No. 68 August 2023

STEEL CONSTRUCTIONTODAY & TOMORROW

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

Feature Article

Sound Maintenance of SteelPort Structures and Bridges
1 Revision of Corrosion Protection and Repair Manual for
Port and Harbour Steel Structures

5 Abrasive Water-jet Treatment (AWT)-New Surface Preparation
Technology for High-speed, Extreme Removal of Salts andCorrosion Products from Severely-corroded Steel Structures

9 Integration of Monitoring and Numerical Modeling for
Rapid Post-Earthquake Assessment

Special Topic

13 Strategy for the Construction Industry in the Age of
Digital Transformation

19 JISF Operations

Published Jointly by

The Japan Iron and Steel Federation
Japanese Society of Steel Construction

Feature Article: Sound Maintenance of Steel Port Structures and Bridges (1)Revision of Corrosion Protection andRepair Manual for Port and Harbour
Steel Structures

by Hiroshi Yokota
Professor Emeritus, Hokkaido University; Councilor,
Coastal Development Institute of Technology

Introduction
In Japan, Port and Harbour Act was revised in 2013, which stipulates basic
rules on maintenance and repair for port
and harbor facilities. At the same time,
Guidelines for Inspection and Diagnosis of Existing Port and Harbor Facilities1) and Guidelines for Formulating
Maintenance and Repair Plans of Portand Harbour Facilities2) were publishedto support the laws and regulations sothat more strategic maintenance and repair can be realized for facilities in offshore and coastal regions. In addition,
Technical Standards and Commentaries
for Port and Harbour Facilities in Japan3)
and Technical Manual for Maintenanceand Repair of Port and Harbour Facilities4) were revised in May and July 2018,
respectively, which describe the technical aspects of maintenance and repair ofport and harbor facilities.
To follow the trend to strengthen themaintenance and repair work for port andharbor facilities, Corrosion Protection
and Repair Manual for Port and Harbour
Steel Structures (hereinafter referred toas “the Manual”) was revised in 2022 for
newly constructed steel structures withcorrosion protection in accordance withthe revised Technical Standards and existing steel structures that should be wellmaintained from the viewpoint of steel
corrosion. At the same time, recent technological development should be thoroughly considered for the revision to
make corrosion protection more rationaland secure. This article presents the major points of the revision of the Manual.
Policy of Revision
The revision policies of the Manual aresummarized as follows:(1) to align with Technical Standards andCommentaries for Port and Harbour
1 Steel Construction Today & Tomorrow August 2023

Facilities in Japan3);(2) to align with Technical Manual for
Maintenance and Repair of Port andHarbour Facilities4);(3) to align with Guidelines for Inspection
and Diagnosis of Existing Port andHarbour Facilities1) and Guidelines for
Formulating Maintenance and Repair
Plans of Port and Harbour Facilities2);(4) to respect international standards; and(5) to reflect the current levels of corrosion
protection and its repair technologies.
Structure of Manual
Steel structures in offshore and coastal
regions are exposed to very severe cor-

Hiroshi Yokota: After finishing the mastercourse at the Tokyo Institute of Technology,
he entered Ministry of Transport in 1980.
Then, he served as professor at the Hokkaido
University in 2009. He assumed his current
position as Councilor of Coastal Development
Institute of Technology in 2021.

rosive environments because of seawater splashing and tidal changes. We haveelucidated the mechanisms of steel corrosion and examined various corrosion
protection techniques for port and harborsteel structures from long ago. As resultsof these efforts, the Manual provides latest information on selection, design andexecution of necessary corrosion protection methods to ensure structural performance over the requirements and to efficiently conduct inspection, diagnosis andinterventions including repair.
The Manual consists of four parts andeleven appendices, as summarized in Table 1.

Table 1 Structure of Corrosion Protection and Repair Manual for Port and Harbour
Steel Structures
Part I General
1 Outline
2 Characteristics of steel corrosion in marine environment
3 Influential factors on corrosion in seawaterPart II Design and execution of corrosion protection
1 General
2 Design and execution of cathodic protection
3 Design and execution of corrosion protection coating (execution in factory)
4 Design and execution of corrosion protection coating (execution on site)
Part III Maintenance and repair of corrosion protection
1 General
2 Maintenance and repair of cathodic protection
3 Maintenance and repair of corrosion protection coating (factory coating)
4 Maintenance and repair of corrosion protection coating (on-site coating)Part IV Performance evaluation and repair of corroded steel structures
1 Performance evaluation of steel structures without corrosion protection
2 RepairAppendix
1 Terms and definitions
2 Comparison with other domestic and international standards on cathodic protection
3 Design examples of cathodic protection
4 Design examples of repair and strengthening
5 Execution examples of repair for corrosion protection
6 Life cycle cost calculation for corrosion protection
7 Sheet of inspection and investigation results (reference)
8 Standards for substrate preparation
9 Underwater welding tests
10 Products relating to corrosion protection and repair
11 Introduction of site exposure tests conducted by research institutes in Japan

Major Points of Revision• Influential Factors on Corrosion
Caused by Macro-Galvanic Cell
The following four factors to have an influence on macro-galvanic cell corrosionthat is a major reason of concentrated
corrosion are discussed: (1) corrosion in
the tidal zone, (2) intrusion of river water, (3) level of lower end of the concrete
superstructure, structural type and water
depth, and (4) marine organisms and local detachment of rust layer.

• Corrosion Rates of Steel Em-

bedded in Seabed Soil, in Rubble and in Backfilling Stone
The corrosion rates of steel embedded
in seabed soil and in rubble and in directcontact with backfilling stone are believed to be sufficiently low. Moreover,
it is difficult to inspect the corrosion stateof steel there. However, we have been reported that concentrated corrosion sometimes occurs under certain conditions.
Accordingly, the Manual recommends
that, if possible, we conduct excavation
survey on those parts of steel members
particularly when we plan to extend thelifespan of the structures.

• Selection of Corrosion Protec-

tion Coating Methods
Table 2 lists the classification of corrosion protection coatings with their updated information in which applicability, expected service life, initial costs andrecords of past application are provided only as guides. The information wascompiled from the records of past application and the results of long-term exposure tests. When using the table, it should
be reminded that the applicability actually depends on the environmental conditions and regional characteristics.

Table 2 Applicability of Typical Corrosion Protection Coating Methods

Factory coating

Marine thick epoxy resin coating
Polyethylene coating*2

Urethane elastomer coating*2

Super thick film
coating
Corrosion
resistant metal
coating

Record of past application

Members joint

JacketSheet pile

Pipe sheet pile

Pipe pile

Under seabed

Submerged zone

Painting
Heavy duty
anticorrosion
coating

Underwater
coatingOn-site coating

Tidal zone

Methods

Splash zone

Marine atmospheric zone

Conditions

Initial application cost *1

Applicability
Member type
Expected service life

Applicability
Zone

Super thick epoxy coating
Super thick polyurethane coating
Seawater-resistant stainless steel coatingThin titanium clad steel coating
Thick clad steel coating*3

Painting-type coating
Putty-type coating
Wetting area-type coating

Petrolatum
coating
Mortar coating
Reinforced
concrete coating

Fiber reinforced plastics cover
Corrosion resistant metal protective cover
Fiber reinforced plastics cover
Corrosion resistant metal protective cover
Removing form typeStay-in-place form type

<Note>
Applicability (zone): Applicable: Generally unapplicable: Unapplicable
Applicability (member type): Applicable: Depending: Unapplicable
Expected service life
: Approx. 50 years: 30-35 years: 20-25 years
Initial application cost (factory): Less costly: Medium: Costly
Initial application cost (on-site): Medium: Costly
Record of past application: Many: Medium: Few*1) Factory application is generally less costly than on-site application.
*2) Expected service life of the heavy duty anticorrosion coating is for only pipe pile, and that isfor sheet pile.
*3) Thick clad steel coating is applicable for bending pipe, while it is unapplicable for spiral pipe and electric resistance welded pipe.

August 2023 Steel Construction Today & Tomorrow 2

• Harmonization with ISO 12944

Series
Revisions to ISO 12944 series titled“Paints and varnishes-Corrosion protection of steel structures by protective
paint systems” has been reflected in the
Manual regarding the classification of
corrosive environments. Standard corrosion rate of as 200 to 700 μm is provided for the extreme corrosive environment.

• Design and Execution ofsion Protection Coating (Factory Coating)Marine epoxy glass flake coating system
has been merged in marine thick epoxy
coating (Table 2). The target steel member has been changed to which polyethylene coating can be applied (Table 2).
The period during which corrosion protection is thoroughly expected for super thick film coating has been updated
to be 35 years based on marine exposure tests. Expected life extension of super thick film coating is specified when
weather resistance topcoat is applied.
Furthermore, the thick clad steel coating
has been added in the corrosion resistantmetal coating method (Table 2).

Marineatmospheric zone

• Design and Execution of Corro-

Splash zone

3 Steel Construction Today & Tomorrow August 2023

Fig. 1 Corrosion Protection Systems for Port and Harbor Steel Structures

M.L.W.L.

L.W.L.

L.W.L.– 1 m
Submerged zone

Sea bottom

Under seabedCorrosion protection coating

Intertidal zone

(C)

Cathodic protection

H.W.L.

(B)

Corrosion allowance(A)

Corrosion protection coatingsion Protection Coating (On-site
Coating)
The period during which corrosion protection ability was confirmed in marine
exposure tests has been added (Table 2).
A reinforced concrete coating has been
included in the scope of application of
the corrosion protection methods (Table2). The details of the design and execution of the reinforced concrete coatingthat is applied for the recovery of mechanical performance of steel members
are described in Part IV of the Manual.
Regarding the petrolatum coating,since the earlier version of the Manual
only described the specifications of theprotective cover, an example of its specifications has been added. Moreover, by
distinguishing between protective covers currently applied and those previously applied, the Manual improves convenience at the selection of protective

Cathodic Protection
Factors to be considered when determining the current density of corrosion protection are identified: (1) classification ofclean sea area and polluted sea area, (2)high current flow, (3) high wave, (4) buried parts, such as under seabed, in rubble and in direct contact with backfillingstone, (5) rust layer formed due to longterm non-corrosion protection, and (6)the effects of corrosion protection coating and concrete superstructure.
Corrosion protection, such as cathodic protection, is not generally applied forthe part of steel member in direct contract
with backfilling stone because the corrosion rate there is generally low. However, particular corrosion protection should
be required when the corrosion rate ofsteel is high under special environments.
The following two examples are provided for such the corrosion protection measures: (1) cathodic protection with impressed current using an external power
supplier applied to tie rods and anchorage piles and (2) cathodic protection withsmall aluminum sacrifice anodes applied
to ring joints and turnbuckles of tie rods.
Regarding the corrosion protection efficiency, it is necessary to determine anappropriate value based on the actual
corrosion protection efficiency in the target environment. In addition, it has been
added that the efficiency of cathodic protection can be evaluated using the corrosion rate during corrosion protection
when the corrosion protection efficiency
cannot be directly obtained.
The reference values of the coefficientof the initial corrosion protection current
density related to the reduction current ofcorrosion in clean seawater are provided.

Cathodic protection• Design and Execution of Corro-covers. In the description of the substrate
treatment, reference photos are provided
for each surface preparation grade to easily identify the differences. In addition,commentaries are given that a residual film after substrate treatment does notcause any problems on corrosion protection ability in the petrolatum coating.

Corrosion protection coatingtion Systems
The corrosion protection systems thatshould be applied to port and harborsteel structures are schematically shownin Fig. 1. The Technical Standards andCommentaries for Port and Harbour Facilities in Japan3) stipulate the combination of coating and cathodic protection
as depicted in the figure, among which
system (A) is regarded as a standard corrosion protection measure. The Manual follows the Technical Standards but
specifies that the lower end of corrosion
protection coating is variable depending
on seawater quality etc. within the principle of the standard, while it is specified
to be L.W.L.–1 m in the Technical Standards.

Steel member• Selection of Corrosion Protec-

• Maintenance and Repair of Cor-

• Performance Evaluation androsion Protection Work
The classification of inspection and diagnosis of port and harbor structures is specified by adding the concept of maintenancework for highly prioritized facilities.
Photos of damages with corrosion areprovided for examples.
Examples of the application of latest
information and communication technologies (ICT) that have high potentials
for use in inspection and diagnosis havebeen added.
Furthermore, the threshold potential
for the judgment of corrosion protection
ability of cathodic protection at the initial inspection has been corrected from–800 mV to –780 mV. In addition, it isnoted that it takes long for the corrosion
protection current to reach the steadystate when a steel member is in a noncorrosion protection state.
As a detailed investigation method,electrochemical impedance measurement technique has been added.
To avoid galvanic corrosion, it is recommended that the potential measurement of cathodic protection be performed every 1 to 2 years. In addition,
thickness measurement of corrosion resistant metal has been added to an inspection and diagnosis item.

Repair of Unprotected Steel
Structures
The flow of maintenance and repair from
inspection and diagnosis of steel members to the evaluation of structural performance for decision making on thenecessity of repair is shown in Fig. 2.
Specifications and commentaries on theprocess according to the flow in the figure have been added.
The commentaries on the reduction
rate of 70% in on-site underwater welding have been modified. In addition, theconsiderations for an underwater welding test have been updated.

• Appendices

The appendices of the earlier version of
the Manual have been updated. In Appendix 3, design examples of cathodic
protection according to the Manual arecompared to those according to DNVRP-B4015) and ISO 131746). The Manual
calculates less number of sacrifice anodes
than the other standards mainly becauseof the difference in effective current capacities of the anodes.
Appendix 11 “Introduction of site exposure tests conducted by research institutes in Japan” has been added.

Fig. 2 Flow of Maintenance and Repair of Corrosion Protected andUnprotected Steel Members
Corrosion unprotected
memberCorrosion protected
memberInspection and diagnosis

Inspection and diagnosis
Decrease in corrosion
protection ability?

Part II
Part III

Yes

Repair for corrosion protection
or
Execution of corrosion protection

Corrosion condition of the member
Evaluation of structural
performance of the member
Necessity of repair?

No

Yes
Survey for repair design
Repair for performance recovery

No

Conclusions
The revision work was conducted as acollaborative study between the Coastal Development Institute of Technology and the Society of the Research forCorrosion Protection Technology for
Maintenance. A revision committee wasestablished, which was composed of researchers, practical maintenance engineers, government officials, port managers, and engineers concerned with themanual, to make the Manual even morepractical and reliable. All the committee members hope that the Manual will
be of help to those in charge of design,
construction, and maintenance and repair
work for port and harbor steel structures.
Acknowledgments
The author, as a chair of the revisioncommittee, would like to extend his sincere appreciation to all the committee
members. A special thank goes to Mr.
Hiroaki Suwa, Researcher of CDIT, fordrafting this article.
References
1) Ports and Harbours Bureau, Ministryof Land, Infrastructure, Transport andTourism: Guidelines for Inspection andDiagnosis of Port and Harbour Facilities, partially revised edition, 2020 (inJapanese).
2) Ports and Harbors Bureau, Ministry ofLand, Infrastructure, Transport and Tourism: Guidelines for Formulating Maintenance Plan for Port and Harbour Facilities, partially revised edition, 2020
(in Japanese).
3) Ports and Harbors Bureau, Ministry ofLand, Infrastructure, Transport and Tourism: Technical Standards and Commentaries for Port and Harbour Facilities inJapan, 2018.
4) Coastal Development Institute of Technology: Technical Manual for Maintenance and Repair of Port and Harbour
Facilities, 2018 (in Japanese).
5) Det Norske Veritas: DNV-RP-B401, Cathodic protection design, 2021.
6) International Organization for Standardization: ISO 13174, Cathodic protectionof harbour installations, 2012.

Part IV - 1
Part IV - 2

August 2023 Steel Construction Today & Tomorrow 4

Feature Article: Sound Maintenance of Steel Port Structures and Bridges (2)Abrasive Water-jet Treatment (AWT)-New Surface Preparation Technology for High-speed, Extreme Removal of
Salts and Corrosion Products from Severely-corroded Steel Structuresby Shigenobu Kainuma
Professor, Kyushu University

Needs for AWT Development
In steel structures exposed to air-borne
salt environments, severe corrosion withhigh corrosion development rates is likely to occur in the structural members
where nearly no effect of rain washingon the adhered salt is observed and thesea salt is accumulated. Once the steel
member has undergone severe corrosion, corrosion products including thesalts in the corrosion pit bottom cannot
be removed by the use of power tools.
Even when blast treatment is applied, it
is difficult to fully remove the salts in thebottom of the corrosion pit1). In particular, it is also difficult to secure an appropriate quality of surface preparationin the corner and narrow sections and thegaps between bolts/nuts and bolt joint
splice plates. As a result, under-film corrosion frequently occurs due to the salts
and corrosion products remaining on thesteel product surface in an earlier period
after recoating.
In the case of applying heavy-duty corrosion-protection coating, becauseof the high durability of the coating film
and its high adhesion to the steel substrate, corrosion does not develop on
the steel product surface but is liable todevelop to the thickness direction. Due
to such corrosion development behavior, when under-film corrosion occurs,
it becomes difficult to remove salts andcorrosion products by means of surface
preparation at the stage of recoating.
Particularly for weathering steel applied in bridge construction, when unusual corrosion occurs due to salt damage,surface preparation (the preparation of
the substrate) is required with the changeof specifications from uncoating to coating. However, a dense and firm corrosive product layer is formed in weathering steel, and a larger amount of salt is
liable to remain in such layers compared
to ordinary carbon steel1). This makes it
5 Steel Construction Today & Tomorrow August 2023

Shigenobu Kainuma: After completing themaster course at the Graduate School, Hosei
University, he served as Assistant Professor
at Nagoya University in 1994 and then as Associate Professor at Gifu University in 2001.
He became Associate Professor at Kyushu
University in 2004 and then Professor in 2022.

more difficult to remove salts and corrosion products in weathering steel than inordinary carbon steel.
In order to cope with these situations, we developed a new technologyAWT (abrasive water-jet treatment)2) thatbreaks through diverse tasks imposed onconventional surface preparation methods for severely-corroded members andallows for the highly-efficient and thorough removal of salts and corrosion
products in severely-corroded members
and narrow structural sections over conventional technologies. Further, AWT
aims at significantly improving surface
preparation efficiency and reducing thegeneration of industrial waste in comparison with the blast treatment method.
In this development, we noticed anultrahigh-pressure water multiphase fluid prepared by mixing the abrasive into the ultrahigh-pressure water that is
applied to conventional AWJ (abrasive
water jet) technology for cutting highhardness high alloys and CFRP-metalcomposite materials at high speed withhigh precision. In addition, we newly focused on the following two aspects: thewater wedge effect to allow the highspeed peeling and removal of corrosion
products by infiltrating ultrahigh-pressure water into cracks inside the corrosion product layer2) while at the sametime exposing these cracks; and the water flow action to allow the efficient removal of corrosion products in narrowand gap sections, which was impossible by means of blast treatment. Fig. 1
shows a schematic diagram of abrasive
water-jet treatment (AWT).
This article introduces part of the basic interdisciplinary examinations employing convergence-type nozzles (AWJ
nozzles) for use for cutting2), which weremade in the process of developing AWT,
and the applicability of diffusion-type
nozzles (AWT nozzles) for use for surface treatments on the severely-corroded
sections, which were newly developed
based on the basic knowledge obtained
from these basic examinations:Fig. 1 Schematic Diagram of AWT
Cutting (AWJ)

Surface treatment (AWT)Ultra high-pressure water

Abrasive head
Abrasive

Abrasive#80

100 μmDivergent
Substrate

Water temperature: 70°C

Testing Methods• Surface Treatments
A carbon steel product (JIS G3106
SM490A, 70×70×6 mm) was adopted as
the test specimen material. Garnet (grain
diameter: #30/60) was used as the abrasive material. Table 1 shows the standoff distance and treatment conditions of
AWT (abrasive water-jet treatment). Further, blast treatment was applied to compare with AWT. In the blast treatment, thestandoff distance was set at 200 mm, thepressure at 0.7 MPa, the angle at 90°and
the time at 5 sec. The AWJ nozzle wasused as the nozzle in AWT processing.
The AWT specimens with standoff distances of 100, 200 and 300 mm are called
AWT-1, AWT-2 and AWT-3 respectively.

• Measurement and Analysis

Methods
The surface property of the steel substrate
subjected to AWT and blast treatment
was observed by means of a digital mi-(abrasive water-jet treatment) and blast
treatment. The peak value of surface
roughness of the AWT specimens was
about 2 times higher than that of theblast-treatment specimens. In particular,
the AWT-1 specimen showed the highest peak value of 410 μm, and as thestandoff distance decreased from AWT3 to AWT-1, the peak value tended to increase. This was attributable to the fact
that, as the standoff distance decreased,
the energy and energy density that collided with the steel surface increased, andas a result the erosion depth increased.
Fig. 3 shows the cross-section profileof the specimens subjected to AWT andblast treatment with a standoff distance
set at 200 mm. The figure shows the results of the surface roughness assessed interms of the contour diagram and surface
roughness profile. The peak/valley range
and surface roughness of AWT-2 showed
considerably higher values compared tothose of the blast-treatment specimens.

croscope. The surface roughness and thecross-section profile of specimens were
measured employing a 3D laser microscope. A micro-Vickers hardness meter
was used to measure the microhardness
value HV of steel substrate. The surface
morphology after surface preparation wasobserved employing the microscope.
In order to make a relative comparison of the compressive residual stressof the specimen surface after respective
surface treatments, the surface was analyzed by means of the x-ray diffraction(XRD) method. For the XRD measurement conditions, the x-ray source was set
at Cu-Ka ray, and the voltage and current of bulb output at 40 kV and 30 mA.
In addition, the scan range was set at
40°~90°.
Test Results• Surface Roughness
Fig. 2 shows the microstructures of steel
substrate surfaces subjected to AWT

Table 1 Test Parameters for AWT Process
SpecimenStandoff distance
(mm)

AWT-1

100

AWT-2

200

AWT-3

300

Abrasive supply(g/min)Pressure(MPa)

Traverse speed
AWT machining(m/min)Nozzle diameter(mm)

Water flow
(L/min)

600

230

1

2

11.9

Fig. 2 Surface Morphologies2)
Peak value(a) AWT-1(b) AWT-2(c) Blast treatment

Fig. 3 Cross-section Profile2)-150 μm

150
0
-150
0

Grooves2

46Distance (mm)(a) AWT-2

8

10

Profile height (μm)

Profile height (μm)+150 μm

150
0
-150
0

2

4
6
Distance (mm)810(b) Blast treatment
August 2023 Steel Construction Today & Tomorrow 6

Fig. 7 shows the plastic deformationof steel product specimens after surface
preparation. Regardless of the surface
treatment methods applied, the hardnessof the specimens increased due to theformation of a surface layer that caused
plastic deformation. In the case of ap-

7 Steel Construction Today & Tomorrow August 2023

18

60

12

30

6
0

AWT−1 AWT−2 AWT−3 Blast treatment

0

200
0
−200
−400

m+2s
m−2s

500
400
300

Lip
AWT−2
Blast treatment−20000 −10000

600
Maximum erosion depth (µm)

24

Ten points mean roughnesst, Rzjis (µm)

Arithmetical mean roughness, Ra (µm)

120
Ra
Rzjis
m+s
90
m−s

30

Fig. 5 Trench Profile2)

200

Lip

0

100

10000

20000

Lateral position, x (µm)(a) Cross-section profile0

AWT−1 AWT−2 AWT−3 Blast treatment(b) Maximum erosion depth

Fig. 6 Microhardness Values, HV2)
280

Vickers hardness, HV• Microhardness Values andCross-section Profiles
In AWT, it is possible to perform surface treatment by the use of abrasivederived collision energy that is obtained by mixing the abrasive into
ultrahigh-pressure water and is considerably higher than the collision energy
in blast treatment. In light of this, theenergy absorbed by steel plates subjected to AWT was assessed based on
the change of microhardness and microstructure beneath the surface ofspecimens, the results of which are introduced below:
Fig. 6 shows the microhardness ofrespective specimens. The mean hardness of untreated specimens (basic material) was 150~200 HV. After being
subjected to AWT, the hardness of thespecimens increased and reached the
maximum level at their surface. The
maximum hardness of AWT-1 with aminimum standoff distance of 100 mm
was 268 HV. The maximum hardnessof AWT-2, AWT-3 and the blast-treatment specimen was 253, 242 and 224
HV respectively.

plying AWT, as the collision energy of
the abrasives increased, the hardness increased, and the maximum compressive
residual stress appeared at the sections
in which the maximum plastic deformation occurred. In the AWT specimen, as
the standoff distance became shorter, theFig. 4 Surface Roughness2)

Depth, d (μm)

Fig. 4 shows the surface roughness
Ra and Rzjis of the specimens subjected to AWT and blast treatment.
The AWT specimen showed a surface
roughness about 2 times higher thanthat of blast-treatment specimens, andas the standoff distance increased, thesurface roughness tended to slightly decrease. It was assumed that thiswas attributable to the fact that the collision energy for the steel substrate of
AWT specimens was higher than thatof blast-treatment specimens.
Fig. 5 shows the cross-section profile and the maximum erosion depthof the specimens subjected to AWT
and blast treatment. It was assumed
from the cross-section profile of AWT2 that a lip was formed on the trenchedge shown in Fig. 5(a) due to the occurrence of plastic flow. On the other
hand, a lip was not formed with blast
treatment.
Fig. 5(b) shows the maximum erosion depth. The maximum erosion
depth of AWT specimens became larger than that of blast-treatment specimens regardless of the standoff distance of 100~300 mm. The maximum
erosion depth of the specimens subjected to AWT by setting a standoff distance at 200 mm was 1.5 times or morethat of blast-treatment specimens.

AWT−1
AWT−2
AWT−3
Blast
treatment

240

200

160
0

500

1000
Depth (µm)

1500

Fig. 7 Microscopic Images of Cross Sections of Microstructures2)(a) AWT-1(b) AWT-2(c) Blast treatment

plastic deformation on the surface and in
the inner layer became larger. However, the depth and range of plastic deformation for blast treatment were less thanthose for AWT.
Fig. 8 shows the x-ray diffraction(XRD) patterns of the untreated specimen and the specimens subjected to
AWT and blast treatment. Every specimen had 3 high peaks including (110),(200) and (211) α-ferrite surfaces. The
diffraction angle of the specimens subjected to AWT and blast treatment slightly shifted to the low side vs the α-Fe
peak at every surface of the untreated specimens. It can be said from theseresults that compressive residual stressoccurs on the surface of steel products.
Further, because the plastic deformation
reached the highest level in AWT-1, thehighest compressive residual stress occurred here, and the shift of α-Fe peakbecame the highest. These results meanthat the highest compressive residual
stress was introduced in AWT-1.

Applicability of AWT Nozzle to
Severely-corroded Structural
Sections
The applicability of the AWT nozzle developed based on basic knowledge obtainedin the above tests is introduced below:
The target section is salt damage-induced severely-corroded bolted joints
collected from an uncoated weathering
steel bridge built in an air-borne salt environment. The thickness of layered rust
was about 10 mm or higher.
Fig. 9 shows the AWT processing ofsteel substrate of a corroded bolted joint
and the surface condition of the bolted
joint after AWT. As shown in Fig. 9(a),the comparatively thick corrosive product layer could be peeled and removed
by means of the water wedge effect of ultrahigh-pressure water introduced above.
Further, as shown in Fig. 9(b), corrosion
products and salts could be completely
removed with one AWT processing, andas a result, the amount of adhered salt decreased to 0~2 mg/m2 or lower.

Fig. 8 X-ray Diffraction Patterns2)

Intensity (a.u.)

α−Ferrite
(110)
(200)
(211)

AWT−1
AWT−2
AWT−3
Blast
treatment
Untreated
40

50

60
70
2Theta (deg.)

80

90

In the case of applying the surface
preparation to the corroded section of thetarget bridge and then adopting the coating specification for the corroded bridge,
it was necessary to reduce the amount ofadhered salt to the standard level (50 mg/m2) or lower by the use of 9 processesremoval of coarse rust using a hammer
and chipper and then repeating blasting
and water-washing about 4 times. Capitalizing on AWT, the total of 9 processes thus required by the conventionalsurface preparation method could successfully be reduced to one process andat the same time the high-speed removal of corrosion products and salts could
be attained.
The high applicability of AWT to thesalt damage-induced severely-corroded sections of steel structures has beenverified for several uncoated weathering
steel bridges, which has made clear that
not only steel substrate quality but construction efficiency can be significantly
improved by means of AWT over the useof blast treatment.
References
1] Subcommittee on Investigation and Research for Recovering Anticorrosion Performance of Steel Structures, Committee of Steel Structures, Japan Societyof Civil Engineers (JSCE): Issues andCountermeasure for Recovering Anticorrosion Performance of Steel Structures in Atmospheric Environment, Steel
Structural Series 30, Maruzen, 2019.
(In Japanese)
2] S. Park, S. Kainuma, T. Ikeda, Y. Toyota
and Y. Morita: Effect of Surface Characteristics of Abrasive Water-Jet Treatment on Corrosion Behavior of Carbon
Steel, Zairyo-to-Kankyo, Vol.72, No.5,
pp.169-178, 2023.

Fig. 9 Applicability of AWT to Severely-corroded Bolted Joint Collected from Weathering Steel Bridge

Peeled-off corrosion
product layer(a) AWT processing(b) After treatment

August 2023 Steel Construction Today & Tomorrow 8

Feature Article: Sound Maintenance of Steel Port Structures and Bridges (3)Integration of Monitoring andNumerical Modeling for Rapid PostEarthquake Assessmentby Tomonori Nagayama
Department of Civil Engineering,
the University of Tokyo

9 Steel Construction Today & Tomorrow August 2023

linear numerical model using small andmedium earthquakes and microtremors,nonlinear characteristics do not appear
until large earthquake motion occurs; it
is difficult to validate the model in nonlinear regions where structures may bedamaged unless a large earthquake occurs. Thus, there are limitations in accurately modeling the nonlinear characteristics and evaluating the degree ofseismic damage through simulation.
With recent advances in ICT andsensing technologies, it has become easier than ever before to measure seismic
motion and seismic responses1) (Fig. 1).
Therefore, a new approach to structural
damage assessment taking advantage ofseismic response measurement is being
studied. The approach could be more effective than the conventional frameworkof damage assessment based on seismic
intensity, seismic response spectrum, or
Fig. 1 An IoT Node to Measure
Acceleration Response
Continuously

forward simulation. In the case of damage assessment based on seismic motion, the uncertainty of the structure directly affects the damage assessment. In
the case of existing structures, the uncertainties may also be influenced by
the aging of the structure and earthquake motions experienced in the past.
On the other hand, if seismic response
measurements can be used, information
on structural uncertainties can be partially included in the measured seismic
responses, thus reducing the uncertainties in the seismic motion and structuralcharacteristics and providing a more reliable damage assessment.
The maximum response displacement, residual displacement, and hysteretic characteristics can be used as evaluation indices of the damage condition.
As shown in Fig. 2, the damage level can be estimated based on displace-Fig. 2 Displacement and Damage Level (Image)
LoadIntroduction
It is important to quickly assess the damage to bridges after an earthquake fromthe viewpoints of safety and economy.
When a large-scale earthquake occurs,
it is essential to assess the structural
damage to determine whether emergency vehicles can travel, to identify evacuation routes, and to prepare for recovery plans. On the other hand, when amedium-scale earthquake hits and temporarily halts the operation of railroads
or highways but does not cause damage
to the structures, the economic and social impacts can be mitigated by quickly assessing the condition of the structures and resuming their services assoon as possible. For example, it took
a long time for railroads to be put backinto service after the 2018 earthquake innorthern Osaka and the October 2021
earthquake in the Tokyo metropolitan
area. In Japan, which is an earthquakeprone country, the effect of reducing theduration of outages due to earthquakes
is not small.
Although seismic intensity information is helpful in estimating the overall
degree of damage in corresponding areas, it is difficult to estimate the damage
to individual structures from seismic intensity information alone because eachstructure has different dynamic characteristics. It is possible to assess the seismic response of individual structures byusing seismic response spectra or to estimate the degree of damage by simulation based on observed ground motions
and numerical models of each structure.
However, there are accuracy limitationsin the assessment due to uncertainties inthe structural models. Although the accuracy of the earthquake response estimation can be improved by updating theTomonori Nagayama: After obtaining his
Ph.D. at the University of Illinois at UrbanaChampaign, USA, he started as an assistantprofessor at the School of Engineering, theUniversity of Tokyo in 2007. He assumed his
current position as a professor at the University of Tokyo in 2022. His areas of expertisecover structural dynamics and monitoring.

Displacement

Displacement Estimation Using
Data Assimilation
A Kalman filter alternates between a
prediction step, which represents theforward analytical model in state space,and a filtering step, which uses observed data to correct the prediction.
Even if the prediction step is inaccurate due to model uncertainty, it can becorrected in the filtering step. However, if the model error is large, the correction by the filtering step is limited.
Therefore, a method that combines anordinary Kalman filter with optimization of the model parameters of a statespace model has been developed (Fig.
3)2). The target structure is represented

as a nonlinear single-degree-of-freedom(SDOF) system, and a trilinear model is
employed as the hysteresis characteristics (Fig. 4). The parameters of the trilinear model are identified using a genetic algorithm.
The target structure is a finite element model of steel bridge piers shownin Fig. 5, in which a kinematic harden-

ing law is set for the shell element. The
hysteretic characteristics of the pier, experienced during a large seismic motion, are shown in Fig. 6. The acceleration response of the finite element
model was treated as measurement data in order to evaluate the displacement.
On the other hand, when the displacement is estimated, a simple SDOF tri-

Fig. 3 Overview of the Displacement Estimation Method

Fig. 5 Target Steel Pier Model

Fig. 4 Trilinear Model Employedin the Estimation Algorithm
and Its Parameters
Force

Point mass: 981 kN

η2・Ke

α2

η1・Ke

α1
Ke

Disp.

Fig. 6 Nonlinear Hysteretic Characteristics of the Pier Model
8

×105

6
4
2
Force (N)ment. Direct monitoring of displacement is a possible method for estimating
displacement. A system that measures
the relative horizontal displacement at
the girder ends and alerts, when the displacement exceeds a threshold value,
has been developed and is considered
to be effective for rapid damage assessment. However, it is difficult to measure
the displacement of the bridge piers relative to the ground because the reference point for displacement measurement cannot be easily obtained. Instead,absolute displacement is expected to be
calculated by numerical integration ofground motion and response acceleration, and relative displacement is estimated by the difference between them.
The difficulty is that long-period components cannot be estimated due to integration errors. If a high-pass filter isapplied to reduce the integration error,
the residual displacement component isalso removed, making it impossible toevaluate the nonlinear response.
Therefore, a method to estimate displacement response has been developed by using data assimilation techniques such as Kalman filter where
ground motion and response acceleration are observed and analyzed with anumerical model. In the forward simulation, the response is calculated based
only on the ground motion and the numerical model. On the other hand, in thedata assimilation, response observation
can also be utilized. Even if the numerical model contains errors, response observations can be used to mitigate theeffects of modeling errors and estimate
state variables.
In this article, the method of displacement estimation using data assimilation is explained.

0
-2
-4
-6
-8
-0.2

-0.1

0

0.1

0.2

0.3

Disp. (m)August 2023 Steel Construction Today & Tomorrow 10

Displacement Estimation
Combining Data-driven Model
Identification and Data
Assimilation
While the aforementioned method represents the structure of interest as a
SDOF trilinear model, the hysteretic
characteristics of a real structure canbe more complex. Various hysteretic
characteristics models are employed in
the forward simulation. However, only Markov process models, i.e., nonlinear models with no hysteretic dependency, can usually be employed fordata assimilation employing the statespace model; the state-space equation
describes the time evolution based only on the current state variables. Hysteretic models cannot be easily dealt
with in the state space. Although the
Bouc-Wen model is available as a hysteretic model that can be expressed instate space, most of the hysteretic models used in the forward simulation cannot be employed in state space.
Therefore, a data-driven state-spacemodel3) is employed in this displacement estimation framework. A finite
element model with complex hysteretic characteristics is used to calculate
the responses to various earthquake
motions, and the input earthquake
motion and response acceleration areused to identify the state-space model. The target structure is the finite
element model of steel bridge piers
shown in Fig. 5. A forward simulationis performed with Takatori, Northridge, and JMA Kobe earthquake
waves as inputs, and the acceleration
velocity and displacement response
data are used as training data to identify the governing equations for thissystem in the state space. More than
100 polynomials are assumed as thebasis functions of the governing equation and their coefficients are identified (Fig. 8). As Fig. 9 shows the identified coefficients for all of the basis
function polynomials, the identified
11 Steel Construction Today & Tomorrow August 2023

Fig. 7 Estimated Displacement Time History

Displacement (m)Error in dot line

KF
KF＋Smoother
Reference

Time (s)Table 1 Displacement Estimation Error for Various Ground Motion
Ground Takatori
motion 800 gal
Max.
3.5%

Error

San Fernando
800 galRes. Max. Res.
3.2% 4.0% 6.6%

Northridge
800 galMax.
7.2%

Kobe JMA
800 galRes. Max.
7.0% 10.4%

Imperial valley
800 galRes.
Max.
17.9% 4.2%

Res.
0.0%

* Max: maximum estimation error, Res: residual displacement estimation error with respect to the
maximum displacement

Fig. 8 Identification of State-Space Model

Fig. 9 Sparse Regression Results of Polynomial Coefficients
2000

0
Coefficientlinear model with parameter uncertainties is used. The estimated displacementin Fig. 7 shows a good agreement withthe reference value including the residual deformation component. The accuracy of the displacement estimation
was evaluated by applying this method to various input earthquake motions,and it was found that the maximum displacement can be estimated accurately
as shown in Table 1.

-2000
-4000
-6000

0

20

40

60
Index

80

100

120

Conclusion
A method for estimating displacement
responses by using the seismic acceleration responses of structures has beenstudied. The method has become a reality with the recent development of
ICT and sensing technologies. Displacement estimation can be accurate
by fusing observation data and numerical structural models even for problems where the numerical models are
difficult to validate, such as the nonlinear response characteristics of real
structures. Although the earthquake response of bridge piers has been studied so far, it is necessary to estimate
the displacement of the entire bridge
system as well as to consider the nonlinear behavior of movable bearings tounderstand the seismic damage of real
infrastructure. Numerical analysis andmonitoring techniques are both becoming more and more sophisticated, andwe would like to realize a data-based
framework for rapidly understanding
earthquake damage by integrating thetwo into this data assimilation framework.

Fig. 10 Displacement Estimation Using Data-driven
State-Space Model and Nonlinear Kalman Filter

Disp. (m)parameters are sparse. The coefficients are estimated by sparse regression using the LASSO algorithm.
Forward simulation using the identified state-space model3) alone has limited estimation accuracy, and the deviation from the true value is not small,as shown in Fig. 10. Therefore, an Unscented Kalman filter (UKF), one of
the nonlinear Kalman filters, is applied
to the identified state-space model, sothat error in the forward simulation canbe compensated through the update
steps. The proposed method obtained
displacement estimates that were almost equal to the true values (Fig. 10).
Table 2 shows the maximum displacement estimation error and root-meansquare error for the training and test
data, indicating that the combinationof data-driven state-space model estimation and the Kalman filter enables
accurate displacement estimation.

Time (s)Table 2 Displacement Estimation Using the Data-driven State-Space Model
Identification
Ground motion
Training data
Test data

Takatori
Northridge
JMA Kobe
San Fernando
Imperial Valley

Maximum error (%)
Without UKF With UKF
15.1
1.4
22.6
3.7
5.1
1.3
10.1
2.0
6.6
3.0

sponse estimation based on measurementof acceleration response and nonlinear
hysteresis model, Journal of Structural Engineering A, JSCE，68，pp275288, 2022. https://doi.org/10.11532/
structcivil.68A.275

RMSE (%)
Without UKF
2.8
9.5
1.6
3.6
1.0

With UKF
0.4
1.5
0.4
1.2
1.1

3) Z. Lai, S. Nagarajaiah: Sparse structural system identification method for
nonlinear dynamic systems with hysteresis/inelastic behavior, Mechanical
Systems and Signal Processing, August 2018, 813–84

References
1) Siringoringo, D.M., Fujino, Y., Suzuki, M., Mehta, V.: Implementation ofWireless Sensor Network for Continuous Seismic Monitoring of Isolated
Cable-Stayed Bridge, Journal of Bridge
Engineering, 27(4), 2022.
2) Ishihara, K., Yang, Y., Nagayama, T.,
Nakamura, T., Su, D.: Displacement reAugust 2023 Steel Construction Today & Tomorrow 12

Special Topic

Strategy for the Construction
Industry in the Age of
Digital Transformation
by Kazuyoshi Tateyama
Professor, Ritsumeikan University
Kazuyoshi Tateyama: Dr. Kazuyoshi Tateyama is Professor,
Research Organization of Science and Technology, Ritsumeikan University.
He has taken on the research and development on the rationalization of
construction for many years and has engaged in many committees ofgovernments and academic societies, among which are the member ofi-Construction related committees of the Ministry of Land, Infrastructure,
Transport and Tourism and the chairperson of the committee for construction
robotics at the Japan Society of Civil Engineers.

13 Steel Construction Today & Tomorrow August 2023

less compared to the level in the 1990s,
the share accounted for by existing infrastructure maintenance and repair

that are more complicated and difficult than new infrastructure construction increased, and this trend is fore-

Fig. 1 Projection of Japanese Population1)
140

Population (million)

120
Total population

100
80

Decrease by 28.2%

60
40Working-age population (15~64 years old)

Actualnumber20
2010

Projection
2020

2030

2040

2050

2060

2070

Fig. 2 Trend of Infrastructure Investments2)
100
90

New
construction

Maintenance/
repairRatio of maintenance/
repair to total investments (%)

80
70
60
50

35 (%)
30
25
20

40

15

30

10

20
10
0

19
90
19
91
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
20
07
20
08
20
09
20
10
20
11
20
12
20
13
20
14
20
15
20
16
20
17
20
18

Social infrastructure investments (¥ trillion)

Emerging Tasks in theConstruction Industry
In terms of examining the future ofJapan, the projection for population
trends constitutes an extremely important point at issue. Fig. 1 shows a projection for the population transitionof Japan1). According to this projection, both the total population and theworking-age population (ages:15 to 64
years old) in Japan will continue to decline, and in 2050, about 30 years fromnow, it follows that the Japanese society will have to be supported with theworking age population with an estimated decrease to 71.5% that in 2020.
Currently, the construction industry is struggling to secure necessary
workers. In the future, we cannot help
but think that the construction industry will be forced into an increasingly difficult situation in securing theseworkers.
On the other hand, while the construction of new social infrastructure
will lose its momentum in line with adecreasing trend in the total population of Japan, the construction workrequired for maintaining existing infrastructure that supports the activities and lives of people will follow a
steady increase in the future. Fig. 2
shows a recent trend in investment into
new construction and the maintenanceand repair of social infrastructure in
Japan2). As can be seen in the figure,while investment into new infrastructure construction decreased to 60% or

50for past 20 years. On the other hand, inthe situation of annually decreasing infrastructure investment, the need to improve productivity has not been recognized in the construction industry due toits oversupply of labor force, and as a result the construction industry has lapsed

into the condition for productivity to decline rather than to rise.

Fig. 3 Annual Frequency of Heavy Rains (50 mm/hour or higher)3)500
Frequency per 1,300 spots

450

Trend of increase in heavy
rain frequency: 29.2/10 years

Five-year moving averagefrequency calculation

Long-term frequency trend

400
350
300
250
200
150
100
50
0
1975

1980

1985

1990

1995

2000 2005 2010 2015 2020
Source: Japan Meteorological Agency

5
4

5.61

17.8%
4.79

4.62

3
2
1
0

All
Manufac- Constindustries turingruction(a) Total annual wage

2.5

2

18.5%

1.5 1.73

2.05

1.94

1
0.5
0

Deaths during work (100 persons)

6

Total annual working hours (1,000 hours)

Fig. 4 Comparison of Working Conditions and Environments by
Industry2)

Total annual wage (¥ million)

cast to continue in the future.
In addition to the above, the construction industry faces the strict taskof how to deal effectively with natural disasters. Fig. 3 shows the annual
frequency of heavy rains (50 mm/h ormore) in Japan3). While there are years
with a lot of rains and others with little
rains, the rainfall trend shows that thefrequency of heavy rains exceeding 50
mm/h is steadily increasing year by year.
The natural disasters such as not only heavy rains but also earthquakes andvolcanic eruptions occurring in Japan are
becoming more serious.
In the situation of growing restrictions
imposed on securing necessary manpower and budget, the construction industry faces operating conditions in which
it must not only manage construction
works that are more complicated and difficult than ever such as the maintenance,
repair and renewal of existing infrastructure but must also tackle the strengthening of disaster countermeasures. As
the construction industry examines how
to cope with these problems employing
conventional or similar approaches, it isconsidered that the industry is falling into the critical condition of being unable
to stably supply infrastructure to society
in future years.
The working environment and condition of the construction industry thatbears these construction works are
steadily being improved, but its level ofwage and working hour is lower than thatof the all-industry average. In addition,
the number of deaths that occurred during work in the construction industry accounts for 1/3 that of all industries2). (Refer to Fig. 4)
In other words, it should be stated thatthe construction industry has not yet removed itself from hard working conditions-the so-called 3D (dirty, danger
and demeaning) conditions. It is thus
feared that the securement of human resources to support the construction industry will become more and more difficult in the future.
One of the reasons considered to be
attributable to the above is the slumping labor productivity of the construction industry. Fig. 5 shows the trend oflabor productivity by industry2). Since
the 1990s, the manufacturing industry
has extended wide-ranging approaches
represented by the introduction of automated and other new operating technologies into production lines, which has led
to notable productivity improvements

All
Manufac- Constindustries turingruction(b)Annual working hours

10
8
6

845
All
industries

4
2
0

269
Construction
31.8%(c) Deaths during
work

Fig. 5 Trend of Labor Productivity by Industry2)(Yen/person•hour)
6,000
5,000

All industries
Manufacturing industry
Construction industry

4,000
3,000
2,000

1996 97 98 99 2000 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15
Note: Labor productivity=Real gross value added (2011 price)/(Number of workers × Total annual working hours)
Source: Cabinet Office - Calculation of National Economy; Ministry of Public
Management, Home Affairs, Posts and Telecommunications - Survey ofLabor Forces; Ministry of Health, Labour and Welfare - Survey ofMonthly Work Statistics

August 2023 Steel Construction Today & Tomorrow 14

Towards the Improvement of the
Operating Structure of theConstruction Industry-Start of“i-Construction”
Given such conditions, the Ministry ofLand, Infrastructure, Land and Tourism has launched a new strategy called“i-Construction.” Its main aim is to reform the construction industry to a renewed one symbolized with three new
specified terms-“high wage levels, sufficient holidays and hopeful work” thatwill be realized through the substantial
improvement of productivity.
Specifically, with i-Construction, productivity is improved by capitalizing on
diverse approaches centered on three tactics: the aggressive application of ICT
in construction operations, which has
lagged behind that of the manufacturing industry; the standardization of con-struction work specifications to improveinefficiencies caused by mono-item andon-site construction operations; and yearround levelled execution of construction
operations vs. the order placements thatare significantly biased depending on theseason, and then “high wage levels, sufficient holidays and hopeful work” canbe realized employing these approaches.
The final goal is to renew the operating
structure of the construction industry bymaking the most of i-Construction4). In
order to securely attain the final goal, expectations are high for productivity improvement by, among others, the aggressive application of ICT technology.
In ICT-applied construction, the highwork efficiency and labor saving are realized by making the most of 3D datacross-sectionally in an entire construction process from surveying and design/

construction planning to inspection andmaintenance, through which the productivity is to be improved (refer to Fig. 6).
After six years since the introduction ofi-Construction, productivity improvement by means of ICT-applied construction has shown steady achievements, but
in the small to medium-scale projects ordered by local governments, the introduction has been delayed due to such
obstacles as high hardware/software introduction costs and the nurturing of necessary engineers who can use them.
Given such conditions, under the banner of digital transformation (DX), thesociety as a whole is undergoing majorchanges capitalizing on digital technologies. In light of this, it is considered that
i-Construction has reached the stage ofentering the next phase.

Conventional construction

Fig. 6 Promotion of i-Construction - Full Application of ICT

From 2D model to 3D model
Website of NPO Green EarthICT construction

Photo: Okumura Engineering Corp.

Website of FUKUICOMPUTER, Inc.

Interference checking of reinforcing bars
by the use of 3D model

15 Steel Construction Today & Tomorrow August 2023

Website of Komatsurental Dotou

From i-Construction to
Infrastructure DX
Digital transformation (DX) refers to
the concept in which a whole concept ofbusiness operations and commercial distribution is reformed by fundamentally transforming existing organizations/mechanisms, procedures and flows ofgoods and information with the optimum
use of high-speed internet, cloud services, AI and other advanced digital technologies and beyond the framework of
the improvement of business operations
efficiency and the promotion of laborsaving.
In this connection, the Ministry ofLand, Infrastructure, Transport and Tourism has advocated infrastructure DX andin March 2022 launched an action planfor its achievement5). The main aim is toradically transform what infrastructure
improvement should be beyond the conventional framework of ICT construction
systematized mainly by the use of 3D data and further by capitalizing on not only ICT and other diverse new technologies but also digital twins, automation,
AI, virtual and other advanced technologies. (Refer to Fig. 7)

It is the concept of the digital twin,among others, that attracts particular attention. Digital twin is a simulation technology with which data is collected in thereal world by making full use of diverse
sensors and IoT to connect them andthe real world is reproduced as faithfully as possible in the cyber space (virtual
space) by the use of this collected data.
In the world of the digital twin, simulations are carried out by freely changing
the scenarios and input conditions in the
cyber space (virtual space) to express real phenomena, and thus simulations canbe repeated many times. (Refer to Fig. 8)
In light of this, for example, the digital twin technology allows for the reproduction of various aspects by means ofsimulation-the damage assumed whenan unexpected disaster occurs, the timeand cost required for reconstruction andthe impact on nature. This enables extraction of the ideas for the state of an
ideal city that minimizes the impact ofdisasters and incorporation of these ideas
into urban planning practice. It also becomes possible to estimate in advancethe effects and costs involved in the in-Fig. 8 Image of Digital Twin
Cyber (virtual) space

Real-time acquisition of information by means of IoT
and simulation of the future by really reproducing it in cyber space

Digital twin

Real (physical) space

Production
Parts line
Worker ProductDuring production

Condition of productapplication
During application

Source of information: SoftBank Business Blog

Fig. 7 DX in the Field of Infrastructure - Action Plans5)

Improved service andapplication of infrastructure

Digital transformation in the field of infrastructure(transformation of operations, organizations, processes, culture/climate, ways of working)
3D indication of hazard maps (flood risk)

Concrete communication by means of
3D indication of risk information

Data on:

Prompt treatment of permission
for special-purpose vehicle transport
On-line, 24-hour treatmentof river use procedure

I-Construction (improved productivity at construction site)
ICT construction

3D surveying

Construction using ICT construction machinery

Full application of ICT in every construction process

Advanced improvement andmaintenance of infrastructureStandardization of concrete-work specifications

BIM/CIM

Map

Digital twin

Data on:

MLIT platform

Facility

ClimateEnergyTransport

Disasterprevention

Tie-up of digital data
Automated and autonomous operation of
construction machinery

Improved construction productivity by means
3D image ofof autonomous construction technology and operation underground space:
Efficientconsultation
Virtual construction site
and attendance
between land ownerand drilling company

Construction site experience in virtual reality,
realization of consultation of 3D design and construction

Construction by means of the combined use of fixed-form members

Distinction of images by the use of AI

Leveling of execution season

Number of levelled construction projects

Current number of construction projects

Settlement of 2-year government bond and contract authorization

Efficient design andconstruction of bothparties that receiveand place orders

Construction industry, construction machinery manufacturer,
construction consultant

Efficient judgment and detection oftransport irregularity by means of AI
Software and communication industry, service industry,
exclusive-use company

August 2023 Steel Construction Today & Tomorrow 16

troduction of new policies and technologies and thus select and implement
the most effective methods and tools
based on the digital twin. In the future,
it is forecast that infrastructure improvements will be based on digital twins andpromoted more efficiently.
From now on, the construction industry will reform its operation structure byintroducing various kinds of digital technology, but reckless introduction will notalways bring about needed effects. To
that end, it is required for the industry to
make efforts toward the effective introduction of digital technologies. In order
to meet such a requirement, lean management is attracting attention.
Introduction of Lean Management
In order to cope with soaring personnel expenses in the bubble economy period in the latter part of the 20th century, Toyota Motor Corporation worked
out the “TOYOTA Production System”
that systematically extracts operational
improvement measures on the production floor and promotes their practicalapplication. The Massachusetts Instituteof Technology systematized a new manufacturing system via research on the
TOYOTA Production System6), which
was named the “Lean Manufacturing
System.” Application of the Lean Manufacturing System filtered into not only the manufacturing industry but othergeneral industries, which led to the establishment of lean management.
The term “lean” means flab-free,compact or slim. In the lean manufacturing system, the total cost and lead timethrough an entire production process are
reduced by the optimized use of diverse
approaches-just-in-time in which necessary materials and parts are accurately secured whenever they are required;
maintaining a waste-free manufacturing
environment by means of the thoroughintroduction of five terms-sort, tidy,
cleaning, clean and discipline; the early detection of malfunctions; revealing
defects by means of visualization; and“KAIZEN” (continuous improvement).
Of these approaches, KAIZEN, whichis accepted as a universal term, is ameans to link the improvement measures
proposed by those working on the production floor to the enhanced efficiency
of an entire production process. It can besaid that KAIZEN is the most sought-after factor needed in reforming construction operations.
Various kinds of approaches are avail17 Steel Construction Today & Tomorrow August 2023

able in the promotion of lean management. In this connection, how to introduce lean management in the field ofconstruction and how to streamline construction operations by capitalizing onlean management are introduced below:
In the Lean Manufacturing System,
on-site works are classified into the following three elements to examine the enhancement of work efficiency and laborsaving to be attained by the use of thissystem:• Value-added work: Direct addition ofadded value required for the product;the essential work required to attain the
purpose of production• Accompanying work: Necessary work
but auxiliary work that does not add value to the product directly• Wasted work: Primarily non-applied, unnecessary work
Below, application of these three concepts to earthwork in road construction
is examined:• Value-added work

The aim of road earthwork is to structure
the filled-up ground and the roadbed prior to pavement. Accordingly, value-added work covers a series of construction

works from the drilling of the natural
ground to the transport of drilled earth,
the laying and levelling of transported
earth and the compaction of the roadbed(refer to Photo 1). In these construction
works, because the earth must be treated by the use of construction machinery,comparatively large-scale measures suchas the introduction of construction robots
are required for enhancing work efficiency and labor saving.
• Accompanying work
Accompanying work in construction include photographing of construction
conditions, surveying, document preparation and the measurement of finishedshapes. While these works do not fall into the building of filled-up ground androadbeds, they are necessary in completing the road construction. In general,these works require workforce and time,
and thus it can be said that it is easy to
improve work efficiency and labor saving by introducing ICT. Enhanced photographing efficiency by the use of electronic blackboards and cell phones andthe use of video in place of documents
can be cited as appropriate examples (refer to Photos 2 and 3).

Small-size electronic
blackboard
Photo 2 Application of small-size electronic
blackboard(Source of information: Okumura Engineering
Corporation and KENSETSU SYSTEM Co., Ltd.)

Photo 1 Value-added work in road earthwork

On-site input of
measurement
data
Photo 3 Treatment of measurement data

(Source of information: Okumura Engineering
Corporation and KENSETSU SYSTEM Co., Ltd.)• Wasted work
Wasted work such as the adjustment time
between processes and the waiting timerequired for inspection is a factor thatis basically not involved in construction, and it is thus necessary to shorten
these times as much as possible. In order to meet such a need, an approach thathas recently attracted attention is construction site-attendance technology employing video. Because the time required
for accessing remotely-located construction sites can be reduced by means of thistechnology, it is possible to broadly reduce construction time and also to carry out closer construction site control byincreasing the frequency of attendance atconstruction sites due to its simple applicability7). (Refer to Photo 4)
Fig. 9 shows an image of the improvement of working hours for constructionengineers brought about by reduced accompanying work and wasted work.
Capitalizing on the reduction of accompanying work and wasted work using diverse tools and devices or the construction of lightweight structures, they can
perform more activities with higher added value while having temporal allowance.
Towards a Construction Industry
in the DX Age
The construction industry is definitely
moving towards transformation. The industry has gained a great opportunity toestablish an operating structure that canovercome diverse problems forecast to
surely visit in the future. While society
is moving into an emerging trend of digital transformation (DX), the construction industry is currently in the midst ofan age in which it can capitalize on thistrend and thus promote its transformation.
In light of this, new transformation
efforts will be made in the industry. Itshould be realized, however, that they
will not always be successful. Some efforts may end in failure. Of great importance in this case is not to criticize such
failures, but to foster a culture of appreciating new challenges. It is also recommended that efforts should start withsmall initiatives for improvement, rather
than embarking on massive efforts fromscratch. If a small-scale attempt produces good results, the scope of the effort
should be expanded. Conversely, if theattempt produces little effect, an effective
way to proceed would be a commitment
to new alternatives by drawing reason-

Photo 4 Remote attendance and remote witnessed inspection using camera(Source of information: Kankyo Fuudo Techno, HORIGUCHI CORPORATION Co., Ltd. and IKEE Group)

Fig. 9 Image of Improvement of Working Hours
Working hours thus far applied
Value-added work

Accompanying work

Wasted work

Working hours in the future
Value-added work

able lessons from previous experiences.
Expectations are high for the construction industry to transform into a vibrant industry through such efforts.
References
1) National Institute of Population andSocial Security Research: Population
Projection of Japan 2017 (as of June
5, 2022)2) Japan Federation of Construction Contractors: Handbook for Construction Industry 2020
3) Japan Meteorological Agency: Longterm Change of Frequency of Short-term
Heavy Rains by Means of AmeDAS (asof June 5, 2022); https://www.data.jma.
go.jp/cpdinfo/extreme/extreme_p.html
4) Ministry of Land, Infrastructure, Transport and Tourism: i-Construction-Innovation of Productivity at Construction
Sites, Report of i-Construction Committee, 20165) Ministry of Land, Infrastructure, Transport and Tourism: DX in the Field of Infrastructure-Action Plans, March 2022

Accompanying work

Wasted work6) Y. Wakamatsu: “TOYOTA Style in theWorld: 4 Mechanisms”-Massachusetts
Institute of Technology and TOYOTA
Style, “All about TOYOTA Style: 192
Wise Ideas That Have Penetrated Among
Manufacturers in the World”-PHP Institute, Inc., 20157) K. Tateyama: i-Construction in Geotechnology-Towards the Next Phase, Journal of Japan Geotechnical Society, Vol.
68, No. 12, Ser. No. 755, pp. 1~4, December 2020

August 2023 Steel Construction Today & Tomorrow 18

JISF Operations

Conclusion of a Memorandum of Understanding
with Thailand on the Use of JIS Copyright and the
FY2022 Japan-Thailand Steel Cooperation Program

The Japan Iron and Steel Federation(JISF) implemented technical cooperation program in the steel sector for Thailand from 2008 to 2016 based on theintergovernmental agreement of the Japan-Thailand Economic Partnership
Agreement (JTEPA). Since 2017, JISF
has been providing the technical cooperation to the Thai steel industry as a cooperation program between JISF and the Iron
and Steel Institute of Thailand (ISIT) onan annual basis. The program mainly involves the standardization of steel product in Thailand, including formulation ofsteel product standards in Thailand andtechnical guidance to strengthen a quality inspection system of the testing laboratory owned by ISIT.
While the majority of the Thai Industrial Standards (TIS) for steel products are based on the Japanese Industrial
Standards (JIS), also by the trust fosteredthrough these cooperation program, JISF
has received a request from the Thai Industrial Standards Institute (TISI) to contact agreement to use the copyright of
JIS steel standards which are held by the
JISF’s Standardization Center. As a result, a Memorandum of Understandingon the use of JIS copyrights was signed
between JISF, TISI and ISIT in July 2022.
The conclusion of the MoU is expected
to increase the compatibility between TIS
and JIS standards for steel products andimprove market access for Japanese steel
products in Thailand. As the MoU includes ISIT publishing an English translation of the TIS steel standards based on
JISF’s request, it is also expected to facilitate the business activities of Japanese
steel companies in Thailand.
Under the steel technical cooperation
program in FY2022, JISF conducted atechnical guidance and seminar by theJapanese experts to the ISIT Testing Laboratory which covered analysis of coating
layer, appropriate use of the testing equipment and management system in Bangkok in January 2023 together with a seminar on JIS steel standards such as Steel
Sheets and Strips, Steel Pipes, Steel Bars,
Steel Sheet Piles and mechanical testingfor Metallic Materials for TISI officials
and ISIT member companies by the experts of JISF’s Standardization Center.

Lecture on “Seismic Evaluation of Steel Frames
Using High-Performance Steel” at SEAISI Event
At the SEAISI Steel Mega Event & Expo held in Kuala Lumpur, Malaysia on
November 17, 2022, Dr. Muslinang
Moestopo of the Indonesian Society of Steel Construction delivered alecture titled “Seismic Evaluation of
Steel Frames Using High-Performance
Steel.” The lecture was given as anachievement of the joint research by
the Japan Iron and Steel Federation,
the Japanese Society of Steel Construction and the Indonesian Society of Steel
Construction.
In this joint research, trial design
was performed on general-purpose
buildings to be constructed in earth-quake-prone Indonesia employing the
local standard and SN steel product, atypical high seismic-performance steel
from Japan, for which seismic evaluation was made. Specifically from the
aspect of the risk assessment of buildings in the event of earthquakes, it wasunderstood from the evaluation resultsthat building performance close to thedesign performance required for local
buildings could be secured by applying
SN steel with less deviations in yield
points and that building performance
to protect human lives and social assets
could be improved by capitalizing on
high-performance steel.

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 https://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

19

After the lecture, there was a Q&A
session with the participants, which suggested growing interest in high performance steel emerging in Southeast Asia.

© 2023 The Japan Iron and Steel Federation/Japanese Society of Steel Construction
Edited byCommittee on Overseas Market Promotion, The Japan Iron and Steel Federation
Chairman (Editor): Takashi Shibuya
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