February 2020 No.87

IDI

Japanese Infrastructure Newsletter

QUARTERLY
InfrastructureDevelopment

Institute—JAPANCONTENTS
21ｓｔ Infrastructure Technology Development Award 2019
Rapid Removal Technology for Replacing Reinforced Concrete Decks of Composite Girder Bridges .

2

Introduction of Fukabari-Method

5

Infrastructure Development Institute – Japan (IDI)
Plaza Edogawa-bashi 3F. 1-23-6, Sekiguchi, Bunkyo-ku, Tokyo, 112-0014, JAPAN
Tel: +81-3-5227-4107 Fax: +81-3-5227-4109 E-Mail: idi17@idi.or.jp Website: http://www.idi.or.jp/en/Infrastructure Development Institute - Japan

2１ｓｔ

Infrastructure Technology Development Award 2019Japan Institute of Country-ology and Engineering

As a result of examination, institutes and(JICE) was established as a public interest

researchers with the following technologies were

corporation to promote construction engineering

awarded 21st prizes.

in Japan by conducting cutting-edge research anddevelopment activities.

The grand prize is “Practical use of monitoring
technology in track maintenance and its

As more incentives should be provided for

application to maintenance management”.

construction technology researchers and research

And the two excellence prizes are “The Automatic

institutes to enhance the level of construction

Placement System of Dam Concrete”, and “Rapidengineering more effectively, JICE commenced

Removal Technology for Replacing Reinforced

Infrastructure Technology Development Award

Concrete Decks of Composite Girder Bridges”.

with Coastal Development Institute of Technology(CDIT) under the auspices of the Ministry of Land,

The one of the two excellence prizes is introduced

Infrastructure, Transport and Tourism (MLIT).

below.

Seventeen technologies competed for the 21st
Infrastructure Technology Development Award.

Any inquiries/ comments please contact to JICE :In principle, the applicants’ technologies should

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

have been developed within the past five years(Japanese version only)

and applied to the real sites already.

E-Mail: webmaster@jice.or.jp

February 20200 No.87
1Infrastructure Development Institute - Japan
Rapid Removal Technology for Replacing Reinforced Concrete Decks of Composite Girder Bridges
Subtitle: Hydro Jet Demolition Technique for Replacing Decks (Hydro-Jet RD Method)

1. Background and reason for development of thisremoval technology while focusing on replacing

technology

reinforced concrete decks of composite girder

Many expressway bridges built during Japan’sbridges.

period of rapid economic growth are now
sufferingfromremarkableaginganddeterioration. Their renewal is one of the

2. Technical details
Replacing the decks of composite girdercountry’s key social infrastructure tasks. In thebridges

case of the Hanshin Expressway, more than 50

configuration of studs on the steel girders which

years have passed since it was opened in 1964,

makes it difficult to remove joints between steel

and its aging structures are deteriorating.

girders and concrete decks. To deal with this,Large-scale renewal and repair project, whichwater jets (WJ) are used to remove concrete frombegan in 2015, covered 62km of the total length

joints. Namely, WJ are used for the bottom sideof 250.4km. Reducing adverse effects on theof decks of bridges open for traffic, to chip thetraffic by shortening the process has been an

joints (Photo-1) and to expose studs for lengths ofimportant

about 50 mm over the entire length (Photo-2).

issue

in

thiswork,along with reducing costs by utilizing improved

includestheproblemofdense

Steelconstruction methods. We have developed arapid
Reinforced concrete deck (steel reinforcement)
WJ nozzle

WJ unit

Reinforced concrete deckStud

About 50 mm
Steelgirder
Upper flange

Steel girder

Joint concrete

Photo-1 WJ application state

Photo-2 Joint removal state(5) Deck removal technology
Cutting studs without heating the steel
girder enables rapid removal of decks(1) WJ technology
Technology used to remove joint concretewith WJ to expose studs(4) Monitoring safety
Technology used to monitor soundness of
temporarily reinforced girders and safety ofpassing vehicles(3) Water- and sound-proofing
suspended scaffolding structure(2) Temporary reinforcement
Providing reinforcement of exposed studs
and flanges to prevent loss of functions ofcomposite girder bridge

February 2020 No.87

Water- and sound-proofing technology
enabling WJ technology on suspended
scaffolding structure

Figure-1

Overview of the developed technology

2Infrastructure Development Institute - Japanreinforcements(Figure-2)

andtemporary

entire length, decks can be removed rapidly andreinforcements made from special mortar aresimply by cutting the studs after closing thefixed to the exposed studs to maintain the design

bridge to traffic (Photo-4). The decks can be cut

performance of the composite girder bridge andwithout regard to the location of the steel

to ensure the availability of bridge for traffic.

girders (Photo-5), which means that the number

With the traffic being regulated, the temporaryof blocks to be removed can be minimized. In

reinforcements are removed, and the studs areconsequence, the period of closing the bridge tocut (Photo-3), for rapid separation and removal of

traffic during the removal of the decks ofthe concrete decks and steel girders.

composite girder bridges can be reduced to halfof the usual time, or even to one-third as far as
the3. Scope of use of this technology
The technology is used for the renewal ofprocess

ofremoving

deckblocks

isconcerned.

reinforced concrete decks of composite girder・ The conventional method requires manualbridges, while reusing steel girders. Currently

chipping of concrete on the girders, and thethe studs are limited to headed studs.

estimated period required for deck removal on abridge with two main girders, one span, and a

4. Effect of technology

span length of 20 meters is 18 days; the bridge

・ By exposing the studs on steel girders over thewill be closed for that length of time. The period
when the bridge must be closed can be reduced

Back piece A
Back piece B
StudPouring hole
Front piece
Upper flange
Steel girder

Figure-2

Bolt joint

Composition of steel reinforcement

Photo-4

February 2020 No.87

Deck removal state

Photo-3

Photo-5

Cutting the stud

Cutting with concrete cutter

3

Infrastructure Development Institute - Japan
Table-1

Estimated shortening of the process

Normal reinforced-concrete deck removal process
Type of work
No. of days
Work before closing

None

Deck cutting

About 6 days

Removing deck block
Blasting above the girder

About 6 daysAbout 4 days

Stud removal

About 2 days

Total days closed

Deck removal using preliminary treatment with WJ
Type of work
No. of days
Chipping with WJ,
About 17 days
temporary reinforcement
Removal of temporary
About 6 days
reinforcement, deck cutting
Deck block removal
About 3 days
Blasting above the girder
None
IncludedinStud removal
previous work

18 days

Total days closed

9 daysto 9 days when the Rapid Removal Method isimprovements will be propagated to theseused (Table-1). This newly developed methodcountries.

enables complete deck removal in 20 days for abridge with a span length of 22 meters, two

6. Applicable record of technology

main girders, and three spans (work executed

Study of cutting studs between steel girders

in daytime only, with work periods of 7 days perand reinforced concrete decks (2) November 2017span). Deck block removal was completed in one

to January 2019 ,1 other case.

day for one span (as compared with thestandard estimate of three days).
・ For urban expressways, loss of toll revenue canTechnology Developer:

be minimized by shortening the period when theHanshin Expressway Company Limited,bridge must be closed for deck removal.

Tobishima Corporation
Joint Developer:

5. Social significance and further development ofDai-ichi Cutter Kogyo K.K.

technology

Contact:

The period of closing expressway bridges canDaisuke Hashizume

be shortened, and the social burden reduced. In

Hanshin Expressway Company Limited

the future, reviewing the overall process ofE-Mail: daisuke-hashizume@hanshin-exp.co.jp

renewal projects, including deck installation, will

TEL: +81-6-6232-6466

enable meeting the need to keep bridges open toFAX: +81-6-6203-8322

traffic during daytime, by closing one lane fortraffic regulation, and by partial reconstruction,

Yasunobu Satakeetc. The Large-scale renewal and repair project

Tobishima Corporation

we currently are engaged in, is a pioneering

E-Mail: yasunobu_satake@tobishima.co.jp

challenge for us as well as neighboring countries.

TEL: +81-3-6455-8324

The

FAX: +81-3-6455-8321

technologicalachievements

and4February 2020 No.87

Infrastructure Development Institute - Japan

Introduction of Fukabari-Method
Subtitle: Easy Reinforcement of Pier by Pile Connection
piers while adding functions to cope with the1. Introduction

enlargement of ships and to strengthen theJapan's social capital stock was intensively

earthquake

developed during the period of high economic

construction period can be greatly shortened andgrowth from the 1950s to the 1970s, and there isthe construction can be carried out while the pierserious concern that the number of aging

is being operated. This paper introduces thefacilities will increase rapidly in the near future,outline of Fukabari-Method and its effects.

resistance.

Furthermore,theand it is required to strategically maintain,

Superstructure

manage, reuse and renew infrastructure. In portberths, in addition to the aging of existing
facilities, in recent years they have been required
to adapt the increase of the size of ships(especially cruise ships) and to strengthen
earthquake

resistanceinpreparationforlarge-scale earthquakes. As a result, the numberof cases where specified performance cannot besatisfiedhasincreased,andExisting piles

reinforcement

Fukabari Beam

Figure-1 Pier Perth of Fukabari-Methodmeasures for existing berths have been required.
According to a survey conducted by the Ministry

2. Summary of Fukabari- Methodof Land, Infrastructure, Transport and Tourism,

As shown in Fig. 2, Fukabari-Method has a merit

the ratio of key port berths exceeding 50 years of

by installing Fukabari in the middle of existing

service will reach 35% in 2024 and reached 60%

piles. The pier becomes a multi-layer momentin 2044. Conventionally, measures such as theframe, which can distribute the bending moment

addition of piles have been taken in piled pier as

generated in the pile head during the load action

a method of reinforcement, but large-scale

to the middle of the pile (Fukabari joint part).

constructionofThus, the pier can be reinforced while making

superstructures (Fig. 1) is required. It causes a

maximum use of existing members such asproblem that the construction period of the site

superstructure.

becomes long and the use of the pier is restricted.

Load

In

order

suchtoas

solve

thetheseremovalproblems,

Load
Large moment

Smaller momentmaximum use of existing members such as piles

BeforeAfterand superstructures, and extend the life of theFigure-2 Reinforcement Effect Image"Fukabari-Method" which is a simple pierreinforcing

methodwasdeveloped.

Fukabari-Method is a construction method for
installing Fukabari (steel box beams) between
existing piles. It is possible to make the5February 2020 No.87

Infrastructure Development Institute - JapanAs shown in Fig. 3, Fukabari is consisted oftreatment is carried out. Then stads are placed"steel box beam part" and "steel u-shapedin the sea (Flow ①). Rebar is wound aroundconnection part". Studs are placed on thethe stud (flow ②). By using a crane, Fukabariinside of the u-shaped connection part and onis immersed in the sea from the superstructure

the existing piles. Fukabari is installed in line

(flow ③ ). The diver places Fukabari at awith the existing piles, and a grout material ispredetermined position in the sea(flow ④). In

placed as a filler after closing the connection

order to integrate the existing pile andpart.

Fukabari, a grout is casted in the gap between
Grout

Fukabari u-shaped connection part and thepile

Connection Part(flow⑤ ),

and

the

installation

iscompleted (flow ⑥). In order to simplify theBox Beam Part

installation of Fukabari, the center part ismade of a box beam, so that it is possible totransporte to a predetermined position as afloating body, and to sink in the sea by pouring
the water into the box beam. In addition, since
Exisiting pile

the U-shaped connection part is attached toStud

both

Figure-3 Structure drawing of Fukabariendsoftheboxbeamvia

the3. Construction flow of Fukabari-Method

opening/closing rotary hinges, it is easy to

The construction flow of Fukabari-Method iscover the piles with the connection partshown in Fig. 4. In order to remove marinestructure, and to integrate with the pile.

organisms adhered to existing piles, surface
Surface treatment and studTransportRebar

Installation
GroutCompletion

Figure-4 Construction Flow

4. Effect of using Fukabariconventional

additional

Fig. 5 compares Fukabari-Method with theFukabari-Method

canpilesshortenmethod.
thesite6February 2020 No.87

Infrastructure Development Institute - Japan
construction period by 60% and the shutdown

the period of service shutdown and theperiod by 90%, and reduce the construction

reduction of environmental impact since a

cost by 20%, compared to the additional pileslarge heavy machinery is not required, can bemethod. In addition, a spillover effects, such asexpected.

the reduction of economic loss by shortening

Figure 5 Comparison of methods

5. Construction results
Records and photographs of Fukabari are(No.2 Pier) 52 blocks
Construction Period:

shown below.

(No.1 Pier) May 2015 – Aug. 2015

① Aomori Port Honkou Area Berth(No.2 Pier) May 2017 – Jul. 2017

Number: 35 blocks
Construction Period: Oct. 2014 – Feb. 2015

Pic. 1 Aomori Port

Pic. 2 Osaka Nanko Ferry Terminal② Osaka Nanko Ferry Terminal③ Fukushima Matsukawaura Fishery Port

(No.1 Pier, No.2 Pier)

Number: 5 blocks

Number: (No.1 Pier) 64 blocks

Construction Period: Sep. 20197February 2020 No.87

Infrastructure Development Institute - Japan
Pic. 4 Shimizu Port

6. In return
In this paper, Fukabari-Method is introduced
as an effective method to solve the various
problems

regarding theexistingpier.

The

reinforcement ofmethod

realizes

thereinforcement while making the maximum useof the existing members and short service
down time.

As aging infrastructures arePic. 3 Fukushima Matsukawaura Fishery Port

rapidly increasing, it is expected that the④ Shimizu Port Hinode Berthstarategic maintenance, reuse and renewal of

Number : (Works 1) 47 blocks

the infrastructures by using Fukabari-Method(Works 2) 10 Blocks
Construction Period:(Works 1) Mar. 2019 – Jul. 2019
(Works 2) Sep. 2019 – Nov. 2019 (planned)

will contribute to the reduction of maintenanceand management costs in social capital stocks.

Technology Developer:
JFE Engineering Corporation
Infrastructure Engineering Sector
Contact:
JFE Engineering Corporation
http://www.jfe-eng.co.jp
TEL: +81-3-6212-0841
FAX: +81-3-6212-0067

8February 2020 No.87

Infrastructure Development Institute - Japan

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9February 2020 No.87