in shear or bond
at small drift and graduately lost axial load capacity. The typical hysteresis relations are
compared for a bare reinforced concrete specimen and a CRS specimen as shown in
Figure 2. The specimens after tests are shown in Photo 1. Concrete prisms and cylinders
confined with the CFRP material were also tested to grasp the confinement by CFRP.
Through these test series, the method is verified to be effective for prevention of the
loss of lateral and axial load capacity under various structural conditio ns. And also, a
structural design guideline for CRS-CL Method was established.
A shaking table test was conducted for the verification of the new strengthening method
under dynamic loading. Each specimen consists of four reinforced concrete columns
and a loading steel slab and tested on the shaking table at the Institute of Obayashi. One
was a bare reinforced concrete column specimen designed to fail in a brittle manner,
while the other was strengthened by the CRS-CL Method. The bare columns without
strengthening failed in shear resulting in collapse associated with loss of the axial load
capacity. On the other hand, the columns strengthened by CRS Method survived against
three times of the same input motion. The bare reinforced concrete columns and
CRS-CL columns after the shaking table test are shown in Photo 2.
2
LM18
500
600
300
400
Load(kN)
Load(kN)
LM00
100
-50
-25 -100 0
25
50
75
100
-300
200
0
-50
-25
-200
0
25
50
75
-400
-500
-600
Displacement(mm)
Displacement(mm)
(a) RC (without CFRP)
(b) CRS-CL (with CFRP)
Figure 2 Typical hysteresis relations of RC and CRS columns
(a) RC column
(b) CRS-CL columns
Photo 1 Specimens after static a loading test
(a) RC column
(b) CRS-CL columns
Photo 2 RC column and CRS-CL column after a shaking table test
3
100
6. Examples in practice
At least, more than 200 of structures (buildings and public
works) in all over Japan have been retrofitted with
CRS-CL Method, including highway piers, a water tank
tower, old office buildings, school buildings, hospital
buildings and museums, etc.
(a) column in an old office building
(b) column in a museum
(Sheet Method)
(Strand Method)
Photo 3 Examples of application
7. References
1) Hideo Katsumata, Yoshirou Kobatake, and Toshikazu Takeda: A study on
strengthening with carbon fiber for earthquake-resistant capacity of existing
reinforced concrete columns, proc. of 9WCEE, Vol. VII, pp.517-522, 1988
2) Hideo Katsumata and Yoshirou Kobatake: Seismic retrofit with carbon fibers for
reinforced concrete columns, proc. of 11WCEE, paper No. 293, 1996.
3) Hideo Katsumata, Kohzo Kimura, and Hisahiro Murahashi: Experience of FRP
Strengthening for Japanese historical structures, Elsevier Science, FRP composite in
civil engineering, Vol. II, pp.1001-1008, 2001
4) Obayashi Corporation, et al.: The design and construction guideline for CRS-CL
Method (revised 2003), Obayashi Corporation (in Japanese)
8. Ownership organization
Obayashi Corporation (Head Office), 1088502, Minato-ku, Tokyo.
Obayashi Corporation (Technical Research Institute), 2048558, Kiyose-shi, Tokyo.
Tel: +81-424-95-1111
Fax: +81-424-95-0901
URL: www.obayashi.co.jp/virtual/index.html
9. Certification
JBDPA Certification No.1675(current), No.1166(previous in 1998, 1995, 1991)
BCJ Evaluation No.C-1985 and Fire Safety-1561, Approval
of
Minister
Construction: 1999 Apr. 6 and 1997 Jun. 12
Patent No.: 1865468(Japan), 1880461(Japan), 1865467(Japan), 2078774(Japan),
3119129(Japan), 3185640(Japan), 3249736(Japan), 3246341(Japan)
4
of
1. Title
CRS Method (Carbon fiber Retrofit System for Chimney)
2. Outline
CRS Method for chimney is a seismic retrofit technique for existing reinforced concrete
chimney using carbon fiber reinforced plastics (CFRP) sheet and strand. Flexural
strength of the chimney is improved by gluing with CFRP sheet and safety margin for
thermal stress is increased by winding with CFRP strand.
3. Specifications for materials
CRS Method for chimney uses carbon fiber (CF) sheet and strand as the reinforcing
material. The design specification values of carbon fiber and Carbon Fiber Reinforced
Plastics (CFRP) show below:
Tensile strength: 2,650N/mm2 (270kgf/mm2 )
Tensile modulus: 216∼255kN/mm2 (2.2∼2.6×104 kgf/mm2 )
4. Typical construction details
The construction process of CRS Method for chimney is as follows: (1) removal of
lightning conductor and ladder, (2) substrate treatment and/or arrangement of concrete
surface, (3) gluing carbon fiber sheet in the longitudinal direction, (4) winding carbon
fiber strand impregnated with epoxy resin along the hoop direction, (5) restoration of
the lightning conductor and ladder, (6) painting according to provisions for safety of
airplanes. Figure 1 illustrates the basic concept of CRS Method for chimney by gluing
CF sheet and winding CF strand. Photos of Figure 2 show the general view by a
scaffold lift and the retrofitting works on the scaffold lift.
Figure 1 Basic concept
(a) General view of execution by scaffold lift
Figure 2 Typical construction details
5
(b) gluing CF sheet
(c) winding CF strand
Figure 2 Typical construction details (continued)
5. Research for verification
The effectiveness of CRS Method for strengthening reinforced concrete chimney has
been verified through a series of flexural tests. Six flexural loading tests on hollow
reinforced concrete cylinder specimens modeled on an existing reinforced concrete
chimney were conducted. The experimental setup is shown in Figure 3. Monotonous
load was applied steadily at two points of the specimen until a load drop occurred due to
fracture of CFRP. The load-displacement relationship is shown in Figure 4. This figure
shows that the maximum strength is much improved and the displacement at maximum
strength become large as the amount of longitudinal CF is increased.
Following fundamental tests on adhesion properties between CFRP and concrete
surface were also carried out: (1) adhesion length of CF sheet to concrete surface, (2)
lap joint length of CF sheet, (3) durability of the adhesive strength by accelerated
artificial exposure. The adhesion tests (1) and (2) suggest that the development length of
CF sheet should be more than 20cm and the length of lap joint needs more than 10cm.
The specimen of durability test, as shown in Figure 5, consists of two concrete blocks,
40×40×100mm, which were jointed with CF sheet. After exposure, the specimen was
pulled at each end. Results of the tensile tests after exposure are shown in Figure 6 and
indicate that the adhesive strength between concrete surface and CF sheet decreases
with the time of accelerated artificial exposure, a decrease of about 10% at 2,000 hours
and about 15% at 4,000 hours compared with the non-exposure specimen.
Figure 3 Specimen and experimental setup
6
Figure 4 Load-displacement relationship
Figure 5 Specimen of exposure test
Figure 6 Maximum load-accelerated exposure time relationship
7
6. Examples in practice
In Japan, over 60 chimneys have been retrofitted by CRS Method, including high-rise
chimney.
Figure 7 Example of application
7. References
1) Yoshiro Kobatake, Kohzo Kimura, and Hideo Katsumata：A retrofitting method for
reinforced concrete structures using carbon fiber，Fiber-reinforced-Plastic(FRP)
Reinforcement for Concrete Structures: Properties and Applications ， Elsevier
Science Publishers, 1993.
2) Kohzo Kimura, Yoshiro Kobatake, Hideo Katsumata, Kensuke Yagi, Takeo
Sawanobori, and Tsuneo Tanaka：A study on seismic retrofit of reinforced concrete
members using carbon fiber (part.2), p.821-p.822, AIJ, 1988 (in Japanese)
3) Yoshiro Kobatake, Kohzo Kimura, and Hideo Katsumata：A retrofitting method for
reinforced concrete structures using carbon fiber ， AIJ J. Technol. Des.No.2,
p.62-p.67, Mar., 1996 (in Japanese)
8. Ownership organization
Obayashi Corporation (Head Office), 1088502, Minato-ku, Tokyo.
Tel: +81-3-5769-1111
URL: www.obayashi.co.jp
9. Certification
The Japan Building Disaster Prevention Association Certification No.1597 (current),
1997 Sep. 17, 1991 Sep. 17 (previous)
Patent No.: 2130247(Japan), 02718459(Japan)
8
1. Title
MARS system (Mend ing Application of Reinforced Sheets)
2. Outline
MARS system is the method of reinforcing existing concrete structures with FRP
(fiber-reinforced plastic) sheets that are strong, lightweight, and superior anti-corrosive.
FRP sheets, by wrapping around surfaces of concrete structures, increase the durability
and the ductility of structural members.
3. Specifications for materials
MARS uses carbon fiber sheet which are arranged in regular order, and made to carbon
fiber dry sheet.. Table 1 lists their design specification values.
Table 1 Specifications of the reinforcing materials
Maker
Name
Tensile strength
Tensile modulus of elasticity
2
TOHO TENAX Besfight 3400N/mm over
2.27×105 N/mm2 over
HTA-12K
4. Typical construction details
Figure 1 sho ws a cross section and view.
1
2
3
4
①Concrete surface treatment(edge cutting more than r=20mm)
②Primer coating
③Matrix resin coating
④CFRP sheet gluing
⑤Matrix resin coating
Figure 1 Typical construction details
9
5
5. Research for verification
The effectiveness of MARS for strengthening reinforced concrete columns has been
verified through a serious of seismic tests. Tests on columns were conducted for
nineteen specimens, which represents reinforced concrete columns in old buildings of
Japan or worldwide. Some of the columns were strengthened using carbon fiber sheet.
The columns strengthened by the new method could maintain relatively high gravity
load until more than ten percent inter-story drift, while the bare specimens without
strengthening failed in shear at small drift simultaneously losing axial load capacity.
The typical hysteresis relations are compared for bare reinforced concrete specimen and
MARS specimen as shown in Figure 2 with after tests photograph. Various types of
concrete prisms and cubes confined with the sheet were also tested, based on which the
resistance mechanisms of the columns were interpreted. Through these test series, the
method has been improved to be effective to prevent the loss of capacity not only
against axial load but also against lateral load reversals.
No reinforcement
400
Axial force rate=0.4
Qmax= 294.6kN, 8.55mm
Qmin=-295.6kN,-6.02mm
300
部材角
Ｒ(rad)
200
-1/50
-1/30 -1/100
100
Shear force(kN)
0
P-δ効果
-100
+1/100 +1/30
+1/50
-200
+1/10
部材角
Ｒ(rad)
-300
-400
-40
-20
0
20
40
60
80
100
Displacement(mm)
(a) RC (without carbon fiber sheet)
2 sheets reinforcement
Axial force rate=0.4
400
Qmax= 275.5kN, 12.60mm
Qmin=-285.5kN,- 9.02mm
部材角
Ｒ(rad)
-1/50
-1/30 -1/100
300
200
Shear force(kN)
100
0
P-δ効果
-100
+1/100 +1/30
+1/50
-200
+1/10
部材角
Ｒ(rad)
-300
-400
-40
-20
0
20
40
Displacement(mm)
60
80
100
(b) SRF (with carbon fiberr sheet)
Figure 2 The typical hysteresis relations and photograph
of RC column and MARS column
10
6. Application Example
Many of constructed facilities have been retrofitted with MARS system.
Columns in buildings
Photo 1 Examples of application
7. References
4) Norimitsu Hayashida and Tomoaki Tsujimura: A strength method using carbon fiber
sheets for improving the earthquake resistance of existing reinforced concrete
columns，Kumagaigumi Technical Research Report NO.55，1996.
8. Ownership organization
Kumagai Gumi Co., Ltd., Shinjyukuku, Tokyo.
Tel: +81-3-3235-8617
Fax: +81-3-3235-9215
E- mail: info@ku.kumagaigumi.co,jp
URL: www.kumagaigumi.co.jp
9. Certification
11
1. Title
AF System (Aramid Fiber retrofitting system)
2. Outline
AF System is a seismic retrofit technology for existing reinforced concrete columns
using aramid fiber sheets against earthquake loading and was certified by JBDPA (The
Japan Building Disaster Prevention Association). Deformability of the column members
can be improved by confining with aramid fiber sheets.
3. Specifications for materials
AF System uses woven aramid fiber sheets as the reinforcing material. Aramid fibers
are arranged to the axial direction of the sheets. Figure 1 shows an aramid fiber sheet
and Table 1 lists their design specification values. Aramid fiber sheets are characterized
by light weight, high strength, no corrosion, and no n-conductivity.
Figure 1 Aramid fiber sheet
Aramid 1
Aramid 2
Table 1 Specifications of the reinforcing materials
Type
Weight Thickness Width
Tensile
(g/m2 )
(mm)
(mm)
strength
(N/mm2 )
40tf
280
0.193
100
2060
60tf
415
0.286
90tf
623
0.430
300
40tf
235
0.169
500
2350
60tf
350
0.252
90tf
525
0.378
Young’s
modulus
(×103 N/mm2 )
118
78
4. Typical construction details
Figure 2 shows a typical construction procedure of AF System. Epoxy resin is used for
matrix of the sheets.
12
Surface treatment
Coating primer
and epoxy resin
Wrapping sheet and
Coating epoxy resin
removing air with roller Finishing with mortal
or painting
Figure 2 Typical construction prcedure
Figure 3 Attaching aramid fiber sheet
5. Research for verification
The effectiveness of AF System for strengthening reinforced concrete columns has been
verified through a serious of seismic tests. Static tests on columns were conducted for
many specimens varying amount of fibers to establish design methods. Figure 4 (a)
shows a bare RC column without aramid fiber sheet which represents columns in old
buildings. The columns strengthened by AF System (Figure 4 (b)) could carry higher
lateral load and show ductility with flexural failure while the bare RC columns failed in
shear with relatively low deformation. The typical hysteresis relations are compared for
bare reinforced concrete specimen and AF specimen as shown in Figure 4.
13
Load (tf)
Lateral deformation (cm)
Load (tf)
(a) RC (without aramid fiber sheet)
Lateral deformation (cm)
(b) AF (with aramid fiber sheet)
Figure 4 The typical load-deformation relations of RC column and AF column
Further research have been continued to develop applications of aramid fiber retrofitting
method after the certification of AF System by JBDPA. Research themes about aramid
fiber sheet developed by many organizations are listed as follows:
Shortened columns by spandrel wall
Columns subjected to high axial force (N/bd=0.6)
Columns with finishing mortal
Columns with wing wall
Columns with low strength concrete of fc=6N/mm2
14
Axial behavior of axially loaded columns
T-shaped girders with slab
Anchorage for aramid fiber sheet with steel plate and bolt
Application of super high quantity sheets up to 1500g/m2
Steel plate and aramid fiber sheet composite method
For example, Figure 5 shows a shortened column by spandrel wall reinforced with
aramid fiber sheets after lateral loading tests. The specimen under constant axial load
maintains maximum lateral force up to deformation of 10% of column height.
Figure 5 Short column with aramid fiber sheet
6. Examples in practice
AF system is certified by JBDPA for existing building columns that require
strengthening for shear. But applications of aramid fiber sheets have been widely
expanding not only for building columns but also for bridge piers, tunnels, and
chimneys etc. More than 500 structures have been retrofitted with aramid fiber in Japan.
Figure 6 Shear strengthening of building columns
15
Figure 7 Strengthening and repair for girders and slabs
Figure 8 Strengthening for bridge pires
Figure 9 Repair for chimney
16
7. References
5) Minoru Oda, Tadashi Okamoto, Hisayuki Yamanaka and Akira Asakurua: Shear
strengthening of existing RC columns wrapped witharamid fiber , Proceedings of
Japan Concrete Institute，vol.15 No.2, 1993
6) Kiyoshige Suzuki, Tomoya Nagasaka, Tadashi Okamoto and Masaharu Tanigaki:
An experimental study on shear capacity of existing RC columns strengthened with
continuous fiber tapes, Summaries of technical papers of annual meeting ,
Architectural Institute of Japan, vol.C-2 , Sept. 1996
7) Masaharu Tanigaki, Kazuhiko Ishibashi and Hideaki Ibuki: Shear strengthening
shortened columns by spandrel using aramid fiber sheets, Proceedings of Japan
Concrete Institute，vol.22 No.3, 2000
8. Ownership organization
AF System Association
AIG Nihombashi Hommachi Bld. 1-1-1 Nihombashi Hommachi, Chuoku, Tokyo.
DU PONT-TORAY Co.,Ltd.
Tel: +81-3-3245-5082
Fax: +81-3-3242-3183
E- mail: koichi_tsukamoto@td-net.co.jp
9. Members of AF System Association
Administration: DU PONT-TORAY Co.,Ltd.
OBAYASHI Corporation, KAJIMA Corporation,
SHINKO WIRE Co.,Ltd., SHO-BOND Corporation,
TEIJIN TECHNO PRODUCTS Limited, TOKYU Construction,
SUMITOMO MITSUI Construction Co.,Ltd.
10. Certification
AF System was certified by JBDPA in 1997 ( No.1624) and revised in 2002
17
18
1. Title
Precast Retrofit Shear Wall System (PRSW)
2. Outline
This system is a seismic retrofit technology, which installs a precast concrete wall in an existing
reinforced concrete flame. The characteristic point of this system is the connection method
between the precast wall and the reinforced concrete flame. The connection method is shown in
Fig. 1.
Fig.1 Outline of precast retrofit shear wall system and a connection detail
3. Specifications for materials
Specifications for materials are shown in Table. 1.
Table. 1 Specifications for materials
Materials
Specifications
Concrete
Reinforcement
21Pa∼36Pa
SR235,SD295A,SD345,SD390
Prestressing
steel bar
SBPR 785/1030,SBPR 930/1080,
SBPR 1080/1230
4. Construction details
This system consists of three types of precast concrete walls as shown in Fig. 2.
Fig. 2 Three types of Precast concrete walls
19
5. Research for verification
The seismic loading tests were done for explained the behavior of precast retrofit shear wall.
Figure 4 shows main test specimens.
RCW-1(retrofit reinforced concrete wall)
PCW-3(Retrofit precast concrete wall)
Fig. 4 Test specimens
Test specimens are on a scale of 1/3. RCW-1 is that the resisting wall is consisted of concrete
placing in existing reinforced concrete frame, while PCW-3 is that the shear wall is consisted
of setting precast retrofit wall in existing concrete frame. Loading method is shown in Fig. 4.
Loading cycle is shown in Fig. 5. Figure 6 describes the behavior of test specimens.
Fig. 4 Seismic loading method
Fig. 5 Loading cycle
20
Fig. 6 The behavior of test specimens
6. Examples in practice
Precast Retrofit Shear Wall System haves 13 examples in practice. Fig. 7∼Fig. 18 show the
example of practice.
Fig. 7 Interior before retrofit
Fig. 8 Removal of existing RC wall
Fig. 9 in-situ of anchoring
Fig. 10 Carrying in of precast wall
Fig. 11 Move of precast wall inside
Fig. 12 Setting of precast walls
21
Fig. 13 Setting of prestressing steel bars
Fig. 14 Prestressing by oil jack
Fig. 15 Connection reinforcement
Fig. 16 Finish of connection reinforcing
Fig. 17 Grouting
Fig. 18 nterior finishing
7. References
1) The Japan building disaster prevention association: Guidelines for Seismic Retrofit of
Existing Reinforced Concrete Buildings, 2001
8. Ownership organization
Pre-cast Retrofit Shear Wall Society Chuoku Tokyo.
Tel : +81-3-5651-8232
Fax : +81-3-5651-8229
22
1. Title
CRS-BM Method (Carbon Fiber Retrofit System for BeaMs)
2. Outline
CRS-BM is a seismic retrofit technique for existing reinforced concrete beams using
carbon fiber reinforced plastic (CFRP) sheet. Shear strength and lateral deformability of
the beam members can be improved by wrapping with CFRP sheet.
3. Specifications for materials
CRS-BM Method uses carbon fiber (CF) sheet as the reinforcing material. Table 1 lists
their design specification values.
Table 1 Specifications of the reinforcing materials
weight
thickness
g/m2
200
300
mm
0.111
0.167
Elastic
modulus
kN/mm2
Fracture
stress
N/mm2
Stress
for design
N/mm2
230
3400
1750
4. Typical construction details
The construction process of CRS-BM Method is as follow: removal of coating,
preparation of surfaces with chamfering of corners, setting of bolts, application of
primer, wrapping CFRP, setting plates, and finishing with coatings. Figure 1 illustrates
wrapping CF sheets.
bolt
flat bar
flat bar
chamfering
Type 1
bolt
CF sheets
Existing
RC Beam
flat bar
Type 2
Figure 1 Typical construction details
23
bolt
5. Research for verification
The effectiveness of CRS-BM Method for strengthening reinforced concrete beams has
been verified through a series of seismic tests. Static loading tests on beams were
conducted for eight specimens in the first phase, and eight and five in the second and
the third, which represent reinforced concrete beams in old buildings of Japan. Many of
the beams were strengthened using CF sheet. The beams strengthened by the new
method could maintain lateral load capacity until more than 5% drift, while the bare
specimens without strengthening failed in shear at small drift. The typical hysteresis
relations are compared for a bare reinforced concrete specimen and a CRS-BM
specimen as shown in Figure 2. The specimens after tests are shown in Photo 1.
600
CF2-P (Two layers)
RC (Unretrofit)
Shear force (kN)
400
CF1-A1 (One layer)
CF1-A1 (One layer)
200
RC (Unretrofit)
0
CF2-P (Two layers)
0.02
0.04
0.06
deflection angle (rad.)
(a) Anchoring methods of CF sheets
(b) Relationships between shear force
and deflection angle
Figure 2 The typical hysteresis relations of RC beam and CRS-BM beam
(a) unretrofit beam
(b) retrofit beam
Photo 1 Specimens during and after tests
24
6. Examples in practice
Some buildings that had weak beams were retrofitted with CRS-BM Method. An
example for a school building in Kobe is shown in Photo 2.
Photo 2 Examples of application (beams in a school building)
7. References
1) Hagio Hiroya, Katsumata Hideo, and Kimura Kohzo: T he Beam Retrofitted by
Carbon Fiber - Experiment and Designs，12WCEE，Feb. 2000.
2) Obayashi Corporation, et al. : The design and construction guideline for CRS-BM
Method (revised 2004), Obayashi Corporation (in Japanese)
8. Ownership organization
Obayashi Corporation (Head Office), 1088502, Minato-ku, Tokyo.
Tel: +81-3-5769-1111
URL: www.obayashi.co.jp
Obayashi Corporation (Technical Research Institute), 2048558, Kiyose-shi, Tokyo.
Tel: +81-424-95-1111
Fax: +81-424-95-0901
URL: http://www.obayashi.co.jp/virtual/index.html
9. Certification
(Current )
JPDPA Certification No.1776
(Previous)
JPDPA Certification No.1280
Patent No. : 3301288(Japan)
25
26
1. Title
Acrypair System
2. Outline
Acrypair System is an advanced technology for strengthening reinforced concrete
structures using carbon fiber sheets and methyl methacrylate (MMA) resin. It is effective
for concrete and RC materials and provide the ease and speed of applications construction.
3. Specifications for materials
The specifications for the CF sheet used to make the specimens are shown in Table 1. The
properties of the MMA resin and those of the reference epoxy resin are shown in Table 2.
Ｔ
ａ
ｂ
ｌ
ｅ1 Specifications for carbon fiber sheets
Unit Weight Design
Fiber
Tensile
of sheet
thickness
density
strength
(g/m2)
(mm/sheet) (g/mm3)
(N/mm2)
300
0.167
1800
3432
Tensile
modulus
(N/mm2)
2.36×105
Table 2 Properties of the resin used for impregnarion and bonding
Resin
Ambient temperature Viscosity Curing time Flexural strength Flexural modulus
(℃)
(Pa･s)
(min)
(N/mm2)
×103(N/mm2)
MMA
30
0.2
43
63
2.77
20
0.26
50
64
2.76
10
0.52
41
60
2.4
0
0.72
42
64
2.64
20
10 or more
600
98
3.33
Epoxy1)
1) Room-temperature-curing epoxy resin commonly used in the CF sheet strengthening method
4. Research for verification
Rehabilitation and maintenance of existing RC structures recently become the subject of
wide interest. The use of composite wraps on concrete materials presents an economical
and efficient means of strengthening the structures. Means using continuous fiber materials,
particularly carbon fiber sheets, are one of the effective approaches. The CF sheet method
involves attaching the sheets to RC and epoxy resins typically use as matrix and adhesives.
However the method using epoxy resins have restriction on field application because of
slow curing reaction, especially at low temperatures such as below 5℃. To eliminate such
restriction, alternative resin systems, which are acrylic resins, have been developed. The
new resin systems have excellent curing properties such as rapid reaction and
low-temperature curing ability.
The acrylic resins are specially designed to cure within an hour at required temperatures.
These short curing times cause limitation of attaching operation area at a time. To secure a
sufficient amount of time for the operation, ABA Two-Component method (ABA-TCM)
was developed. The concept of ABA-TCM is represented in Fig 1. Two types of resin
fluids, one containing only a hardener and the other containing only an accelerator, are
prepared. These fluids are brought into contact and mixed together at applied surface
during impregnation to CF sheets. ABA-TCM has been already confirmed on mechanical
27
properties of the composites.
Apply primer
Cure primer
Apply B resin fluid
Apply A resin fluid
Apply A resin fluid
Impregnate by roller
Finish
Figure 1 Concept of ABA-TCM
RC pillars wrapped with CF sheets were tested for shear. The test variables consisted of the
number of CF sheet piles and two load conditions as summarized in Table 3. The test series
specimens were applied a static axial load and a cyclic lateral load and symbolized. The
details of the tests are illustrated in figure 2. CF sheets were wrapped around RC pillars in
the hoop direction and the lap joint lengths were 200 mm.
Table 3 Details of shear test specimens
Specimen
Load
Hoop steel
CF sheet
C-08-0 Cyclic lateral load pw=0.08%
None
C-08-3
&
1 ply (pf=0.0835%)
C-08-6 Axial load : 530kN (□D6-@200) 2 plies (pf=0.111%)
pf : CF volume percentage of specimen
pw : hoop steel volume percentage of specimen
Axial load
1200
Lateral load
400
400
C series specimen
Figure 2 Schematics of RC strengthening test and specimens geometry (mm)
The load-deformation curves of the test series specimens are shown in Fig 3. The
maximum forces and the ultimate deformations on specimens wrapped with CF sheets
28
Shear force (kN)
600
300
C-08-0
600
300
600
C-08-3
300
0
0
0
-300
-300
-300
-600
-600
-20
0
20
-50
Deformation d (mm)
0
Deformation d (mm)
50
C-08-6
-600
-50
0
50
Deformation d (mm)
100
Figure 3 Relationship of deformation and shear force at shear test
Ｔ
ａ
ｂ
ｌ
ｅ4 Results of RC pillar shear test
Specimen Maximum shearShear strength
force (kN)
(MPa)
C-08-0
303
1.89
C-08-3
434
2.72
C-08-6
513
3.21
were extremely improved as shown in Table 4.
The acceptability of CF sheets/MMA resin system for strengthening concrete was
confirmed. This system exhibited superior strengthening effect for concrete subjects on
compression and shear. The acrylic resins for matrix and primer in this system had rapid
curing and low-temperature curing ability without reduction of mechanical properties of
the composites. Thus the availability and the versatility of CF sheets strengthening method
for construction applications could increase by using this system. Evaluation of durability
of this system on mechanical properties has progressed.
5. Examples in practice
The concrete pillar exceeding 10 affairs was reinforced with Acrypair system. Moreover,
30 or more reinforcement was performed in structures other than a pillar.
1) Reinforced pillar of the station building.
29
2) Reinforced pillar of factory.
Photo 1 Examples of application
6. References
1) Y.Sakai, S.Ushijima, S.Hayashi and T.sano, “Mechanical characteristics of carbon fiber
sheet with methyl methacrylate resin”, Proceedings of the third International Symposium
on Non-metallic(FRP) Reinforcement for Concrete Structures. Vol.2, 1997, pp.243-250.
2) T.Sano, S.Hayashi and T.Furukawa, “Studies on applicability of CF sheets/MMA resin
system for strengthening concrete structures”, 43rd International SAMPE Symposium,
1998.
7. Ownership organization
Ryoko Co., Ltd. Construct Chemicals Division
14-1 Koami-cho, Nihonbashi Chuo-ku, Tokyo, 103-0016 JAPAN
PHONE:03-5651-0656
FAX :03-5651-0055
URL: http://www.kkryoko.co.jp/
8. Certification
Patent No. 10-110536(Japan)
30
1. Title
SR-CF System (Seismic Retrofit by Carbon Fiber sheet)
2. Outline
The SR-CF system 1) is a seismic retrofitting technology for existing reinforced concrete
buildings by adhering carbon fiber sheets with epoxy resin on the concrete surfaces.
This system can improve the structural properties of independent columns, columns
with wing-walls 2), beams 3), and walls 4) by using special devices called CF-anchors,
while conventional seismic strengthening by carbon fiber sheets has been considered to
be effective only to independent columns. The use of the CF-anchor is the most
characteristic in this system.
3. Specifications for materials
PAN type unidirectional carbon fiber sheets and carbon fiber strands are used in the
SR-CF system. Carbon fiber strands are used as materials of the CF anchors. Sizing
level of the carbon fiber strand is regulated smaller in order that the epoxy resin can be
easily impregnate into the strand. Table 1 lists their design specification values.
Table 1 Specifications of the carbon fiber sheets
Fiber areal weight (g/m2 )
200
300
Thickness (mm)
0.111
0.167
Tensile strength (MPa)
3400
3400
Young's modulus (GPa)
230
230
Table 2 Specifications of the carbon fiber strands
Type
12K
24K
Cross section (mm2 )
0.435
0.870
Tensile strength (MPa)
4500 for strands
4500 for strands
3400 for CF-anchor
3400 for CF-anchor
Young's modulus (GPa)
230
230
4. Typical construction details
Figure 1 shows a schematic diagram of the SR-CF system. The innovative technique
called CF-anchor is used in this system. The CF-anchor is a bundle of carbon fiber
strands which are strings of 2 to 3 mm in diameter consisting of 24,000 or 12,000
filaments. There are two types of CF-anchors. One is penetrating type, and another the
fixing type.
The penetrating anchors are used for the shear strengthening of columns with wing
walls. A bundle of carbon fiber strands is penetrated through a hole drilled at the wing
wall. The ends of the bundle are spread like a fan and adhered to the carbon fiber sheet
which is previously applied on the column. The bundle joins the both ends of the carbon
fiber sheet, which was separated by the side wall. Consequently, it is made possible to
envelop the column by the carbon fiber without demolishing a part of wing walls.
Beams with slabs can be strengthened by the same method.
The fixing- type CF-anchors are used for the shear strengthening of walls. The carbon
31
fiber sheet is adhered on the wall surface diagonally. An end of the CF-anchor is spread
like a fan and adhered to the carbon fiber sheet. The other end is inserted into a hole
drilled on the peripheral reinforced concrete frame and is fixed with injected epoxy
resin. The CF-anchors fix the edges of the carbon fiber sheets on the wall to the
peripheral columns and beams.
Figure 1 Schematic diagram of the SR-CF System
5. Research for verification
A number of specimens were tested to evaluate the effect of strengthening for each type
of structural members, such as independent columns, columns with side-walls, beams
with slabs, and walls. Photo 1 shows specimens of columns with side-walls after the
tests. (a) is a specimen without strengthening and (b) is a specimen strengthened by the
SR-CF system. The specimen without strengthening failed in sheer at small drift angle.
On the other hand, the column of the strengthened specimen was not so much damaged
even at 3.0% of drift angle while the wing walls were considerably damaged. Figure 2
shows the test results of the wall specimens. It shows that the shear strength of the
strengthe ned walls increase in proportion to the amount of the carbon fiber sheets on the
wall surfaces.
6. Examples of Application
Photo 3 show the execution of CF-anchors to the column with spandrel walls and
windows. The CF-anchors are penetrated through the walls at the narrow space between
the column and the window frame (a). As a result, the strengthening was completed
without temporally removing the windows (b). Photo 4 shows a strengthening of a beam
and Photo 5 shows a strengthening of a wall.
32
(a) Specimen not strengthened
(b) Specimen strengthened by SR-CF system
Photo 1 Failures of column with wing-walls specimens after tests
Photo 2 Beam specimens after tests
Figure 2 Test results of wall specimens
(a) The CF-anchor under installation
(b) Strengthening completed
Photo 3 Application to the column with wing walls
33
Photo 4 Application to the beam with slabs
Photo 5 Application to the wall
7. References
3) SR-CF System Research Association：Design Guidelines for SR-CF System, Feb.
2002 (in Japanese)
4) K.Masuo, S.Morita, Y.Jinno, H.Watanabe ： Advanced Wrapping System with
CF-anchor -Seismic Strengthening of RC Columns with Wing Walls-, FRPRCS-5,
Vol.1, pp.299-308，May 2001
5) Y.Jinno, H.Ts ukagoshi：Seismic Strengthening of Reinforced Concrete Beams with
Slabs by Carbon Fiber Sheet and CF-anchor, Proceedings of Structural Engineers
World Congress 2002, Session T8-3-a-1, pp.1-8, Oct.2002
6) Y.Jinno, H.Tsukagoshi：Seismic Strengthening of Reinforced Concrete Walls by
SR-CF System, Proceedings of the first fib congress 2002, Session 6, pp.109-118,
Oct.2002
8. Ownership organization
SR-CF System Research Association, Tokyo, Japan
Tel: +81-3-5623-5558
Fax: +81-3-5623-5551
E- mail: inq@sr-cf.com
9. Certification
JPDPA Certification No.1399
Patent No.: US 6330776 B1(USA), 10-2000-7002781(Korea) , 121278(Taiwan)
Patent Application No.(Published): 10-206983(Japan) etc.
34
1. Title
CFRP Sandwich Panel Roof
2. Outline
The CFRP sandwich panel roof is the lightweight monocoque roof which is made by
CFRP (Carbon Fiber Reinforced Polymer) sandwich panel. Its weight is about one-forth
as heavy as existent prestressed precast concrete shell. Due to the lightness, it is
possible to improve the earthquake resistance of many steel reinforced concrete
gymnasiums in Japan by replacing precast concrete shell with the CFRP sandwich panel
roof while it is possible to reduce reinforcing sub-structures.
3. Specifications for materials
3.1 Components and Materials
CFRP sandwich panel is composed of skins, core and ribs (see Fig.1). Skin is made of
CFRP. The cubic ratio of CF is 5%, GF(Glass Fiber) 45% and phenol polymer 50%. The
thickness of the skin is 4mm. Core is made of phenol foam. The thickness of the core is
75mm. Rib is made of GFRP. The thickness of the rib is 2.2mm. These components are
formed into one piece with VARTM (Vacuum Assisted Resin Transfer Molding).
3.2 Material Properties
The material properties of the components are showed in Table 1.
Table 1 Material Properties
CFRP skin
Young's modulus
（ N/mm2 ）
4
unit：mm
GFRP rib
Poisson's
ratio
EL
ET
GLT
ν
Skin
30300
30300
5390
0.13
Rib
19600
12700
8160
0.42
7.80
0.01
4
83
75
phenol foam
core
Shear
modulus
（ N/mm2 ）
CFRP skin
Figure 1 Section of CFRP
sandwich panel
Core
20.6
3.3 Allowable Unit Stress
The sandwich structure can exhibit local buckling of the skin under bending or
compression. In case of an one-way hyperbolic paraboloidal shell, the design criterion is
usually due to compressive stress of the skin. Table 2 shows material strengths, standard
strengths and allowable unit stresses. Material strengths are decided by coupon tests.
Standard strengths (F) are decided by the product of the average of coupon tests and the
statistical coefficient of 0.72. This coefficient is more wide range than three-sigma. The
design of CFRP sandwich panel roof is based on allowable stress design. Because of the
brittleness of CFRP materials, the safety factors are decided as 4 for sustained loads and
2 for temporary loads.
35
Table 2 Standard Strength and Allowable Unit Stress
Skin
Rib
Standard
strength
(F)
Allowable unit stress
for sustained
for temporary
loads
loads
Stress
Strength
Compression
Local B uckling Stress
(rib space: 450× 400)
Local Buckling Stress
(rib space: 450× 200)
230
165
F/4
F/2
78
56
F/4
F/2
105
75
F/4
F/2
Tension
300
215
F/4
F/2
In-plane Shear
45
32
F/4
F/2
Bearing
320
230
F/4
F/2
In-plane Shear
170
122
F/4
F/2
4. Typical construction details
The specifications of CFRP sandwich panel roof is showed in Table 3. Figure 2 shows
the shape of the shell. The original shape is out of a hyperbolic paraboloidal surface.
Figure 3 and 4 show the connections of shell- tie beam and shell- shell respectably.
Figure 5 shows a roof plan and a section.
Table 3 Specifications of
CFRP sandwich panel roof
Shape
Radius of Curvature
Maximum Span
Width
Height
Structural Weight
Fireproofing etc. Weight
Shell-Tie Beam
Connection
Shell-Shell Connection
Roof Plan
Figure 2
180 m
24.5 m
2.5 m
0.9 m
500 N/m2
100 N/m2
Unit: mm
Bolt (Fig.3)
Figure 2 Shape of CFRP sandwich
panel shell
Bolt (Fig.4)
Figure 5
CFRP Sandwich
Panel
CFRP Sandwich
Panel
Filler PL
Bolt
Fastener PL
Tie Beam
Bolt
Fastener PL
Tie Beam
Bolt
CFRP Sandwich
Panel
Grouting
Figure 3 Shell-Tie Beam Connections
36
Figure 4 Shell-Shell
Connections
Figure 5 Roof Plan and Section
5. Research for verification
The coupon material tests and the structural experiments were conducted. The structural
experiments were compression tests and bending tests about the elements of the flat
panels. It was found on these experiments that local buckling (wrinkling) of skin was
critical. The various strengths (Table 2) were decided upon these experiments. On the
other hand, the sandwich shells which had a real section were tested under bending
force. About the real size shell, local buckling of the skin occurred at the stress
concentrated point. Reference 1 and 3 show the details about the structural experiments.
Reference 2 and 4 show the comparisons between the theory and the experiments about
local buckling.
concavity
convexity
(a) Compression Tests on Panel Element
(b) Bending Tests on Real Size Shell
Photo 1 Structural Experiments
6. Examples in practice
The CFRP sandwich panel roofs have been applied to ten school’s gymnasiums in Japan.
In the case of the 24m×35m plan which had fourteen shell roofs, the roof replacing
work including scaffold cost only three weeks. It is enough less time than a summer
vacation term.
37
(a) Under construction
(b) After replacing
Photo2 Examples of application
7. References
1) Tateishi Y., Sugizaki K., Fujisaki T., Kanemitsu T., and Yonemaru K., “Experiment
and Application of CFRP Sandwich Panel”, CD-ROM Proc. IASS symp., NAGOYA,
2001, TP037.
2) Tateishi Y. and Yamada S., “Theory and Experiment of Local Buckling in CFRP
Sandwich Panel”, CD-ROM Proc. IABSE symp., Shanghai, 2004, (IABSE reports vol.88,
pp376-377 (short version))
3) Tateishi Y., Sugizaki K., Fujisaki T., Kanemitsu T., and Yonemaru K., and Kondo T.,
“Development of CFRP Sandwich Panel (in Japanese)”, AIJ Journal of Technology and
Design, No.14, pp133-138, Dec., 2001
4) Tateishi Y. and Yamada S., “Local Buckling of CFRP Sandwich Panels with Latticed
Ribs (in Japanese)”, Journal of Structural and Construction Engineering, AIJ, No.573,
pp119-127, Nov., 2003
8. Ownership organization
Toray Industries, Inc. 2-2-1, Muromachi, Nihonbashi, Chuo-ku, Tokyo
Tel: +81-3-3245-5736
Fax: +81-3-3245-5726
E- mail:Kenjiro_Ota@nts.toray.co.jp
URL: http://ns.toray.co.jp/composites/application/app_g002.html
Shimizu Co. 1-2-3, Shibaura, Minato-ku, Tokyo.
Tel: +81-3-3820-6644
Fax: +81-3-3820-5955
E- mail: tateishi_yasutoshi@shimz.co.jp
9. Certification
Patent Application No. (Published): 2000-322829(Japan), 2000-197036(Japan),
2000-120227(Japan), 2000-336854(Japan), 2001-207597(Japan), 2001-058319(Japan),
2001-254456(Japan)
38
39
1. Title
PITACOLUMN Method
2. Summary of the Method
The PITACOLUMN method is a completely external type earthquake-proof reinforcing
method targeted at low- to mid-rise reinforced concrete buildings. This method is a low cost,
short construction period, and environmentally friendly method. Since it is not required to
works inside a building for reinforcement physically at each phase, no transportation of interior
equipment and removal and/or installment of existing fixtures are needed. Therefore it allows
continuous use of the building. Reinforcing structure is a reinforced concrete member
containing a steel plate, and the method is surpassing in maintenance and does not require any
special finish comparable to that of the existing structure. The reinforcement working procedure
is as follows; drive post-installed anchors into the external surface of the existing structure,
attach a steel plate by using these anchors and arrange reinforcing bars around the plate, and
then cast concrete to complete.
One of two types of reinforcing pattern can be selected according to performance based
reinforcement volume or reinforcement target. That is a frame reinforcement is targeted at
ductility reinforcement and a frame reinforcement with braces is targeted at strength
reinforcement. ( Fig. 1)
Steel Plate
Post-installed Anchor
Cleavage Preventing Bar
Steel Plate
Post-installed Anchor
Cleavage Preventing Bar
Existing (RC) Column
Existing (RC) Column
Reinforcing Member
Reinforcing Member
ａ）frame Reinforcement
ｂ）frame Reinforcement with Braces
Approx. 200 mm
Post-installed Anchor
Cleavage Preventing Bar
Steel Plate
Existing (RC) Column
Brace
Reinforcing Member
c) Detail of the Section of Member
Figure. 1 - Summary of the Method
39
3. Specifications of Materials
The standards for the specifications of materials for the PITACOLUMN method are
shown in Table 1.
Table 1 – Standards for Specifications of Materials
Post-installed
Use adhesive type anchor
Anchor
Steel Plate
JIS G 3136 Rolled Steel for Building Structure - SN400B, SN400C
JIS G 3101 Rolled Steel for General Structure - SS400
JIS G 3106 Rolled Steel for Welded Structure - SM400B, SM400C
Reinforcing Bar
Anchor Bar
D16,D19,D22
SD345
Assembly Bar
D13,D16,D19
SD345，SD295A,B
Cleavage
D6, φ6
SD295A, B, SMW -P, R, I
Preventing Bar
Concrete
Normal concrete or super -plasticized concrete
Specified-design strength is more than or equal to 24N/mm2 and less
than or equal to 36N/mm2.
4. Detail of Standard Structure for the PITACOLUMN method
The PITACOLUMN method means a method in which post- installed anchors are
driven into an existing structure at uniform space, a steel plate is attached using these
anchors, cleavage preventing bars are arranged around the plate, and concrete is cast.
The construction process is described below and the details of section of this method are
shown in Fig. 2.
Existing
Existing
(1) Drive post- installed anchors
Structure
Structure
into existing structure
(2) Removal of existing finishing material
Finishing
(3) Installment of reinforcing steel plate
(4) Arrangement of cleavage preventing bars (１)Drive anchor
(３)Installment
(5) Assembly of mold form
steel plate
(6) Casting of concrete
Existing
Existing
(7) Disassembly of mold form
Structure
Structure
(8) Finishing
(４)Arrangement of
of
(６)Casting of concrete
cleavage preventing bars
Figure. 2 –Section of the Method
40
5. Experimental Verification
The test specimens of 1/3 size model of 2 layers and 1 span were made and were
tested with static loading to confirm the effectiveness of this method. The test results of
the brace type reinforcement are shown here as the representative example.
The view of testing are shown in Photo 1 and the final state of cracking is shown in
Fig. 3. The cracks in the existing parts were due to shear failure (accompanying bond
splitting failure) of columns as with a test specimen without reinforcement, and it was
observed that there is no change in the failure modes. And all cracks on the reinforced
side are bending cracks only.
The relationship between load and displacement is shown in Fig. 4. The vertical axis
is load and the horizontal axis is displacements of 2 layers. A dashed line in the figure
indicates the test specimen without reinforcement. The test specimen with
reinforcement was improved in both strength and ductility significantly compared to the
test specimen without reinforcement and it was confirmed that it showed stable
hysteresis up to drift angle of R = 1/60. Maximum strength (Max load) was 500 kN at
drift angle R = 1/60. Though the brace of 2nd floor was buckled at R = -1/460 with Q
=-183 kN during loading of R =-1/60, it sustained the increase of load and showed Q
=-340 kN at R =-1/60. After that the brace of 1st floor was buckled at R = 1/44 with Q =
477 kN during loading of R = 1/30, and then its deformation progressed rapidly and led
to a failure. It was also confirmed that the yielding process of members was preceded by
the yielding at reinforced part and then the existing part was yielded.
Left
Side
Right
Side
West to East
East to WestLeft
Side
East to West
Right
Side
West to East
Buckled
Buckled
West to East
East to West
WEST
Reinforced Side
West to East
East to West
EAST
EAST
Existing Side
WEST
Figure.3 – Final State of Cracking
600
１
ＦBrace buckled
LOAD(kN)
400
Non-Reinfoced Specimen
200
DISP(mm)
0
-100
-80
-60
-40
-20
0
-200
20
40
１/２５０
１
/６０
１/１２５
60
80
100
１/３
０
Drift Angle R
-400
２
ＦBrace buckled
-600
Photo 1 – Loading Situation
Figure. 4 – Load - Displacement Relationship
41
6. Construction Examples
There are 120 construction examples reinforced by this method, mainly applied for
school buildings, to date.
a)Junior High School Building (School Colored)
b) Junior High School Building (Designed by Students)
c)University Building (with Exterior Panels) d)Elementary School Building (with Balconies)
Photo 2 – Examples of Reinforcement
7. Reference
Y. Ban, T. Yamamoto, M. Kato and Y. Ueda: “New Outside Retrofitting Method
Contained Steel Plate in Concrete Member (Test Results of One-bay and Two- Layers
frame)”. The 10th Japan Earthquake Engineering Symposium, K-15, 1998.11
8. Company
Yahagi Construction Co., Ltd. 3-19-7, Aoi, Higashi-ku, Nagoya-shi, Aichi, Japan
TEL: +81-(0)52-935-2351
9. Patent
Patent No. 3022335(Japan)
Patent No. 3051071(Japan)
Patent No. 3290635(Japan)
42
43
1. Title
Aoki Seismic Retrofit Method by means of Energy Dissipation Braces
2. Outline
In this seismic retrofit method, external energy dissipation braces (braces consisting of
steel pipes and friction dampers embedded in the pipes) are installed on the external
walls of an existing building to be retrofitted so as to absorb earthquake energy input to
the building and thereby enhance its seismic performance (Photo 1). One advantage of
this method is that by using friction dampers as response control devices, earthquake
energy can be absorbed efficiently even under small amplitudes of the story drift angle
(around 1/2000 to 1/1500 rad). This makes it possible to reduce the maximum response
story drift angle of existing buildings to about 1/200 rad. Since friction dampers absorb
earthquake energy efficiently, damper strength; frictional force of the damper, can be
specified to 200 to 400 kN per unit so that the expected effect of strengthening can be
attained simply by installing external damping braces to the external walls of the
building. Although the conventional strengthening methods require removing sashes
and interior and exterior finishes and reinstalling them, the newly developed method
makes it possible to use the building without interruption while retrofit work is in
progress. Thus, manpower requirements can be reduced significantly, and both cost and
construction period can be also reduced. In addition, this retrofit method is
environmentally considerate because the volume of waste materials to be disposed at
which the interior and exterior parts are removed is small and noise level is low.
Photo 1 Example of application of Aoki seismic retrofit method
3. Performance of friction dampers
Fig. 1 shows the configuration, mechanism and the hysteretic properties of the friction
damper. The friction damper consists of a die, a rod, an outer cylinder and an inner
cylinder. The diameter of the close- fitting rod in the die is slightly larger than the inside
diameter of the die so that the rod is able to move in the axial direction while
maintaining a constant frictional force. Earthquake energy causing dynamic motions of
the building is transformed into frictional heat and is thus absorbed while the friction
damper built into the damping brace is moving forth and back in the axial direction. As
shown Fig. 1(b), the damper shows hysteresis loops of the perfectly elasto-plastic type.
Frictional forces show a slight variation as damper strokes are repeated, and
energy-absorbing performance of the damper is clearly observed.
43
500
load[kN]
Inner cylinder Outer cylinder
400
300
200
Force acting on circumference
(tightening force from die)
100
Damper axial force
0
Friction force
Rod
Rod
Die
Die
-100
-200
-300
-400
-500
-15
-10
-5
0
5
10
15
stroke[mm]
(a) Configuration and mechanism
(b) Hysteresis loops of damper
Fig. 1 Friction damper
4. Typical construction details
Photo 2 shows an example of the external damping brace installation. External damping
braces are installed on the existing structural frame (main structure) through anchorage
bases. The space between the anchoring base and the side of the existing structural
frame is filled with grout and the anchorage base is fastened to the main structure by
using prestressing steel bars.
Steel pipe brace :φ 190.7× t 19
Friction damper： 400kN
Connection: secured in place with
four prestressing bars ( 23 mm dia.)
Connection with foundation: connected indirectly by post-construction anchors
Photo 2 Installation method of external energy dissipation braces
5. Research for verification
The effect of the damping retrofit method has been confirmed through the full-scale
seismic tests using a three-story R/C school building planned to be demolished. The
central part of the building in the longitudinal direction (three stories, 1 x 2 span) was
used as a specimen, and concentrated loads were applied to the rooftop by the pseudo
dynamic testing method. The effect of the damping retrofit on the building was
confirmed by comparing the test results obtained without retrofit and the pseudo
dynamic test results obtained by using the external damping braces with friction
44
Input ground motions; El Centro 1940 N-S record 65cm/sec
80
階4
FL.
60
3
Disp [mm]
40
20
2
0
-20
-40
制震補強実験
Retrofit
無補強実験
Non-retrofit
-60
-80
0
1
2
3
4
5
6
7
8
Time [sec]
3000
3000
Disp [mm]
(a) Retrofit
Fig. 3
0
0.2
0.4
0.6
0.8
1
R [%]
Ｑ[kN]
Disp [mm]
80 -80
-3000
0
Comparison of the re trofit and non-retrofit test results
Ｑ[kN]
-80
制震補強実験
Retrofit
無補強実験
Non-retrofi
t
(b) Maximum story
deformation angle
(a) Time history of response displacement
Fig. 2
1
80
-3000
(b) Non-retrofit
Load-disp. relationship at the top
Photo 3
Full view of the test
dampers. Photo 3 shows the test setting. Fig. 2 compares the results of the retrofit and
non-retrofit tests regarding the time history of response displacement and the maximum
response. Fig. 3 shows the load-displacement relationships at the top of the building in
the retrofit and non-retrofit tests.
6. Examples in practice
This retrofit method has been used in a total of 20 projects consisting of sixteen school
buildings, one hospital, one city office, and two apartment buildings. Photo 4 shows an
example of the installation on a school building with balconies. Photo 5 shows an
example of the application to an apartment building.
7. References
1) Keiji Kitajima, Hideaki Ageta, Mitsukazu Nakanishi and Hiromi Adachi: Research
and Development of Response-Control Retrofitting Techniques by means of Friction
Damper, 12th World Conference on Earthquake Engineering, Paper No.0868, Jan.
2000
2) Hajime Yokouchi, Keiji Kitajima, Hideaki Ageta, Hideaki Chikui, Mitsukazu
Nakanishi and Hiromi Adachi: Pseudo-Dynamic Test on An Existing R/C School
Building Retrofitted with Friction Dampers, 13th World Conference on Earthquake
Engineering, Paper No.2111, Aug. 2004
45
Steel Pipe Brace
Connection
Friction damper
Photo. 4 Application to an balconied school building
Photo. 5
Application to an apartment building
3) Keiji Kitajima, Hideaki Chikui, Hideaki Ageta and Hajime Yokouchi: Application to
Response Control Retrofit Method by means of External Damping Braces using
Friction Dampers, 13th World Conference on Earthquake Engineering, Paper
No.2112, Aug. 2004
8. Ownership organization
Asunaro Aoki Construction Co. Ltd, 1050014, Minatoku, Tokyo.
Tel: +81-3-5439-8513
Fax: +81-3-5439-8531
E- mail: Brace@aaconst.co.jp
URL: www.aaconst.co.jp
9. Certification
JDPBA Certification No.1498
Patent No.: 3341822(Japan)
46
47
1.Title
Seismic Retrofitting Technology of Existing RC Frame Structures by External Steel
Brace Reinforcement
2.Outline
For seismic retrofit of existing reinforced concrete structure in Japan, steel braces are
usually inserted into the existing reinforced concrete frame and joined to it using mortar
filling of high compressive strength. This is called the conventional retrofit method.
According to this construction method the outer finishing materials such as existing
windows and sashes must be removed, after the reinforcing work is finished. This is
disadvantageous in that it lengthens the construction period, and that construction cost
also becomes expensive. A new method, which installs the steel braces to the outside of
the existing reinforced concrete frame, was considered in order to improve these defects
in the conventional method. This new method is known as the Yokosuka Type seismic
retrofit method. Comparing the new seismic retrofit method with the conventional, the
primary merits are as follows;
(1) The time necessary for construction is shorter because the steel braces are directly
installed in the existing reinforced concrete frame structure.
(2) The retrofitting can be carried out while the building is in use.
(3) The cost for retrofitting is reduced by approximately thirty percent compared to
conventional retrofitting.
Stud bolt
Steel brace
Steel brace
Hanging wall
Hanging wall
Skirting wall
Skirting wall
Existing RC frame structure
Existing RC frame structure
Steel frame for retrofitting
grout mortar
Resin bolt
Resin bolt
Resin anchor installed to RC frame
Steel frame for retrofitting
Resin anchor installed to RC frame
Installation of
Installation of
(b)Yokosuka Type seismic retrofit method.
(a)Conventional retrofit method
Fig 1. Seismic retrofit methods for existing RC frame structure
3. Specifications for materials
The present seismic retrofitting is consists of a steel frame structure with studs in which
steel braces are connected, resin bolts inserted into the existing RC frame structure, and
grout mortar which is filled between the steel frame and the existing RC frame.
H-shaped steel members are ordinarily used for the vertical members of the frame
structure and the braces. Channel and angle shaped steels are used for the lateral
members on the outer side of the floor and roof beams, respectively. Also, the studs are
connected along the inside of the web portion of the steel frame structure for the
purpose of enhancing the bond with the steel frame by means of grout mortar. Resin
bolts are driven into the existing RC frame structure to which the steel frame structure
47
with braces is connected so that they may lap with the studs connected along the web in
steel frame. The grout mortar, which is filled between the existing RC frame and steel
frame structures, possesses the property of non-shrinkage and high compressive strength
above 30N/mm2 .
Item
Steel frame
Steel Braces
Stud bolt
Resin bolt
Grout mortar
Table 1.Main materials used for seismic retrofitting
Materials and its specification
Vertical member, H-shaped steel; Lateral member, channel and angle
shaped steel
H-shaped steel with larger size than 175×175
Two kinds of 16φand19φstuds
Three kinds of deformed bar with diameter of 16,19 and22mm
Mortar is constructed by mixing Portland cement and fine aggregate as
well as add- mixtures. It has compressive strength over 30N/mm2 and is
reinforced by spiral and mesh hoops.
H20
0×
20
0×
8×
1
+2 2
PL
-9
H15
0×
15
0×
7×
10
H15
0×
15
0×
7×
10
4. Typical construction details
The main construction for the seismic retrofitting begins with driving resin bolts into the
existing RC frame structure. They are driven into the outer side of the column and beam
of the story in which seismic
Roof
retrofitting is necessary. Next the steel
frame structure with braces and stud
bolts is installed to the outer side of
the existing RC frame structure for
Site welding
each individual story. As the
3rd floor
channel-shaped lateral steel in the
frame is divided into two parts in the
horizontal direction, both steel parts
are welded at the site along the central
2nd floor
Site welding
portion. After installation of, the steel
frame structure to the existing RC
frame, form work is fixed to both
structures so that the grout mortar does
1st floor
not flow out. Spiral and mesh
GL
reinforcement
are
placed Top of beam into ground
simultaneously into the grout mortar
for the purpose of crack control which
may be caused by the bolts. An
A-A section
applicable example of seismic
retrofitting for one existing RC frame
B-B section
structure with three stories is shown in
fig .2.
Fig. 2 Typical details
5. Research for verification
5.1 Outline of test
One-span and mono- layer frame models for the first floor and ridge direction of a
reinforced concrete school building as well as one-span and two-layer frames for the
48
375
375
1775
1075
BH
-75
×7
5×
4.5
×8
250
125 200
190
upper most and next lower floors were considered, and test specimens at 1/3 scale were
manufactured.
250
The beam in the reinforced
concrete frame is joined
140
together in the plane which is
identical with the centroid of
the column. Consequently, the
BC-300×1205×5×5
Stiffner 4,5
PL-4 5
Resin anchor
column-beam
connection
Stud bolt
becomes
eccentric.
The
Filler morutar
connection
system
that
BH-75×75×10×7
integrates
the
reinforced
concrete frame with the steel
frame built up from V type
CL
625
625
575
300
250
1250
250 300
steel braces is constituted from
2350
anchor bolts (D13) behind
Fig.3 Details of Specimen(1FB -2)
resin systems and stud bolts (9
φ) welded to the steel brace and filling mortar. Specimen (1FB-2), which installed the
steel brace system using this joining method from the outside of the reinforced concrete
frame and, a specimen of shear wall (1FB-2W) were produced. Specimen (1FO), a bare
frame without the steel brace, was also produced. A total of 3-test specimens were
produced. The detail drawing of specimen (1FB-2) is shown in Fig.3.
5.2 The test method.
In order to apply a horizontal force to the reinforced concrete frame reinforced by steel
braces, a PC steel bar fixed in the beam is joined to an oil jack (1000kN and 500kN).
For push and pull loadings these they were amounted at right and left sides, and the
loading is given for the test specimen by a half push and half pull. A level steel member
for the mono-layer specimen was joined together in the capital portion of the column in
order to load the column with axial force, in which the two- layer specimen was given a
fixed axial force 0.15Fc･b･D by a 1000kN oil jack. The horizontal loading schedule was
carried out by each cycle alternating repetition for 1/1000, 1/400, 1/200, 1/100, 1/50,
1/25 radian as joint translation angle. The horizontal loading was applied only to the top
of the second layer. The axial force of the column of 0.12Fc･b･D was applied by a PC
steel bar installed in a sheath tube in the column and 300kN center hole jacks.
5.3 Test result
The envelope curves for the hysteresis loop of load-horizontal displacement of the
mono- layer specimen are shown in Fig.4. The following are also shown in the figure:
cracking load, load at the yield of main longitudinal steel bar in column, maximum load
and curves for steel brace yield as well as load of plastic buckling. It was found that, the
maximum load for specimens 1F0, 1FB-2, 1FB-2W occurs at 1/100rad joint translation
angle. These specimens with out-of-plane deformation due to torsion were remarkable.
The column also produced shear failure in each specimen. Therefore, the load also
decreases after the maximum load. Still, it is based on the out-of-plane deformation by
the torsion increasing on specimen 1F0 and 1FB-2W where the ultimate state occurred
on 1/50rad or less, after which loading became impossible. The load at which the
reinfo rcement brace reaches the yield strength has appeared in the maximum load
vicinity. Joint translation angle is also arising on the plastic buckling at 1/50rad. The
envelope for the hysteresis loop of load-first layer horizontal displacement was obtained
49
form the horizontal loading test a
two- layer specimen in Fig.6. From this,
joint translation angle shows the
maximum load at 1/100rad. Since the
second layer column shows a resistance
mechanism by the flexural failure, the
deterioration of the strength after
maximum load is not observed.
6. Examples in practice
The present seismic retrofitting method
Fig.4 Envelope Curves for Mono -layer Specimen
has been applied mainly to existing RC
school and office buildings since 2001. Two examples of a four-story school and a
three-story office buildings which were constructed in 1970 and 1967 respectively, are
indicated by photographs 1 and 2. Damper devices are installed into the steel braces for
seismic retrofitting in the latter building. The cost necessary for retrofitting by the
present method is decreased about thirty percent in comparison with that of the
conventional seismic method.
Photo1. Retrofitted school building
Photo2. Retrofitted office building
7. References
(1) Structured design manual for retrofit by steel braces: development and test report,
by the Architectural Division, Yokosuka City Hall, 2001.
(2) E. Makitani, H. Arima and S. Marumo, Aseismic structural performance of existing
RC frame structures by external steel brace reinforcement, Proceedings of 6th ASCCS
Conference, Los Angeles, USA, 2000.
8. Owner ship organization
Architectural Division of Yokosuka City Hall, Ogawa-cho, Yokosuka
TEL: +81-46-822-8412
FAX: +81-46-822-8537
E- mail:tsutomu- marumo@city.yokosuka.kanagawa.jp
9. Certification
JBDPA Certification NO. 1499
Patent NO: In application
50
1. Title
Tufnes method
2. Outline
The Tufnes method uses U-shaped Tufnes forms lined with carbon fiber sheets. The
form is installed around the column, and grout is injected into the interstice between the
form and column, to make an integrated structural member. This improves the shear
strength and toughness of the column.
3. Specifications for materials
Table 1 lists the specimens. Fifteen specimens in total were used. Series I includes
specimens reinforced with Tufnes forms made of 20 mm thick preformed mortar board
(GFRC board), a non-reinforced specimen, and specimens lined directly with carbon
fiber sheet layers. The test parameters are joint position and number of carbon fiber
sheets. Series II includes specimens reinforced with Tufnes forms made of 13- mm
thick lightweight calcium boards (PB form). The joints of carbon fiber sheets are
provided in both directions, that is, parallel and normal to the loading direction. The
carbon fiber sheet joint lap is 100 mm long for both series.
Table 1 Specimen List
Series Ⅰ
Series
Hoop
pw(CF)
(％)
Ópw
(％)
None
None
None
Direct
lining
1
2
Specimen
Reinforcing
method
No.1
RC-14
No.2
CRC-20
No.3
CRC-26
No.4
GRC-20
No.5
GRC-26
óB
(MPa)
Join position
0.14
25.5
None
0.07
0.21
27.0
0.13
0.27
27.9
1
0.06
0.2
33.8
2
0.12
0.26
36.8
3
0.18
0.32
27.8
2
0.12
0.26
29.6
No.8 GRC-32P
3
0.18
0.32
29.9
No.9 GRC-38P
4
0.24
0.38
29.3
1
0.06
0.2
36.0
2
0.12
0.26
36.0
No.6 GRC-32R
No.7 GRC-26P
No.10
Series Ⅱ
All main
Tensile main
reinforcement reinforcement CFRP
pg(％)
pt(％)
layers
No
No.11
Section
12-D22
(1.86)
4-D22 (0.62)
Tufnes
(GFRC form)
PB-20
12-D22
(1.86)
PB-26
No.12 PB-20-FC
No.13 PB-20-S
No.14 PB-20-RB
No.15 PB-26-N
Tufnes
(PB form)
4-D22 (0.62)
25.7
12-D29
4-D29 (1.03)
(3.08)
12-ö22 (1.82) 4-ö22 (0.61)
12-D22
(1.86)
4-D22 (0.62)
1
0.06
0.2
35.8
Axial
force
ratio
Normal to the
loading
direction
0.2
Parallel to
the loading
direction
Both
directions
0.2
35.8
2
0.12
0.26
36.0
0.4
Notes:
-(Common for both series) :Column section bxD=50x50 (cm), Internal height ho=150 (cm), M/QD=1.5, Amount of ties D10 at 200 mm
intervals
-No.6 (GRC-32R) is a specimen made by repairing and reinforcing No.1.
51
4. Typical construction details
Fig. 1 shows the reinforcement details of the specimens of both series.
150
C FRP
r=30
重ね
継手
joint
lap
L=100
L=100
600
重 ね継 手
joint
lap
L=100
L=100
グラウト
grout
重ね 継手
joint
lap
L=100
30
L=100
586
600
600
250
30
20
r=30
600
CFRP
グラ
ウト
grout
150
250
13
CFRP
20
グラウト
grout
30
r=30
586
Fig. 1 Reinforcement details
5. Research for verification
The test results of a non-reinforced specimen and specimens lined directly with carbon
fiber sheets, were compared with those of the specimens using the Tufnes forms. The
comparison verified that the reinforcement effect of the Tufnes method was equivalent
to that of the direct lining method.
The specimens compared were No. 10 and No. 11 of series II (Tufnes method with
lightweight-calcium-board form) and No.2 and No.3 of series I (directly lined with
carbon fiber sheets). The load-deformation relationships of these specimens are shown
in Fig. 2. The test parameters are the same for both types of specimens, except the
reinforcement methods.
Since the concrete strengths of these specimens are
significantly different, the loads in the test were divided by the shear force calculated
from bending strength for comparison. However, since No.2 and No. 12 have almost
the same concrete strength, their test results were compared directly.
As shown in Fig. 2, the strength of the Tufnes specimens declined when deformation
was high (R=1/33 to 1/25) because the carbon fiber sheet broke. But, the behavior up
to failure was almost the same for both types of specimens. From the fact that No.2
and No.12, which have almost the same concrete strength, showed a similar behavior,
we can conclude that the Tufnes method provided a reinforcement effect equivalent to
the direct lining method.
52
1.5
1
eＱ c ／ cＱ
um
-40 -30 -20 -10
0.5
0
-0.5
10 20 30 40
67
R（x10-3rad. ）
-1
No.2(直
巻 1層 direct )lining)
No. 2 (1-layer
No.10（
ﾀ
ﾌ ﾈ ｽ Ⅱ TufnesⅡ)
1層
No.10 (1-layer
-1.5
(a) Reinforced with 1-layer carbon fiber sheet
1.5
1
eＱ c ／ cＱ
um
-40 -30 -20 -10
0.5
0
-0.5
10 20 30 40
67
R（x10-3rad. ）
-1
-1.5
-90
No.3(直
巻 2 層lining) )
No.3 (2-layer
No.11(ﾀﾌﾈｽⅡ
層
No.11(2-layer2 TufnesⅡ
)
-60
-30
0
30
60
δ c （m m）
90
120
(b) Reinforced with 2-layer carbon fiber sheet
900
600
eＱ c （k N）
-40 -30 -20 -10
300
0
-300
10 20 30 40
67
R（x10-3rad. ）
-600
-900
-90
-60
-30
0
30
60
90
(1-layer
lining
No.2No.2
（ 直
巻 direct
1層σB=
2 σB=27.0)
No.12（
No.12
ﾀ ﾌ(1
ﾈ ｽlayer
Ⅱ 1TufnesⅡσB=25.7)
層σB=25
120
δ c （m m）
(c) Reinforced with 1-layer carbon fiber sheet
Fig. 2 Q-δ relationships (with different reinforcement methods)
53
1-layer reinforcement
2-layer reinforcement
(a) Direct lining method
1-layer reinforcement
2-layer reinforcement
(b) Tufnes method (Primer mold)
Photo 1 Views of final failure
54
6. Examples in practice
Used for reinforcing independent columns (about 580 m2 in total) of eight buildings
including multifamily residential buildings, department stores and office buildings.
(a) Erection of Tufnes form
(b) Seismic retrofit completed
Photo 2 Example of application
7. References
1) Y.Ishiwata, M.Ichikawa, et al., Experimental study on deformation performance of
columns shear-reinforced with premolded mortar boards lined with continuous carbon
fiber sheet, Summaries of the convention of the Architectural Institute of Japan,
Structure IV, pp697-698,1997.9
2) Y.Ishiwata, M.Ichikawa, et al., Experimental study on deformation performance of
columns shear-reinforced with GFRC and carbon fiber sheet, Summaries of the
convention of the Architectural Institute of Japan, Structure IV, pp229-230,1998.9
3) Y.Ishiwata, M.Ichikawa, et al., Experimental study on seismic retrofit of columns with
GFRC and carbon fiber sheet, Annual Study Report of Concrete Engineering, Vol.21,
No.3, pp1405-1410, 1999
4) M.Ichikawa, Y.Ishiwata, et al., Experimental study on seismic retrofit of columns with
stay-in-place form and carbon fiber sheet, Summaries of the convention of the
Architectural Institute of Japan, Structure Ⅳ pp827-828,2002.8
55
8. Ownership organization
Tufnes method workshop
Represented by Tekken Corporation, 2-5-3 Misaki-cho Chiyoda-ku Tokyo
Tel: 03-3221-2184
Fax: 03-3239-1685
URL:www.tekken.co.jp
Bureau: Nippon Steel Composite Co.,Ltd., 3-8 Kofune-cho Chuo-ku Tokyo
Tel:03-5623-5550
Fax:03-5623-5551
URL:www.nick.co.jp/
9. Certification
Certified by the technological evaluation by the Japan Building Disaster Prevention
Association, No.1528 dated 7 December, 2001.
56
1. Title
SRF (Super retrofit with flexibility)
2. Outline
SRF is a seismic retrofit technology for existing reinforced concrete columns using
high-ductility material such as polyester sheet. Shear strength, lateral deformability and
axial capacity of the column members can be improved by confining with polyester
sheet.
3. Specifications for materials
SRF uses woven polyester sheet as the reinforcing material. Table 1 lists their design
specification values.
Table 1 Specifications of the reinforcing materials
SRF450
SRF465
mane
material
thickness(mm)
polyester
4.0
width(mm)
45.0
2
Effective Yong’s Modulus（N/mm ）
Ultimate strength（N/mm2 ）
64.5
4,500
400
Ultimate elomgation（%）
10.0
Where effective Young’s modulus is measured at secant modulus at 1% elo ngation.
4. Typical construction details
SRF does not require the rounding of corners nor impregnation with resin. Figure 1
shows a cross section and view.
Cross section
View
Figure 1 Typical details of SRF for stre ngthening column
57
5. Research for verification
The effectiveness of SRF for strengthening reinforced concrete columns has been
verified through a serious of seismic tests. Static tests on columns were conducted for
eight specimens in the first phase, and fourteen and ten in the second and the third,
which represents reinforced concrete columns in old buildings of Japan or worldwide.
Some of the columns were strengthened using polyester sheet. The columns
strengthened by the new method could maintain relatively high gravity load until more
than ten percent inter-story drift, while the bare specimens without strengthening failed
in shear at small drift simultaneously losing axial load capacity. The typical hysteresis
relations are compared for bare reinforced concrete specimen and SRF specimen as
shown in Figure 2. The specimens after tests are shown in Photo 1. Various types of
concrete prisms and cubes confined with the sheet were also tested, based on which the
resistance mechanisms of the columns were interpreted. Through these test series, the
method has been improved to be effective to prevent the loss of capacity not only
against axial load but also against lateral load reversals.
Dynamic tests were planned and conducted for the verification of the new strengthening
method. The specimens are two one-third scaled reinforced concrete wall- frame
structures with considerable stiffness and strength eccentricity in the first story. The two
specimens with the same sectional dimensions and reinforcement details were
constructed and tested simultaneously on the large shaking table at NIED. One was a
bare reinforced concrete structure designed following old reinforcement detail practice
in Japan, while the other was strengthened by the SRF method. The two columns
without strengthening failed in shear resulting in collapse associated with loss of the
axial load carrying capacity, whose collapse process was traced on the basis of test
results. On the other hand, the frame strengthened by SRF not only responded stably to
the same input motion with minor damage but also survived still higher levels of
succeeding input motions. The frames with reinforced concrete columns and SRF
columns after the shaking table test are shown in Photo 2. The cost of retrofit by SRF
would remarkably be reduced from that by existing technology.
300
Qmax(+)=219.49kN
(R=3.0/400rad.)
Qmax(-)=-217.29kN
(R=-3.0/400rad.)
-64
-48
-150
100
-32 - 1 -6 8
-100
-64
0
0.8Qmax
-200
-300
-48
50
8 16
100
32 48
150
200
-200
-150
-100
-
-50
0
0.8Qmax
Qmu=-189.2kN
δ H(mm)
0
-100
0.8Qmax
0.8Qmax(+)=175.59kN
(R=6.4/400rad.)
0.8Qmax(-)=-173.83kN
(R=-6.3/400rad.)
Qmu=189.2kN
kN
0.8Qmax
100
-16
-8
-6
64
×1/400rad.
With SRF
200
-32 δH(mm)
0
-50
-100
Qmu=-189.2kN
Qmax(+)=224.09kN
(R=4.0/400rad.)
Qmax(-)=-222.65kN
(R=-4.0/400rad.)
Qmu=189.2kN
kN
0.8Qmax
200
-6
-200
300 Q(kN)
RC(without SRF)
Q(kN)
-200
-300
50
8 16
100
32 48
150
0.8Qmax
0.8Qmax(+)=179.27kN
(R=24.2/400rad.)
0.8Qmax(-)=-178.12kN
(R=-20.1/400rad.)
(a) RC (without polyester sheet)
(b) SRF (with polyester sheet)
Figure 2 The typical hysteresis relations of RC column and SRF column
58
200
64
× 1/400rad.
RC
SRF
(a) Ultimate state (80% of maximum load)
RC (loss of longitudinal stiffness)
(b) After test
Photo 1 Specimens during and after tests
SRF
(a) reinforced concrete column
(b) SRF columns
Photo 2 reinforced concrete column and SRF column after the shaking table test
59
6. Examples in practice
40 constructed facilities have been retrofitted with SRF, including bullet train piers
(Shinkansen), old buildings in Tokyo, School in Sendai, Hospital in Gunnma and Ward
Office in Aichi.
(a) columns in old school buildings
Photo 3 Examples of application
(b) Bullet train piers
7. References
1) Toshimi Kabeyasawa, Akira Tasai and Shunichi Igarashi：A New Method of
Strengthening Reinforced Concrete Columns against Axial Load Collapse during
Major Earthquake，EASEC-8，Dec.2001.
2) Shunichi Igarashi：SRF (in Japanese)、Jan. 2003、Structural Quality Assurance, Inc、
ISBN4-902105-00-4.
8. Ownership organization
Structural Quality Assurance, Inc. 1028220, Chiyodaku, Tokyo.
Tel:+81-3-5214-3431
Fax: :+81-3-5214-3432
E- mail:square@sqa.co,jp
URL:www.sqa.co.jp
9. Certification
JBDPA Certification No.1624
Patent No.: 3484156(Japan), 173122(Taiwan), 146149(Taiwan)
Patent Application No. (Published): 10/089,108(US), EP1 258 579 A1 (EU), CN
1529783A(China) etc.
60
1. Title
Seismic Retrofit for Existing R/C Buildings using SNE-Truss
2. Outline
SNE-Truss is a seismic retrofit technology, which reinforce existing R/C buildings from the
outside of the building using aluminum alloy space grids latticed wall. The purpose of the
reinforcement by SNE- Truss is to improve the seismic capacity of existing R/C buildings by
the in-plane strength and stiffness of this aluminum latticed wall. Fig.1 shows a computer
graphic drawing of existing R/C buildings reinforced by SNE-Truss.
As for the main characteristics of SNE- Truss can be stated as follows:
(1) Because of outer reinforcement for existing R/C buildings, the work of retrofit can be
carried out in residence in the existing R/C buildings.
(2) The low specific gravity and a high strength to weight ratio of aluminum can be held low
the dead load added by the reinforced member of SNE- Truss to the existing R/C buildings
and its foundations.
(3) The high performance of corrosion resistance of aluminum can be maintained the facade
of the existing R/C buildings being fine sight.
SNE-Truss
Existing R/C
-Buildings
Steel framework
Fig.1 SNE-Truss composed of aluminum alloy
3. Specifications for materials and reinforced member
Fig.2 shows the shape and materials of the connection that is adopted in SNE- Truss and
mainly composed of aluminum alloy. All the applied struts, hubs, collar, and end plugs are
extruded aluminum (6061-T6). Bolts are high-tension bolts made of Cr-Mo steel quenched
and annealed at about 425°C. The 6061 alloy is an Al-Zn-Si heat-treated alloy, subjected to
solid solution treatment at about 500 °C followed by age hardening at 170 - 180°C for about 8
hrs.
Fig.3 shows the relationship between the strength and the deflection of SNE-Truss in
horizontal direction. The ultimate shear strength of SNE-Truss is determined by the strength
of the squeezed part of bolts which reaches the tensile yield force leads in other components
materials．
The standard design of truss member is shown in Table 1. The relation of the strut section,
bolt diameter and maximum length of struts are based on the theory of Fig.3.
61
Hub (6061-T6)
End-plug (6061-T6)
Friction welding
Bolt (Steel)
Squeezed part
Strut (6061-T6)
Collar (6061-T6)
Fig.2 Shape and materials of SNE-Truss connection
Buckling load of Struts s Qcr
or Tensile strength of friction welding section s Qy
Q
Shear strength
sQ y ＞bQ u
sQ cr＞bQ u
sQ cr ,sQ y
bQ u
bQ y
Ultimate strength
of squeezed section of bolts
Yielding
of squeezed section of bolts
Story Deformation
bφy
Φ
bφu
Fig.3 Relationship of shear strength and deflection
Table 1 Specifications of the reinforcing materials
Struts
Bolts
bN y
bN u
sN y
sN cr
Type
(mm)
(mm)
(kN)
(kN)
(kN)
(kN)
SNE533 φ125×t12.5
33
380.1
594.0
662.7
621.4
Lmax.
(m)
2.3
SNE636 φ150×t12.5
SNE639 φ150×t15.0
36
39
452.4
530.9
706.9
829.6
809.9
954.3
727.0
846.8
3.0
3.0
SNE842 φ200×t12.5
42
615.8
962.1
1104.5
1022.0
3.9
SNE845 φ200×t15.0
SNE848 φ200×t17.5
45
48
725.8
824.5
1134.1
1288.2
1307.7
1505.0
1200.4
1370.4
3.9
3.9
SNE852 φ200×t20.0
52
973.1
1420.5
1696.5
1532.1
3.9
Where, bNy and bNu are yield force and ultimate strength of bolts, and sNy and sNcr are yield
force of friction welding section and buckling force of struts, respectively.
62
4. Example of structural design
Example of structural design using SNE- Truss is shown in the following.
Fig.4 is a typical existing R/C building for Japanese public school. Table 2 shows the results
of structural design for reinforcement. SNE-Truss model applied for reinforcement is shown
in fig.4. Where, numbers of truss unit are one for vertical and two for horizontal direction
around one plane of structure (each story and span) of the objective existing R/C building,
respectively. In table 2, Qu is the yielding shear load of the SNE-Truss wall and 1/φy the
yielding story drift for one plane of structure. “I S” is “seismic index of structure”, which is
prescribed in Japanese building code and regulations, and usually required more than 0.7 for
the public school. “I S” is defined by the following Equations in Japanese building regulations.
R I S > α ⋅ I SO
R I S = I S + ∆I S
∆I S = E0 ⋅ S D ⋅ T
E0 = ( n + 1) /( n + i ) ⋅ C ⋅ F
C = ∑ i Qu / ∑ iW
where, RI S is the IS after reinforcement, αis the safety factor required more than 1.2 and ISO
is the required I S in objective reinforce design. SD is the reduction factor corresponding to the
eccentricity between the center of gravity and stiffness of the objective existing building. F is
the extra coefficient corresponding to the plastic deformation capacity. “(n+1)/(n+i)” is the
reciprocal number of the distribution coefficient of the seismic load for the height direction.
“IS” is easily the ratio of the horizontal load carrying capacity to the weight of each story of
the objective existing buildings. “⊿IS” is the increased “I S” by the reinforcement using
SNE-Truss. Table 2 shows that “I S” after the reinforcement can exceed the value of 0.7 when
the “I S” of the result of the seismic capacity evaluation for the existing building is supposed
0.4 to 0.5.
36m
9.2m
(3story, story height=3.75m)
Truss unit=2×1
4.5m
4.5×4=18m
SNE-Truss wall installed
for each 1st and 2nd floor
Fig.4 Example of structural design using SNE-Truss
SNE533
SNE639
Table 2 Results of structural design for reinforcement
Qu
⊿Is
Struts
Bolts
1/φy
st
(kN)
1 Fl.
2nd Fl.
33
706
1/304
0.23
0.26
φ125×t12.5
985
1/313
0.32
0.32
φ150×t15.0
39
SNE845
SNE852
φ200×t15.0
φ200×t20.0
Type
45
52
1347
1806
63
1/314
1/304
0.44
0.59
0.44
0.59
5. Loading tests and investigations
Standard design of SNE- Truss was established based on the following loading tests and
investigations.
Full scale loading tests of the simple beam of the space grid used in SNE- Truss was
executed and a proportional and cyclic loading was applied to the unit space grids in order to
investigate the buckling characteristics of the truss members with different member
slenderness ratios. The loading test confirmed that the effective member slenderness ratio is
predicted to correspond to 0.7 times the calculated ratio assuming the unsupported length LK
to be the distance between the grids. (Fig.5)
Regarding the double layer space grids latticed wall, to investigate the load carrying
capacity, plastic deformation capacity and collapse mode, loading tests subjected to the
in-plane direction were carried out. (Fig.6)
Fig.5 Simple beam loading test
Fig.6 In-plane loading test
6. References
1) Ishikawa, K., Hiyama, Y., Kato, S., Okubo, S.: Dynamic Buckling Behavior of an
Aluminum Double Layer Latticed Wall and its Possibility of Earthquake Resistant Element,
IASS International Symposium, pp. E2.21-E2.30, Sep.1999, Madrid.
2) Hiyama, Y., Ishikawa, K., Kato, S., and Okubo, S.: Experiments and Analysis of the
Post-Buckling Behaviors of Aluminum Alloy Double Layer Space Grids applying Ball
Joints, Structural Engineering and Mechanics, Vol. 9, No. 3, pp. 289-304, 2000
3) Okubo, S., Hiyama, Y., Ishikawa, K., Wendel, W., Fischer, L.: Load Capacity and Plastic
Deformable Ability of Aluminum Alloy Double Layer Latticed Wall Subjected to Plane
Load, IASS International Symposium, TP101, Oct. 2001, Nagoya.
7. Ownership organization
Sumikei-Nikkei Engineering Co. Ltd., 2-35-13, Kameido, Koto-ku, Tokyo 136-0071
Sales Department for Aluminum Structures
Tel: +81-3-5628-8519
Fax: +81-3-5628-8518
E- mail: shizuo- morimoto@sne.co.jp
URL: http://www.sne.co.jp
Dec.24, 2004
Yujiro Hiyama, Dr. Eng.
yujiro- hiyama@sne.co.jp
64
1. Title
TARS (Taisei Anchor- less Retrofit System)
2. Outline
TARS is a seismic retrofit system for existing R/C buildings to improve a horizontal
retained capacity and a stiffness with a moderate ductility, by settling a stiff infill to a
bare frame without dowel anchors cohered by epoxy resin at connections.
3. Specifications for the retrofitted frames
Two types of the infill are used, one is a steel framework with H section interconnecting
braces and the other is a concrete shear wall. These infill are firmly connected to the
inside of a bare frame by grouting with high strength mortar. Shear transfer at the
horizontal connections simply depends on a resistance caused friction in compression
area, because the basic measure of the TARS involves nothing but the grouting mortar
to settle the infill. Some variations of constraints at the horizontal connections are
described below if more enhancement of the shear capacity is required.
1. Constraining forces which are given with PC bars directly connecting the steel
frameworks of upper and lower story.
2. Semi-cylindrical cotters which are carved top and bottom surface of a beam.
3. Embedded bolts which are fixed with the grouted mortar into the carved holes of a
beam in the vertical direction.
Shear tests on the connection for a R/C beam and a steel of the framework were carried
out to investigate its abilities of shear transfer with these constraints.
4. Typical construction details
The strong axis of the steel framework being arranged the in-plane direction of the beam,
the stiffness of the framework is higher and the space grouted with mortar became
narrower than those of a conventional measure.
The semi-cylindrical cotters, of which height is a ha lf of the radius, and the embedded
bolts, of which embedded length into the beam is four times of the diameter, are placed
at the horizontal connections to constrain a slip displacement.
Grouting is executed with premixed high strength mortar without shrinkage, which was
designed to have a 7-day strength of 50 MPa.
The concrete shear wall is cast at sites but have no dowel bars at the wall- frame
connections. The wall involves shear reinforcement of which ratio is around 0.3%, and
the concrete which is specified to a strength of 30 MPa is used.
TARS facilitates to improve seismic performances in a shorter period, and easy
construction procedure makes a reduction in a budget.
5. Research for verification
The seismic performance of the strengthened frames applying TARS has been verified
through a serious of structural experiments. Reversed cyclic loading tests on the infilled
frames with a steel framework were conducted for ten specimens, and another four
specimens retrofitted with a shear wall were tested in the same way. The geometry and
the reinforcing details for a specimen with a shear wall are shown in Fig.1 and the
loading apparatus for the specimen is shown in Photo.1.
65
梁心
8-M20
D13
200
200
〃
200
〃
〃
200
N=
300kN
50
Ｎ
10 10
軸力
D25
4-D19
梁 380*600（380*230）
100
梁端部目荒し処理（梁せい領域）
D6@140(pw=0.2%)
S30のみ
グラウト
50
50
添筋：4D13, L=1600
打設口
幅止筋
D6
1410
pw=0.15%
M20
D13
コーナー補強：D13
40
40
350
梁幅：230
1325
500
S33
350
150
[-100*50*5*7.5
H-300*70*9*19
境界梁
開口:500*1080
S32
Fig.1 Details of a specimen retrofitted with a shear wall
Photo 1 Loading Apparatus
66
40
50
90
増打壁：D6@80,pw=0.44%
シアキー：D13,L=50
4-D13@140
上部梁型
40
3000
60
既存壁：D6@200,pw=0.27%
30
0
600
D6@120
S31
40
100
26
40 135 135 40
S30
8-M20 L=240
端部目荒し処理，深さ６mm
40 135 135 40
35 35
S30
390
4D19+
4D16
125 130 125
100
600
t=120, Fc30
：ゲージ貼付位値
40
40
230
1600
40
D6@120ダブル,pw=0.44%
All specimen similarly behaved infilled frame walls with a stiff shear panel. The
hysteretic response was gradually pinched in larger drifts, because the slip displacement
at the horizontal connections became larger in proportion to the drift. But load carrying
capacities generally increased 300% or more than the calculated values of the bare
frames with moderate ductilities.
The similar punching shear failure at the top part of the column was observed around
the 0.8% drift angle. A shear failure occurred thereafter on the other column, the
development of these failures was mostly in common. Situations after loading for
specimens with a framework and a shear wall are shown in Photo.2 and 3 respectively.
The specimen with constraining force dissipated considerable energy, other constraints
resulted in being effective to enhance a stiffness as well as a shear capacity.
Photo 2
Overall view of a specimen after loading
Photo 3
Overall view of a specimen after loading
67
Based on the test results, mechanism of shear resistance would be postulated as a frame
action of an existing bare frame combined with the shear strength of the infill, which
provided a diagonal compression strut. Both of the framework and the shear wall having
much higher strength and stiffness compared to the column, the reaction force from the
framework balanced with horizo ntal load caused the punching shear failure.
The design procedures described that the horizontal retained force of the retrofitted
frame was given by the summation of the strengths of the columns and the shear force
transferred by friction and the constraints at the horizontal connection below the beam.
6. Examples in practice
Approximately ten existing facilities have been retrofitted with TARS, including
department stores, office buildings and school buildings in Japan.
7. References
3) Kazuhiro Kanata et al, Strengthening methods for R/C frames with infilled panel by
using friction at the panel- frame joint, Part1~Part10, Summaries of technical papers
of annual meeting, AIJ, 2000~2004 (in Japanese).
4) Kazuhiro Kanata and Ken- ich Kikuchi,：Retrofitting methods for existing frames to
enhance strength by using friction at Steel-Concrete joint, Proceedings of JCI
symposium on evaluation of the effect of seismic retrofit of existing concrete
structures, June 2000 (in Japanese).
5) Kazuhiro Kanata et al,：Evaluation for strengthened frames with an infilled panel by
using friction, Proceedings of the JCI,Vol.25,No.2, July 2003 (in Japanese).
8. Ownership organization
Taisei Corporation. 163-0622 Nishi Shinjuku 1-25-1, Shinjuku, Tokyo
Tel: +81-3-5381-5070
Fax: +81-3-3344-1094
E- mail: kanada@kiku.taisei.co.jp
URL: http://www.taisin-net.com/
9. Certification
JBDPA Certification No.1658
Patent No.: 3525418(JP)
Patent Application No. (JP):
1999-61013,1999-113312,
2001-196309,2001-271360,
2002-2391,2003-219101, etc.
68
1. Title
OFB (Outer- frame brace)
2. Outline
OFB is a new seismic strengthening method using Outer- frame brace. Seismic
strengthening of the building can be carried out easily without decreasing the
serviceability and quality of living condition. We can occupy the building during retrofit
construction works.
3. Typical construction details
The braces are attached outside the structural frames of existing buildings. The
connecting beam was cast on the existing frame, and the anchorage device was jointed
to the connecting beam. The braces were tied to the anchorage device with pin joints at
both ends. The existing building, connecting beam and anchorage device were joined
under normal stress conditions by pulling the prestressing bars.
Column
Connecting beam
Veranda
Brace
Joint pin
High-strength rods
Anchorage device
Figure 1 Outline of strengthening method
4. Research for verification
The performance of the strengthened reinforced concrete frame has been investigated
through same serious of tests. Loading tests for the connecting beams and reinforced
concrete frames were conducted to develop design procedure for strengthening
reinforced concrete frames by attaching outer-frame braces. The experiment confirmed
the load-deflection curves of the connecting reinforced concrete beam, and the
performance and lateral load-carrying capacity of the strengthened reinforced concrete
frames.
69
A 1/3-scale test was arranged in order to study the behavior of the strengthened
reinforced concrete frames using attached braces. The specimens are shown in Table 1,
and details of the original and connecting beams are shown in Fig. 2.
Table 1. Details of specimens
No.1
No.2
No.3
Specimen
Failure Mode
Attached Brace
Concrete
Column, Beam
Strengt h
Connecting
(MPa)
beam
No.4
Shear failure
Shear failure
Flexural
failure
Flexural
failure
without
24.6
With
25.5
without
25.6
with
29.5
-
40.3
-
37.8
Shear failure type
Flexural failure type
Brace for strengthened
specimen
(a) Original frame
Anchorage device
High-strength non-shrinkage mortar
Brace (φ25)
Brace (φ25)
(b) Connecting beam
Figure 2 Details of experimental specimen (Unit : mm)
70
400
Story Shear Force ( k N )
Story Shear Force ( k N )
Figure 3 illustrates the lateral load-displacement behavior of each specimen. The
horizontal displacement of the beam was divided by the height between the upper and
lower beam centers to obtain the drift angle. The lateral load-displacement peak
envelopes of each specimen are provided in Fig. 4. Herein, strengthened specimens No.
2 and No. 4 use the lateral load, subtracting the horizontal component of the axial load,
which had been acting on the brace from the jack load measured with the load cells. The
brace axial load was obtained by multiplying the section area, using Young’s module,
by the average strain of the brace. Original and strengthened specimens exhibited
responses up to the lateral load-carrying capacity with very similar lateral
load-displacement curves. This is seen in both shear and flexural failure type specimens.
Lateral load-carrying capacity of the strengthened specimens can be estimated by
adding the strength of the original frame to the brace strength.
No.2
No.1
300
200
100
0
400
No.4
No.3
300
200
100
0
0
0.25
0 . 5 0.75
1
1.25
1 . 5 1.75
2
0
0.5
1
Drift Angle ( % )
1.5 2
2.5 3
Drift Angle ( % )
3.5
4
4.5
(a) Shear failure type
(b) Flexural failure type
Figure 3 Lateral load-displacement response
350
Lateral Load (kN)
Lteral Load (kN)
350
N o . 2 O r i g i n a l F r a m e
300
250
200
150
100
No.1 Original Frame
50
N o . 2 B r a c e
0
N o . 4 O r i g i n a l F r a m e
300
250
200
150
N o . 3 O r i g i n a l F r a m e
100
50
N o . 4 B r a c e
0
0
0.5
1
Drift Angle ( % )
1.5
2
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Drift angle ( % )
(a) Shear failure type
(b) Flexural failure type
Figure 4 Lateral load-displacement response( peak envelopes)
Shear force during an earthquake is transferred from the existing structure to the braces
through connecting beams. Therefore, accurate evaluation of connecting beam
performance is essential. Based on the biaxial loading tests for the connecting beam, a
multi- linear skeleton curve can be identified and it is possible to evaluate the capacity
of the beam and the drift angle at yielding of the brace.
71
5. Examples in practice
Photo 1 Examples of application
6. References
1) Japan Building Disaster Prevention Association:Seismic Evaluation Standard for
Existing Reinforced Concrete Buildings(in Japanese), Japan Building Disaster
Prevention Association, 2001
2) Tsunehisa Matsuura, Kazuyuki Sumi, and Toshirou Makita:Development of
strengthening method using attached brace in outer- frame, 13th World Conference on
Eathquake Engineering, Conference Proceedings Paper No.2105
3) Tsunehisa Matsuura and Kazuyuki Sumi:Experimental study on seismic
strengthening method using brace of outer-frame(in Japanese), Proceedings of the
Japan Concrete Institute, Vol. 23, No. 1, 2001
4) Tsunehisa Matsuura, Kazuyuki Sumi, Toshirou Makita, Minoru Suzuki and Yasuyuki
Hinohara:A Study on Seismic Strengthening Method Using Braces of
Outer-Frame(in Japanese), Summaries of Technical Papers of Annual Meeting
Architectural Institute of Japan, 2003, C-2, pp. 721-722 (in Japanese)
7. Ownership organization
HAZAMA Corp., 2-5-8 Kitaaoyama Minatoku, Tokyo.
Tel: +81-3-3405-1157
Fax: +81-3-3470-4760
E- mail: taishin@hazama.co,jp
URL: www.hazama.co.jp
SEIBU Construction Co.,Ltd. 1-11-2 Kusunokidai Tokorozawashi, Saitama
Tel: +81-4-2926-3360
Fax: +81-4-2926-3383
E- mail: narihito-sekiya@seibu-const.co,jp
URL: www.seibu-group.co.jp/kensetsu
8. Certification
JBDPA Certification No.1746
72
1. Title
Seismic retrofit technology for steel structures using
Tomoe Friction Damper (TFD see Figure 1)
Figure 1 TFD
2. Outline
The aim of this retrofitting technology is to improve seis mic resistant performance of
existing steel structures by giving damping. Once a great earthquake occurs, TFD
installed in a structure controls the structural deformation by absorbing dynamic energy.
The performance of TFD and how to install TFD into a structure is validated by DPBA.
This retrofitting method is not applicable for high-rise buildings due to the capacity of
TFD.
3. Basic principle and features of TFD
TFD changes the dynamic energy into heat by the friction between the two metal
parts, the ‘dice’ and ‘rod’ inserted into the dice. Figure 2 illustrates the principle.
Figure 3 illustrates the force-displacement relation. It can be regarded as rigid-plastic
bilinear where the elastic modulus is very high. This leads superb efficiency in energy
absorption because the energy absorption occurs for very small displacement.
The friction load of TFD is 100 and 200KN and axial extension range is within ±
100mm. The influences of velocity, amplitude and initial temperature on the friction
load are not large and negligible for ordinary use.
Dice
Friction
Figure 2 Principle of energy absorption
120
100
80
60
40
20
kN
Rod
-120
0
-100
-80
-60
-40
-20
-20
0
20
40
60
80
100
-40
-60
-80
-100
-120
mm
Figure 3 Force-displacement relation
73
120
4. Typical construction details
TFD is installed into a structure by two forms, shear- link and brace forms (see Figure
4). Ordinary details, not specially developed, used for steel structures are applied.
However, when designing and constructing the details, it must be reminded that the
advantage of TFD is shown only when the rigidity and strength of the connections
between TFD and the existing structure are sufficiently secured.
既 存フレ ーム
既存フ レ ーム
摩 擦ダ ンパー
摩擦ダ ン パー
鋼 製ブ レース
鋼 製ブ レース
Figure 4 Typical construction details
5. Research for verification
Full-scale tests are carried out to verify the dynamic performances of TFD. The
deviation of friction load, influences of velocity, amplitude and temperature on friction
load and limit accumulated displacement were tested.
The dependency of the above factors is generally small and the load-displacement
relation is stable until the accumulated displacement reaches 8000mm. However, it is
found that too large velocity (20cm/s at average) leads some decline of friction load for
the 200KN-damper, so the average of velocity during an earthquake shall be limited
within or equal to 15cm/s.
6. Ownership organization
Tomoe corporation, 1040054, Chuo-ku, Tokyo.
Tel: +81-3-3533-7931
Fax: +81-3-3533-7951
E- mail: bosai@tomoe-corporation.co.jp
URL: www.tomoe-corporation.co.jp
7. Certification
JBDPA Certification No.1756
Patent No.: 3290912(Japan)
74
1. Title
PPMG-CR (Seismic Retrofit Technology of Columns with a Special Polymer-cement
Mortar)
2. Outline
PPMG-CR is a seismic retrofit technology for existing columns using a special
polymer-cement mortar and shear reinforcements. Targeted columns are of reinforced
concrete buildings and steel encased reinforced concrete buildings with grid and lattice
frames. Shear strength and ductility of columns are greatly improved by jacketing
retrofit using shear reinforcements and the special polymer-cement mortar (MagnelineType II) or using steel plate and the special polymer-cement mortar (Magneline-Type I).
Jacketing by steel plate can particularly contributes to mitigation of the axial force limit.
3. Specifications for materials
PPMG-CR technology uses Magneline polymer-cement mortar comprising a powdered
component of white cement, silica sand and a special admixture and a water soluble
emulsion of polyacrylic ester copolymer admixed on site. Magneline-Type I and Type II
are distinguished by the mix proportion of the powder component and the emulsion.
Magneline- Type I is used as a grouting material for a gap between steel plate and
existing concrete and as a primer for the concrete surfaces. Specification of MagnelineType I is shown in Table 1. Magnline-Type II is used as a plastering material for
thickening existing structures in jacketing by the shear reinforcement. Specification of
Magneline- Type II is shown in Table 2.
Table 1 Specifications of the Magneline -Type I
Properties
Specified value
Test method
28-day compressive strength
Greater than 21.0 N/mm2
JIS A 1108
Consistency
Bond strength to concrete
10 to 40 seconds
Greater than 1.5 N/mm2
J 10 Funnel test
BRI method
Table 2 Specifications of the Magneline -Type II
Properties
28-day compressive strength
Consistency
Specified value
Test method
2
greater than 30.0 N/mm
130 to 200 mm
JIS A 1108
Flow test
4. Typical construction details
PPMG-CR is a seismic retrofit technology using welded wire fabric as shear
reinforcement or steel plate jacketing on existing columns. Figure 1 shows two types of
construction: the welded wire fabric jacketing with subsequent plastering of MagnelineType II and steel plate jacketing with grouting of Magneline-Type I.
75
We l d e d
wi r e f a b r i c
Ex i st i ng
c o l u mn
Sl i t
( a p p r o x . 3 0 mm)
She a r
r e i n f o r c e me n t
Ma g n e l i n e - T y pe Ⅱ
( Pl as t e r i ng)
< We l d e d wi r e f a b r i c j a c k e t i n g >
S t e e l p l at e
Sl i t
( a p p r o x . 3 0 mm)
Ex i st i ng
c o l u mn
Ma g ne l i n e - T y p e Ⅰ
( Gr ou t i n g )
< S t e e l p l a t e j ac k e t i n g >
Figure 1 Column retrofitting with PPMG-CR method
5. Research for verification
PPMG-CR has been approved by a test for the half- scale model columns representing a
4 to 5 storied building in Japan. Of the eleven specimens prepared, seven specimens
with a shear span ratio of 1.0 were subjected to Phase 1 test and the other four with a
shear span ratio of 1.5 to Phase 2 test. In Phase 1 test, three specimens were retrofitted
with a steel jacket (1.6 and 3.2 mm thick) and another three specimens with a welded
wire fabric jacket (4 mm in diameter with a pitch of 50 or 25 mm) leaving the other one
as a original specimen. In Phase 2 test, three specimens were retrofitted with a welded
wire fabric jacket (6 mm in diameter with a pitch of 50 or 25 mm) leaving the other one
as a original specimen.
Typical load-displacement curves and ultimate state of a retrofitted and original
specimen are shown in Figure 2. Maximum load of the steel jacketed specimen was
1.66 to 2.05 times greater than that of original specimen and the displacement was as
large as the rotation angle of 1/50 radian. Maximum load of the welded wire mesh
jacketed specimen was 1.36 to 1.72 times greater than that of original specimen and the
displacement was as large as the rotation angle of 1/50 to 1/100 radian. Both retrofitting
methods were found to increase strength and ductility compared to the specimen
without retrofitting. A welded wire mesh jacketed specimen with a shear span ratio of
1.5 showed a transition of failure mode from shear to bending with a remarkable
increase in ductility and a slight increase in strength.
These experiments proved that PPMG-CR technology was sufficiently effective in
seismic retrofitting of columns.
76
No.1
400
Fc18
load
水平荷重Q(KN)
original specimen
+Qmax=186.8kN
- Qmax=204.1kN
300
試験体No1
200
100
0
-30
-20
-10
0
-100
10
20
30
水平変位δ（ｍｍ）
displacement
(無補強）
-200
-300
loading side
cross side
loading side
cross side
loading side
cross side
-400
No.8 Fc18
mesh barφ4@25
+Qmax=309.8kN
- Qmax=306.0kN
load
水平荷重Q(KN)
(a) Original Specimen
400
300
200
100
0
-30
-20
-10
0
10
20
30
displacement
水平変位δ（ｍｍ）
-100
試験体No8
(メッシュφ4@25全周巻き）
-200
-300
-400
(b) Wire-mesh Jacketed Specimen
load
水平荷重Q(KN)
No.2 Fc18
Steal Plate (1.6mm)
+Qmax=345.7kN
- Qmax=302.4kN
400
300
200
100
0
-30
-20
-10
0
-100
-200
10
20
30
displacement
水平変位δ（ｍｍ）
試験体No2
(鉄板1.6mm全周巻き）
-300
-400
(c) Steel Plate Jacketed Specimen
Figure 2 Typical load-displacement curves and fracture mode
77
6. Examples in practice
PPMG-CR has not yet been applied to full-scale structures.
7. References
1) T. Kubota, M. Fukuda, T. Mitani, T. Kaminosono, T. Akiyama, S. Tsukazaki and H.
Kato: Shear Strength of RC Columns Strengthened by Steel Plate and Wire Mesh
with Polymer-cement Mortar (Part 1, 2 and 3), Prep. Annual Meeting of AIJ, Sep.
2003.
2) K. Ariki, T. Yamamoto, T. Kaminosono, S. Tsukazaki, T. Akiyama and Y. Kado:
Shear Test of Polymer-cement Mortar to Concrete and Steel Surface, Prep. Annual
Meeting of AIJ, Sep. 2003.
8. Ownership organization
Magune Chemical Co., Ltd.
2-4-25,Takeshita,Hakataku,Fukuoka
Tel :+81-92-477-3533 , Fax:+81-92-477-3532
E- mail:tsuka@magnekagaku.co.jp
TOKYO SOIL RESEARCH CO., LTD.
Department of Building Research & Engineering
Tel :+81-3-3463-4825 , Fax:+81-3-3463-4876
E- mail:akiyama-t@tokyosoil.co.jp
URL: http://www. tokyosoil.co.jp
9. Certification
The Japan Building Disaster Prevention Association Certification No. 1761
Two patents are being applied (2001-224349 and 2002-219797)
78
1. Title
PCa Brace System
2. Features
PCa brace system has some features as follows.
1) This bracing system consists of two precast concrete diagonal elements in
order to construct easily during a short period.
2) These diagonal elements are attached to the outside of the existing building by
binding joint in order to lessen the work performed inside it.
3) This system has the friction control joints. The role of friction joints is to dissipate
seismic energy by flectional
sliding and to control the axial
PC bar
forces to diagonal elements in
Existing beam
order to reduce the shear force in
Existing column
the existing beams and to avoid
the brittle collapse of diagonal
Auxiliary
elements.
4) These diagonal elements are
Precast brace
prestressed by post tensioning in
Friction joint
order to raise the tension cracking
Existing beam
strength.
5) The damage to peripheral beams,
PC bar
columns and reinforcing bars is
Fix
minimized only making a hole for
inserting pc bars used for binding
Fig.1 Model of seismic upgrading by PCa brace
joints.
3. Specifications for materials
Materials is shown in Table 1.
Table 1. materials
materials
Specifications
concrete
Fc=60N/mm2
cement mortar
Fc=50N/mm2
pc bar
SBPR1080/1230
friction plate
granite
4. Details of method
Detail of the friction control joint is indicated in Fig. 2.
The top of brace system is connected to the centre of an upper (or lower) beam through
a friction control joints. The friction control joint consists of two friction plates and a
prestressing bar for binding. The material of friction plate is granite. Lateral resistance
of brace system depends on resistance of the friction control joints, and the product of
friction coefficient of materials and prestressing force gives the maximum friction
resistance. Therefore the expected resistance of a friction joint (the maximum input
force to the brace) is easily realizable by choosing an appropriate binding force. The
friction coefficient between two granite plates is given based on the test results.
79
The purpose of this joint is to control the lateral force induced to this brace system.
When the lateral force induced to a brace exceeds the friction resistance of the top
connection, slip deformation occurs, with retaining the lateral resistance of a brace is
kept constant.
The restoring force characteristics of the joint show bi- linear behavior with high
stiffness in the first branch and small positive stiffness in the second branch. Therefore
the hysteretic loop has almost rectangular shape.
Bottoms of two legs of a brace are fixed to the both ends of lower (or upper) beam
through cement mortar by post tensioning as indicated in Fig. 3. Friction coefficient of
fix joint is 1.0, and sufficient prestressing force is given to it to avoid slipping, this
value is over 1.3 times of the required prestressing force.
PCa brace
mortal
granite plate
anchor plate
anchor plate
anchor plate
anchor nut
unbonded
PC bar
anchor nut
anchor nut
anchor plate
anchor nut
PC bar
existing beam
mortal
PCa brace
Fig.2 Friction joint connected to beam
existing beam
Fig.3 Fixed joint connected to beam
5. Research for verification
5.1 Static loading test on a reinforced concrete frame with the brace system
Static loading test was performed using the testing frame of 1/2 scale of the assumed
structure.
The amount of binding force in a friction joint is 148(KN). Therefore calculated shear
strength of a friction joint is 96.2（＝148×0.65）(KN). Section of concrete brace was
13.0x13.0cm square and prestressed at 60KN.
Calculated tension cracking strength of concrete brace is 129 KN. Load - deflection
relation obtained by test and calculated load - deflection relation calculated by
non- linear two-dimensional analysis are indicated in Fig.4.
In the test results, flexural cracking at column bottom section and the slip at friction
joint were observed at the lateral load of 90KN, and lateral stiffness was reduced. The
experimental value of first slip is correspondent to the calculated value. Then, flexural
yielding of column bottom section occurred at the load of 330KN and the considerable
reduction of stiffness was observed. However the load carrying capacity kept on
increasing 1% drift and no reduction was observed up to 2 % drift. The load increase
from 1 % to 2 % drifts in test results is due to the increase of binding force at the
friction joint.Many of the calculated values were correspondent to the values obtained
by the experiment, and the effect of seismic upgrading by brace system has been
confirmed.
80
400
200
0
-200
test result
predicted result
predicted result
(without brace)
-400
-40
-20
0
20
40
Drift of portal frame(mm)
Photo.1 Static test of brace
Fig.4
Load deflection curve
5.2 Shaking test of brace system
Shaking tests were performed using the 2 specimens for the purpose of investigating the
dynamic behavior of the brace system. Tested original frames consist of reinforced
concrete top and foundation beams and steel columns, and pin joints were used to
connect steel columns to beams.
Moreover, The top of the brace was binding to upper beam by prestressed bar through
friction joint formed on two granite plates, and the bottom was fixed to foundation beam
by prestressed bar through cement mortar.Therefore, during the shaking tests, only
concrete brace resisted the inertia force through friction joint.
Section of concrete brace was 13.0x13.0cm square and prestressed at 60KN. Calc ulated
tension cracking strength of a diagonal element is 129 KN. The only difference between
these 2 specimens was the binding force at friction joint.
Specimen-1 with ordinary binding force at friction joint of 148(KN) is expected to show
the predicted slip behavior and energy dissipation without any damage to concrete
diagonal elements. Predicted maximum shear strength of friction joint was 96.2（＝148
×0.73）(KN).
For specimen-2, the larger binding force of 373(KN) was applied, where the damage to
concrete diagonal element was expected to unexpected huge input acceleration.
Predicted maximum shear resistance of friction joint was 272KN (0.73x373KN).
Each specimen was tested under several levels of sinusoidal waves and recorded
earthquake waves. The maximum input acceleration was 1300 gal.
In Specimen-1, The friction coefficient of the first slip was larger than 0.40 and
gradually increased as the increase of deflection response. Beyond the deflection of 10
mm, the friction coefficient exceeded the design value of 0.65. Observed maximum
value of friction coefficient was 0.73 and did not exceed 0.85. Friction coefficient of
Specimen-2 also showed the similar values of specimen-1. Therefore, the established
friction coefficient in order to calculate the shear strength is appropriate also in shaking
tests.
Further, in specimen-2, when the response acceleration showed 1600 gal., the tension
force of concrete brace reached at 113 KN. It didn't exceed the cracking strength of
136KN, and the tension crack was not observed. At the acceleration response of 2460
gal., the tension force of concrete brace exceeded the cracking strength and reached
174.1 KN. Then, little tension cracks were observed. However the damage to the
concrete brace was very slight.
81
6. Example in practice
An example is introduced where PCa brace system was adopted for seismic upgrading
work of a certain junior high school building. Photographs before and after upgrading
are shown in Photo 2. This building was built in 1961, and concrete strength used for
this building was 15.0 (N/mm2 ). The total of Increased capacity was 27500 (KN), and
the capacity per one brace system was 150-200KN.
Construction work could be completed during short period and without interrupting the
use of buildings because this brace system consisted of two precast concrete diagonal
elements and were installed in the perimeters of building.
before
Photo.2
after
Example of Upgraded Building
7. References
1)
Kisihiko Moriyama, Yutaka Osanai,
Miyuki Ooshima, Yosio Kimura:
Experimental Reports on Seismic Strengthening with the Precast Prestressed
Concrete Braces.(in Japanese)，Journal of Prestressed Concrete, Japan, Vol.40, No.4,
Jul.1998
2) Yutaka Osanai, hirokazu Asakawa, Kouichi Yamamoto, Masataka Tanimoto: Design
& Construction in the Seismic Strengthening with the PCa Braces.(in Japanese)、
Journal of Prestressed Concret, Japan, Vol.41, No.4, Jul.1999
8. Ownership organization
Oriental Construction Co.,Ltd. 2-1-1 Hirakawa-cho, Chiyoda-ku, Tokyo.102-0093
Japan
Tel: +81-3-3261-1176
Fax: +81-3-3261-1139
E- mail: hidetoshi.taga@oriken.co.jp
URL: //www.oriken.co.jp/
9. Certification
JBDPA Certification No.1762
Patent No.: 3096664(Japan)
82
1. Title
PCaPC External Frame Aseismic Strengthening System
2. Outline
A precast prestressed concrete (hereafter referred to as PCaPC) external frame aseismic
strengthening system is an aseismic strengthening method of building which heightens
the shear strength of the building and raises earthquake resisting capacity by attaching
the PCaPC frame to the existing reinforced concrete building (RC) or the existing steel
reinforced concrete building (SRC). An outline of this method is presented in Fig.1.
The PCaPC frame is built up with the factory product precast concrete column and
beam by the post-tensioning system. Connection between the existing building and the
PCaPC frame is carried out by floor slab or shear transfer block. The horizontal force
and the axial force of the PCaPC frame are transmitted to the ground by the foundation
of the PCaPC frame, or by joining PCaPC foundation and the existing building one.
This method is able to reduce the repair or restoration work inside the building on
account of connect the asismic strengthening member to the existing building from an
outside, and also produce well lighting and good facade of the building after
reinforcement. Furthermore, using the precast concrete member lead to shorten the
construction term and improve in quality.
Fig. 1 Outline of PCaPC External Frame Aseismic Strengthening System
3. Scope
This method is applicable to the low or middle rise RC or SRC structures whose
concrete strength is more than 18MPa. The strength of the precast concrete used for the
PCaPC frame is more than 30MPa, and the strength of the cast in place concrete is more
than 18MPa.
83
4. Connecting method the PCaPC frame to the existing building
The PCaPC frame and the existing building is connected by chemical anchors in case of
using floor slab and by the shear transfer block using post-tensioning system.
Earthquake load
Existing Building
Earthquake load
Shear resistance of
existing building
Compression
Shear resistance of
existing building
Floor slab
Bending moment
Shear force
Axial force
Bending moment
Tension
Shear transfer
block
Shear force
Shear resistance of
PCaPC frame
Shear resistance of
PCaPC frame
PCaPC Frame
Fig.2 Shear Transfer Mechanisms (plane view)
5. Evaluation method of strength contribution of the PCaPC frame
The earthquake resiting capacity of the building reinforced with this method is
evaluated with Seismic Index of Structure calculated by formula (1) based on a
seismic diagnosis standard (Ref. 1).
F
FIS
I S =F E0 ⋅F S D ⋅T
(1)
: Seismic Index of Structure of the building reinforced with this method
: Basic seismic capacity index of the building reinforced with this method
: Shape index of the building reinforced with this method
: Time index of the building
FE0
FSD
T
Basic seismic capacity index of the building reinforced with this method is calculated by
formula (2).
F
n
Q1
αj
RCQ
Fαj
FQ
Wa
F1
E0 =
n + 1  ∑ Q1 +∑ (α j ⋅ RC Q )+ ∑ ( F α j ⋅ F Q) 
⋅ F1

n + i 
W
∑ a

(2)
: The number of building stories
: Shear strength of the 1st group of the existing building
: Strength contribution coefficient of the j-th group of the existing building
: Shear strength of the j-th group of the existing building
: Strength contribution coefficient of the PCaPC frame
: Shear strength of the PCaPC frame
: Total weight of the existing building and the PCaPC frame
: Ductiluty Index of the 1st group (0.8 , 1.0 or 1.27)
The strength contribution coefficient of the PCaPC frame is calculated in consideration of
the rigidity of the connectiong component (floor slab or shear transfer block).
84
6. Performance of the joint of post-tensioning system
The shearing slip test was conducted in order to check the performance of the
post-tensioning joint between high strength concrete for the precast concrete and low
strength concrete of the existing building. The test apparatus and the relationship between
shear force and slippage are shown in Fig.3 and Fig.4, respectively.
Vertical Force
Oil Jack
Reaction Frame
Shear Force
Oil Jack
High Strength Concrete
Low Strength Concrete
(Precast Concrete)
(Existing Building)
Fig. 3 Test Apparatus
-10
-5
120
100
80
60
40
20
0
-20 0
5
-40
-60
-80
Specimen A
-100
-120
Slip (mm)
10
Maximum Shear Stress (N/mm
Shear Force (kN)
2
)
12
previous test
test result
10
8
6
4
2
coefficient of friction=0.5
coefficient of friction=0.5
0
0
Fig. 4 Test Results
85
2
4
6
8
Post-tensioning Stress (N/mm2)
10
7. Typical detail
An example of the joint using the shear transfer block is shown in Fig.5.
Protect motar
Anchorage plate
Existing building
Shear
PCaPC Frame
PCaPC Beam
Shear
Joint mortar
transfer
700
transfer
Beam of existing building
350
900
B
Floor Level
950
A-A Section
A
A
600
Anchorage
device
PCaPC beam
Post-tensioning bar 26
PC cable 7-15.2φ
B
PCaPC column
B-B Section
PCaPC Frame
Fig.5 Typical Detail of the joint using the shear transfer block
8. Reference
1) The Japan Building Disaster Prevention Association : Standard for Seismic Diagnosis
of Existing Reinforced Concrete Structures 2001
2) Yasuhiro Shioda, Masaaki Ohnuma, Hiromitsu Chiba and Kazuhiro Watanabe: Shear
transfer strength of post-tensioned RC-PC frame connection in outside strengthening
method, Summaries of Technical Paper of Annual Meeting 2004, Architectural
Institute of Japan.
9. Ownership organization
P.S. Mitsubishi Construction Co., Ltd. (Architectural Division)
G-7 Bldg., 7-16-12 Ginza, Chuo-ku, Tokyo 104-8215, Japan
TEL
：+81-3-4562-3057
FAX
：+81-3-4562-3065
E-mail ：webmaster@psmic.co.jp
URL
：www.psmic.co.jp
86