January 2018 No.80

IDIJapanese Infrastructure Newsletter

QUARTERLY
InfrastructureDevelopment

Institute—JAPANCONTENTS
The 19th Infrastructure Technology Development Award 2017
“Re-pier method” for efficient seismic retrofitting of piled piers in service
Restoration for Preservation of Himeji Castle Main Keep, National Treasure of the Heisei Era

Infrastructure Development Institute – Japan (IDI)
Suido-cho Bldg, 3-1, Suido-cho, Shinjuku-ku, Tokyo, 162-0811, JAPAN
Tel: +81-3-5227-4107 Fax: +81-3-5227-4109 E-Mail: idi17@idi.or.jp Website: http://www.idi.or.jp/english/00index.htm

25

Infrastructure Development Institute - JapanthThe 19 Infrastructure Technology Development Award 2017
The Japan Institute of Country-ology andThe grand prize is “Next-generation construction

Engineering(JICE) was established as a public

production system centered on automation ofinterest corporation to promote construction

construction machinery A4CSEL”.

engineering in Japan by conducting cutting-edge
research and development activities.
As more incentives should be provided for

And the three excellence prizes were awarded to“RE-PIER METHOD for efficient seismic

construction technology researchers and researchretrofitting of piled piers in service”, “Restoration

institutes to enhance the level of construction

for Preservation of Himeji Castle Main Keep,engineering more effectively, JICE commenced

National Treasure of the Heisei Era”, andInfrastructure Technology Development Award“Network Compatible Unmanned Construction

with Coastal Development Institute of TechnologySystem”.

(CDIT) under the auspices of the Ministry of Land,
Infrastructure, Transport and Tourism(MLIT).

The grand prize and one of the three excellence
prizes are introduced below.

Thirty-six technologies competed for the 19th
Infrastructure Technology Development Award.
In principle, the applicants’ technologies should

For any inquiries/ comments please contact
JICE :

have been developed within the past five years

Homepage: http://www.jice.or.jp/

and applied to the real sites within the past three(Japanese version only)

years.

E-Mail: webmaster@jice.or.jp

As a result of examination, institutes andresearchers with the following technologies wereawarded 19th prizes.

January 2018 No.80
1

Infrastructure Development Institute - Japan“ R e - p i er m e t h o d ” f o r e f f i c i e n t s e i s m i c r e t r o f i t t i n g o f p i l ed p i er s i n s e r v i c e
1. Background of Technology Development

cost-efficient method enabling the seismic retrofitting

The Ministry of Land, Infrastructure, Transportof mooring facilities without reducing their existing

and Tourism of Japan formulated the “Emergency

physical distribution function or while minimizing theProgram

effect of the retrofitting work on the use of theforDevelopmentofHigh

Earthquake-Resistance Mooring Facilities” in 2006,

mooring facilities.

and is making efforts to attain the objectives. In thiscontext, the ministry has to extend service lives and2. Detailed Description of the Technology

implement seismic retrofitting of existing structuresThis technology was developed for the seismicwith a limited budget for social capital development inretrofitting, extension of the service life and deepening

order to enhance the earthquake resistance ofof existing piled pier structures. It is a method tostructures.

reinforce an entire pier structure by connecting steel

Many private companies that own

mooring facilities for exclusive use do not have any

pipe piles with stiffening members (Fig.-1).

other facilities that they can use when the service

The stiffening member has a nested structure

lives of their mooring facilities have expired, so they

consisting of two steel pipes with different diameters.

have a need to extend the service lives of theirThis structure makes the length of the member

mooring facilities at low cost without suspending theiradjustable (Photo-1, Fig.-2).

services. Therefore, there has been a demand for a

Fig-1. Conceptual diagram of pier retrofitting

Fig-2. Mechanism for the length
adjustment of the stiffening member

Photo-1. Stiffening member (strut member)

1member)January 2018 No.802Infrastructure Development Institute - JapanThe members are transported to a retrofitting siteand outer pipes of the member are filled with mortar

in the shortest form with the inner pipe fully inserted(Fig.-3) to form rigid joints between the stiffening

in the outer pipe.

member and the existing structure.

They are extended to required

While alengths at the site and installed between two existingsuperstructure on piles has to be removed before

piles.

stiffening members are to be placed by inserting piles

The stiffening member has a casing-pipe part which

into the casing parts from pile top ends in theconsists of two parts manufactured by splitting a steel

conventional seismic retrofitting technology, thispipe in half at either end. These two parts are joined

technology allows the installation of additionalat their flanges after the member has been installed

stiffening

between two piles.

superstructure.

Then, the spaces between themembers

without

removing

theexisting piles and casing parts and between the innerFig-3. Section drawings of the overlapping partThe

characteristics

ofthistechnology

aresummarized in the following:・The nested structure consisting of two steel pipeswith different diameters allows the length of thestiffening member to be changed in a wide range.
When in storage and transport, the length of themember will be shortened than the gap between two
existing piles, and it can be placed between the piles
easily in its shortest form. Then, it is extended toconnect the two existing piles in order to integrate themember in the pile structure.
There is no need to remove a superstructure on
piles for the installation of additional stiffening
members.

This characteristic significantly reduces

not only the impact of the retrofitting work on thePhoto-2. Retrofitting while using a piled pieroperation of the pier (Photo-2) but the cost and timerequired for executing it.
January 2018 No.80
3Infrastructure Development Institute - Japan・Even if the distances between pairs of piles of an

3. Scope of Application

existing pier structure vary because of construction

Pier structures in general (including vertical pileerrors, the same length-adjustable stiffening members

structures, coupled/battered pile structures andmass-produced in a plant (standardized members) candolphin structures)

be used to connect them. (Fig.-4)

4. Advantage of the Technology
This technology significantly reduces the cost andtime required for the retrofitting (by 43 % and 61 %,respectively), compared with the conventional
technology that requires the removal of asuperstructure on piles before applying stiffening
members between the piles. (The time required at
a retrofitting site is compared. The time tomanufacture the stiffening member in a plant ishowever required when the new technology is to beused.)

Fig-4. Stiffening members installed on pairs of steel
pipe piles at different distances

5. Installation Record
Approximately 10 % of the mooring facilities inJapan had been in service for at least 50 years as of・The stiffening members can be installed manually

2014. This percentage will increase to approx.

by divers because the member can be kept at neutral

35 % in ten years and approx. 60 % in twenty years.

buoyancy with the use of a float specifically designed

The application of this technology will reduce theto give buoyancy to the member (Photo-3). Therefore,

maintenance cost of social overhead capital. It

work vessels will not occupy the water in front of thewill also contribute to building national resiliencepier during the retrofitting because they are notwith the extension of the service life ofrequired in this technology.

infrastructure and improvement of seismic
resistance of existing structures.
6. Record of the Application of the Technology
This technology has been used in five projects.
Technology Developer:
Aomi Construction Co., Ltd.
Contact:

Photo-3. Float specifically designed for thestiffening members

Tohru Yoshihara, Aomi Construction Co., Ltd.
E-Mail: netis@aomi.co.jp
TEL: +81-3-5439-1001

January 2018 No.80
4Infrastructure Development Institute - Japan

Restoration for Preservation of Himeji Castle Main Keep, National Treasure of the Heisei Era（Reborn of Himeji Castle by Melding Traditional and Contemporary Technologies）
1. Background of Technology Development
Under many constrained conditions restoration forpreservation of Himeji Castle, a National Treasure
and a World Cultural Heritage, posed issues of“accurateandappropriaterestoration

forpreservation” and “higher durability and improved
seismic resistance”, but we successfully did solve theissues by melding traditional artificer’s skills andcontemporary technologies, and then implemented
the restoration work. Before the commencement of therestoration work for preservation, a protective roof

Photo2 Dismantling Process of the Protective Roof Scaffolding

scaffolding covering the structure from the weather
and a huge gantry used for transportation and liftingof the building materials were constructed.
After completion of the restoration for preservation,
dismantling of the protective roof scaffolding wascarefully implemented without any delay, accident, ordamaging Himeji Castle Main Keep, which wasreborn as a shining white castle.
Photo3 Unitization of the Truss Beam for the Steep Rafter Roof

The interval between eyelet holes in mesh sheets(with a 30 % effective perforation rate) was reduced tohalf (from 300 mm to 150 mm) against gale winds.
Risky work of re-covering mesh sheets was eliminatedthrough the idea. (Photo4)

Photo1 Full view of Himeji Castle Main Keep

2. Detailed Description of the Technology
By unitizing the steel frames of the protective roof
scaffolding for the steep rafter roof, some of risky
construction processes were eliminated and the work
was simplified (Photo2, 3).

Photo4 Flameproof Mesh Sheet Rafter Roof

January 2018 No.80
45

Infrastructure Development Institute - Japan

According to the traditional construction method,roofing soil and batten cleats preventing roof tiles
from sliding were partially nailed and fastened withcopper wire. This time, wood batten cleats wereassembled on the roof tile base and roofing soil wasapplied in strips, and all roof tiles were fastened using
nails and copper wire as fall-preventive measures.
(Photo5)
Chemical Reaction
Ca(OH)2+SiO2→CaSiO3+H2O

Photo7 Spraying Water Absorption Inhibitor

As seismic reinforcements of columns, flat bar
frames were fixed using wooden wedges in order toreacttothepossible

slackening

andensurebreathability of wood parts in the future. (Photo8,DetailFigure1)

Photo5 Combination Method of Roofing Soil and Wood

Because it was impossible to change the shape ofWooden

the roof tiles to stop the water leak, we obtained

Wedge

permission to use copper plates as substrate roofing
material under roof tiles. (Photo6)

Flat bar frame

Photo8 Seismic Retrofitting for wood parts

Copper plate

Photo6 Copper plates under roof tiles

Inorganic water absorption inhibitor whose effecthad been verified in the outdoor exposure test wassprayed to prevent deterioration of the carbon coating
on roof tiles, cracking by freezing in the wintertimeand suppress the growth of mold to delay blackening

Figure1 Structure of a Flat Bar Frame Setand deterioration. (Photo7)

January 2018 No.80
6

Infrastructure Development Institute - Japan

3. Scope of Application of the Technology

The construction method used for Himeji Castle isConcerning the steel frames for protective roof

efficient when it is in a complicated situation like this.

scaffolding, unitization of the truss beam for the steep

Moreover, the technology to increase durability andrafter roof and integration of the suspended

seismic resistance appropriately investigated from ascaffolding

viewpoint of cultural heritage preservation will

areeffectiveinassembling

anddismantling of protective roof scaffolding on complex

contribute to achievement of long-term preservation ofterrain. This unitization eliminates some of risky

historic buildings and their beautiful appearances

construction procedures. In addition, reinforcement ofthat continue to give strong impressions on people. In

flameproof mesh sheet against strong winds, which

addition, melding of the traditional and contemporary

was done for the mesh sheet around the steel frames

technologies can contribute to the succession of thefor the protective roof scaffolding, is effective in windy

traditional technology as well as ancient cultures andregions as well as in the case of constructions thatbuildings to future generations.

may cause internal damage by removing mesh sheet.

4. Effect of Technology

6. Achievement of the Technology Application

As the protective roof scaffolding was gradually

The technology was applied to restoration work fordismantled and the current state of Himeji Castle waspreservation of Himeji Castle Main Keep for the firstuncovered, it became an evident that the restoration

time.（November 2009 – March 2015）

work for preservation was proceeding safely. Manymass media requested coverages of the dismantling,

Technology Developer：Kajima Corporationand it was aired on TV. Consequently, people became

Contact:

more interested in Himeji Castle as well as

Kajima Corporation Public Relations Officerestoration work of cultural heritages.

E-mail: h-takeda@kajima.com
FAX: +81-3-6438-2733

5. Social Significance and Possibility for
Further Development of the Technology
Protective roof scaffoldings are indispensable incultural heritage preservation work. Because Himeji
Castle was built as a fortress to keep away enemies,
there is not sufficient construction ground around it.

January 2018 No.80
76

Infrastructure Development Institute - Japan

About IDI and IDI-Quarterly
Infrastructure Development Institute (IDI)-Japan is a general incorporated
association operating under the guidance of Ministry of Land, Infrastructure,
Transport and Tourism of Japanese Government.
IDI provides consulting services for mobilizing International Assistance todeveloping countries, promoting international exchange of information and humanresources, and supporting globalization of project implementation systems targeting
both developed and developing countries in the field of infrastructure.
IDI has been publishing the free quarterly journal “IDI Quarterly” since1996 for the
purpose of introducing information relating to public works and construction
technologies developed in Japan to foreign countries. We have distributed thejournal to administration officials in more than 90 countries around the world bye-mail.
It is highly appreciated if you would send us your opinions, impressions etc on thearticles.
We are also welcoming your specific requests on articles to pickup for the following
Quarterly issues.

January 2018 No.80
8