Aug 2020 No.89
Japanese Infrastructure Newsletter

IDI

QUARTERLY
InfrastructureDevelopment

Institute—JAPANCONTENTS
Friction Damper for Seismic Retrofitting on Existing Road Bridges

2Construction with soil hardener STEIN

6

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

F ri ction Damper for Sei smi c Retrofitti ng on Existing Roa d Bri dges
SUBTITLE: Dice & Rod Type Friction Damper (DRF-DP)

1. Background of Technology Development

installed in the transverse direction (at right angles toIt has recently been required that roadthe main girder) because there is limited space andbridges keep functioning immediately following afixed bearings are frequently required against small togreat earthquake. Measures have been taken since themedium earthquakes. Thus, we developed a method

Kobe Earthquake of 1995 to prevent road bridges fromfor seismically retrofitting existing road bridges using

falling or collapsing as a minimum requirement forthe “Dice & Rod Type Friction Damper (DRF-DP)”seismic retrofit. Despite the bridge being free from(Fig.1).

collapsing, if the bases of the road bridge are damaged
severely, restoring traffic functions requires much time.

2. Detailed Description of the Technology

Therefore, studies are being made on seismic retrofit

DRF-DP is a damper which utilizes friction

methods that improve performances using dampers.

between metal parts called a die and a rod. They are

Most of the methods, however, involve seismic retrofit

already being used for the seismic reinforcement ofin the longitudinal direction (in parallel to the mainbuilding structures. They are not displaced under thegirder). Not many seismic retrofit dampers have been

designated load. If the designated load is reached, they

Superstructure

SlabBridge girder

Bearing
Rubber bearing(Without side blocks)
Substructure

Dice & Rod Type Friction
Damper (DRF-DP)
Longitudinal
direction
Bridge pierTransverse
direction

Fig.1 - Method of seismically reinforcing a bridge using friction dampers
Anti-slipping nutDie(metal ring)Rod(metal rod)

LoadLoadFrictionalforce
Displacement

Frictional force
Tightening forcewhich acts on theperiphery of the rod

Inner cylinder
Outer cylinder(a) Friction mechanism

Maximumstroke(b) Rigid-plastic hysteretic characteristic

Fig.2 - Outline of DRF-DP2

Infrastructure Development Institute - Japan

DRF-DP slides, andthe inertial force of the superstructure
reaches a peak.

The side block is removed, andDRF-DP is installed.

The rubber bearing is fixedby the side blocks

Superstructure
Bearing

Greatly
damagedLevel-1earthquake

The damageis reduced !!

Level-2earthquake

Level-1earthquake

Level-2earthquake(a) Before reinforcement

Substructure(b) After reinforcement

Fig.3 - Conceptual illustration showing the effectiveness of seismic control using this method
are displaced with constant frictional force. This isefficiently to reduce the response of the substructure

known as the rigid-plastic hysteretic characteristic(right sides of Fig.3 (a) and (b)).

(Fig.2).

DRF-DPs applied at the bearings of roadbridges are assumed to be displaced with a high

3. Scope of Application
DRF-DPs are installed in existing road

amplitude exceeding 10 cm at a high speed of 100
cm/secorgreater.

Thus,weverifiedbridges. They are so compact that they can bethat DRF-DP exhibited the rigid-plastic hysteretic

installed in narrow spaces at the crown or sidecharacteristic and steadily absorbed energy under suchof the bridge pier. One end of DRF-DP is fixed

severeat the crown of bridge pier and the other end atexperiment (Pic.1). Fig.4 shows comparison between

the side of bridge girder.

the results of experiment and analytical simulation.

conditions

ina

high-speed

excitation

Fig.4(a) and (b) display that DRF-DP exhibited the4. Effect of Developed TechnologyThe strength of the DRF-DP lies on its

rigid-plastic hysteretic characteristic similar to that intheanalyticalsimulation

duringthetworigid-plastic hysteresis characteristic (Fig.3). It does

type earthquakes, although the load of DRF-DP tended

not slide during level-1 earthquakes (which are

to increase slightly at low amplitude. Fig.4(c)defined as small to medium earthquakes that aredescribes that the energy time history obtained in thehighly likely to occur (Japan Road Association 2012)).
Due to this characteristic, DRF-DP acts as a substitutefor the side block which restrain bearing displacement(left sides of Fig.3 (a) and (b)). On the other hand, itslides during level-2 earthquakes (which occurs lessfrequently but are expected to cause serious damage tobridge piers (Japan Road Asociation 2012)). As aresult, DRF-DP sets a limit to the inertia force of thesuperstructure. Furthermore, it absorbs seismic energy

Pic.1- General view of excitation experiment

3Infrastructure Development Institute - Japan
実験
Experiment

解析シミュレーション
Analytical simulation

900900600600600
600

300300300300

荷重 [kN]

Load (kN)荷重 [kN]

Load (kN)

実験
Experiment
900
90000-300-300-600-600

解析シミュレーション
Analytical simulation

00-300-300-600-600-900-900-25 -20-20 -15-15 -10-10 -5-5 00
10-2555 10
変位 [cm] (cm)Displacement

151520202525-900-900-25 -20-20 -15-15 -10-10 -5-5 00
1055 10-25
変位 [cm] (cm)Displacement(a) Load-displacement (Great East Japan Earthquake)
実験
Experiment

Energy (kN-m)

エネルギー [kN･m]

1500
1500

15 20
20152525(b) Load-displacement (Kobe Earthquake of 1995)
Analytical解析シミュレーション
simulation

12001200type I

900900type II

600
600
300
300000010102020303040405050606070708080

Time[sec](sec)
時間(c) Energy absorption time history

Fig.4 - Results of excitation experiments
experiment was in agreement with that in thereinforcement. It was found that the installation ofanalytical simulation. It was thus verified that

DRF-DPs reduced the maximum response value fromDRF-DP could absorb energy as expected against

26 mm to 11 mm.

level-2 earthquake motions. The Dependency and thedurability of the DRF-DP when subjected to repetitiveearthquakes were also verified in the experiments.
A large-scale shaking table

test wasconducted to confirm the behavior of the entire RCpier using DRF-DPs (Pic.2). This experimental modelis based on the RC single column bridge pier currently
used on the Metropolitan Expressway. Fig.5 shows theresponse displacements of the pier before and after

Before reinforcement: 26mm

Reduction
to 42%
固定
Lower interlayer［mm］
displacement

下段ゴム支承の変位［mm］

Pic.2 - Shaking table test situation

ゴム支承+2tfダンパー

After reinforcement: 11mm

3030

2020
1010
00-10-10-20-20-30-30404060608080
時間［sec］

100
100
time［sec］

Fig.5 - Response displacement time history of pier (Great East Japan Earthquake)4

Infrastructure Development Institute - Japan
5. Installation Record

Technology Developer:

Seismic retrofitting of bridges with rocking

Metropolitan Expressway Co., Ltd.

piers are urgently required in Japan ever since some of

Asunaro Aoki Construction Co., Ltd.

themcollapsedEarthquake.

Induetothe2016

Kumamoto

2020,

Metropolitan

Expressway

installed DRF-DPs (two 650 kN dampers and fourContact:
E-mail: tech-info@aaconst.co.jp

1000 kN dampers) in the rocking piers of Route No.11

gijyutukenkyusho@aaconst.co.jp

Daiba Line for seismic retrofitting (Pic.3). DRF-DPHP

was applied to one of specifications for the design andFax number; +81-3-5419-1018: https://www.aaconst.co.jp/english/

construction guidelines of Metropolitan Expressway.

Box girder

Box girder

DRF-DPDRF-DPBox girder

Box girder

DRF-DPDRF-DP

T-type pierT-type pierRocking pierRocking pier(a) General view (650kN DRF-DPs)(b) General view (1000kN DRF-DPs)

Length = 1622mm
Diameter = 203mm
Girder sidebracket

Girder side bracket
Length = 1632mm

Weight= 389kg

Diameter = 249mm

Pier side bracket(C) Installed 650kN DRF-DP’s position(Crown of the pier with bracket)

Weight= 649kg

Pier sidebracket(d) Installed 1000kN DRF-DPs position(Side of the pier with bracket)

Pic.3 - Installed DRF-DPs5

..//////Construction

with1） . INTRODUCTION

soil

Infrastructure Development Institute - Japanhardene r STEI N///////

2） DETAILS ABOUT STEIN

STEIN, a high-quality inorganic soil-STEIN consists of two factors, STEIN

hardening agent, was developed by a Japaneseelements, which

engineer named Mr. Takao Matsumura in 1975.

inorganic additives such as Mg, Ca and Al,

Around that period, Mr. Matsumura worked atand Portland cement. By mixing 5% of

Honda Motor Co., Ltd. At first, he developed

STEIN element and 95% of ordinary cement,

STEIN for preventing the elution of heavy metals

STEIN, an environmentally friendly soil

such as hexavalent chromium and arsenic in

hardener, is created. It can be utilized toconcern of environmental protection. It fixedcreate a robust structure in a short period ofheavy metals in the soil through a chemicaltime by mixing it with on-site soil and water,reaction known as the Pozzolanic reaction andlater rolling it down to the land surface.

hydration. After realizing how STEIN could be

STEIN can be used flexibly according to theused for road constructions due to its function ofcondition of the soil by adjusting thehardening soil into a strong and solid mass, hepercentage of the STEIN against soil. It isstarted manufacturing STEIN in Hokkaido, hisused in over 1,500 public work projects such

hometowntheas irrigation riverbeds improvement, farmimprovement of construction works for roads androads construction, etc., conducted by therivers. Using STEIN is very simple. The process

Ministry

involves mixing on-site soil with an appropriate

Fisheries, the Ministry of Defense, and manyamount of water and STEIN.

local government bodies in Japan. STEIN

inJapan,utilizing

itforofare composed ofAgriculture,Forestry

27andelements are also exported to various
countries in South-east Asia (Malaysia,Thailand,Myanmar,Indonesia,

thePhilippines, Sri Lanka, Cambodia), East Asia
(China, Korea, Taiwan), America(USA),Europe(Italy, Germany) and Africa (Kenya).

Photo 1 STEIN is a powder-type soil hardener

Figure 1 STEIN element

6

Infrastructure Development Institute - Japan3） CONSTRUCTION PROCESS OF STEIN

3） Compaction

Before construction, we inspect the soil inthe project site and conduct mixture tests withSTEIN. These tests for soil analysis include
measuring the moisture content, density of soil
particle, wet unit weight, grain size, and liquidand plastic limits. There are also tests performed
to measure the moisture density of the final
mixture rate between soil and STEIN. After 7 daysof measuring, we conduct a strength test by
testing the pieces with different mixing rates ofthe STEIN and on-site soil to determine the best
mixing rate. The construction process of STEIN

4） Watering and curing

is very simple, as shown below.
1） Spreading STEIN over the land surface5） Completion

2） Mixing of STEIN with soil

The construction site can be opened for
traffic after 24 hours of completion. This is one of
the biggest advantages of STEIN, as the roads canbe opened after a short period of time.

7Infrastructure Development Institute - Japan4） EFFECT OF USING STEIN
Regarding the soil strength for roads, itwith STEIN.

depends on the type of soil and mixture rate of

The durability of roads using STEIN-mixed soil

STEIN. Our first target is 30kgf/cm in a week

has another big advantage; they need lessafter construction, and in two weeks later, themaintenance. We set the goal of the life span ofstrength of mount sand mixture and laterite

roads to be 20 years, preserved with minimal

mixture can reach up to 60kgf/cm2. (Fig. 2)

maintenance. The longest life span was 45 years,

Vehicles with the wheel loads of 6.8kgf/cm , forwhich is located in Hokkaido, one of the most cold

example, will be able to pass the roads constructed

and snowy areas of Japan.

22Figure 2 Result of the strength test
As a result, we would like to emphasize that STEIN can make road construction simpler (withoutreinforcing bars, etc.), with a lower cost (40 to 60% more reasonable than asphalt roads). Furthermore,
STEIN gives the soil high durability, which can lessen road maintenance activities.

5） EXAMPLES OF CONSTRUCTION
1） A farm road located in Hokkaido. This road2） A water pond with its slopes covered bywas constructed in 1975 and functions as aSTEIN mixed soil to prevent soil erosion inwaterway after the snowy winter.

Kenya.

8

Infrastructure Development Institute - Japan
3） Spill ways of water ponds that prevents flood
disaster caused by heavy rains.

4） Park roads of local and national parks, school
playground, etc.

STEIN is a good solution to this issue, as the6） APPLICATION OF TECHNOLOGY
Today, in Japan, weed prevention treatmentstrength of the STEIN roads become more thanon roadsides are required to reduce cost, time and30kgf/cm2. (Fig. 3)

labor of road maintenance, which is repeatedly

In the middle of February 2020, we constructed a

conducted every year. The roots of weed cannot

test site in Japan.

grow if the soil load is over 30kgf/cm , and thus
2Condition of roots

Easy to grow

Possible to growDifficult to growImpossible

togrow
Strength

0-10

10-20

20-30

More than 30(kgf/cm2)
Figure 3 Relationship between the strength of surface and condition of roots

9Infrastructure Development Institute - Japan

Before construction

After construction

7） BUSINESS MODEL OF STEIN
In most cases of construction work abroad,

During the construction process, thewe ship the STEIN (STEIN elements andcooperation of local

cement)main

companies is also essential for conducting

is ordinary cement, andconstructions. Moreover, our relationships

thus it is possible to use each country’s local

between national and local governments,

cement to make STEIN more accessible. We

stakeholders

export STEIN elements from Japan and ask local

important to conduct the road and/ormixing companies to mix it with machines.

irrigation projects.

fromJapan.

component of STEIN

However,theandroad

construction

contractors

arealso10

Infrastructure Development Institute - Japan8） THE FUTURE OF STEIN
We are confident about the possibility ofSTEIN; we believe that it can significantly
contribute to the development of infrastructure.
Although the STEIN elements are strictly mixed
in a factory in Japan, Portland cement is available
all over the world, and thus our next goal is toestablish a manufacturing plant abroad. We planto not only sell STEIN, but also to make anopportunity for people to work with and learn thetechnology about construction projects using
STEIN. We hope that our knowledge and knowhow of STEIN will be passed on to future
generations.
Here below is the contact information ofSPEC COMPANY LIMITED.
If you are interested in our product, please feel
free to contact us.
Lastly, we greatly appreciate the opportunity ofwriting for IDI Quarterly.
Contact
Shiyo Kamibayashi (Ms)kamibayashi@spec-env.jp
SPEC COMPANY LIMITED
4-5-5 Shimotakaido Suginami Tokyo JAPANZIP CODE: 168-0073
http://www.spec-env.jp

11About IDI and IDI-quarterly
Infrastructure Development Institute-Japan (IDI) is a general incorporated
association operating under the guidance of Ministry of Land, Infrastructure,
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countries, to promote international exchange of information and human resources,
and to support globalization of project implementation systems targeting bothdeveloped and developing countries in the field of infrastructure.
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to introduce information related to public works and construction technologiesdeveloped in Japan to foreign countries. We have distributed the journal toadministration officials in more than 90 countries around the world by e-mail.
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