With Society, the Past, thePresent and the Future of Our
B r i d g e Te c h n o l o g y a n d
Development
AKIO KISHISHOZABURO MIURA
ATSUSHI ISODAYOSHIHIKO KAWAIICHIRO MASUDAWorld War II, MHI manufactured more than 10000 tonsof bridges in overseas countries that included China,
Korea and Taiwan. In 1920s, many bridges were constructed such as the Takamatsu Bridge, a basculebridge, while in addition many job orders were received
from the Ministry of Railways for utilizing MHI’s welding technology in welding reinforcement of railroad
bridges and test girders by full welding. After the war,
the leading technologies in Europe and America werelearned, and rational, economical bridge construction
was studied. The unique achievements realized at thattime included the Sakagoe Bridge of composite latticegirder (1955), the Iizuka Bridge using 50 kgf/mm 2
strength steel (1955), the box girder Yotsugi Bridge(1956), the Ikada Bridge using prestressed concrete inits main girder (1958), and the Kema Bridge of continuous composite girder (1959). In the Nagara River Bridge(1963), 60 kgf/mm2 strength steel was used for the firsttime, and its steel specifications are inherited in
SM570Q of JIS.
Arch bridges include the trussed Langer bridge andthe Nielsen system bridge of high order statically intermediate structure with inclined hangers. The firstexamples in Japan are the Ao Bridge (1965) and the Aki
Bridge (1967).

1. Introduction
From the postwar restoration until the period of
rapid economic growth, freeway networks were constructed from the metropolitan area and major cities
to various regions around the nation. Steel bridge technical development in this period contributed
dramatically to numerous technical innovations including use of high-strength steel and its manufacturing
technology, erection technology for cable structure andprecision control system, and wind resistant andaseismic measures to solve problems of severe natural
conditions. These technical developments provided thebases for construction of long-span bridges such as the
Honshu-Shikoku Bridge. On the other hand, the destruction of a viaduct by the Great Hanshin Earthquake
in 1995 was a lesson for recognizing the importance ofsafe distribution systems and utilities, and it shed lighton the role of maintenance control and extension of lifeof bridges as an important subject for traffic management in the future. Further, as the capital investment
is depressed today, there is an ever-greater demand for
reduction of traffic jams and improvement of the roadside environment from the viewpoint of recovery of urban function, and bridge technology is now beginningto change its direction.
The history of steel bridges of Mitsubishi Heavy Industries, Ltd. (MHI) starts with the history of
construction of bridges in Japan, dating back to
Kurogane Bridge (Nagasaki) in the early days of the Meiji
era. The history of steel bridges of MHI is introduced inthis paper, together with social needs and the present
and future outlook of the technical development of steel
bridges.

2. Development of bridges and history of MHI
Fig.1
Kurogane Bridge (Fig.1
Fig.1), the first iron bridge in Japan, was manufactured in 1868 by Nagasaki
Seitetsusho, the former name of MHI. Until the end of

Fig. 1 Kurogane Bridge

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Technical Review Vol.40 No.1 (Feb. 2003)

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Fig. 2 Minato Bridge
Fig. 4 Tatara Bridge

Fig. 3 Akashi Strait Bridge
Fig. 5 Kurushima Strait Bridge

Regarding truss bridges, MHI participated in the conFig
struction of the Minato Bridge (Fig
Fig.. 2 ), the third biggest
cantilever truss bridge in the world in 1973. This bridge
was built by using 70 and 80 kgf/mm 2 strength steel
massively for the first time in Japan.
In the latter half of the 1960s, Japan’s first cablestayed bridge was erected-the Maya Bridge (1966), andin the 1970s, MHI jointly constructed the multicablesystem Kamome Bridge. On the basis of MHI’s leading
and up-to-date structural design, analytical technology,
wind-resistant design, and precision management technology, many cable-stayed bridges were built in quick
succession.
MHI also participated in the construction of suspension bridges such as the Kanmon Bridge (1973) and
Hirato Bridge (1977), and the Greater Naruto Bridge,
North and South Bisan Seto Bridges, Honshu-Shikoku
Bridge which had been thought to be a “Dream Bridge.”
In this history, various technologies have been developed in order to construct more rational and longer steel
bridges. In order to evaluate the stability against wind,a diffusion wind tunnel of the biggest scale in Japan was
installed to test by using large models and a three-dimensional full-scale model, while to test the aseismic
strength, a large-scale three-dimensional shaking table

was built to reproduce three-dimensional behavior withhigh precision.

3. Era of longer bridges
These technologies nurtured for decades contributed
greatly to the construction of the Honshu-Shikoku
Bridge. MHI played a central role in the construction of
Fig
the Akashi Strait Bridge (Fig
Fig.. 3 ), the world’s longest suspension bridge completed in 1998, the Tatara Bridge
Fig(Fig
Fig.. 4 ), the world’s longest cable-stayed bridge, and the
Fig
Kurushima Strait Bridge (Fig
Fig.. 5 ), the world’s first threebridge suspension bridge. These bridges were constructed
between many islands in the beautiful Seto Inland Sea
National Park. The bridge construction required technical developments taking account of natural conditions
such as fog, tidal currents, strong winds and earthquakes, and the busy international navigation routes.
The Akashi Strait Bridge has an overall length of 3 911
m, with a center span of 1 991 m, and the main tower
stands 283 m high. The main tower was constructed bya climbing crane system in order to shorten the construction period. A damping device to prevent oscillation bywind was installed on the top of the crane, and both
economy and safety requirements were satisfied. These
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Technical Review Vol.40 No.1 (Feb. 2003)2

restricted. An exclusive self-propelled barge having afixed point holding function was developed, and thebridge was erected within a short period of time.
These bridge erection technologies contributed laterto construction of representative bridges in Japan, including the Rainbow Bridge, Yokohama Bay Bridge,
Higashi Kobe Bridge, and Trans-Tokyo Bay Highway.
In 2000, MHI also participated in the construction ofFig
the Yume-Mai Bridge (Fig
Fig.. 6 ), the world’s first floating
swing arch bridge linking the man-made islands ofYumeshima and Maishima in Osaka Bay. This is a new
type of bridge featuring economy in foundation and substructure, since it is required to keep a free space beneaththe girder for international navigation. To understandthe elastic response in cases where a slender structuresuch as a bridge is exposed to waves, the “elastic response
analysis technology of structures exposed to waves” wasdeveloped and applied by combining the ship oscillation
analysis technology and bridge elastic response analysis technology accumulated over the years by MHI.

Fig. 6 Yume-Mai Bridge

technologies were applied to the Kurushima Strait
Bridge and also to the Megami Bridge now under construction. For the stiffening girder, too, wind-resistantand aseismic measures are important matters: by development of a girder damper connecting the main tower
and the stiffening girder, oscillation of the main towerby wind and of the stiffening girder by earthquake wereboth controlled.
The Tatara Bridge is a hybrid cable-stayed bridge witha center span of 890 m and overall length of 1 480 m. Ina cable-stayed bridge, the horizontal component of force
is applied to the main girder for fixing the cable, but ina long cable-stayed bridge, the compressive force in theaxial direction is dominant, and the design method wasestablished by the ultimate strength test for overall buckling, and its structural stability was verified. During
construction, the cantilever length of the main girder
was about 440 m, and the stability against wind measure was determined by wind tunnel tests.
Thanks to these technical developments, the Tatara
Bridge was undamaged when hit by a typhoon at thetime of maximum cantilever during construction, andthere was no problem in stability against wind. To confirm the oscillation characteristic assumed in the windtunnel test, an actual bridge oscillation test was conducted using the originally developed oscillation machine
featuring small size and large excitation force.
The Kurushima Strait Bridge is a three-bridge suspension bridge, and the foundation and ground condition
for supporting each bridge are different. Accordingly, thedynamic earthquake analysis technique capable of inputting seismic waves with a phase difference in eachfoundation was applied. Stiffening girders were installedby the lifting-up erection method just under the bridge,
and the stiffening girders were kept in fully hinged condition during the erection period. In this way, both
economy and shortening of construction period wereachieved. Since the Kurushima Strait includes international navigation routes with fast tidal currents, theworking hours of transportation barges were severely

4. Outlook and technical development of bridgebusiness
Construction of longer bridges is one thing, and costis another thing. The Japanese government having unveiled its action principle concerning reduction of public
work cost, the concept of life cycle cost (LCC) and benefit/cost (B/C) ratio has been introduced into the bridgebusiness. Also on the occasion of the Great Hanshin
Earthquake, the importance of preventive conservationand maintenance management was newly recognized,
and the need for comprehensive technical development
is increasing.
Key points of the recent revision of technical standards (Specifications for Highway Bridges) are
performance-based design and durability, and one of theobjectives is the promotion of efforts toward new technology and new processes.
In the light of such changes in various social needs,
MHI is promoting technical developments related to rational structure and process for curtailing theconstruction cost, maintenance management technology
aiming at renewal period of road bridges constructedduring the period of rapid economic progress, regeneration of cities and environmental improvement.
4.1 Development of inexpensive bridges
With the purpose of expanding the application of steel
two-main girder bridges hitherto employed in inexpensive bridges of span length of up to 60 m, the following
subjects are being studied.
(1) Strength and stability against lateral torsional buckling and dynamic stability against wind for torsionalvortex-induced oscillation
To realize a longer span, the torsional strength ofthe entire bridge is increased by installation of lower
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Cast-in-place
concrete
Wheel load running test
(Public Works
Research Institute)

Bottom steel platePre-placed
concrete panel
Stud

Fig. 7 Development of Dia Slab.

Fig. 8 Fatigue flaw monitoring system

lateral supports in the necessary range of intermediate supporting points, Vierendeel design of lower
flanges of lateral girders, and integration of lower
flanges (open section box girder), while wind-resistant measures include a wind stabilizer that also
serves as a main girder section, and a small, inexpensive damping device.
(2) Rationalization of erection method
In the launching method, which seems to be employed widely at locations where it is difficult to makevents in the river and mountain districts for bridges
with longer spans, new developments include alaunching device using caterpillar for speedy and continuous launching, and system for controlling thelaunching point height to minimize the reinforcementof the girder main body. Through further improvements, reduction of erection cost can be expected. As
spans become longer, the effect of using high-strength
steel material also increases substantially. Concerning problems of fatigue in weld zones and increase of
live-load deflection, there is a need to establish a more
realistic evaluation method by performance-based
design specifications taking account of the floor slab
composite effect and oscillation acceleration level.
4.2 Development and expansion of technology
conforming with performance design
In the process of transfer of design from the specifications-based type to performance-based type, MHI isdeveloping new rationalization structures of specifications-based type, on the basis of new design techniques
including experiment and verification.
(1) “Dia Slab” or composite floor slab without steel stiffener, which was developed as new rationalized floorslab, has already been shown to have high durability
and high cracking resistance in dynamic load tests,
and the design and construction method has been esFig
tablished (Fig
Fig.. 7 ).
(2) As rationalization structure of box girder, a system
in which the flanged transverse stiffener and web
plate are not welded, has been developed, and favor-

able results have been obtained in load tests and fatigue tests. This has dramatically decreased the jobof internal welding, which is a difficult process in theconventional manufacturing method of box girders,and much labor saving is expected in the assemblingwork.
(3) Necessary feasibility studies are planned throughinvestigation of the problems arising in use of newmaterials such as low-strain steel plates, fatigue-resistant steel materials, high-strength steel, and superhigh strength bolts, or applying tensile joint structure in actual bridges.
4.3 Maintenance and management
Since the bursting of the bubble economy, new road
constructions have been decreasing, whereas the importance of maintenance and management of public
facilities. Maintenance includes checking, repair, reinforcement, and preservation of function. Advanced
technology is required in all aspects, and technical development must be promoted in order to operate the roadmanagement business efficiently (at lower cost) in the
future.
(1) In maintenance and management, it is essential toidentify the causes of damage such as fatigue, salt
damage and corrosion as a means of determining therenewal period or life-extending measures. As an appropriate technology, the bridge monitoring system
is being developed. This system can monitor the fatigue and deterioration status of floor slabs, main
girders and other members continuously from a remote place, and can be applied to road network
function monitoring in case of earthquakes or otherabnormalities for evaluation of the remaining life ofFig
bridges (Fig
Fig.. 8 ).
Individual technologies include a database libraryof cases of damage to bridges, rational flaw judging
method, and aseismic reinforcement of medium-scale
bridges using the original damper brace technology.
(2) For road operation management, MHI will alsopresent engineering services on the basis of its conMitsubishi Heavy Industries, Ltd.
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Fig. 9 Rapid launching method

Fig. 10 Rapid grade-separated elevated crossing

struction know-how and monitoring technology.
(3) For disaster inspection, a next-generation inspection
system is being studied in order to save labor substantially in investigations of road structures
immediately after earthquakes.
4.4 Contribution to urban regeneration
Concerning urban regeneration-related technology,
the following new techniques are being developed in order to meet new needs.
(1) At traffic nodal points in cities, a rapid method isrequired in erection of grade-separated elevated roads
in order to ease traffic jams. MHI has developed a“rapid launching method” as an erection method in
urban districts, and applied this method in construction of the Arimatsu Viaduct which was completed inFig
2002 (Fig
Fig.. 9 ). In the case of this bridge, for the steel
girder of 12 000 tons, an overnight launching distanceof 130 m was realized, which proved to be an ideal
method for continuous grade-separated structures.
Further, for grade-separated crossing at intersections, the "Sui-Sui MOP (Module On Pier) Method"has been developed, which not only shortens construction period but also minimizes traffic jams during
consturuction. In the superstructure, the grade-separated road surface repair system was also installed.
The module structure is employed by making best useof the merits of the comprehensive heavy machinery
manufacturer, and a new rationalization foundation
structure suitable for construction in cities is being
Fig
developed. (Fig
Fig.. 10
10).
In planning the field construction method, MHI developed the technique of qualitative evaluation ofsocial loss (loss due to delay in work) by combining
the traffic flow simulation on the basis of field conditions, construction period and traffic regulation
method, with calculation of benefit. A system of selecting the best process comprehensively has been
established.
(2) Regarding environmental problems, MHI is planningto develop a system for improving the road side environments and lowering noise levels by fully utilizing

its original technologies.

5. Conclusion
As the twentieth century ended, the boom of construction of longer bridges in Japan declined, and publicconstructions are being criticized from the viewpoints ofcost differences between Japan and other nations, deregulation, etc. Further, since the Great Hanshin
Earthquake and 10 year’s stagnation of Japan’s economy,
the demand for steel bridges has drastically changed.
Today, key points are reduction of life cycle cost, roadmanagement geared to the new age, and regeneration of
cities. Technical standard has also changed from thespecifications-based type to performance-based type, andpublic works are being ordered according to new methods based on new technologies. At present, developing
technologies are being highly evaluated and fully utilized. As a comprehensive machinery manufacturer, MHI
continues to contribute to society by leading the development of new bridge technologies, including the common
technology of environment conservation, disaster prevention and road and traffic technology.

STEEL STRUCTURES & CONSTRUCTION HEADQUARTERS
Managing Director,
General Manager,
Steel Structures &Construction Headquarters
Akio Kishi
Shozaburo Miura
Kobe Shipyard &Machinery Works

Yokohama Dockyard& Machinery Works

Hiroshima
Machinery Works

Atsushi Isoda

Yoshihiko Kawai

Ichiro Masuda

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Technical Review Vol.40 No.1 (Feb. 2003)

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