No. 33
July

2011
A Joint Publication of The Japan Iron and Steel Federation and Japanese Society of Steel Construction

Special Feature

Corrosion Protection for
Steel Pipe Piles andSheet Piles

http://www.jisf.or.jp/en/index.html

Steel Sheet and Pipe Piles
for Port Steel Structures— Corrosion Protection Technology: Today and Tomorrow —By D
 r. Hidenori Hamada (Kyushu University), Dr. Toru Yamaji (Port and Airport Research Institute), andDr. Yoshikazu Akira (Port and Airport Research Institute)
Hidenori Hamada:
Professor, Department of Civil and
Structural Engineering, Kyushu University. He received adoctor of engineering degree from Kyushu University in
1998. He has been
engaged in “concrete technology andcorrosion engineering” for about 25 years.

The history of corrosion-protection technologies in Japan extends more than 50 years.
As a result, these technologies have developed to the remarkable level where protection against the corrosion of port and harborsteel structures is nearly complete. Also, theconditions affecting the application of corrosion protection technologies will differ
from country to country, so the methods
used will differ accordingly. However, thediversity of experience acquired in this fieldin Japan will also be of use in other countries. This article discusses corrosion-protection technologies applied to port and harbor steel structures in Japan. We believe that
this article will contribute to the development of appropriate corrosion-protection
technologies for steel structures in theworld.
Port and Harbor Steel Structures inJapan● History
The oldest steel harbor structure built in Japan is a pier constructed using steel screw
piles in the Port of Kobe in 1876, followed
successively by the Ports of Yokohama, Nagoya, Osaka, and Tsuruga. In the last part of
the Taisho era (1912~1926), steel sheet piles
1 Steel Construction Today & Tomorrow July 2011

Toru Yamaji:Group Leader, Ma
terials Group, StructuralEngineering
Fields, Port and Airport Research Institute. He received adoctor of engineering degree from Kyushu University in2010. He has been engaged in “concrete
technology and corrosion engineering” forabout 13 years.

Yoshikazu Akira:Researcher, Materials Group, StructuralEngineering Fields,
Port and Airport Research Institute. He
received a doctor ofengineering degreefrom Kagoshima University in 2004. He
has been engaged in “corrosion engineering and corrosion-protection technologies” for about 8 years.

were imported to restore damage caused by
the Great Kanto Earthquake. The first steel
sheet pile-type mooring quay was constructed in 1926 at the Port of Osaka.
Entering the Showa era (1926~1989),
imports of steel sheet piles increased, initially totaling 25,000~35,000 tons annually.
Then in 1929, trial manufacture of steel
sheet piles started at the government-run
Yawata Steel Works, and full production
started in 1930. In 1931 at the Port of Miyako, the domestically-produced steel sheet
piles were first applied to port steel structure. Also, steel sheet pile mooring quays
were constructed in the early Showa era in
Osaka, Nagoya, Fushiki, Hakodate, and Rumoi. In the post-war period, steel pipe piles
were extensively used for port and harbor
facilities. The application of piles in pierfoundation structures was expanded following the construction of Shiogama Port in
1954. The first cell-type mooring quay using
flat steel sheet piles was constructed at thePort of Shiogama (1954~1959), followed by
the Ports of Tobata, Nagoya, Naoetsu, Aomori, and Yokohama.
Entering the 1960s, steel pile piers weredeveloped and were increasingly used tobuild large-capacity mooring quays in many

ports. The Yamashita pier at the Port of Yokohama and the Maya pier at the Port of
Kobe are typical structures.
Very recently, jacket-type steel structures
are increasingly being adopted for port andharbor facilities. The Ooi container berthand the new D-Runway at Tokyo International Airport are typical structures.
●F eatures of Port and Harbor Steel
Structures
Currently, nearly a half of the mooring
quays in Japan are constructed using steel
products. This is a feature in Japanese ports.
A couple of major reasons for the greater useof steel products in Japan are the development of the Japanese steel industry as a coreelement in the country’s rapid economic
growth in the 1960s. Because Japan’s rapid
economic development beginning in the
1960s demanded that port and harbor facilities be quickly improved, the possibility of
rapid construction was an additional reason
for the enthusiastic adoption of steel structures. The total extent of mooring quays employing steel structures has reached 490 km.
At the Port of Tokyo, the ratio of steel structures to total port and harbor facilities (including breakwaters) has rapidly grown. Of

Corrosion Protection
Fig. 1	Typical Structure of Steel Sheet Pile-type Mooring
Quay

Fig. 2 Typical Structure of Steel Pipe Pile-type Mooring Quay

Fig. 3	Representative Examples for Vertical-direction
Corrosion Rate of Steel Pipe and Sheet Piles

ronments occurs. The area where serious
problem arises regarding the corrosion ofsteel structures without corrosion-protection measures is the splash zone and just beneath the mean low water level (M.L.W.L.).
Corrosion tendencies by corrosive environment are introduced (Fig. 3).
● Atmospheric zone
In most cases, the corrosion rate (corrosionloss) for such structures is mostly around 0.1
mm/year.

the total extension of more than 200 km ofport and harbor facilities, steel facilities
have surpassed 150 km.
● Typical Port and Harbor Steel
Structures— Steel Sheet Pile-type Quays
Steel sheet pile-type mooring quays are constructed by driving steel sheet piles into theground to form an earth-retaining wall(Fig. 1). The most common steel sheet piletype mooring quay is formed using tie rods
to connect the steel sheet pile wall to a strut
structure (steel pipe, steel sheet pile, shape,etc.) installed behind the wall. Dependingon the scale of the load to be supported, twokinds of piles are used for the pile wall—commonly adopted U-type steel sheet piles
and steel pipe piles having connection joints.
In cases when a small load is applied, as inports with shallow water depth, a self-supporting wall structure is adopted without theuse of a strut structure and tie rods. Even
when using steel sheet piles or steel pipe
piles, the front surface of the pile wall is subjected to harsh corrosive marine environments.

—P ier-type Mooring Quays
Pier-type mooring quays are constructed byplacing the upper structure on column members (Fig. 2). The pier-type quay consists ofa pier located at the front of the quay and anearth-retaining structure to the rear, withsteel products widely used for the front pier.
Reinforced concrete or precast concretebeams and floor slabs are installed on theupper structure. Among port and harbor facilities, the RC (reinforced concrete) upper
structure is the site where structural deterioration due to salt damage most frequently
occurs.
Features of Corrosion in Marine
Environments
The environments where port and harborsteel structures are applied are roughly classified into five zones, namely, atmosphericzone, splash zone, tidal zone, submergedzone, and mud zone. In cases where longsteel products such as steel sheet pile andsteel pipe pile extend through multiple environments (tidal zone, submerged zone, andmud zone), macro-cell corrosion attributable to differences in these application envi-● Splash zone
In the splash zone, the structure is constantly subjected to seawater splashing, andtherefore a large amount of seawater and oxygen can be supplied to steel surface. Accordingly, the splash zone is the most corrosive environment. In general, corrosion ratein this zone reaches the level of 0.3 mm/
year. According to surveys in the Okinawa
area, there are examples of corrosion rate
reaching 0.5~0.6 mm/year due to the effectof high temperature and high humidity.
● Tidal zone
The tidal zone is where structures undergo
periodic immersion in seawater and exposure to the atmosphere due to tidal action. In
this zone, corrosion rate in the vicinity of themean seawater level (M.S.L.) is small, however, corrosion rate in the vicinity just beneath the M.L.W.L. is extremely large. The
reason for this is the formation of a macrocell with the cathode area around the M.S.L.
(high dissolved oxygen concentration), andthe anode area, the vicinity just beneath the
M.L.W.L. (low dissolved oxygen concentration). There are cases, depending on thecircumstances, when corrosion rate in thevicinity just beneath the M.L.W.L. exceedsthat in the splash zone. This phenomenon iscalled “concentrated corrosion.” The conJuly 2011 Steel Construction Today & Tomorrow 2

centrated corrosion caused some example ofstructural collapse of port steel structures.
● Submerged and mud zones
Corrosion in the submerged zone is nearly
uniform. Corrosion rate at depths below –1
m or more is about 0.1~0.2 mm/year. In the
mud zone, because of reduced oxygen supply compared to the submerged zone, corrosion rate becomes smaller: about 0.03~0.05
mm/year.
Corrosion-protection Technologies
for Port and Harbor Steel Structures●H istory of Corrosion-protection
Technologies
The most prevalent concept of corrosion
protection in old days was “corrosion allowance.” Accordingly, the thickness of steel
products was increased beforehand by amargin for corrosion loss. It was in 1953 thatthe cathodic protection was first applied ona harbor steel structure. This was the Port ofAmagasaki in which an anodic system employing magnesium alloy anode was applied. The protection was an external current source system.
Entering the 1960s, attempts were madeto use cathodic protection (external current
source system) in various port and harbor
structures. Around 1960~1970, oil paint andtar epoxy resin paint were developed and increasingly adopted for corrosion protectionin the zones above the submerged zone. In
coating/lining corrosion protection, zincrich paint was developed and used as an undercoat for tar-epoxy resin coating. Further,attempts were made to cover the upper section of pier steel pipe piles with concrete asa corrosion-protection method for structures
above seawater level where the effect of cathodic protection could not be obtained.
Around 1970, chlorinated rubber paint wasdeveloped, followed by the development ofurethane paint in 1972. In cathodic protection, high-performance aluminum alloy anodes were developed, and the full-scale application of anodic corrosion protection
started. Also around 1970, underwater welding technology was developed to reduce thework period and increase safety when attaching aluminum alloy anodes.
Starting in 1980 and for some years, diverse kinds of highly durable coating/lining
corrosion-protection methods were developed, among which were the cement-mortar/FRP cover method, the petrolatum lining
method, and the underwater hardening-type
3 Steel Construction Today & Tomorrow July 2011

lining method. Around 1982, polyethylene
lining and polyurethane lining (the so-called
heavy-duty corrosion protection method)were developed. In the coating-type system,
ultra heavy/thick type epoxy resin paint andfluorine resin paint having high weather resistance were developed.
However, even in those days, corrosionprotection systems were not necessarily applied for all port and harbor facilities, but the“corrosion allowance” system was still remained. As a result, in 1983, an accident occurred at the Port of Yokohama involving
the subsidence of a harbor facility. Triggered by this accident, cathodic protection
was established in 1984 as the standard
method of corrosion protection for existing
steel structures in the submerged and mudzones, and coating/lining protection as thestandard method of corrosion protection forexisting steel structures in the tidal, splash,and atmospheric zones.
During the same period, the practical application of titanium as a corrosion-protection material began in the form of titanium
cladding for steel plates, as did the use of
corrosion-resistant stainless steel linings.
Titanium materials had already been adopted for actual structures such as the bridgepiers of the Trans-Tokyo Bay Highway (forwater depths ranging between –2 m and +3m) and the Yumemai Bridge (floating, revolving-type). Seawater-resistant stainlesssteel linings were applied as a corrosionprotection measure for the jacket-type quays
used to improve the Ooi Quay (for water
depths of –1 m and above).
Further in the “Technical Standards forPort and Harbor Facilities” revised in April
1999, corrosion protection methods basedon corrosion allowance was eliminated, andas a rule cathodic protection was stipulated
for zones below the mean tidal level and thecoating/lining protection method for allzones upwards from 1 m below the mean
tidal level.
● Concepts for Standard Corrosionprotection Methods
Regarding concentrated corrosion occurringin the vicinity just beneath the M.L.W.L., it
is difficult to visually find it and, further, torepair it by the use of coatings, and thus it isnecessary to implement appropriate countermeasures. Three standard corrosion-protection systems are established to treat concentrated corrosion (Fig. 4).
(A):This method applies coating/lining corrosion protection to the section above
L.W.L. –1 m and cathodic protection to
the section below the M.L.W.L. It is themost widely applied method.
(B):This method applies the coating/lining
corrosion protection of method (A) to
sections deeper toward the sea bottom.
This method is most economical and effective in cases where the large corrosion-protection current density of cathodic protection is necessary in open
seas and in areas subject to the flow ofhigh tides. There are many examples ofmethod (B) being applied to long-spanbridges and floodgates.
(C):This method applies coating/lining corrosion protection to those parts of thesplash zone where the severest corro-Fig. 4	Standard Corrosion-protection Methods for Port andHarbor Steel Structures

Corrosion Protection
sion occurs, tidal zone, submerged zone,
and mud zone. In general, this method isapplied to steel sheet pile revetments installed in areas of shallow water. In suchapplications, the coating/lining methodshould possess particularly excellent
corrosion protection and durability. In
most cases, polyethylene linings andurethane-elastomer linings are applied
to newly-installed structures, and petrolatum linings and mortar linings to existing structures. In most cases, the limit application depth for the coating/lining method is up to G.L. –1 m. The
corrosion-protection method is not applied to the mud zone at G.L. –1 m or
below. In such an application, it is necessary to adopt a steel product having
increased thickness sufficient for the
corrosion loss expected in the corresponding sea area.
● Materials for Coating/Lining Corrosion Protection
Five major coating/lining corrosion-protection methods are applied to port and harborsteel structures—coating, organic lining,
petrolatum lining, mortar lining, and metallic lining.
A representative coating system uses
heavy/thick film-type zinc-rich paint plus
epoxy resin paint. Organic lining has higher
corrosion resistance. The organic lining applied to port and harbor steel structures ispolyethylene lining, urethane elastomer lining, extra-heavy/thick film-type lining, andunderwater lining. Underwater lining isavailable in two types—the putty type inwhich the lining material, in a putty-likestate, is applied by manual cladding; and thepainting type whereby the lining material isapplied using rollers and brushes. One of thefeatures of the underwater lining system isthat the lining can be applied to complexshaped structures such as the sections wheresteel sheet piles are joined.
Petrolatum lining has many recorded applications and is effective as a corrosionprotection method for port and harbor steel
structures. In this system, petrolatum-typelining is tightly bonded to the steel productsurface, which is protected by the use ofplastic or reinforced plastic covers or corrosion-resistant metallic covers. There are cases in which a buffer material is inserted between the petrolatum material and the cover.
The integrated system features underwater
applicability, comparative ease in surface
grinding, and no need for a curing period af-

ter lining.
Mortar lining is a method whereby corrosion protection is attained by forming a
dense passive film on the surface of a steel
product by fully utilizing the alkaline in cement. When lining is with concrete, themethod is frequently called mortar lining.
Mortar lining has long been applied in the
corrosion protection of port and harbor steel
structures. When deterioration in the formof cracking, peeling-off, neutralization oflining mortar occurs, the corrosion protection performance of the lining is lost. To
remedy this, various countermeasures are
adopted—increased lining thickness, mixing of organic polymers and steel fibers, surface coating, and the use of protectors thatare also used as FRP and metal molds.
Metallic lining is particularly superior in
impact resistance and abrasion resistance,
and is high in corrosion resistance. Highly
corrosion-resistant stainless steel and titanium are used as the metallic lining materials.
● Cathodic Protection— Principle
In cathodic protection system, the direct
current that overcomes the corrosion current
flowing from the steel product into the electrolysis (seawater) is continuously flowedfrom an external source into the steel product so as to prevent ionization (corrosion) insteel products. There are two types of cathodic protection—the external current
source system and the sacrificial anodic system. In the sacrificial anodic system, large/
small and/or high/low trends toward the ionization of metallic materials is utilized insuch a way that metallic materials such asaluminum, zinc, magnesium, etc. are connected to the steel and are ionized (corroded) instead of the steel so as to protect thesteel product from corrosion.
— Application
The prescribed application range for cathodic protection is the section extending from
M.L.W.L. downward. Cathodic protection
is very effective in preventing concentrated
corrosion from occurring in steel products
located just beneath M.L.W.L. In cathodic
protection as currently applied, the sacrificial anodic system using aluminum alloy
anodes is almost exclusively adopted. The
major reasons for this are many advantages
offered by the sacrificial anodic system—noneed to use a current source once the system
is installed (in contrast to the external current source system), no need for power expenditures, and the possibility of inspection
and maintenance by periodically measuring
electric potential.
New Topics on Corrosion-protection Technology— Tokyo International Airport(Haneda Airport) —Fig. 5 shows a recent Haneda Airport with
the new 4th Runway (in 2009, under construction). The feature of this runway iscomposed of reclaimed part (2,020 m inlength) and wharf part (1,100 m in length).
As previous experience on “Port and Harbor
Steel Structure” described above, well established corrosion prevention technology
is required on wharf structures for long term
design service life, 100 years for the new 4th
runway. For this very important structure,steel piles composing the steel jacket are allprotected with stainless steel plate, 0.4 mm
in thickness at the part of tidal and splash
zones (Fig. 6). Steel beams composing theframe of the upper structure are protectedwith epoxy resin coating. The design service

Fig. 5 New Haneda Airport with 4th Runway

July 2011 Steel Construction Today & Tomorrow 4

PC, concrete-steel hybrid) and steel structures (steel sheet pile,steel pipe pile, jackettype).
Fig. 7 shows the performance degradation
curve and maintenanceeffect. In this figure,three different maintenance levels are also
shown. Maintenancelevel is defined as the“level I” as the highest
grade, “level II” formiddle grade, and “level III” for the lowest
grade. The level is set for each structure considering several important factors such as“important level of the structure,” “environmental condition,” and “difficulty of the inspection/survey.” Main­te­nance work should
be based on the LCM concept of individual
structure. A series of maintenance is composed of “periodic inspection,” “required
investigation,” and “evaluation of deterioration or performance degradation,” and if

Fig. 6 Lower Structure of Wharf Type Runway

life of 100 years is a challenge for marine
steel structures, exposing to very severe environmental condition. As just explained,
highest level of corrosion protection technology is adopted for jacket-type steel structure. However, it is certain that proper maintenance is necessary to achieve the service
life of 100 years.
Future Insight in Performance-driven Design and Maintenance ofCorrosion Prevention Technology
Roughly speaking, in history of corrosionprotection technology in Japan, in the 1980s,
the “corrosion allowance theory” was diminished and “corrosion-prevention methods” such as cathodic protection and coating/lining were established. In the 2000s,
the main part of infrastructure managementchanged from new construction to maintenance of existing structures. And, design
system was gradually changed from the“specification” to the “performance-driven.” Also, the design of corrosion protection
system was gradually shifted to the performance-driven method. The definition of theperformance of corrosion prevention system is “within the design service life, to prevent steel from corrosion (rusting).”
The design service life of general steel
structures is mostly 50 years, except for the
new runway of Haneda Airport (100 years).
Table 1 presents the lining or coating method and expected service life. At present
technological condition, the 50 year period
is the highest durability. Normally, 20 years
and 30 years are the expected level. Thismeans the proper maintenance system isnecessary to achieve the expected service
life of more than 50 years for marine steel
structures. In recent decade since 2000, major discussion was concentrated on themaintenance system of port and harbor
structures, both of concrete structures (RC,5 Steel Construction Today & Tomorrow July 2011

necessary, “repair and reinforcement” and“data base construction for high level andlow cost maintenance system.”
At present 2011, to some degree, corrosion-protection technology is well developed. However, in future, following upgrades, 1) performance-driven design
system of corrosion protection system and2) higher level maintenance system, are stillnecessary to be established.
Concluding Remarks and Acknowledgements
For this article, the Port and Airport ResearchInstitute supplied many useful data and materials, for which we express our greatest thanks.
While it is clear that corrosion-protection technologies have made great strides, the current
technologies are not necessarily perfect. In Japan, new R&D efforts are being promoted inthis area, and authors hope to contribute tothese efforts in one way or another. In this regard, we would be very grateful if we could collaborate with engineers and researchers in allover the world, pertaining to corrosion protection in the construction of port and harbor steel
structures.

Table 1 Lining or Coating Method and Expected Service Life
Lining or coating

Precoated type

Coated on-site type

Materials and method

Expected service life

Thick epoxy resin type painting
Glass flake contained epoxy resin type20 years

Polyethylene lining typePolyurethane lining type
Thick epoxy resin type lining

30 years

Seawater resist type stainless steel lining
Thin titan plate clad type50 years

Underwater-hardened resin type20 years

Resin covered petrolatum tape type
Metal covered petrolatum tape type

30 years

Reinforced concrete covered type
Cement mortal covered with protective cover

30 yearsFig. 7 Performance Degradation Curve and Maintenance EffectRepair and Reinforcement

Steel Pipe Piles and Sheet Piles— Repair and Reinforcement Technology —By K azuhiro Masuda (Yoshikawa-Kaiji Co., Ltd.)
Research Group on Corrosion-protection and Repair Methods for Marine Steel Structures
Hiroshi Shiraishi (Nakabohtec Corrosion Protecting Co., Ltd.)
Research Group on Corrosion-protection and Repair Methods for Marine Steel Structures
Atsuo Moriwake (Toa Corporation)
Research Group on Corrosion-protection and Repair Methods for Marine Steel Structures
Concerns about Concentrated
Corrosion
Because port/harbor steel structures are exposed to severely corrosive environments,
the inappropriate application of corrosion
protection and maintenance is likely tocause fatal structural deterioration, such asa significant reduction of loading capacity.
During the period of high economic growth
in Japan from the latter part of the 1950s
through the 1960s, numerous port/harbor
facilities were constructed, as were manyother steel structures. At that time, corro-sion-protection technologies for such
structures had not yet been established, in
contrast to the current rapid progress ofthese technologies. Accordingly, among
the structures constructed then, there weresome that suffered severe deterioration due
to concentrated corrosion.
Photo 1 shows an example of concentrated corrosion occurring in a steel product installed underwater. Photo 2 shows anexample of pitting corrosion in the corrosion-protection coating applied to thesplash zone of a steel product. Under theconditions at work in these examples, if
sufficient maintenance control is not applied in time, deterioration will develop
further, inevitably leading to fatal structural damage.
The development of corrosion-protec-

tion technologies for port/harbor steel
structures in Japan can be organized asshown in Fig. 11). From the latter part of the
1950s through the 1960s when a number of
port/harbor structures were constructed,
cathodic protection relying on impressedcurrent system was applied to submerged
structures, and design methods employing
corrosion allowance were applied to structures installed above the tidal zone.
In those days, because the importance of
maintenance was not yet recognized to theextent that it is today, there were many cases of steel structures experiencing fatal deterioration due to concentrated corrosion
and pitting corrosion, as described above.
A typical example of such fatal deterioration occurred in 1981 when concentrated
corrosion caused the buckling of steel pipe

Fig. 1	Development of Corrosion-protection Technology for Port/Harbor Steel
Structures in Japan1)
Cathodic protection

Coating

1960
Impressed
current system

Photo 1	Example of concentrated corrosion inunderwater steel structure
1970

1980

Photo 2	Example of pitting corrosion in corrosion-protection coating

1976: Specification of cathodic protectionin the design standard as a meansof corrosion protection for
newly-installed structures
1981: Concrete upper structure collapse
incident at Yamashita Wharf

1990

1989: Specification of cathodic protectionin the design standard as a meansof corrosion protection for existing
structures

2000

1999: Prohibition of the use of corrosion
allowance

Galvanic
anodes system

Application of
corrosion allowance
as a principal
method for corrosion protection

Recognition ofimportance ofcorrosion protection→Application of
coating

July 2011 Steel Construction Today & Tomorrow 6

Fig. 2	Conceptual Drawing of Severe Lowering of Cross-section Capacity due to Corrosion

Calculation of member
force working as theoriginal steel product(rigidity)±0.00

Corrosionof steel
product−2.00

Design cross-section capacityof steel product365.3 kN∙m

Range targeted for repair
and reinforcement+1.30

Designmemberforce
Design cross-section capacity ofcorroded part of steel product117.9 kN∙m
Design cross-section capacityof steel product158.0 kN∙m

Underwater concrete

steel structures is standard practice, and,further, the implementation of appropriate
maintenance for such structures is mandatory.
Nevertheless, a number of steel structures designed using corrosion allowance
criteria are in use, and further the corrosionof steel products still occurs due to insufficient maintenance practices previously applied. Accordingly, steel structures still exist that are likely to suffer serious
deterioration. To this end, it is now necessary to repair and reinforce these structures
capitalizing on the Corrosion-protection
and Repair Manual.
This article introduces the latest technologies for repairing and reinforcing thesteel structures in which corrosion has already developed.

advanced technologies was promoted and,at the same time, the Corrosion-protection
and Repair Manual for Port/Harbor Steel
Structures2) was prepared. Currently, as aresult of accidents like this, the provisionof corrosion protection to newly installed

Repair and Reinforcement Using
Reinforced Concrete● Basic Practices in Design
The basic practice in this method is to use
reinforced concrete members to repair andreinforce structural steel sections that havedecreased in design cross-section capacity
due to severe corrosion and that thus fallshort of the design member force (refer tothe dotted line in Fig. 2). In this case, repair
and reinforcement are provided so that
Equation (1) is satisfied.

Fig. 3	Conceptual Drawing of Repair and Reinforcement Employing Reinforced
Concrete(Existing) upper concrete

Underwater stud welding

Corrosion, hole
ing
ver
r co
o
f
late
el p
Ste

Vertical reinforcing bar
Lateral reinforcing bar

Underwater stud welding(Existing) corroded steel pipe pilepiles and the subsequent collapse of the superstructure at the Yamashita Wharf in the
Port of Yokohama.
Triggered by this accident, the importance of corrosion-protection technology
was recognized, and the development of
7 Steel Construction Today & Tomorrow July 2011

Repair and Reinforcement

±0.00

−2.00

Fixing range

Calculation of member
force working as thereinforced concrete(rigidity)

Range of repair andreinforcement using
reinforced concrete+1.30

Fixing range

Fig. 4	Conceptual Drawing of Recovery of Cross-section Capacity of Steel Product after Repair and Reinforcement457.8 kN∙m
Design member
force (considerationof rigidity change
due to repair andreinforcement)

Design cross-section capacity ofexisting steel product

Design cross-section capacity
after repair and reinforcement
Setting of repair/reinforcement
section so as to become(working) design member
force ≤design cross-section
capacity (reinforced concreteor steel plate)

209.2 kN∙m

Design cross-section
capacity of existing
steel product79.0 kN∙m

Where
Sd : Design member force
Rd : Design capacity of cross-section
γi :	Coefficient of structure (in thecase of adopting reinforced
concrete)
Specifically, reinforced concrete is firmly affixed using underwater studs to thesound section of the steel pipe pile or sheet
pile, the target member for repair and reinforcement, in order to integrate both theconcrete and the pile so that the reinforced
concrete, the repair and reinforcement
member, can securely maintain the sectional strength.
Fig. 3 shows a conceptual drawing of
the repair and reinforcement method using
reinforced concrete. The underwater studs
are weld-joined to both sides of the targeted repair and reinforcement member, towhich the underwater reinforced concretehaving the reinforcing bar arrangement tosatisfy the equation (1) is affixed.
The conceptual cross-section capacity
recovered by use of this method is shownby the dotted line in Fig. 4.

● Execution Outline
In executing the method, the marine organisms and loose rust that adhere to the target
structure are removed using scraping bars,
air chippers etc, and, in addition, surface
preparation is conducted on the stud bolt
joining section until the surface is suitablefor welding (Photo 3).
Because the underwater studs are important members for integrating the pipe or
sheet pile with the reinforced concrete, anunderwater stud welding method that allows secure weld-joining underwater is adopted (Photo 4). To ensure quality control
over the underwater stud welding, themethod is adopted that confirms the weld
quality using the waveform of the current
flowing during welding.
Then, reinforcing bars are installed on
the pile as necessary. And, when installing
reinforcing bars on sheet piles, a frequently
used method is to employ bars that werepreassembled on land.
As regards the concrete, commonly applied underwater concrete is adopted, but
in cases requiring that due attention be paid
to the effect on water quality in the surrounding sea area, antiwashout underwater
concrete with high separation resistance iscommonly adopted.
Photo 5 shows the condition after con-

Photo 3	Marking of stud welding position andsurface preparation

Photo 4 Underwater stud welding

crete form removal. As seen in the photo,
the integration work can be carried out
without damaging the configuration of thepipe pile or sheet pile, and, accordingly,
when conducting subsequent maintenance,
visual inspection can be done in the same
July 2011 Steel Construction Today & Tomorrow 8

Photo 5	Reinforced concrete after completion

way as for the other installed piles.
Repair and Reinforcement Using
Steel Plates● Basic Practice in Design
In this method, steel plate is used instead ofconcrete. Specifically, steel plate with therequired thickness is attached to a sectionof steel pipe or sheet pile in which corrosion has caused a marginal drop below thedesign sectional strength. The plate is fixedwith underwater welding to the sound sections at either end of the pipe pile or sheet
pile in need of repair or replacement.
The basic conditions for sectional
strength lowering and recovery by the useof steel plate are the same as for reinforced
concrete. However, an important feature of
the steel plate method is that, because thethickness of steel plate members is lessthan that of concrete members, the stressoccurring in the pipe pile or sheet pile after
repair and reinforcement is similar to that
present before repair and reinforcement.
Thus, fewer adverse effects are caused byrepair and reinforcement.
● Execution Outline
After using air chippers etc. to remove themarine organisms and loose rust that adhere to the target steel product, the prefabricated steel plate used for repair and reinforcement is installed in the prescribed
position. The reinforcing steel plate that is
applied to the steel pipe pile is frequently
fabricated as two pieces (Photo 6).
Then, the prefabricated steel plate is
weld-joined to the pipe pile or sheet pile by
9 Steel Construction Today & Tomorrow July 2011

Photo 6	Installation of steel plate for repair andreinforcement

Photo 7	Integrated repair/reinforcement steel
plate and steel pilemeans of wet-type underwater welding(Photo 7). In weld joining, because theweld quality is governed by the welder’sability and the hydrographic conditions, it
is important to secure a sufficient and safe
welding length. For this purpose, the characteristic value for the yield stress of wettype underwater welds is set at 70% that
achieved in shop welding using a similar
welding method. However, in cases of severe working environments marked bywave action or when the pipe pile or sheet
pile is subjected to strict, repeated stress, avalue of 70% is sometimes insufficient,and thus it is necessary to pay due attention
to weld application.
Meanwhile, because the method inquestion premises the provision of a corrosion-protection method, it is necessary toapply cathodic protection to underwater
steel piles, and corrosion-protection coating to steel piles installed in the tidal andatmospheric zones, referring the Corrosion-protection and Repair Manual.

proaches to maintenance. If the Manual isproperly used to carry out repair and maintenance within the context of lifecycle
costs related to steel structures that previously were insufficiently maintained, suchendeavors will contribute to ensuring a safe
social infrastructure. We hope this article
will be helpful to such endeavors.

Corrosion-protection and Repair
Manual for Port / Harbor Steel
Structures
Currently, there are numerous steel pipe
piles and sheet piles still in service that require repair and reinforcement. However,given the recent severe economic situation,
it is difficult to provide repair and reinforcement to all these piles in a short periodof time.
In this regard, the Corrosion-protection
and Repair Manual for Port/Harbor Steel
Structures (2009)2), published in November 2009, informs us not only about the importance of maintaining port/harbor steel
structures but also about practical ap-

Acknowledgements
In preparing the current article, reference wasmade to results obtained from the revision ofCorrosion-protection and Repair Manual for
Port/Harbor Steel Structures (2009), a joint
work by the Research Group on Corrosion Protection and Repair Methods for Marine Steel
Structures and the Coastal Development Institute of Technology. Similarly, reference wasalso made to achievements obtained from revision of the Handbook on Practical Corrosionprotection and Maintenance3) (slated for publication in the fall of 2011 by the Research Groupon Corrosion Protection and Repair Methods
for Marine Steel Structures). We wish to deeply
thank the individuals of those organizations fortheir generous cooperation.
References
1) Masami Abe: “Development of Corrosionprotection Technologies for Port/Harbor
Steel Structure,” Materials and the Environment, No. 60, pp. 3-8, 20112) Coastal Development Institute of Technology: Corrosion-protection and Repair Manualfor Port/Harbor Steel Structures (2009),
Nov. 20093) Research Group on Corrosion Protection andRepair Methods for Marine Steel Structures:
Handbook on Practical Diagnosis, Corrosion-protection and Maintenance for Port/
Harbor Steel Structures

Nhat Tan Bridge

Nhat Tan Bridge in Vietnam— Bridge Design and Substructure Construction —Project Outline
The Nhat Tan Bridge project represents an
8.5-km highway construction project thatcrosses the Red River and extends south tonorth in Hanoi, the capital of Vietnam. The
project commemorates the 1,000th anniversary (October 2010) of Hanoi being established as the nation’s capital. The newbridge is a cable-stayed structure with fivemain towers and is expected to become asymbol of friendship between Vietnam andJapan.
Design and project execution control
are undertaken by a joint venture of ChodaiCo., Ltd. and Nippon Engineering Consultants Co., Ltd. Construction package 1, including construction of the main bridge, isbeing undertaken by a joint venture between IHI Corporation and Sumitomo Mitsui Construction Co., Ltd. and is financed
as a yen-based STEP (Special Term for
Economic Partnership) loan, a special Japanese government ODA loan. Construction
work started in October 2009.
The following introduces mainly the design and construction of the steel pipe sheet
pile well foundations adopted for the tower
foundations of the main bridge.

   Main towers:   Reinforced concrete A-shaped towers   Foundations:   Steel pipe sheet pile well founda-

Plan and Design of the Nhat Tan
Main Bridge● Bridge Outline―Project owner:  
Ministry of Transport of Vietnam,
Project Management Unit 85―Bridge length: 1,500 m―Length of Spans:   150 m + 4 × 300 m + 150 m―Type   Superstructure:   Six-span continuous composite
dual I-girder cable-stayed bridges   Slabs:    Precast reinforced concrete slabs

75500

By H
 iroki Ikeda, Shigeyoshi Ando, Tsukasa Akiba and Harukazu Ohashi
Nippon Engineering Consultants Co., Ltd.

tions
(Refer to Figs. 1~2)
● Selection of Bridge TypeThe Red River flows west to east, and in theFig. 1 Section of Superstructure
35600
33200

1200
3300

750

3 x 3750=11250

1200
3 x 3750=11250

1500

150

150
PH

2%

4x3330=13320

3280

3000

2%

750

Asphalt pavement t=75mm

2700

4500

PH

400

3300

2500

400

3280

4x3330=13320
33200

Fig. 2 General Drawing of P12 Main Tower
3000
3000

11000

109310

45600

77500

27800

7200

5000

8000

13000

+1.33
-3.0

28810

3200

Design water level:+13.67

8200
φ1200

φ1200
37500

3500
5500
500
28000

37500

28810
5000
25910

8000

48878

-40.5

16891

-34.40 (P12)
Estimated bearing stratum line
July 2011 Steel Construction Today & Tomorrow 10

Fig. 3 Elevation of Entire Bridge
1500m

P11

P12

P13

P15

Fig. 4 Perspective of Nhat Tan Bridge upon Completion (Computer Graphics)

vicinity of the bridge construction site it isseparated into two channels that sandwich
a sandbar. According to the historical record, the riverbed is known to change overtime with regard to the location of the river
channels and the sandbar. Because of this,future movement of the river channels andsandbar were taken into consideration in
selecting a six-span continuous cablestayed bridge plan having spans of equal
length (Figs. 3, 4).
● Applied Standards
The bridge design conforms to the Specification for Bridge Design 22TCN-272-05 ofVietnam, which is based on the AASHTOLRFD of the U.S. Further, such items as
steel pipe sheet pile well foundations andbase-isolated bearings, which are not described in the Specification, followed specifications in the design standards of Japan.
● Major Structural Materials
The major structural materials are as follows:―Steel products:  SS400, SM400, SM490, SM490Y,
SM520, SM570
11 Steel Construction Today & Tomorrow July 2011

150m
109.31m

111.56m
P14

300m
110.81m

300m

300m
110.81m

300m
109.31m

150m(Courtesy: Sumitomo Mitsui Construction Co., Ltd.)―Cables:  Parallel strands using 7 mm-diameter
galvanized steel wire (tensile strength:
1,770 MPa)
―Steel pipe sheet piles: SKY400, SKY490―Design standard strength of concrete:  40 MPa (main tower, slab); 30 MPa(end piers, cast-in-place piles); 25
MPa (top slab of steel pipe sheet pilefoundations)―Reinforcing bars: SD390―PC strands: SWPR7BL● Road Composition
The road is composed from its center: two
automobile lanes (3.75 m wide), a bus lane
(3.75 m wide), a dual-use motorcycle-bicycle lane (3.3 m wide), and a walkway (0.75m) along the outer edge.
● Superstructure
The superstructure is a continuous structure spanning 1,500 m in total length. The
main structure consists of two main I-girders located along each edge of the roadway
to which cross beams to support the slabs
are arranged at 4-m intervals. The cables
are anchored to the outside surface of the

P16

P17

main girder webs. The main girders andcross beams form a composite girder structure to which precast slabs are connectedusing dowels. Fairings are installed on theouter edges of the slabs to improve windstability.
The cables employing parallel wire
strands are arranged in a fan-shaped form,
and the girders are suspended in a doubleplane format from the main towers.
● Main Towers
The reinforced-concrete main towers adopt
an A-shaped structure to secure rigidity
perpendicular to the bridge axis. Below thecrossbeams that support the superstructure,
the support columns of each tower draw
steadily inward as they descend, thereby
narrowing the space between the columns
in order to decrease the plane shape of thefoundation.
Because axial tension force works on
the crossbeams, a prestressed concrete
structure was adopted. Anchor boxes employing steel plates are embedded near the
top of the tower, and the cables are anchored to the bearing brackets within theboxes.
● Steel Pipe Sheet Pile Well Foundations
With the aim of improving upon the construction quality of cast-in-place piles thathave occasionally offered application concerns in Vietnam, steel pipe sheet pile wellfoundations were adopted for the first timein Vietnam. Because this type of foundation was developed in Japan, two Japanese
specifications were adopted for design andconstruction―Specifications for Highway
Bridges IV (2002) and Design and Construction Manual for Steel Pipe Sheet Pile
Foundations (1997).
The scouring depth accounted for in thedesign was estimated to be, at maximum,
15 m from the riverbed. The driving method for pile installation was adopted withthe aim of securing bearing capacity. The

Nhat Tan Bridge
Fig. 5 Schematic Diagram of P13 Foundation

H.W.L.

+13.670

13500

Water level at the time of construction +9.500

31500

5500

-3.000

M.W.L.

+4.400Site ground surface
Minimum water level+0.180−3.000

Scouring surface at usual time

−6.830

Scouring surface at the time of flood−18.000-34.500

16891

48743

piles were to be embedded in the bearing
stratum, a gravel layer with N>50, to adepth more than five times the pile diameter. The top surface of the top slabs was set
at a position equal to sea level –3 m, taking
into account changes in the riverbed.
The adopted pile diameter was 1,200mm, and the wall thickness of the piles is16~21 mm. The well foundations have an
oval plane shape with the dimensions of
48.7 m x 16.9 m. The maximum length of
the steel pipe sheet pile well foundations,
including temporary cofferdams, is 50 m.
The number of pipe piles used, including
the bulkhead and internal piles, amounted
to 632. The reinforcing bar stud method
was adopted for connecting the top slabs.
(Refer to Fig. 5)
Progress in Construction
At the end of May 2011, construction of themain tower foundations was underway at
P13~P15; and driving of the steel pipe
sheet piles was completed and underwater
excavation, installation of the lower slabs
and upper slabs, etc. were underway at P12
and P16. (Photos 1, 2).
● Execution Yard and Machinery
The sandbar in the Red River where P14 is
being constructed is utilized as a structural
material yard, reinforcing bar fabrication
yard and emergency evacuation base. At
P12, P13 and P15, which are located with-

Photo 1 Full view of construction site

Photo 2 On-land construction at sandbar

in the river, underwater construction is being conducted using a crane ship, materialtransport and other barges (Photo 3).
● Driving of Steel Pipe Piles
In order to construct large-scale founda-

tions and to drive and close steel pipe sheet
piles with a maximum length of 50 m, it isimportant to execute precise vertical driving of the piles. At the construction site, thepipe piles were driven using hydraulic vibratory hammers in combination with theJuly 2011 Steel Construction Today & Tomorrow 12

Photo 8	Full-scale model prepared to examine
installation of reinforcing bar cage formain tower bottom section

Photo 3	Barges used for underwater construction
Photo 6 Interior of well foundation

shortages in 2010. Because of this, construction work continued without interruption even during the summer season, moreover, it was possible to lower the height ofthe cofferdam by 1 m below the design level.
● Underwater Excavation
The method adopted to conduct underwater excavation inside the steel pipe sheet
pile well was using pumps to dischargeboth water and riverbed sand (Photos 6, 7).

Photo 4 Water jetting nozzle● Subsequent Processes
After excavation, underwater placement of
the bottom concrete slabs, stud welding, reinforcing bar arrangement and concrete
placement of the top slabs will be undertaken; following this, the main towers will
be constructed. These subsequent processes will be introduced at the next opportunity. (Refer to Photo 8)

Photo 7	Discharge hole of underwater drillingpumpfirmed by means of PDA (pile driving analyzer).

Photo 5	Final driving of steel pipe piles using
diesel hammer

water jet method. This driving method wasapplied to drive piles up to a depth of 6D(D=pile diameter) above the pile tip,whereas final driving into the bearing stratum was undertaken using diesel hammers.
(Refer to Photos 4, 5)
One test pile was driven for each foundation, and the bearing capacity was con13 Steel Construction Today & Tomorrow July 2011

● Temporary Cofferdams
In the design stage, historical water level
data for the Red River was relied upon to
set the water level at the time of construction at sea level + 9.5 m, excluding the twomonths in summer when the water rises to
its maximum level. Because of the large
difference in water heads, various measures were taken to reduce the residual
stress on the driven piles. These included
studies and improvements for multi-steptimbering, water level regulation, arrangement of the bottom slab placement period
and other devices.
During the actual work, the water levelrose to sea level + about 7 m due to waterHigh Expectations for JapaneseTechnologies
The next two and a half years will see thecontinuation of on-site, high precision construction work, such as construction of themain towers, installation of the anchor
boxes at the top of the towers and cantilever erection of the main girders. We expect
that, by capitalizing on Japan’s advanced
technological capabilities, the Nhat Tan
Bridge will be safely completed and opened
to traffic, and that the bridge will contributeto the development of the Vietnamese
economy.
Acknowledgments
We wish to express our sincerest gratitude to
Mr. Yamaji, Project Manager, and Mr. Mimura,
Design Manager of the Nhat Tan Bridge Construction Site Office of Sumitomo Mitsui Construction Co., Ltd. for their generous cooperation during our inspection of the construction
work on the steel pipe sheet pile well foundations.

Tokyo Gate Bridge

Tokyo Gate Bridge— Design and Construction of
Steel Pipe Sheet Pile Foundation—
By D
 r. Osamu Kiyomiya
Professor, Waseda University

Project Outline
At the Port of Tokyo, construction project
has begun on an 8-km section of the Tokyo
Port Coastal Highway to enhance thesmooth distribution of international cargo
between the Port of Tokyo and its coastal
cities. Constituting a segment of this sectionof the highway, the Tokyo Gate Bridge is alarge-scale structure composed of a main
bridge (continuous 3-span truss-box composite bridge) that spans the No. 3 fairwayof the Port of Tokyo and two offshore-onshore approach bridges (continuous multispan steel slab box girder bridges) at bothsides of the main bridge. The bridge has atotal length of 2.9 km and is scheduled to becompleted in fiscal 2011.
Because the construction area of the Tokyo Gate Bridge is located at a layer of alluvial clay (N value ≈ 0) that is 30 m or more
thick, the foundation of the bridge rests on
bearing strata of sand and gravel located at
the deepest section of the No. 7 stratum. And
since the foundation lies at least 65 m below
the sea mud line, it is built as a great-depth
type structure. Because the foundation is required to possess a seismic deformation capacity suitable for expected seismic motion
between 534.7 Gal and –434.2 Gal and because economical structural sections must
be built, it was decided that a large-scale
steel pipe sheet pile well foundation (pipepile diameter: 1,500 mm; checkered steel
plates + high-strength mortar-filled interlocking joints) is adopted.
In this article, the large-scale steel pipe
sheet pile well foundation that was adopted
for construction of the Tokyo Gate Bridge is

Osamu Kiyomiya : Professor, Civil and Environmental Engineering, Waseda University.
After graduating from the School of Engineering, Tokyo Institute of Technology, he entered
the Ministry of Land, Infrastructure, Transport
and Tourism in 1973. Then he filled key postsat the Ministry’s Port and Harbor ResearchInstitute. He became professor of Waseda
University in 1997.

outlined and its construction method is discussed.
Two features should be cited regarding
the construction of the Tokyo Gate Bridge.
One is that the bridge spans the No. 3 fairway of the Port of Tokyo (crossing width:about 310 m; below-girder clearance: A.P.
54.6 m), and the other is that the construction work had to adapt to impediments
posed by the restricted area surrounding Tokyo International Airport (A.P. +98.1 m). In
order to satisfy these restrictions at both thedesign stage and the construction stage andto construct both a safer and higher-quality
bridge through the pursuit of structural andeconomical rationality, it was necessary toadopt the latest in bridge technology: steelslabs utilizing large-size ribs, truss welds attained by eliminating the use of splice plates,
BHS (bridge high-performance steel) products, large-size base-isolated shoes etc.
Design of the steel pipe well foundation
was made in accordance with the Specifications for Highway Bridges (Japan Road Association) and the Design and Constructionof Steel Pipe Piles (Japanese Association for
Steel Pipe Piles). These two specifications
state that the required performances of thefoundation is constantly satisfied with regard to bearing force and overturning andthat, in level 1 seismic motion, the structural
materials remain within the allowable stressand the horizontal displacement is within 50
mm, and that, in level 2 seismic motion, thematerial remains within the yielding value
and the yielding area of the foundation
ground is within 40%.

Foundation Structures
The substructure of the Tokyo Gate Bridge(total length: 2.9 km) is composed of two
abutments and 21 piers (Fig. 1), of which 9
piers are located in the offshore section (extension: about 1.6 km) of the substructure.
Of the offshore piers, the main piers (MP2,3) are of the RC wall type (Photo 1) and theside-span piers (MP1, 4) are of the RC hollow type.
As shown in Fig. 2, a layer of soft alluvial clay (AC2 layer, N value ≈ 0) is thickly
deposited over the foundation ground in thevicinity of the steel pipe well foundation.
Further, the layers that serve as the bearing
strata of the piers are located at great depth:
the gravel layer (Dg1 layer) for the
CP9~MP2 piers is located at A.P.–75 m or
deeper, and the sand layer (Ds2 layer) for the
MP3~WP6 piers at A.P.–50 m or deeper.
The gravel layer at A.P.–75.5 m mostly
serves as the bearing stratum of theCP9~MP2 piers, and the sand layer in thevicinity of A.P.–54.5 m~–50.5 m, shallower
than the above, serves as the bearing stratumof the PM3~WP6 piers.
Photo 2 shows the driving of the pipe
piles. Each pile is first driven into the bearing stratum using a vibratory hammer andthen a hydraulic hammer. The hammers
used are IHC-S280 and IHC-S200. The
planned embedding length to the bearing
stratum is 3.0D~3.2D. The outer diameter ofthe steel pipe piles used is 1,500 mm, andthe wall thickness of the pile tip is 17 mm.
Photo 3 shows the construction of the steel
pipe sheet pile well foundation.
July 2011 Steel Construction Today & Tomorrow 14

Fig. 1 Entire Drawing of Tokyo Gate Bridge
Bridge type: 3-span truss-box composite bridge (760 m)
Road classification: Type 4, Class 1
No. of lanes: 4 lanes (for both directions)
Total extension: 2,933 m (offshore section: 1,618 m)
Design speed: 50 km/hr
Planned completion: 2
 011 (project undertaking in 2001 by the Ministry of Land, Infrastructure, Transport and Tourism)
Total expenditure: ¥141,000 million(Central breakwater side)(Wakasu side)

No. 5 construction area: 3-spancontinuous steel slab box girder(352 m)No. 6 construction area (No. 3 fairway section): truss-box
composite bridge (760 m)

No. 7 construction area: 4-span continuous
steel slab box girder (506 m)

No. 3 fairway

CP9

CP10

MP1

MP3

MP2

Photo 1 Construction of MP2

Photo 2 Driving of steel pipe piles

Fig. 2	Foundation Structure and Soil Property

28.0

30.5

N value
m
3.0
9.0

70.5

5.0

–8.0

10.0 10.0

+2.1

Sand
compaction
pile

8.0

8.0
4.0
2.0
3.0
3.0
2.5
3.0
4.0
4.0
2.0
6.0

–78.5

6.0

Unit: m15 Steel Construction Today & Tomorrow July 201110 20 30 40 50

Loading Tests for Vertical Bearing Capacity
In applying steel pipe sheet
piles (diameter: 1,500 mm)
in the construction of the Tokyo Gate Bridge, on-siteloading tests were carried out
in 2003 prior to the start ofthe construction work. The
aim of the tests was to clarify
the bearing mechanism oflarge-diameter steel pipe
sheet piles that previously
had incurred problems insimilar work implemented inTokyo Bay, and to modify
conventional design andconstruction management of
the foundation.
Three kinds of loading
tests were carried out: dynamic loading tests (DLT),
static loading tests (SLT)(horizontal and vertical) and
rapid loading tests (STN),
which led to the following results:

MP4

WP8

WP7

WP6

Photo 3	Construction of steel pipe sheet pile
well foundation● Pile tip resistance by means of wave
matching analysis from the dynamic test
● Skin friction resistance from the static
loading test
● Set-up ratio (ratio of pile-tip static resistance during installation to tip resistanceafter ground recovery) of tip resistancefrom the dynamic and static loading tests● Relation between the skin friction resistance and the N value from the rapid loading test
(Refer to Tables 1 and 2, Fig. 3)
In relation to the design of the steel pipe
pile well foundation, the embedding lengthof the steel pipe piles into the foundation
layer and the enclosure ratio of the pile tip
are prescribed. Further, the ground reaction
coefficient, vertical-direction ground reaction and other factors described in the Specifications for Highway Bridges are confirmed. Photo 4 shows the static loading test.
Utilizing four pipe piles as the reaction pile,
test pipe piles were pressed into the bearing
stratum to a depth three times the pile diameter by means of a multi-cycle system employing hydraulic jacks. The hydraulic jackcapacity was 48,000 kN for pile ④, andTokyo Gate Bridge

Test kind
DLT
DLT
DLT, STN, CPT
DLT, SLT, HLT, CPT
DLT, SLT, CPT
DLT
DLT
DLT
—

• Static (vertical) loading test
• Static (horizontal) loading test
• Dynamic loading test
• Rapid loading test
• Pile diameter
Test parameters • Embedding length to bearing stratum• Soil property of bearing stratum (sand or gravel)• Embedding length• Tip bearing capacity
friction resistanceExamination of •• Skin
Ground reaction coefficient (vertical and horizontal
design values
directions)• Coefficient in bearing capacity calculation equation• Enclosure ratio and correction coefficient of safety factor
Kinds ofloading tests

tween the respective measured secLoad-residual displacement
curve
tions
can
be
Load-elastic return curve
converted as friction resistance. The
skin friction resis24000 80
tance is somewhat
low in the upper
12000 40clay layer, but becomes larger in the
12
9
6
3
800
160
240
3200
Load Po (kN)
Hourlower layer. Fig. 6
60shows the relation120
between the pile tip
bearing capacity
180
and the total load
displacement,
240
which were obtained by separatLoad-displacement curve
Time-displacement curve
ing from the total
force. It can beseen from the figure that the skin friction resistance is considerably larger than the tip
bearing capacity for pile ⑤. Further, thefriction resistance of both the inside and outside surfaces of the pile can be separated
from the friction resistance at the pile tip. It
was found in the test that the inside-surface
friction resistance becomes considerably
Photo 4 Static loading test
larger than the outside-surface friction resistance and that the sand and gravel inside the56,000 kN for pile ⑤.
pile are compacted.
Fig. 4 shows the relation between the apAs shown in Fig. 7, in the rapid loading
plied load and the vertical displacement of test, the 160-ton reaction mass affixed to thepile ⑤. The maximum load was 36,000 kN, pile head was lifted upward at an acceleraand the maximum displacement, 280 mm. tion of about 20G by the combustion presDisplacements up to about 60 mm were sure of the propellant, and the load waswithin the elastic range, and the yielding pseudo-dynamically applied to the pile headload was 2,000 kN. The strains were mea- using the reaction thus generated by lifting
sured at 13 sections of the pile, and the axial with a loading time of about 0.1 second.
force distribution and the skin friction resis- This test offers advantages such as shortertance were calculated from the measure- test times and the elimination of reaction
ment results. Fig. 5 shows the distribution of piles. Photo 5 shows the loading device. The
the axial force of the pile. The axial force axial force and acceleration distribution are
was calculated from strain meters set in the calculated using a load cell, strain meter andpipe pile. The difference in axial force be- accelerometer installed on the pile. Fig. 8

Fig. 3	Relation between Bearing Stratum Thickness and N-value at
Test Position
−40

0

10

20

30

40

50

Existing result
Test position−50

Displacement (mm)Fig. 4 Results of Static Loading Tests

Test
position

Test pile Pile diameter Pile tip depthNo.
D (mm)
A.P. (m)
−86.0
①
φ1500
−78.5
②
φ1500
−72.6
③
φ1200
−73.5
④
φ1500
−86.0
⑤
φ1500
−86.0
⑥
φ1500
−86.0
⑦
φ1500
−89.0
⑧
φ1800
−42.0
⑨
φ 800

Table 2 Kinds and Objectives of Loading Tests

Existing
resultTable 1 Test Piles and Kinds of Loading Tests−60

Depth (AP−m)

Ds2
Ds2
Dc2

Dc2
Ds2

−70

AP-69.0
Ds2

Tip of test pile ③
Dg1
Dg1

−80

Tip of test pile ④

Dg1/Ds3
Ds3

Tip of test pile ⑤
Ds3

−90

July 2011 Steel Construction Today & Tomorrow 16

Depth (m)Fig. 5 Vertical Distribution of Axial Force

Fig. 6	Tip Bearing Capacity and Total
Bearing Capacity

0

Load (kN)

20

30000

40

20000

60

10000

Total
Pile tip

80
10000

20000
Axial force (kN)

Fig. 7	Structure of Rapid Loading Test
DeviceSilencer

Reactionmass

Crushedstone

Combustion ofpropellant
PistonPile cap
Load

Pile

100
200
Displacement (mm)30000

Photo 5 Loading deviceshows the relation between the measured
load and the displacement. Fig. 9 shows themodel used to calculate the pile tip bearing
capacity and the skin friction resistance.
Calculation is made by setting the pipe pileas the elastic body and linking the peripheral ground, spring and dashpot while at thesame time changing the ground constant byusing the pile head input load so that thewave forms of both the measurement andthe calculation agree each other. Fig. 8
shows the temporal changes of both the load
and the displacement calculated together
with the measurement results. Further, theinput wave (hammer load) and the reflection
wave (ground resistance) can be calculated
from the axial force and acceleration. These
value forms are shown in Fig. 10.
Fig. 11 shows the axial force and skinfriction resistance of the piles as obtained
from wave-form matching analysis. Whilethe design of the steel pipe sheet pile wellfoundation was basically implemented according to the method described in the Specifications for Highway Bridges, various values applied in the design were modified
based on the loading test results. Modification was made mainly of the following:● The driving depth of pipe piles with anouter diameter of 1,500 mm (D) was set at
3D. The apparent enclosure ratio was 53%

Fig. 8 Matching Condition for Wave Form
40000
35000
ULP 32.161kN

Force (kN)

25000
20000
15000
10000
Measurement (Fstn)
Analysis (ULP)

5000
0

0

30

60

90

120

Disp (mm)17 Steel Construction Today & Tomorrow July 2011150

Loading Tests for High-strength
Steel Pipe Sheet Pile Joints
Commonly, the deformation strength of asteel pipe sheet pile well is obtained fromthe bending rigidity of the steel pipe sheet
pile structure and the shear resistance of theinterlocking joints. In the case of adopting
commonly applied pipe-to-pipe joints, thepipe piles are interlocked to each other by
the use of steel pipes with a diameter of
165.2 mm, and mortar with a compression
strength of about 20 MPa is used to fill theinterlocked pipe joints. In the current Tokyo
Gate Bridge project, it was necessary to increase the rigidity of the joints so that thehorizontal displacement of the steel pipe
sheet pile well foundation could remain
within its allowable value during earthquakes.
In order to increase the rigidity of thesteel pipe sheet piles, high-strength mortar
was used to fill the joint openings (Fig. 12)
to increase the adhesion between the mortar
and the pipe joints. In the current project, thestrength of the fill mortar was increased tomore than double (40 MPa) the conventional level, and, further, checkered steel plate
was used as the material of the pipe joints toincrease the adhesion. As a
Fig. 9	Calculation Model for Tip Bearing Caresult, it was confirmed that
pacity and Skin Friction Resistancesufficiently large shear resisStatic resistant component of ground:tance could be obtained by
Spring + Slider
the use of these two ap(spring coefficient, maximum resistantPile
component)
proaches.
Dynamic resistant component of ground:
As the results of the modDashpot(dumping coefficient)el loading test, a maximum
shear resistance of about
Slider1,640 kN/m was obtained as
Dashpot
Springshown in Fig. 13. The values
obtained in the test wereabout six times the upper
Tip resistancelimit (200 kN/m) of theSkin friction resistance30000

for the sand layer and 74% for
the gravel layer. When a crossrib was attached to the pile tip,
the pile tip resistance increased
by about 30%.
● The skin friction resistancewas estimated to be added tothe pile-inside resistance, andthe value shown in Table 3
was adopted.
● It was found in the horizontal
loading test that the deformation coefficient of the groundwas 2~3 times larger than that
described in the Specificationsfor Highway Bridges.

Tokyo Gate Bridge

25

Fig. 11 Results of Wave Form Matching Analysis

(MN)
Fd
Fu

20
15
10
5

Depth (AP m)

0
-5
−10
−15
−20

0

20

40

60

0

0

−10

−10

−20

−20

−30

−30
Depth (AP m)

Fig. 10 Input Wave Form Fd and Resistance
Wave Form Fu

−40
−50
−60

80

Time (ms)Test pile ③

−40
−50
−60

−70

−70
Tip AP-72.6

Table 3 Fixing of Skin Friction ResistanceFixing by Specifications Fixing by loadingfor Highway Bridges
test result(kN/m2)(kN/m2)2N (≤100)

2N (≤100)

Clay soil

10N (≤150)

10N (≤150)

Gravel layer

2N (≤100)

3N (≤150)

−90

−80

0

5000 10000 15000 20000 25000 30000

100

200

300

400

2500

Joint
φ165.2 or 216.3mm

1000mm

2000
1500
HPJ-1
HPJ-2
HPJ-3
HPJ-4
HPJ-5
HPJ-6
HPJ-7
HPJ-8

1000
500
0

0

5
10
15
Relative displacement (mm)

20

17478

8739

15730.2

31460.4

15730.2

Table 4	Comparison of Designs of Steel Pipe
After acquiring knowledge
Sheet Pile Well Foundationof the bearing mechanism at theNo. of pile
construction site from the loadPlanar configuration (MP2, MP3)
Pile length
ing tests conducted on large-diInitial
ameter steel pipe sheet piles,
designvarious design factors were re136
considered. Based on these, amore compact foundation configuration was successfully
achieved by the combined use
84.5 m15730.2
12234.6
12234.6of large-diameter steel pipe
40199.4
piles and interlocking joints
Finalmade of checkered steel plate
designfilled with high-strength mor98
tar. Similarly, the construction
management procedures werealso determined by the effec81.5 m
12235
12235
12235
tive use of the loading test re36704
sults. As a result of these considerations,the structuraldimensions of the steel pipe sheet pile foun- tion cost and improvements in structural
dation were reduced, thereby simultaneous- quality.
ly producing greater reductions in construc8739

Reduced Construction Cost andImproved Quality
The steel pipe sheet pile well foundation of
the Tokyo Gate Bridge was constructed on
soft ground, and, further, large sectional
force and deformation capability during
earthquakes were required in its construction. Thus in the design stage, the foundation structure necessarily became quite large
in terms of structural configuration.

0

Fig. 13 R elation between Load and Displacement

Fig. 12 Interlocking Structure and Loading Test Device

shear resistance described in the common
design specifications for steel pipe joint material (Manual for Design and Constructionof Steel Pipe Sheet Pile Foundations, Japan
Road Association).
The configuration of the steel pipe sheet
pile well foundation designed in the initialstage was greatly reduced through the appropriate use of the loading test results anda reexamination of the ground coefficients,
which allowed for economical construction(Table 4).

−90

Skin friction resistance (kN/m2)

Axial force (kN)Shear resistance (kN/m)

Sandy soil

H300

Tip AP-72.6−80

July 2011 Steel Construction Today & Tomorrow 18

Special Report

Great East Japan Earthquake andTsunamiTakeshi Oki
Chairman, Committee on Overseas Market Promotion
The Japan Iron and Steel Federation
The Great East Japan Earthquake that occurred at 14:46 on March 11, 2011, registered amagnitude of 9.0, making it the largest quake ever recorded in Japan. The resulting damage was unprecedented in its extent and ranged mainly along the Pacific coast of East Japan (Iwate, Miyagi, Fukushima and Ibaragi prefectures). The number of dead and missing
together reached more than 27,000 and the number of completely destroyed buildings exceeded 65,000.
This massive earthquake was of the interplate type, with its epicenter at a point 24 km
below sea level off the Sanriku Coast in the Pacific Ocean (approximately 130 km eastsoutheast of the Oshika Peninsula). Following the initial displacement of the fault at theepicenter off the Sanriku Coast, fault plane displacements subsequently occurred in the
hypocentral region of the original earthquake, covering an extensive area off the coastlinethat runs from Iwate to Ibaraki and measures about 500 km south to north and 200 km east
to west. Shortly after the main shock, a number of major aftershocks with magnitudes of
7.0 or over occurred in rapid succession in the region.
The devastating tsunami that followed the earthquake made the damage even morecritical. Tsunami waves exceeding 3 m in height hit the main ports and harbors along the
Pacific Ocean and caused considerable damage. A 9.5 m-high tsunami was observed
sweeping far to the interior of Port of Ofunato. According to a schematic drawing of flooded areas prepared by the Geospatial Information Authority of Japan, the Ministry of Land,
Infrastructure, Transport and Tourism, land areas extending inwards from the coast for 5
km or more were flooded, covering a vast expanse of land that extends from Ishinomaki
in Miyagi Prefecture to the central part of Fukushima Prefecture.

A large vessel running onto the quay of
Sendai Port due to the tsunami

View of a tsunami-struck area near the
Natori River, Miyagi Prefecture

Acknowledgements
We wish to express our concern for all those citizens and their families who have suffered greatly
as a result of the Great East Japan Earthquake. Much mail expressing sympathy and encouragementin overcoming the severe conditions has been received not only from people in Japan but fromabroad. We would like to take this occasion to express our sincere gratitude to everyone, including
our readers, who have extended extensive support and great kindness.
The Japan Iron and Steel Federation offers diverse steel construction methods and technologies
in the civil engineering and building construction fields that will be helpful for the early restoration
and reconstruction of the stricken areas. In the future, we will conduct research and surveys on thedamage caused by the earthquake and tsunami, and will strive to develop and disperse steel construction as one link among many endeavors to promote better disaster-prevention measures.
19 Steel Construction Today & Tomorrow July 2011

Special Feature
Corrosion Protection for Steel Pipe Piles andSheet Piles
1
Steel Sheet and Pipe Piles for Port
Steel Structures		 ―Corrosion Protection Technology:
Today & Tomorrow―
6
Steel Pipe Piles and Sheet Piles		 ―Repair and Reinforcement Technology―
10
Nhat Tan Bridge in Vietnam
		 ―Bridge Design and Substructure
Construction―
14
Tokyo Gate Bridge
		 ―Design and Construction of SteelPipe Sheet Pile Foundation―

COVER(top) Seawater-resistant stainless steel lining ofsteel piles composing the steel jacket at the new
No. 4 Runway of Tokyo International Airport (fordetails, see page 1); (bottom) Steel pipe sheet
pile foundation used for the construction of Tokyo Gate Bridge (see page 14)
A magazine published jointly by
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