No. 57 August 2019

STEEL CONSTRUCTIONTODAY & TOMORROW

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

Feature Articles

Latest Technological Trends
in Port and Harbor Structures
1 Outline of Revision of Technical Standards and Commentaries
for Port and Harbor Facilities in Japan

5 Infrastructure Maintenance, Renovation and Management:

Research and Development of Governmental Program in Japan

7 Development of Life-cycle Management System for Port andHarbor Facilities: Integrated Framework from Inspection toAssessment-SIP Infrastructure Maintenance, Renovation andManagement

9 Study of the Introduction of Steel Pipe Piles to Pile Foundations
in Southeast Asia

12 Assessment of Long-term

Durability of Various Metallic
Construction Materials by
Means of Exposure Tests at
Okinotorishima and Suruga Bay

Special Topic

15 Proposals Conducive to“Building National Resilience”
Employing Steel Structures

Back cover JISF Operations: Lecture Delivery at SEAISI Forum

Published Jointly by

The Japan Iron and Steel Federation
Japanese Society of Steel Construction

Feature Articles: Latest Technological Trends in Port and Harbour Structures (1)Outline of Revision of TechnicalStandards and Commentaries for Portand Harbour Facilities in Japanby Masafumi Miyata, Ministry of Land, Infrastructure, Transport and Tourism (Adjunct Professor,
Graduate School of Management, Kyoto University), and Takashi Niimura, Ministry of Land,
Infrastructure, Transport and Tourism
Masafumi Miyata: After graduating from the Graduate
School of Engineering of the Tokyo Institute of Technology in 1994, he worked at the Port and Airport Research Institute of the Ministry of Land, Infrastructure,
Transport and Tourism (current name) and the Ministry’s National Institute for Land and Infrastructure Management. He assumes his current position as Director,
Port Research Department of the National Institute forLand and Infrastructure Management since 2012.

Introduction
Technical Standards and Commentaries for Port and Harbour Facilities in Japan1) (hereinafter referred toas “TSCPHF”) is regarded as the bible for design of port/harbour facilities
such as breakwaters in Japan. In May
2018, it was entirely revised (hereinafter referred to as “TSCPHF2018”) for
the first time in 11 years. TSCPHF2018
is consisted of Technical Standards forPort and Harbour Facilities (hereinafterreferred to as “TS”) and Commentaries
for the TS.
Outline of TS, Position of
TSCPHF2018 and Japanese/
English Versions• Outline of TS
The Port and Harbour Act (Article 562-2) in Japan stipulates that “waterways
and basins, protective facilities for harbours, mooring facilities, and other port

Takashi Niimura: After graduating from the
Graduate School of Engineering of the Kobe
University in 2003, he worked at the Ministryof Land, Infrastructure, Transport and Tourism. He assumes his current position as Director for Technical Standards, Engineering
Planning Division, Ports and Harbours Bureau of the Ministry of Land, Infrastructure,
Transport and Tourism since 2018.

facilities that the Cabinet Order prescribes (hereinafter referred to as “portfacilities subject to the TS”) must be
constructed, improved, and maintainedso as to comply with the TS.”A content of the TS is stipulated by
Ministerial Ordinances and related public notices. The content stipulated byministerial ordinances is composed of
the reason (purpose) why a facility isrequired and the performance that thefacility should exhibit (performance requirement). Contents of public notices
are provisions that concretely describe
the performance requirement (performance criteria). (Refer to Fig. 1) Further, standard performance verification
methods that confirm whether facilities
satisfy the performance criteria or not,are described in the TSCPHF.
The current TS stipulates only theperformance that is exhibited by port facilities subject to the TS, and is called as‘performance-based design framework’
that does not stipulate the detailed process of design. Within this framework,
the TS stipulates only the purpose, performance requirement and performance
criteria as mandatory provisions. On
the other hand, the performance verification method is optional. Therefore,
within this framework, it has become
possible for designers to introduce various design methods based on their own
judgement.

• Position of TSCPHF2018

The TSCPHF2018 is a technical document (2,218 pages in total) supervisedby the Ports and Harbours Bureau of the
Ministry of Land, Infrastructure, Transport and Tourism. An outline of its contents is shown in Table 1.
In the TSCPHF2018, provisions of
the TS, “interpretation” and “commentary” are published. The “interpreta-

Fig. 1 Legal Framework for Technical Standards for Port and Harbour Facilities in JapanPort and Harbour Act(Article 56-2-2)
Technical Standards for Port and Harbour
Facilities(Article 56-2-21)
Issuing Recommendations to Bodies
Managing Specified Port Infrastructure
subject to Technical Standards(Article 2-5)
Definitions: Port Infrastructure

Cabinet Order of Port andHarbour Act(Article 19)
Facilities subject to Technical Standards

Ministerial Ordinance of Port andHarbour Act(Article 28)
Stipulation of Facilities Excluded from Coverage(Article 28-22)
Specified Facilities subject to Technical Standards

Technical Standards for Port and Harbour Facilities in Japan

Ministerial ordinance to prescribe Technical Standards establishing
Technical Standards for Port and Harbour Facilities

The Public Notice to set forth the details necessary for Technical Standards
The Public Notice to set forth the details necessary for construction of the facilities
subject to Technical Standards

The Public Notice to set forth the details necessary for maintenance of the facilities
subject to Technical Standards
Design methods designated by the proviso stated in the Article 56-2-2 (3) of the Port and Harbour Act

1 Steel Construction Today & Tomorrow August 2019

Table 1 Outline of Contents of Technical Standards and Commentaries
for Port and Harbour Facilities in Japan (Revised in 2018)
Part I General
Chapter 1 General Rules
Chapter 2 Construction, Improvement, orMaintenance of Facilities Subject to
the Technical Standards
Chapter 3 Environmental Considerations on
Facilities Subject to the TechnicalStandards

Chapter 3 Waterways and Basins
Chapter 4 Protective Facilities for Harbours
Chapter 5 Mooring Facilities
Chapter 6 Port Transportation Facilities
Chapter 7 Cargo Sorting Facilities
Chapter 8 Storage Facilities
Chapter 9 Facilities for Ship Service
Chapter 10 Other Port Facilities

Part II Actions and Material Strength
Requirements
Chapter 1 General
Chapter 2 Meteorology and Oceanography
Chapter 3 Geotechnical Conditions
Chapter 4 Earthquakes
Chapter 5 Earth Pressure and Water Pressure
Chapter 6 Ground Liquefaction
Chapter 7 Ground Subsidence
Chapter 8 Ships
Chapter 9 Environmental Actions
Chapter 10 Self Weight and Surcharge
Chapter 11 Materials

Part IV Reference Technical Information[For Part I]
Chapter 1 Major reference documents
Chapter 2 Reliability-Based Design
Chapter 3 Environmental Considerations[For Part II]
Chapter 1 Observations, Investigations and
Tests
Chapter 2 Investigations and Tests after Large
Earthquake with Tsunami Attack[For Part III]
Chapter 1 Basic Information on Seismic Design
Chapter 2 Dedicated Use Barthes
Chapter 3 Planning Method of Port Transportation Facilities
Chapter 4 Tables and Charts for Design Calculations

Part III Facilities
Chapter 1 General
Chapter 2 Items Common to Facilities Subject
to the Technical Standards• Publication of Japanese/

ed to refer to it. The English-version
TSCPHF2018 is scheduled for publication in spring 2020.
Outline of Key Revisions of
TSCPHF2018• Revision Content pertaining toStrengthening of International
CompetitivenessIn order to enhance marine transport efficiency, technical information for ship
dimensions was renewed so as to meet
trends toward the increasing size ofcontainer and cruising ships, and, corresponding to such a trend, a revision
was also made pertaining to auxiliary
equipment for mooring facilities suchas mooring posts and fender materials.
The revision allows for a response toship dimensions of container ships witha loading capacity of 20,000 TEUs or
more and cruising ships with 220,000
GT or more. Also, in order to determine the scale of mooring basins, descriptions were added so that ship track
analysis by means of automatic identification system (AIS) can be used as areference.
Further, the descriptions were added pertaining to measures for preventing crane overrun caused by wind andaccidents occurring during ship-mooring works. It is expected that these revisions will not only promote the acceptance of larger-size ships but also securesafety and improve efficiency of loading/unloading operations and contribute tostrengthening and securing international competitiveness of Japanese industry.
In addition, in the current revision, remote-control movable loading/unloading equipment was added to port facilities subject to the TS (Fig. 2). In the TS,‘performance requirement’ and ‘performance criteria’ are also added in order
to secure safe and efficient port/harbour
functions. The movable loading/unload-tion” denotes the practical concepts thatare considered appropriate at the stageof a practical application of the TS, andthe content to be strongly recommended
in application (content to be observed in
the case of governmental organizations)is covered. In addition, in the “commentary,” two items are publishedtechnical information that serves as areference at the stage of implementing
construction, improvement or maintenance of facilities subject to the TS, andexamples of design methods that areconsidered standard at that stage. However, it is possible for designers to adopt
other design methods based on theirown judgement because the “commentary” section is an optional item.

English-version TSCPHF
Table 2 shows recent publications of
the Japanese/English-version TSCPHF.
The first Japanese version was issued
in 1979, and since then a revised version was issued approximately every
10 years. The English version is issued
within two years after the publication ofeach Japanese version.
The English version has thus far
been used in designs of many overseas
port/harbour facilities constructed using Japan’s official development assistance (ODA). The latest English versionof TSCPHF is available to download
free from the publisher’s website2), andthus interested readers are recommend-

Table 2 History of TSCPHF (Japanese
Version and English Version)

Fig. 2 Image of Remote-control Operation of Movable Loading/
Unloading Machinery

Japanese version

English version

Issue year

Pages

Issue year

1979

692

1980

1989

968

1991

1999

1,181

2002

2007

1,485

2009

2018

2,218

2020 (planned)

August 2019 Steel Construction Today & Tomorrow 2

ing equipment mentioned here are rubber-tired gantry cranes (RTG), automated guided cargo vehicles (AGV) andstraddle carriers.

• Revision Content pertaining to

Maintenance and Countermeasures against Deterioration
Considering the situation of ongoing
deterioration of social infrastructure
constructed within the high economic
growth period, maintenance items forwhich due considerations are to be madeat design stage were well described,
such as the installation of inspection
holes and catwalks (Fig. 3) contributing to properly maintaining port facilities. Further, various measures were incorporated that prolong service life with
the introduction of structural materials
with high durability and performance.
Also, application of information andcommunication technology (ICT) andthree-dimensional data in a serial process from design and construction tomaintenance was promoted, and theFig. 3 Example of Design with
Consideration to Maintenance Stage (Inspection
Catwalk Applied in Jackettype Wharf)

Installationof inspection
catwalk fromthe design
stage so as
to allow foreasy maintenanceconcept of upgrade design for existing
facilities was enriched.

• Revision Content pertaining to

Design Methods
Considering that the working population is forecasted to decline in Japanand how to improve on-site productivity is an urgent issue, basic philocaly involved in productivity improvement was newly described in the
TSCPHF2018. In this regard, the reliability-based design method (partial
factor method) has been revised fromthe original method that was incorporated in TSCPHF2007, since the original method was too complicated for designers to apply in the practical designwork.
Specifically, revision has been madefrom the former ‘partial factor method
based on the material factor approach’
where each material or other individual design parameter is multiplied bya corresponding partial factor respectively, to a ‘partial factor method basedon load and resistance factor approach’
where each integrated value of various
loads or resistant capacities is multiplied by the corresponding load factor
or resistance factor respectively (Fig.
4). One notable advantage cited for theuse of a ‘partial factor design method
based on load and resistance factor approach’ is that designers can easily image the most likely behavior of structures up to the final stage of design. The
main aim of the current revision of thepartial factor method is to improve efficiency of design work and to create an

Fig. 4 Difference between Material Factor Approach and Load and Resistance
Factor Approach
Cohesive strength C

Weight W

Surcharge q

Shear resistance angle φenvironment that promotes further introduction of free ideas and new technologies. Please see the references3), 4)
for details in the revision on the load
and resistance factor design approach.
Meanwhile, in reliability analysis,Monte Carlo simulation (MCS) was applied instead of the conventional firstorder reliability method (FORM). Thiswas because the introduction of reliability analysis by means of MCS offers
many advantages: easy incorporation of
optional probability distributions, easy
response to diverse issues involved instrong nonlinearity and the possibility to create an environment in whichlevel 3 reliability-based design (RBD)
can easily be applied. These advantages will enhance for designers to apply
RBD more widely on a design of a new
structural type or an existing facility. In
other words, the reliability analysis using MCS has a great extensibility in the
future.
In the calculation of load and resistant factors, MCS results were also
applied. With MCS results, these factors can easily be calculated by using
the positioning relationship between
the characteristic value (the representative value of sum of resultant forces
and resistance capacities) and the design point (the point where collapse ismost likely to occur). These factors canbe calculated by dividing design point
coordinate by the characteristic value
coordinate (Fig. 5).

Fig. 5 Evaluation of Collapse
Probability, and Relation
between Design Point andCharacteristic Value Applied in
Settling Partial Factor

Former
TSCPHF (2009)

Partial factor method based on “material factor approach” where
each material or individual design parameter is multiplied by thecorresponding partial factor respectively

Shift to:Partial factor method based on “load and resistance factor approach”
where each integrated value of various loads or resistance capacities ismultiplied by the corresponding load factor or resistance factor respectively(Integrated resistance term calculated by intact design parameters (characteristic values))

Revised
TSCPHF (2018)

Loading value S (kN)

Failure sphere

Failure/Non-failureboundary line

Design point

Characteristic value
Non-failure sphere(Integrated load term calculated by intact design parameter (characteristic values))

3 Steel Construction Today & Tomorrow August 2019

Resistance value R (kN)

to Disaster Prevention and
Mitigation
In order to prepare for large-scale disasters due to such as ‘Nankai Troughearthquake’ or ‘Tokyo epicentral
earthquake’ forecasted to occur in thenear future, descriptions about disaster prevention and mitigation measures to treat major earthquakes andtsunamis were added based on new
knowledge and lessons obtained fromthe Great East Japan Earthquake ofMarch 2011.
In the field of seismic design, abending strength of steel pipe piles
used for wharves was reexamined. As
a result, designs that take into accountrobustness or redundancy of steel pipe
piles can be made for the level 2 seismic ground motion (largest-class seismic ground motion). As the ratio ofthe diameter (D) to the wall thickness (t) of steel pipe piles increases,
their bending strength becomes smaller than full plastic moment obtainedby simple calculation. Further, as theaxial force ratio increases, the abovementioned trend becomes more apparent. To that end, the bending strength
performance of steel pipe piles, whichtakes into account these effects, wasintroduced in the TSCPHF2018.
With the above-mentioned method, designers can determine the proper combination of diameter and thickness of steel pipe pile that does notcause lowering of bending strength up
to a range of large curvature against
large-scale earthquake.
In tsunami-resistant design, it isnecessary to examine the persistent
breakwater structure. To meet such aneed, various new technical information was added, such as a method thatassesses tsunami wave force, a design
method for breakwater with installation of backfill (reinforcing embankment) in the rear, and a design methodthat takes into account the lowering of
bearing capacity due to tsunami flowing-in inside the mound of breakwater
foundations (Fig. 6). These descriptions will make it possible to promote
effective disaster prevention/mitigation measures and at the same time
will lead to securing safety and security in the hinterland of ports and harbours.

•Revision Content pertaining to

Facilities in Japan (Japanese version),
The Ports and Harbours Association ofJapan (PHAJ), 2018. (in Japanese)
2) Ports and Harbours Bureau, Ministryof Land, Infrastructure, Transport andTourism (MLIT): Technical Standards
and Commentaries for Port and Harbour Facilities in Japan (English version), The Overseas Coastal Area Development Institute of Japan (OCDI),
2009. (http://ocdi.or.jp/en/technical-sten)3) M. Takenobu, S. Nishioka, T. Sato and
M. Miyata: A basic study of the Level
1 reliability design method based onload and resistance factor approach,
TECHNICAL NOTE of National Institute for Land and Infrastructure Management, No. 880, 2015.(in Japanese)(http://www.nilim.go.jp/lab/bcg/siryou/tnn/tnn0880pdf/ks0880.pdf)
4) M. Takenobu, M. Miyata, Y. Otake, T.
Sato. A basic study on the application of
LRFD in “the technical standard for port
and harbour facilities in Japan”: a case ofgravity type quay wall in a persistent design situation. Georisk: Assessment andManagement of Risk for Engineered Systems and Geohazards (2019): 1-10.

Environmental Considerations
Aiming at attaining sustainable development of ports and harbours and restoration and preservation of natural environments, new technical information
was added, such as practical examplesof living creature symbiosis-type structures (port facilities that possess not only basic functions for port structures but
also living functions for creatures inhabiting in tidal flats and shore reefs, refer to Fig. 7); nature restoration technologies for tidal flats; shoals and seaweed
forests; and eco-friendly application ofrecycled materials.
The main purpose targeted by theserevisions is not only to incorporate environmental considerations into every
function of ports and harbours but also to create affluent sea area environments and places of recreation and relaxation. ￭References
1) Ports and Harbours Bureau, Ministryof Land, Infrastructure, Transport andTourism (MLIT): Technical Standards
and Commentaries for Port and Harbour

Fig. 6 Image of Persistent Breakwater in Tsunami-resistant Design
Overtopping flow

Tsunamis having ascale larger thanthat of design
tsunamis

Devising of breakwater crest
Maintaining of stability
as high as possible=• Revision Content pertaining

Persistent structure
Seepageflow

Installation ofcovering block
Installation ofreinforcing
embankment

Rubblemound
Laying of scouring-prevention mat

Fig. 7 Examples of Structural Types of Living Creature Symbiosis-type
Port and Harbour Structures
High tidal zone
Medium tidal zone
Low tidal zone(a) Coating type

Livingcreature
floor(b) Pier type(c) Caisson type

August 2019 Steel Construction Today & Tomorrow 4

Latest Technological Trends in Port and Harbor Structures (2)Infrastructure Maintenance, Renovationand Management-Research and Development of Government Programs in Japanby Yozo Fujino
Distinguished YNU Professor
Yokohama National University

Yozo Fujino: After receiving the Ph. D from the University of Waterloo, Canada, he became Assoc. Professor in 1982 and Professor in 1990 of the Faculty of Engineering, the University of Tokyo.
He assumed his current position as Distinguished YNU Professorof the Institute of Advanced Science, Yokohama National University in 2014. He received the Japan Academy Prize in 2019. Heserves as the Program Director of the Cross-Ministerial Strategic
Innovation Promotion Program (SIP) of the Cabinet Office.

Introduction
The Cross-Ministerial Strategic Innovation Promotion Program (SIP), in which
the Council for Science, Technology andInnovation (CSTI) plays the role of playmaker, has been established to realize
scientific technology innovations (Fig.
1). As a cross-ministerial and cross-field
program, SIP will drive forward withthe focus ranging from basic research tocommercialization/industrialization.
“Infrastructure maintenance, renovation and management” (hereinafter referred to as “SIP infrastructure”) is oneof the issues currently under the focus of
the programs. Civil infrastructures, suchas roads, railways, harbors and airports,
support our everyday life and social economic activities. Many of them, however, were built during the high economic growth period. As they get older, theincrease in maintenance and repair expenditures, along with the possibility ofa serious accident occurring during theservice, become serious social issues.
This program aims at preventing accidents and reducing the burden of maintenance by constructing a systematic infrastructure management that utilizes themost advanced information and robotics
technologies.
Unlike mass-produced products, suchas vehicles and laptop computers, infrastructures are single products that are designed, constructed, and manufactured
individually. Initial conditions of infrastructures vary depending on the timeand condition they were built. As a result, in addition to the difference in usage
environment, the speed of infrastructure
deterioration also varies. Some infrastructures that have been used for several tens of years may pose a higher risk ofaccident due to damage. To allow for aneffective and efficient preventive main-

tenance manageInnovative manufacturing design
Combustion
ment of infraInnovative agriculture
structures and toPower electronics
establish a safe
and secure infra- New materials
structure system,
it is therefore
Fig. 1 Council for Science,crucial to haveTechnology
and Innovation
technologies thatcan precisely diResilience
Prof Masayoshi
agnose and takeNakashima
appropriate meaEnergy carrier
Infrastructure maintenance,
renovation and management
sures by closely
Prof Yozo Fujino
examining large
Ocean natural resources
Automatic driving
number of infrastructures individually on-site. It is also essential to mated to be over 800 trillion yen. Inframinimize the hazards and risks associ- structures should function for several deated with manual handling in the work- cades. Our responsibility to the future isplace.
to create an infrastructure information
For infrastructure management run platform and to pass on the infrastrucby local governments, cost reduction is tures that can be used safely with a minalso a particularly important viewpoint. imum maintenance burden to the next
Currently, infrastructures are being con- generation. The objective of “SIP infrastructed across Asia; however, mainte- structure” is to establish the system andnance has already become a big issue. we will work hard to achieve it. (Fig. 2)“SIP infrastructure” aims at introducing
new exciting advanced technologies in- Outline
to the range of infrastructure manage- In Japan, amid the aging of infrastrucment technologies. Specific examples tures, emerging risk of a serious acciinclude the following: support from or dent such as the Sasago tunnel accident
replacement with robots for infrastruc- in 2012 and the increase in maintenanceture inspection; on-site damage detec- and repair expenditures are topics oftion inside concrete members; inspec- concern. Systematic infrastructure mantion of tunnels and bridges by mobile agement utilizing new technologies issensors that do not require traffic con- essential both for preventing accidents
trol; technologies to aerially detect dam- based on preventive maintenance sysage/deformation of river levees, dams, tem and minimizing life cycle cost of inand harbors; highly accurate deteriora- frastructures under the conditions of thetion estimation technology for concrete; tight financial grounds and the decreasdeveloping ultra-high durable repair ma- ing number of skilled engineers. Parterials; efficient infrastructure manage- ticularly, technologies that utilize thement technology using big data process- world’s most advanced ICRT are exing; and artificial intelligence.
pected to create new business opportuniJapan’s infrastructure stock is esti- ties in the existing infrastructure mainte-

5 Steel Construction Today & Tomorrow August 2019nance market and Fig. 2 SIP Research and Development for Infrastructure Maintenance, Renovation, andManagement Technologies
to offer businessexpansion oppor(1) Inspection, Monitoring(2) Structural Materials, Deterioration
tunities into Asianand Diagnostics Technologies
Mechanisms, Repairs, and Reinforcement Technologies
countries that face
X-rays, Neutron beam, Lasers, Microwaves, Near-Infrared
Establishing a structural material research center, maintenance
Spectroscopy, Electromagnetics, Acoustics, etc.
similar problems
technologies, luminescent materials, new thermal spray materials,
Public Works Research Institute, National Institute for Land Infrastructure Management,ultra-durable concrete
To achieve this,PDCEN, Japan, AIST, Tsukuba Technology, Alcoetta Technology, Pacific Consultants,
NIMS, AIST, Osaka Prefecture University, Okayama University
Shutoko Engineering, Okayama University, Gifu University,
we will improve
Tokyo University of Agriculture and Technology
the standard of(5) Asset Management Technologies
maintenance byInfrastructure
Regional Governments
Private Technology Development
Roads, railways, harbors, airports,
using low - cost
Implementation of road infrastructure management cycles inContracts, Bids
irrigation facilities, water supply
Japan and overseas; mechanisms for concrete bridge deterioration;
preventive mainteCooperation with Regional Universities(underground structures),asset management for irrigation facilities and harbor structures
Overseas Expansion
river embankment,
nance while stressembankment slopes, dams
University of Tokyo, Kyoto University, Tokyo Institute of Technology,
Kanazawa University, NARO, PARI
ing the necessity
to match the needs(4) Robotics Technologies
of infrastructure(3) Information and Communications Technologies
Adjustable girders, flexible guide frame, flight robotics,
maintenance withRoad
and bridge screening technologies, freeway sensing datasemi-submerged unmanned construction
processing, storage, analysis technologies, optimization of
the seeds of techShibaura Institute of Technology, Tohoku University, Waseda University,
wireless communications
Meijo University, Kyoto University, Association of Unmanned Construction Technology,
nical development,
National Institute of Informatics, NEXCO East Japan,
HiBot, NEC, Fujitsu, Public Works Research Institute, Ministry of Land,
NTT, JIP Techno Science, Hitachi
Infrastructure, Transport and Tourism
and developing
new technologies *Infrastructure Operations and Management Overview (participating organizations as of November 13, 2014
into more attractive technologies
that can be used on-site. By achieving screening is a natural choice. In SIP-in- can only detect surface defects. In thisthis, we aim at contributing to regional frastructure, various types of unmanned study, we developed a magnetoresistancerevitalization, as well as maintaining the aerial vehicle (UAV) including drones (MR) sensor based on two types of NDTimportant internal infrastructures to high are being developed for inspection of instruments that can detect not only surstandard while backing up a variety of re- bridges and tunnels (Fig.３).
face defects but also inner defects.
gional economic activities. Furthermore,
One of the advantages of use of UAV is
To detect the thinning depth caused by
we will create an attractive and ongoing to capture the surface conditions of bridge corrosion of thick steel plate, extrememaintenance market and build a base for components such as RC bridge decks by ly low-frequency eddy current testingoverseas expansion based on successful video and/or camera and can be stored in (ELECT) with an applied magnetic fieldregional examples.
digital data. Automatized process to iden- ranging from 1 Hz to 1 kHz was develtify cracks in concrete surface from the oped. The steel thickness was estimated
UAV for Bridge Inspection:
photos is also being developed.
by analysis of the magnetic spectroscoDrones and Others
py, which was traced using the obtained
After the Sasago tunnel accident, visual Ultrasensitive Magnetic Nondemulti-frequency magnetic vector signals
and hands-on inspection of bridges, tun- structive Testing for Evaluation of as shown in Fig. 4. As a result, steel platenels and other facilities in highways and Steel Infrastructure
thinner than 20 mm could be measured
roads became mandatory. The interval is Professor Tsukada’s team is developing a within 0.1 mm resolution. Moreover, the5 years and hammering is to be done if nondestructive testing (NDT) method us- shape of the back-side corrosion was denecessary.
ing highly-sensitive magnetic measure- termined by scanning with a magnetic
Hands-on bridge inspection of bridge ments for evaluation of steel infrastruc- probe. Compared with ultrasonic testing,from the back side and high piers needs ture such as bridges. To ensure the safety ELECT has the advantage of noncontact,
special equipment and hence can be very of infrastructure, simple and accurate in- which enables detection even on rough,expensive. It is also labor consuming. spection methods are essential. Conven- corroded or coated surfaces. ￭To overcome these problems, applying tional magnetic testing techniques are
UAV to bridge inspection, at least to its simple and inexpensive; however, theyFig. 3 Drones Being Developed in SIP for Inspection of
Bridge Girders and Piers

Fig. 4 Bridge Corrosion Investigation Using ELECT

August 2019 Steel Construction Today & Tomorrow 6

Feature Articles: Latest Technological Trends in Port and Harbor Structures (3)Development of Life-cycle Management
System for Port and Harbor Facilities:
Integrated Framework from Inspection toAssessment-SIP Infrastructure Maintenance, Renovation andManagementby Ema Kato
Port and Airport Research Institute

SIP (Cross-ministerial Strategic
Innovation Promotion Program)and LCM System for Port andHarbor Facilities
In order to realize the strategic maintenance of port and harbor facilities,
the author is proceeding with examinations that aim at establishing thelife-cycle management (LCM) system
for the facilities shown in Fig. 1 andimproving the elemental technologies
involved in it. The LCM system has
two major purposes: the sure implementation of collaborative work between respective stages of planning,
design, construction, maintenance,

Ema Kato: After graduating from the School of Engineering of the Tokyo Instituteof Technology in 1997 and receiving the degree of Ph. D from the University ofTokyo in 2002, she entered the Port and Airport Research Institute (PARI). She
served as chief researcher at PARI’s Life Cycle Management Research Center in2007 and assumed her current position as group leader at PARI’s Structural Engineering Department in 2013. Her specialization is concrete engineering.

demolition and renewal of port andharbor facilities; and the enhancementof elementary technologies such as forinspection, diagnosis, prediction, assessment and countermeasure in thestage of maintenance of port and harbor facilities.
The author engaged in promoting a
research project in FY2014~2018 titled “Development of Life-cycle Management System for Port and Harbor
Facilities: Integrated Framework from
Inspection to Assessment” to examine
the inspection and diagnosis technologies and the asset management approach targeted for piers. Of the re-Fig. 1 Life-Cycle Management System for Port and Harbor Facilities1)
Plan
Design• Conceptual design• Service life determination• Performance verification

LCM

scenario
Execution
Maintenance• Functional obsolescence• Service life and future use• Performance assessment• Prediction

Scenario
updateDemolition/Re-use
Intervention

7 Steel Construction Today & Tomorrow August 2019

Recordsults obtained in this research project,
two technologies were introduced asfollows-a PTC Sensor, a monitoring
sensor that is targeted at petrolatumlining corrosion protection applied in
port and harbor steel structures, andSAMSWING, an inspection systemthat makes the remote monitoring of
sensors possible.
PTC Sensor (Nakabohtec Corrosion Protecting Co., Ltd.)The inspection and diagnosis for the
petrolatum lining corrosion protection
is still depending on the visual observations of protective cover and materials for fixing the protective cover tothe steel substructure. When the deformation is observed on those parts,
the steel surface is directly observed
after partially removing the corrosion
protection.
In this study, an approach has been developed that quantitatively assesses theperformance of petrolatum-lining corrosion protection employing a PTC Sensor. Moreover, the maintenance threshold (cumulative current) was proposed tojudge the deterioration of corrosion-protection performance. (Refer to Fig. 2)
SAMSWING (TOA CORPORATION)SAMSWING (sensor-aided maintenancesystem with information technology) is amaintenance system that opens the sensor data to the user (port and harbor construction and administration organs, professional engineers) on a website. It wasdeveloped by TOA CORPORATION in
2004. SAMSWING has two features interms of performance: a performanceFig. 2 PTC Sensor and Petrolatum Lining System
t

145

1.0

FRP cover

Steel pipe pile

100

Petrolatum material
10

Formed PE sheet［mm］
20
PTC sensor

Installation of PTC Sensor on
steel pipe pilethat automatically sends warnings to theuser when some abnormalities are detected by the sensors installed in the target structures, and a performance thatindicates some comments on the judgements against the abnormalities and thecountermeasure to be taken based on theprofessional engineers.
In this study, the existing SAMSWING system has been improved tomake it possible to apply to the following four kinds of sensors; one is a sensor
that assesses the durability of reinforced
concrete, two kinds of sensors that confirm the corrosion-protection conditionof steel pipe piles (one of two sensors is
the PTC Sensor mentioned above), andthe other one is an environment measurement sensor (temperature, humidity, wave height and velocity etc.). (Refer to Fig. 3)
Promotion of Improved Inspection
Technologies
In order to diffuse and firmly establish

these improved inspection technologies, it is essential to consolidate a basis that introduces these technologies
while at the same time taking into account the features of prevailing maintenance systems for port and harbor
facilities. To that end, we are striving
to reflect these inspection technologies in the Guidelines for Inspection
and Diagnosis of Port Facilities (partially revised in June 2018), the Maintenance Manual for Port Facilities(supervised in July 2018) and othermaintenance guidelines published andsupervised by the Ports and Harbours
Bureau of the Ministry of Land, Infrastructure, Transport and Tourism. Additional endeavors being promoted are
to diffuse these developed technologies at the national training course andlecture meeting for the staff under the
Ministry’s direct control and for port/
harbor administrators.
Meanwhile, the maintenance guidelines mentioned above have been pre-pared by assuming their application in
port and harbor facilities in service inwider areas in Japan. They only indicate the standard maintenance plans
required for maintaining the performance of each facility and the technological standards pertaining to inspection, diagnosis and maintenancemeasures.
For the practical maintenance ofport and harbor facilities, it will benecessary that the maintenance plan isworked out to take into account the service plan, location conditions, structural materials applied and construction conditions peculiar to respective
facilities, and that the worked-out
plan is steadily implemented. In its
implementation, the less cost and labor the better. To attain these goals, it
is considered extremely important tosurely implement collaborative works
between the respective stages of planning, design, construction and maintenance of port and harbor facilities thatwill be built in the future. ￭Reference
1) Yokota, H., “Practical Application ofLife-Cycle Management System for
Shore Protection Facilities,” Structure and Infrastructure Engineering,Vol. 13, No. 1, pp. 34-43, 2017

Fig. 3 Outline of SAMSWINGInternet

Sensordata

Facility
administrator

Detection ofabnormality• Data confirmation• Advice

Facility
owner

Maintenanceprofessional engineer
Website system administrator

August 2019 Steel Construction Today & Tomorrow 8

Feature Articles: Latest Technological Trends in Port and Harbor Structures (4)Study of the Introduction of Steel Pipe
Piles to Pile Foundations in Southeast Asia

by Yoshiaki Kikuchi
Professor, Tokyo University of Science

Introduction
The concrete piles have been mainly used
for foundation piles in Southeast Asian
nations. However, when taking into account the easy availability of large-diameter, long-length piles, concerns about
the corrosion of concrete piles appliedin port and harbor areas and redundancy
for the bending of piles to be applied forpiers, it is expected that the applicationof steel pipe piles will increase in the future in Southeast Asian nations.
In this study, the main target was directed towards the following three areas:• Comparison of the estimation methods
for pile vertical bearing capacity thatare applied in Japan, the US and EU
nations. These methods are likely to
be applied in Southeast Asian nations;Examinationon the toe bearing capaci•ty mechanism of open-ended steel pipe
piles; andUnderstandingof design and construc•tion conditions in Southeast Asian nations pertaining to how pile bearing capacity is assessed
Study Content
Table 1 compares the representative static bearing capacity estimation equations
that are applied to estimate the axial-direction resistance of piles1), 2), 3). It is generally accepted that pile bearing resistance is examined by dividing it into
shaft resistance and pile toe resistanceand that the ground condition is examined by dividing it into sandy soil groundand cohesive soil ground. Accordingly,
under these conditions, an international comparison of pile bearing capacity
estimation methods can relatively easily be made. Among these conditions,the difference of estimation methods forpile toe resistance on sandy soil groundgreatly affects the estimation results forpile bearing capacity, which was therefore subjected to examination.
9 Steel Construction Today & Tomorrow August 2019

Yoshiaki Kikuchi: After finishing the master’s course at the
University of Tokyo in 1983, he entered the Ministry of Transport (currently Ministry of Land, Infrastructure, Transport andTourism: MLIT). Then, he worked at MLIT’s Port and Airport
Research Institute. He assumed his current position as Professor, Faculty of Science and Technology of the Tokyo University of Science in 2012. His specialization is geotechnicalengineering and geo-environmental engineering.

Table 1 International Comparison of Static Bearing Capacity Estimation
Equations for Steel Pipe Piles
Technical Standards andEurocode 7 US Army Corps
Commentaries for Port and(EC7)of Engineers
Harbor Facilities in Japan (JSPH)(USACE)Toe resistance
Nqsσ' v0300N
Nqσ' v0
qp (kN/m2)
Sandy soil
groundShaft resistanceKs σ' v0 tan δ
Ks σ' v0 tan δ2N
qs (kN/m2)
Toe resistance
9cu + σ' v0
9cu
6cu
qp (kN/m2)
Cohesivesoil ground Shaft resistance
cu
αcu
αcu
qs (kN/m2)
Notes
N: SPT-N value; cu: shear strength of the ground; Nq: bearing capacity coefficient; σ'v0: effective
over burden pressure; Ks: earth pressure coefficient; α: adhesion factor; δ: shaft friction angle
between pile and ground

While the estimation methods for pile
toe resistance on sandy soil ground in the
US (USACE: US Army Corps of Engineers) and EU nations (EC7: Eurocode7) are theoretical methods, it can be said
that the method in Japan (JSPH: Technical Standards and Commentaries forPort and Harbor Facilities in Japan) is
an empirical method. However, as canbe seen in Fig. 1, the difference between
the bearing capacity coefficients appliedin the US and EU nations reaches about
double at higher internal friction angles,
and thus it cannot currently be said thatthese theoretical methods do not always
excel to others.
Regarding pile toe bearing capacity
estimation methods, the method based on
cavity expansion theory is also known,
and the following equation is proposedby Yasufuku4).

Fig. 2 shows the comparison offour estimated values of pile toe bearing capacity on sandy soil ground, obtained by using the equation specified
in JSPH, USACE and EC7 and basedon cavity expansion theory. In this figure, while the internal friction angle isrequired to obtain the bearing capacity coefficient, the value was estimated by using the Japanese method (theJSPH’s method to estimate the shear resistance angle using the N value). According to the comparison results, theEC7 has a tendency to excessively assess the bearing capacity, and the JSPH
has a tendency in which the change ofbearing capacity to a depth direction
cannot be indicated.
Further, Fig. 3 shows the comparison
between measured and calculated valuesof pile toe resistance. It can be under-

Where, K0: coefficient of earth pressure at rest (=0.5); and G: shear rigidity(G=7000 N0.72, N: SPT-value). Further, the shear resistance angle φ’cv is to be
at a level from 28°to 32°.

Fig. 1 Comparison of Bearing Capacity
Coefficients between Eurocode 7
and US Army Corps of Engineers

200

0
0

180

10

160

120
100

USACE-U

30

EC7

40

80

10000

20000

30000

40000

SPT-N=50
γ'=7 kN/m2

50

40

70

20

80

0
20

90

30

35

40

Internal friction angle (degree)

JSPH

60

60

25

Unit bearing capacity q (kN/m2)

20

USACE-L

140

Depth (m)Coefficient of bearing capacity Nq(Both upper limit value USACE-U andlower limit value USACE-L are specified
in US Army Corps of Engineers)

Fig. 2 Comparison of Estimation
Results for Pile Toe Bearing
Capacity in the Case of N Valueof Ground=50

45

USACE-L

USACE-U
EC7

Cavityexpansion
theory100

Fig. 3 Comparison between Measured Pile Toe Resistance andCalculated Pile Toe Resistance0

Pile toe resistance per unit area (kN/m2)
05,000 10,000 15,000 20,000 25,000 30,0000Calculated value (EC7)Calculated value (cavity expansion theory)
Calculated value (JSPH)
Measure value (pile toe)

-10

-20

-20

-30

-30

Embedded depth (m)Embedded depth (m)-10Pile toe resistance per unit area (kN/m2)
0

-40
-50
-60

In this equation, the most criticalproblem is that the value of μKh is unknown. Then, it was decided to obtainthe value by experiment. The experiment
was undertaken by penetrating piles
with an outside diameter of 50 mm andwall thicknesses of 2, 3 and 4 mm into
dry sandy soil ground (relative density
Dr=80%).
As a result of this experiment, theμKh inside the pile in the case of penetrating by 100 mm was estimated asshown in Fig. 5. It was learned from theexperimental results that μKh has twotendencies: the nearer to the pile toe, thelarger the μKh becomes, and the highFig. 4 Pile Toe Resistance ofOpen-ended Piles

-50
-60
-70

-80

-80

(a) Pile diameter: 1,000 mm or lower

Calculated value (EC7)Calculated value (cavity expansion theory)
Calculated value (JSPH)
Measure value (pile toe)

Where, Rfl,z: total value of pile internalskin resistance; Ain: sectional area of pileinternal cross section; Din: pile inside diameter; γt: unit volume weight of soil
inside the pile; μ: friction coefficient ofwall surface; and Kh: earth pressure coefficient inside the pile.

-40

-70

-90

5,000 10,000 15,000 20,000 25,000 30,000

pressed in the following equation.

-90

RfI

Rp

(b) Pile diameter: More than 1,000 mm

Ropen=Rp+RfI
resistance of open-ended piles like thesteel pipe piles. The open-ended pile toe
resistance Ropen will be demonstrated by
the total of the toe resistance Rp of thesubstantial pile section and the frictional force Rfl between the pile internal skinand the soil inside the pile (Fig. 4). In
this case, how to appropriately assess Rfl
become the most important task. When
Yamahara’s assumption5), 6) is applied,the vertical earth pressure σv inside thepile in the section apart by x to the axial direction from the pile toe at the stage
where the pile is embedded up to z is ex-

Fig. 5 Estimated μKh along Pile Axial
Direction (z=100 mm)
Distance from pile toe x (mm)stood from Fig. 3(a) that the EC7 has atendency towards excessive assessment
and that the JSPH or cavity expansion
theory serves as a comparatively appropriate estimation method. However, as
shown in Fig. 3(b), when the pile diameter surpasses 1,000 mm, the measured
value becomes considerably smaller thanthe calculated value, and the effect ofpartial soil plugging inside the pipe pile
becomes apparent.
From these comparison results, it becomes necessary to examine a more rational method that estimates the pile toe

125

Dr =80%, D=50 mm, z=100 mm

100

t=2 mm
t=3 mm
t=4 mm

75
50
25
0

0

2

4

µKh

6

8

10

August 2019 Steel Construction Today & Tomorrow 10

er up from the pile toe, the smaller theμKh becomes. It was also learned thatthe μKh does not change even when thewall thickness changes. In addition, because the friction coefficient μ takes avalue of around 0.5, it was learned that
Kh in the vicinity of pile toe takes thevalue of around 7~10. In the future, experiments will be made by changing thepile diameter and the ground density to
examine how these changes will affect
the Kh.
Surveys were made of eight pipe pilefoundation projects in six countries undertaken in Southeast Asian nations.
The port and harbor facilities completed
in these eight projects are all piers. The
standards applied to calculate the pile
bearing capacity were three from British Standards, two each from API Specifications and Technical Standards ofJapan (JSPH), and one from the US Army Corps of Engineers. The reason why
the number of standards does not coincide with the number of projects is thatboth JSPH and the British Standards
were applied in one project.
Table 2 shows the ground conditions and loading tests applied. In alleight projects, plural dynamic loading
tests were implemented. Further, static or rapid loading tests were also implemented in most of the projects. In
light of the ground conditions, it seems
that whether the ground conditions weregood or bad was not necessarily a determining factor for whether or not loading tests were to be implemented. Regarding the static loading tests, it seems
that they were implemented, as a rule,in accordance with a policy of confirming the provision of a bearing capacity
twice the working load. There was only
one project in which the design was revised as a result of these loading tests.
In principle, it seems that the loading
tests were applied to confirm the appropriateness of the design.

In addition, a loading test was applied for pile driving depth control. For
pile driving depth control, while the Hiley formula is applied, the formulae isrevised by every piling site as follows:
At the time of piling start, both the static (rapid) and the dynamic loading tests
are implemented, and the test results arecorrelated with the Hiley formula to revise the pile driving depth control formula. Then, the dynamic loading tests
are applied usually to 20% of the total
piles driven, and piling work is undertaken while at the same time confirming
whether or not the prescribed bearing
capacity is secured. This piling work
system is commonly implemented inmost nations.
When large-diameter steel pipe piles
will be applied in the future, it is considered that the soil plugging level inside open-ended pipe piles will cometo largely affect the estimation of pile
bearing capacity. Therefore, it will benecessary to propose a method that canappropriately estimate the bearing capacity of open-ended piles so that steel
pipe piles will become easy to apply
even in Southeast Asian nations.

count, the bearing capacity cannot appropriately be assessed.
• Due to the above, when examining thebearing capacity of open-ended piles,
it is necessary to examine the mechanism that manifests the pile internalskin friction force. In its examinationin this study, the concept by Yamahara was applied. However, in the case offollowing this concept, it has become
clear that consideration should be madeto the fact that the earth pressure coefficient inside the pile changes along to
the pile axial direction. In this regard,
future examination will be required.
• As a result of surveys of steel pipe pileapplication examples in Southeast Asian
nations, it was learned that the design
standards of the EU, the US and Japan
were applied. Further, it became clearthat the combined use of various loading tests was made to confirm the design and to implement piling work control. In order to promote the applicationof steel pipe piles in Southeast Asian nations, it is considered important to supply a method that allows the highly precise estimation of bearing capacity evenof large-diameter steel pipe piles. ￭Conclusions
The conclusions obtained from this study
are summarized as follows:• When applying steel pipe piles with diameters of 1,000 mm or lower, whileboth the Japanese method (JSPH) andthe cavity expansion theory can be said
to be the appropriate method that estimates the pile toe bearing capacity even
without consideration to the soil plugging level of the pile end, the method
prescribed in the Eurocode 7 has a tendency where the pile toe bearing capacity is excessively assessed. On the other
hand, in applying large-diameter steel
pipe piles with diameters of 1,000 mm
or more, when the soil plugging level of the pile end is not taken into ac-

References:
1) Ports and Harbors Bureau, Ministryof Land, Infrastructure, Transport andTourism: Technical Standards and Commentaries for Port and Harbor Facilities in Japan.
2) Orr, T. L. L. and Farrell, E. R.: Geotechnical Design to Eurocode 7, p.113,
1999.
3) US Army Corps of Engineers: Designof Pile Foundations, p.20, 1993.
4) Yasufuku, N., Ochiai, H. and Ohno,
S.: Pile End-bearing Capacity of Sand
Related to Soil Compressibility, Soils
and Foundations, Vol.41, No.4, pp.5971, 2001.
5) Yamahara, H: Plugging Effect of SteelPipe Piles and Bearing Capacity Mechanism (1), Transactions of the Architectural Institute of Japan, No. 96, pp.
28-35, 1964
6) Yamahara, H: Plugging Effect of SteelPipe Piles and Bearing Capacity Mechanism (2), Transactions of the Architectural Institute of Japan, No. 97, pp.
34-41, 1964

Table 2 Ground Conditions and Loading Tests Applied
Project
numberStatic loading
test◯

Loading tests applied
Rapid loading
test

1
2
3
◯
◯
◯
4
◯
◯
5
◯
6
◯
7
◯
8
◯
Note: ◎: Plural tests, ◯: Singular test

11 Steel Construction Today & Tomorrow August 2019

Dynamic
loading test
◯
◯
◯
◯
◯
◯
◯
◯
◯
◯
◯
◯
◯
◯
◯
◯

Ground condition
Solid cohesive soil
Good
Bad
Cohesive soil
Soft
Sandy soil
Sandy soil
Hard cohesive soil/Soft rockFeature Articles: Latest Technological Trends in Port and Harbor Structures (5)Assessment of Long-term Durabilityof Various Metallic Construction
Materials by Means of Exposure Tests at
Okinotorishima and Suruga Bay

by Tomonori Tomiyama
Public Works Research Institute

Okinotorishima, an atoll located in thesouthernmost tip of Japan, is located in thetropical zone, where not only temperature,humidity and sunshine radiation but also
tidal currents and wave heights are high.
Further it is constantly subjected to seawater splashing. In this way, the corrosive environment there is far stricter than the sea
area of the Japan mainland. In order to develop a corrosion-protection technology
targeting offshore steel structures and toassess their long-term durability, the Public Works Research Institute and the Japan
Iron and Steel Federation jointly conducted offshore atmospheric exposure tests formetallic construction materials over 19.5
years at Okinotorishima (Fig. 1).
In parallel with this, in order to understand the long-term durability of thesematerials in a sea area in the vicinity ofthe mainland, they also conducted offshore atmospheric exposure tests over 24
years at the Marine Engineering Research
Facility in Suruga Bay (Fig. 1), installed
250 m off the coast of Yaizu, Shizuoka
Pref. In this article, the exposure test results between two different corrosive environments are compared and studied.
Exposure Test Methods
At both test sites, a total of 28 kinds ofmaterials in groups A~D were exposed(Table 1). Plate-shaped test specimens
with sizes of 210×30~75 mm and thicknesses of 1.2~9 mm were prepared. The
test specimens were exposed at an angleof 5° (60°) using exposure racks oriented to face south with a height of 15 m (13m) from sea level (the values in brackets show those at Suruga Bay). Table 2
shows the major environmental conditions at both test sites, and Table 3 shows
the survey items by material.

Tomonori Tomiyama: After receiving Dr. Eng. from the Tokyo
Institute of Technology, he entered the Public Works ResearchInstitute (PWRI) in 2003 and served as Senior Researcher at
PWRI‘s Advanced Materials Research Team in 2007. He assumed his current position as Senior Researcher at PWRI‘sMaterials and Resources Research Group in 2015. His main
research fields cover durability of polymeric materials and anticorrosion engineering for steel structures.

Exposure Test Results and Studies• Ordinary Carbon Steel (Group A)
After exposure tests, while pitting corrosion was found on the surface of many specimens at Okinotorishima, nearlyno pitting corrosion was found at Suruga
Bay. Further, when calculating the corrosion rate using the corrosion loss after
exposure, while the rate at Okinotorishima was 0.18 mm/a, that at Suruga Bay

Table 1 A List of Test Specimens Used for Exposure Tests

Group
Type of materials
A: Ordinary carbon steel
Ordinary carbon steel (SS400)
B: Stainless steel
18Cr-8Ni (SUS304)
17Cr-12Ni-2.5Mo (SUS316L)
19Cr-13Ni-3.5Mo (SUS317L)
18Cr-13Ni-3Mo-0.15N
20Cr-25Ni-5Mo-Ti
Austenitic type20Cr-17Ni-4.5Mo-N-L.C
20Cr-18Ni-6Mo-0.7Cu-0.2N (SUS312L)
25Cr-13Ni-0.9Mo-0.3N (SUS317J2)
25Cr-22Ni-4.5Mo-0.2N
22Cr-23Ni-5Mo-1.5Cu-0.2N
25Cr-6Ni-3.5Mo-0.2N (SUS329J4L)
Dual-phase type25Cr-7Ni-3.5Mo-0.5Cu-0.16N (SUS329J4L)
19Cr-2Mo-Ti-Nb-Zr (SUS444)
Ferritic type26Cr-4Mo
C: Nonferrous metal
Titanium
Titanium [JIS H 4600 TP35H(KS50)]
CopperCopper [C-1220]
Aluminum alloy
Aluminum alloy [5083]
D: Coated/lined steel plate
Aluminized stainless steel plateHot-dip galvanized steel plate
Metallic coating
Zinc-aluminum alloy-sprayed steel plate
Aluminum-sprayed steel plate
Polyethylene-lined steel plate
Polyurethane-lined steel plate
Polymer lining
Ultra high build epoxy resin-lined steel plate(Epoxy resin/polyurethane resin)-coated steel plate
Heavy-duty(Epoxy/fluororesin)-coated steel plate
corrosionprotection coating(Epoxy resin/acrylic silicone resin)-coated steel plate

Specimen No.
A-01
B-01
B-02
B-03
B-04
B-05
B-06
B-07
B-08
B-09
B-10
B-11
B-12
B-13
B-14
C-01
C-02
C-03
D-01
D-02
D-03
D-04
D-05
D-06
D-07
D-08
D-09
D-10

Table 2 Main Environmental Conditions at Exposure Test Sites(Implementation of Exposure Test: Marine Atmospheric Zone)

Annual average
Annual time of
Sunlight radiation index
Location Temp. Seawater Humidity
wetness(setting Suruga Bay as 1.0)
(ISO 9223)(°C) temp.(°C)(%)
Okino20°25’N28*73*4476 hrs
1.3
torishima 136°5’E 27.2*
Suruga34°47’N21**
67**1392 hrs
1.0
Bay
138°19’E 16.6**
Note: Data *JAMSTEC (2001) ** Japan Meteorological Agency (2001)
Exposure
test site

August 2019 Steel Construction Today & Tomorrow 12

Table 3 Major Survey Items at Exposure Tests
Survey item
Appearance observation
Mass loss
Local corrosion depthFilm thickness
Insulation resistance(volume resistivity)
Coating section
observation (SEM)

was 0.015 mm/a,
which means thatthe corrosion rate
at Okinotorishima
was about 12 times
that at Suruga Bay.

Ordinary
carbonsteel (A)◯◯◯Stainlesssteel (B)◯◯◯

Nonferrous
metal (C)◯◯◯Coated/lined steel plate (D)Metallic Polymer Heavy-duty
coating
coatinglining
◯
◯
◯
◯
◯

◯

◯

◯

◯

◯

◯

◯

Fig. 1 Overview of Exposure Test Sites• Stainless Steel(Group B)
Okinotorishima
At the Suruga Bay,slight pitting corrosion occurred andcrevice corrosion
occurred at the gap
Marine Engineering
between the insu- Research Facility
lation washer and in Suruga Bay
the specimen forthe specimens ex"GSI Maps"
cluding B-07, both Source:( Geospatial Informationof which were not
Authority of Japan)
assessed as notablecorrosion loss. Meanwhile, at Okinotori- rosion depth or maximum crevice corroshima, slight pitting corrosion and crev- sion depth and the PREN (Figs. 2 and 3).
ice corrosion occurred for every type ofIn the arrangement results at Suruga
stainless steel material, which showed Bay, when the PREN was 30 or more,a trend of a corrosion depth higher than both the maximum pitting and crevice
that at Suruga Bay.
corrosion depths reached 100 μm or less.
The maximum pitting corrosion Meanwhile, at Okinotorishima, when thedepth at general sections of all speci- PREN was 30 or more, the maximum pitmens and their maximum crevice cor- ting corrosion depth at the general secrosion depth at the washer-specimen tion reached 100 μm or less in the same
gap were arranged using the pitting re- way as at Suruga Bay, but it was the casesistance equivalent number (PREN: with a PREN at 40 or more that the max[Cr(%)]+[3.3×Mo(%)]+[16×N(%)]), imum crevice corrosion depth reached
and it was learned from the arrangement 100 μm or less.
results that there was a loose correlaWhile the difference of maximum
tion between the maximum pitting cor- pitting corrosion depth between Suru-

Okinotorishima: Austenitic type

Okinotorishima: Dual-phase type
Okinotorishima: Ferritic type
Suruga Bay: Austenitic type

Suruga Bay: Dual-phase type
Suruga Bay: Ferritic type

13 Steel Construction Today & Tomorrow August 2019• Nonferrous Metal (Group C)

No corrosion including pitting corrosion
at the general section and crevice corrosion at the washer-specimen gap was observed for pure titanium (C-01) at either
test site. Regarding copper (C-02) andaluminum alloy (C-03), while a loss ofmass due to corrosion was not found, pitting corrosion at the general section andcrevice corrosion at the washer-specimen gap were observed. It was impossible to clearly understand a trend in the
differences in levels between pitting corrosion and crevice corrosion occurring
due to the differences in corrosion environments.

• Coated and Lined Steel Plates(Group D)-Metallic Coating
While the formation of corrosion products was observed on aluminized stainless steel plate (D-01) at both testingsites, the aluminum coating layer remained, and thus it is considered thatthe plate had a sound corrosion-protection performance even at the completionof the exposure tests (Fig. 4(a)). Meanwhile, while the coating layer of hot-dip
galvanized steel plate (D-02) remainedin the exposure test at Suruga Bay, itnearly disappeared in the test at Okinotorishima (Fig. 4(b)).
Regarding the zinc-aluminum alloysprayed steel plate (D-03) and the aluminum-sprayed plate (D-04), while theformation of corrosion products was observed, the sprayed layer remained, andthus it is considered that these two plates

Fig. 3 Relation between Maximum Crevice Corrosion
Depth at Washer-Specimen Gap and PREN
of Stainless Steel

Maximum crevice corrosion depth (μm)

Maximum pitting corrosion depth (μm)

Fig.2 Relation between Maximum Pitting Corrosion Depth
at General Section and PREN of Stainless Steelga Bay and Okinotorishima was slight,
the maximum crevice corrosion depth at
Okinotorishima was clearly higher thanthat at Suruga Bay. The reason for these
phenomena seems to be attributable toa higher average temperature, by 11°C,
and a longer wetting time at Okinotorishima than at the Suruga Bay.

Okinotorishima: Austenitic type

Okinotorishima: Dual-phase type
Okinotorishima: Ferritic type
Suruga Bay: Austenitic type

Suruga Bay: Dual-phase type
Suruga Bay: Ferritic type

Fig. 4 SEM Images of Sections of Metallic-coated Steel Plates

Stainlesssteel

Coating
Stainlesssteel

Coating film thickness
at section: 27 μm(Measured value bycoating thickness
gauge: 36 μm)

Coating film thickness at
section: 40 μm(Measured value by coating
thickness gauge: 57 μm)(a) Aluminized stainless steel plate

Spraying
Steel
plate

Spraying

× 1000

Average coating
loss rate=2 μm/a

Corrosion Coatproduct
ing
Steel
plate
Coating(incl.
corrosion
product)
Steel
plate

Coating film thickness at
section: 97 μm(Measured value bycoating thickness gauge:
153 μm; initial value: 88 μm)

Coating film thickness at
section: 57 μm(Measured value by coating
thickness gauge: 79 μm; initialvalue: 81 μm)

Okinotorishima(19 years)

Suruga Bay(24 years)(b) Hot-dip galvanized steel plate

Suruga Bay(24 years)
Corrosion
product

× 100

Okinotorishima(19 years)

Average coating
loss rate=4 μm/a

Corrosion
product

Steel
plate
Spraying film thickness
Spraying film thickness at
at section: 161 μm
section: 242 μm(Measured value by coating(Measured value by coating
thickness gauge: 179 μm; thickness gauge: 290 μm; initial
initial value: 173 μm)
value: 168 μm)

Spraying

× 100

× 1000Corrosion
product

Suruga Bay(24 years)

× 1000× 100

Coating

Okinotorishima(19 years)

× 100

Suruga Bay(24 years)

Steel
plate

Spraying

× 1000Okinotorishima(19 years)

Steel
plate
Spraying film thickness
Spraying film thickness at
at section: 290 μm
section: 194 μm(Measured value by coating(Measured value by coating
thickness gauge: 320 μm; thickness gauge: 256 μm; initial
initial value: 299 μm)
value: 220 μm)(c) Zinc-aluminum alloy-sprayed steel plate(d) Aluminum-sprayed steel plate

had a sound corrosion-protection performance even at the completion of the exposure tests (Fig. 4(c) and (d)). The film
thickness of the zinc-aluminum alloysprayed steel plate after exposure wasincreased from the thickness before exposure due to the formation of corrosion
products. The increased level at Suruga
Bay was higher than that at Okinotorishima. Similarly the film thickness of thealuminum-sprayed steel plate increased
due to exposure, but the difference of theincrease in film thickness between Suruga Bay and Okinotorishima was unclear.

-Polymer Lining and Heavyduty Coating
At both testing sites, the polyethylenelined steel plate (D-05) showed considerable peeling-off of lined polyethylene
from the plate edge due to possibly inferior quality of edge sealing materials, andthus the plate was excluded from the assessment target. In other polymer-lined/
coated steel plates (D6~D10), the lined/
coated layer remained on all the plates.
While the insulation resistance (volume resistivity) of the lined/coated layer lowered due to exposure, they showed

Initial value
Okinotorishima (19 years)
Suruga Bay (24 years)

D-06
Polyurethane
lining

D-07
D-08
D-09
Ultra high Epoxy+ Epoxy+build
UreFluoepoxy thane
roresinliningcoating coating

D-10
Epoxy+
Acrylic
siliconcoating

Useful Exposure Test Results
Offshore atmospheric exposure tests
were conducted at two site having different corrosive environments, and it
was indicated even from the test results
for the corrosion rate of ordinary carbon steel that the corrosive environment
at Okinotorishima is harsher than that at
Suruga Bay. Of the test results, regarding stainless steel, nonferrous metal andmetallic-coated material excluding galvanized material, there was no notabledifferences in corrosion deterioration attributable to the corrosive environment
and they showed
Fig. 6 Film Thickness Loss of Polymer Lining and Coating high corrosion re(Lower Table: Total Loss/Site)
sistance. Regardingorganic lining andheavy-duty corrosion-protection
1.5 times
coating, while it isconsidered fromthe value of insulaNo clear trend is observedtion resistance (volume resistivity) thatthe corrosion resistance is maintained,
D-06
D-07
D-08
D-09
D-10
PolyureUltra high Epoxy+
Epoxy+
Epoxy+
the fall of insulathanebuild epoxy Urethane Fluororesin Acrylic
liningliningcoating
coatingsilicontion resistance wascoatinglarger at OkinotoriOkinotorishima(after 19 years)
shima. ￭Annual film thickness loss (μm/a)

Volume resistivity rate (Ω.cm)

Fig. 5 Insulation Resistance(Volume Resistivity) of Polymer
Lining and Heavy-duty Coatinga high insulation resistance of 1010Ω/cm
or more-the value reported as no corrosion occurrence in the steel material under coating-at both testing sites and inevery type of steel materials, and thus it
is considered that they maintained corrosion-protection performance even at thecompletion of the exposure tests (Fig. 5).
Because the fall of insulation resistancedue to exposure at Okinotorishima waslarger than that at Suruga Bay, it is assumed that Okinotorishima is in a harsher environment that causes the deterioration of lined/coated layers.
It was the polyurethane-lined steel
plate that showed the highest value interms of annual average film loss (difference of film thickness before and after
exposure÷exposure year), and the loss at
Okinotorishima was 1.5 times that at Suruga Bay, which nearly coincided withthe ratio of sunlight irradiation of 1.3(Fig. 6). In other types of lined and coated steel plates, the loss at Okinotorishima was larger than that at Suruga Bay,but according to the test results, the film
loss only of epoxy resin/acrylic silicone
resin-coated steel plates was larger at Suruga Bay than that at Okinotorishima.

Suruga Bay(after 24 years)

August 2019 Steel Construction Today & Tomorrow 14

Sp ecial Topic

Proposals Conducive to“Building National Resilience”
Employing Steel Structures
The Japan Iron and Steel Federation
Triggered by the Great East Japan Earthquake of March 2011, the “Basic Act for National Resilience Contributing to Preventing
and Mitigating Disasters for Developing Resilience in the Lives of the Citizenry” was established in Japan in December 2013. Thenin June 2014, the Japanese cabinet approved
the “Fundamental Plan for National Resilience” in conformity with the Basic Act.
In order to keep up with these government
policies, the Japanese steel industry launched
the Committee on National Resilience in April
2014 within the Japan Iron and Steel Federation. Destined for regional development bureaus of the Ministry of Land, Infrastructure,
Transport and Tourism and local governments
as well, the committee has thus far promoted diverse activities to propose steel-structuretechnologies and methods conducive to preventing and mitigating natural disasters.
Because diverse natural disasters haveoccurred in succession in Japan, the government revised in the Fundamental Plan in December 2018 through the emergency inspection of important infrastructure carried out
in November 2018, and the Japanese cabinet approved the “Three-year Emergency
Measures for Disaster Prevention/Mitigation and Building National Resilience.” Inorder to accelerate the reinforcement of thefunctions of important infrastructure used
for disaster prevention nationwide, a sum of￥7 trillion (US$62.5 billion) will be intensively invested over the next three years under the Three-year Emergency Measures.
Aiming at contributing towards building national resilience through extensive applicationsof disaster-preventive steel-structure technologies and methods, the Committee on National Resilience has promoted diverse activitiescontinued proposal of these technologies andmethods for regional development bureaus andlocal governments, promotion of understanding of the high performance peculiar to steel
structures and grasping of emerging needs.
Further, based on knowledge newly obtained
from activities of various research committees and subsidy systems for steel-structure research and training of the Japan Iron and Steel
15 Steel Construction Today & Tomorrow August 2019Federation, the committee is striving to examine the content of proposals to diverse tasks andto further organize and enrich related data. An
outline of these proposals is introduced below:
National Measures to Improve Disaster-resistant Social Infrastructure
The Ministry of Land, Infrastructure, Transport
and Tourism is promoting positive measuresfor not only the restoration and reconstructionof Great East Japan Earthquake-stricken areas
but also preparations for serious natural disasters that are forecast to occur in the near future such as Tokai, Tonankai and Nankai greatearthquakes and large-scale floods. In addition, the Ministry is tackling the renewal of superannuating social infrastructure stock andthe reinforcement and promotion of disasterpreventive measures. Specifically, the following four measures are being promoted:• Promotion of seismic retrofitting and tsunami countermeasures for public facilities(embankments, bridges, highways, port/harbor facilities, airport facilities, railway facilities, river facilities, houses, buildings, etc.)
Reinforcementof preventive maintenance and•renewal of flood-control countermeasures (threemajor metropolitan areas in Tokyo, Osaka andNagoya and major cities in flooding areas)• Reinforcement of disaster-preventive measures in areas where serious flooding andearth/sand-induced damage has occurred
Securementof the safety of houses and build•ings (promotion of seismic retrofitting, construction of tsunami-evacuation buildings)
Steel-structure Technologies andMethods Conducive to Improving Disaster-resistant Social Infrastructure
Steel products have high performance thatsatisfies the need for highly stabilized quality in addition to the high toughness andworkability required of construction materials. Steel structures employing thesehigh-performance steel products offer thefollowing application advantages:• Possible to reduce on-site construction terms• Possible to construct on narrow congested
sites and soft ground due to the applicationof lightweight steel structures made available by the use of steel products
Flexibility
in design such as curved struc•tural design• Flexibility and simplicity in combined use
with concrete, lumber, glass and other structural materials
Possibleto produce flexible spaces and struc•tures with consideration paid to landscaping
Making the most of the performance offeredby steel products, the Japan Iron and Steel Federation presents practical proposals that can allow earlier improvements and construction ofdisaster-resistant social infrastructure by applying accumulated steel-structure technologies andmethods high in terms of disaster-preventive performance, application advantage and eco-friendliness. Typical examples are introduced below:
Proposals of Steel-structure Technologies and Methods to Improve
Disaster-resistant Public Facilities
and Disaster-preventive Bases
Table 1 and Fig. 1 show the disaster-preventive technologies and methods employing
steel structures, proposed by the Japan Iron
and Steel Federation (JISF), among which are:
• Improvement of disaster-resistant public facilities and disaster-preventive bases (newstructural system buildings employing innovative structural materials, steel-structurebuildings used as disaster-preventive bases, earthquake/tsunami-resistant manmade
platforms, steel-structure school facilities)
Earthquake-resistanthouses (steel-framed•houses, etc.)• Early restoration and improvement of port/harbor and coastal facilities, and earthquake/tsunami-resistant measures (port/harbor facility
renewal methods employing steel products,
seismic reinforcing methods for piers, revetments and breakwaters employing steel products, water-cutting off revetments employing
steel pipe piles and sheet piles, high tide/tsunami-resistant methods employing steel products)
Renewal,improvement and seismic retro•
fitting of bridges (bridges applying bridge
high-performance steel, reinforcing methods for existing bridge foundations usingProposed technologies
and methods

Restoration of ground sunken/flooded
area
Measure for flooding/earthquakeinduced collapse of river embankment
Slope stabilization and measure fordebris flow

Application fields

Improvement and seismic retrofitting ofbridgeMeasure for liquefaction

Tsunami evacuation building, disasterprevention base during damaging
Seismic retrofitting and multi-purpose
application of public facility
Reconstruction and seismic retrofittingof house
Repair and improvement of breakwaterand tide embankment
Tsunami measure for coastal facility

Table 1 Proposed Steel-structure Technologies and Methods Resistant to Disasters

1 -1 New structural system building

using innovative steel materials

1 -2 Steel-structure disaster-preventionbase

1 -3 Seismic/tsunami resistant2manmade platform
Steel-structure school facility

3

Steel-framed house

Port renewal method using steel
product
5 Seismic reinforcing of pier, revetment
and breakwater using steel product6 Reinforcing of existing bridge foundation
using steel pipe sheet pile and pipe pile
7 Embankment reinforcement using
steel sheet pile
8 Permeable debris flow-control dam
using steel pipe
9 Land slide-prevention method using
steel product10 Bridge applying bridge
high-performance steel
11 Cut-off revetment using steel sheet
pile and steel pipe sheet pile
12 Measure for side liquefaction ofrevetment in coastal area
13 Floating disaster-prevention base4

earthquake using steel sheet pile

B Measure for high tide and tsunamis

using steel product

C Measure for high tide using steel product(double wall-cofferdam sheet pile method)• Maintenance Technologies forFig. 1 Application of Steel-structure Technologies and Methods Resistant toDisasters
8
2

9

7

C

A
A

11

1
B
A

10
12

1

1
13
4

for the side liquefaction of revetments incoastal areas, measures for liquefaction andearthquakes using steel sheet piles)• Afforestation and flood-control measures(permeable-type debris flow-control dams
using steel products, land slide-suppressing measures using steel products)
By making the most of collaborative relationships with the Japanese Society of Steel
Construction and other related organizations
and an industry-academia-government tie-up
system, JISF has fostered steel-structure countermeasure technologies and methods that protect the national land from natural disasters
and mitigate disasters. To that end, JISF considers that these technologies and methods will
not only allow for the realization of proactive
town-making that is highly resistant to disasters
and conducive to promoting industrial development but will also contribute to the restructuring of safe and secure Japan.
Examples of Countermeasure Technologies and Methods Attracting
Close Attention
At the regional development bureaus and local
governments to which the Committee on National Resilience has thus far promoted proposal activities, they are concerned not only withnew facility construction but also maintenancemethods for existing facilities and their repair
and reinforcement. Further, because of the recent and frequent large-scale flood damage
in Japan, the importance of countermeasuresagainst such damage is growing. Some of thetechnologies and methods that are closely related to the above are introduced below:

A Measure for liquefaction and3steel pipe sheet piles and steel pipe piles)• Measures for land liquefaction (measures

5

6

Port and Harbor Steel Structures
Port and harbor steel structures are subjected toseverely corrosive environments. Accordingly, in order to secure higher performance than
the required performance, technologies are required that suppresses the corrosion of steel
products and appropriately assess their soundness, and maintenance and repair methods are
required that restore deteriorated steel products
and corrosion-protection performance to theoriginal level, examples of which are shown in
Figs. 2, 3 and 4 and introduced below:- Corrosion-protection methods
Coating and lining corrosion protection: Corrosion-protection methods with which steel products are covered directly with coating/lining
materials to shut out corrosion factors. These
are classified into coating, organic/inorganic lining and petrolatum lining and are applied mostly in low tidal areas (L.W.L.) or higher areas.
Cathodic corrosion protection: The corrosionprotection method with which corrosion-proAugust 2019 Steel Construction Today & Tomorrow 16

tection current is continuously supplied froman external source to steel products. Two
methods are in use: anodic and external power source methods, which are applied mainly
in submerged and sea bottom zones.
- Repair and reinforcing methods
In the case of reinforcing steel structural members: The method with which section loss sections are reinforced using steel
plates or reinforced concrete
In the case of entirely repairing corrosionprotection measure: On-site repairing method that uses mortar covering, petrolatum lining and underwater hardening-type coating
In the case of partly repairing corrosion-protection measure: The method that recoats
polyurethane-deteriorated sections with repairing polyurethane

the debris flow into running water and driftwood- Retention of capturing space
Retention of capturing space by flowing
earth/soil through capturing space during
normal times because of the adoption of
permeable-type structures

Fig. 2 Type of Corrosion-protection Measures for Port/Harbor Steel Structures
Coating, lining, cladding
Coating

Organic lining

Metal cladding
Titanium cover

Polyurethane lining

Coating• Measures to Control Debris Flows

Highly corrosion-resistant
stainless steel cover

Cathodic
protection

Anodic system

Fig. 3 Examples of Assessment of Soundness of Port/Harbor Steel Structures
Loss of function
Entire repair

Cathodic corrosionprotection (example
of anodic system)

Lining corrosion-protection(example of urethane-lined
steel sheet pile)

Application condition of corrosion-protection measures

Employing Steel Pipes
With debris flow-control measures employing steel pipes, mountain stream environments(continued slope of river beds) are preserved
while retaining the capturing space by passing
soil and running water through debris flow-control steel structure during normal times, and at
the time of occurrence of debris flows, the debris
flow and driftwood are surely captured by separating the debris flow into running water and thesoil/rock and driftwood, examples of which are
shown in Photo 1. Among major features are:
- Sure capturing of debris flows
In arranging vertical and lateral steel pipes, thecapturing space is set at 1.5 times the maximum diameter of on-site conglomerates; demonstration of high impact absorption capacity
in the case of direct hits by debris flows; andthe sure capturing of debris flow
- Capturing of driftwood flown out
together with sand/rock
Effective capturing of driftwood by separating- Preservation of mountain stream
environments
Eco-friendly structure that secures continued slopes for riverbeds without dividing
mountain stream
After occurrence of debris flows, it is

Deterioration level
Partial repair

Maintaining of function

No need for repair

No need for repair
Coated/lined section

1/2 ormoreof theflangeWeb
FlangePeeling-off and lossof lined material arenotable, steel
product is exposed,
and rusting occurs

Example in which
anode completely
disappears

Damage that reaches
steel product occurs
in part of corrosionprotection measure,and occurrence ofrusting is judged

Many damages that
do not reach steel
product are
observed

Whether or not the corrosion-protection
electric potential (-800 mV) is maintained

Nearly no change
from initialcondition is seen,
and lined section
shows soundcondition

Anode in initialconditions

Fig. 4 Examples of Repair and Reinforcement of Port/Harbor Steel Structures
In the case of reinforcementof steel member
Reinforcement using
steel plate

In the case of entire repair of corrosion-protection measure
Mortar coating method
Surfacepreparation

Steel sheet pile
Side surface
fillet welding

Front
surfacefilletwelding

Slitting

Mortar(concrete)

Corrosionprotection
coating

Corrosion-protection
treatment ofreinforced section

Surface preparation

Underwater hardeningtype coating method

Repair method using
repairing polyurethane

Surface preparation

Stud bolt-attached hoop
Petrolatum corrosionprotection thick tapeContinuously-foamed
polyethylene sheet
FRP protection cover(convex)

Steel plate
Welding ofsteel plate

Petrolatum coating method

Top-end sealing(underwater hardening-type epoxy resin)

In the case of partial
repair of corrosionprotection measure

FRP protection
cover

Corrosion-protection cap
Top-end sealing (underwater
hardening-type epoxy resin)
FRP protection cover (dent)

Mortar is filled inside
FRP protective coverSteel member is coated withpetrolatum and covered with
FRP buffer material

Underwater hardeningtype epoxy resin

Steel member is coatedwith underwater hardening-type epoxy resin

Repairing polyurethane
is coated on polyurethane coating-deteriorated section

Note: Source of information on Figs. 2, 3 and 4-Extraction and compilation of data from:
1) Manual for Corrosion Protection and Repair of Port and Harbor Steel Structures (1999, 2009), Costal Development Institute of Technology
2) Handbook on Practical Applications of Port and Harbor Steel Structures, Research Working Group on Corrosion Protection and Repair
17 Steel Construction Today & Tomorrow August 2019necessary to recover the performance ofdebris flow-control steel structures to theoriginal level, and thus repair and reinforcement measures are applied depending on the level of damage of steel pipe
members. Fig. 5 shows an assessment of
the soundness of debris flow-control steel
structures and their repair measures.

• Application of Weathering Steel in

Bridge Construction
In weathering steel, a dense rust layer is formedon its surface at the initial stage of application,and this protective layer suppresses the further
development of corrosion. Capitalizing on thisprotective rust layer, weathering steel demonstrates high corrosion resistance without coating. Photo 2 shows an example of applicationsof weathering steel for bridges. Major application advantages are:During ordinary time: Passing of earth and sand and running water

Condition of capturing of debris flow

-Reduction of lifecycle costs: Eliminationof recoating-Mitigation of environmental load: Applicability without coating-Harmonization with the environment:
With the lapse of time, the protective
rust layer produces a stately appearance
that harmonizes with nature.
In order to continuously demonstrate
the property peculiar to weathering steel, it
is necessary to conduct the periodic inspection of rust layers and make soundness assessments so that favorable rust conditions
are maintained. The rust layer soundness is
assessed using appearance ratings from 1
to 5 depending on the rust condition. With
ratings 3~5, the rust condition is assessed
as favorable; with rating 2, follow-up observation is required; and with rating 1, detailed inspection is carried out, and as theneed arise, repair is required to take. Fig.
6 shows examples of the soundness assessment of weathering steel.

Photo 2 Application of weathering steel bridge inremote mountainous area

Photo 1 Examples of debris flow-control measures using steel pipes

Fig. 5 Soundness Assessment of and Repair Methods for Debris Flow-control Measures Using Steel Pipes
Inspection and Soundness Assessment

Damage level Performance-deteriorated level and definition
Repair measure
Judgement (hollow pipe)
Level 1:
No lowering of performance compared to the level
Deformation rate of steel pipe: less
No
need
for
repairSoundat completion and no obstacle in use
than10% of steel pipe diameter
Level 2:Lowering of member durability and fears for lowering Examination of need for repair by Deformation rate of steel pipe: 10% or more
Damagedof performance compared to the level at completion means of structural verification
to less than 40% of steel pipe diameter
Level 3:
Loss of performance and impossible to demonstrate Sure implementation of repair
Deformation rate of steel pipe: 40% or more
Collapsed
performance when design load subsequently worksof steel pipe diameter*Extraction from Design Handbook on Steel Erosion-control Structures, Sabo & Landslide Technical Center
Before debris removal
Level 1
Deformationrate:
D0/D<10%

Level 2
Deformationrate:
10%≤D0/D<40%

Level 3
Deformationrate:
D0/D≥40%

After debris removal
Because of no damage, service
is continued without repair*Extraction from the website of Research Group on Erosion-control Steel Structure
Structural verification is conducted, and the section in which
occurrence stress surpasses
yield stress is repaired bywelding two semicircular-divided
steel pipes on damaged section*Extraction from Design Handbook on Steel Erosion-control Structures, Sabo & Landslide Technical Center
Damaged section is on-site cut
and repaired by on-site welding
factory-manufactured newmembers

August 2019 Steel Construction Today & Tomorrow 18

Fig. 6 Examples of Assessment of Soundness of Weathering Steel (Examplesof bridge with lapse of more than 10 years after erection)

Appearance rating 5

Appearance rating 4

Appearance rating 3

Rust amount is less, and appearance
presents comparatively bright color(Standard for future treatment: noneed) (Less than about 200 μm)*

Rust particle size is about 1 mm or
lower, and rust is fine and uniform(Standard for future treatment: noneed) (Less than about 400 μm)*

Rust particle size is 1~5 mm,
and rust is coarse (Standard for
future treatment: no need) (Lessthan about 400 μm)*

Layered peeling off of rust occurs(Standard for future treatment:
measurement of plate thickness)(More than about 800 μm)*

Employing Steel Sheet Piles
With this method, the embankment collapse
factor occurring during flooding and earthquake is shut out by driving steel sheet piles
into the slope of embankments or into theembankment so that the collapse of the embankment can be prevented. Fig. 7 shows
examples of embankment reinforcement using steel sheet piles. Specific measures are:- Countermeasures against seepage at embankment baseIn the case where the ground under an embankment is composed of sand and gravel, when highwater levels continue, the embankment causes
collapse due to the penetration of water flow into the embankment base. Steel sheet piles are
driven into the embankment slope to cut off thepenetration of water flow into the ground so that

*Figures in parenthesis show
standard rust thickness
measured as a supplementarymeans for assessing rustappearance.

Fig. 7 Examples of Embankment Reinforcement Using Steel Sheet Piles
No provision of measure

Seepage atfoundation• Embankment Reinforcing Method

Overtopping, seepage
into bank structure

Rust particle size is 5~25 mm, and rustis scale-shaped (Standard for future
treatment: need for follow-up
observation) (Less than about 800 μm)*

Appearance rating 1

After provision of measure

Seepage
Sand/gravel ground
Penetrating water
Slope collapse due to overtopping

Shut off ofpenetrating
water
Steel sheet pile
Securement of embankment height

Seepage inside embankment

Sinking of embankment
Liquefaction

Appearance rating 2

embankment collapse is prevented.
- Countermeasures against overtopping and embankment seepage
In order to break off the embankment collapse cycle-embankment slope erosion due
to overtopping→lowering of embankment
height→increasing overtopping→enhancing
collapse, the lowering of embankments due toovertopping is prevented by driving steel sheet
piles at both sides of the embankment so thatthe collapse of embankments is prevented. Pile
driving into embankments is also effective inpreventing seepage into the embankment.
- Countermeasures against liquefaction occurring during earthquakes
Ground deformation in the liquefied layer of embankments is effectively treatedby steel sheet piles embedded into the nonliquefying layer in the vicinity of embankment slopes, thereby demonstrating the effect of suppressing embankment collapse
occurring during earthquakes. ￭Liquefied ground

Steel sheet pile
Securement of embankment height

Steel sheet pile or drainage function-attached pile

JISF Operations

Lecture Delivery at SEAISI ForumThe South East Asia Iron and Steel Institute(SEAISI) held the 2018 ASEAN Iron andSteel Sustainability Forum in Ho Chi Minh city
in Vietnam on November 26, 2018, to which
the Japan Iron and Steel Federation (JISF) dispatched Dr. Masahide Takagi of Nippon SteelCorporation (formerly known as Nippon Steel& Sumitomo Metal Corporation) to participate

in a lecture meeting. He delivered a lecture titled “Introduction of Weathering Steel & Actual Application for Bridge Structure.”
The lecture was delivered in reply to a request from the SEAISI’s Sub-Committee on
Steel Application in Construction Sector. It is
one of the lectures delivered at the Session titled“Steel Construction: Developments and Appli-

STEEL CONSTRUCTION TODAY & TOMORROW
Published jointly by

The Japan Iron and Steel Federation
3-2-10, Nihonbashi Kayabacho, Chuo-ku, Tokyo 103-0025, Japan
Phone: 81-3-3669-4815 Fax: 81-3-3667-0245
URL http://www.jisf.or.jp/en/index.html
Japanese Society of Steel Construction
3F Aminosan Kaikan Building, 3-15-8 Nihonbashi, Chuo-ku, Tokyo 103-0027, Japan
Phone: 81-3-3516-2151 Fax: 81-3-3516-2152
URL http://www.jssc.or.jp/english/index.html

cations” in the Forum. In the lecture, diverse aspects of weathering steel were introduced-specific properties, trends in application in bridge
construction in Japan, cares to be paid in application, inspection of corrosion conditions andrepair approaches for corroded sections andpractical application examples. JISF participates in the Sub-Committee as an observer. ￭© 2019 The Japan Iron and Steel Federation

Edited byCommittee on Overseas Market Promotion, The Japan Iron and Steel Federation
Chairman (Editor): Kazuhito TsujimotoP u b l i s h e d t h r e e t i m e s p e r y e a r, S T E E L C O N S T R U C T I O N TO D AY &TOMORROW is circulated to interested persons, companies and publicorganizations to promote a better understanding of steel products and theirapplication in the construction industry. Any part of this publication may be
reproduced with our permission. To download content (PDF format), please go
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