• Journal of Ocean Engineering and Technology
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• v.19 no.1 s.62
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• pp.71-76
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• 2005

This paper describes basic structural design for the large floating crane barge of fixed undulation type. Structural analysis was performed separately after dividing the floating crane into two parts, The crane part was composed of jib boom, back stay and back tower and the barge part supported the crane part. The structural strength for jib boom structural members are in compliance with JIS B 8821 and scantling of all barge structural members are in compliance with the requirement of KR (Korean Register of Shipping) Steel Barges and Rules for Classification of Steel Ships. For the structural analysis of large floating crane, MSC/NASTRAN and MSC/PATRAN software were used.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.42-47
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• 2004

This paper describes basic structural design for the large floating crane barge of fixed undulation type. Structural analysis is performed to divide two parts because crane barge is composed two parts, crane part of jib boom back stay and back tower and barge part to support crane part. The structural strength for jib boom structure members are in compliance with JIS B 8821 and scantling of all barge structural members are in compliance with the requirement of KR (Korean Register of Shipping) Steel Barges and Rules for Classification of Steel Ships. For the structural analysis of large floating crane, MSC/NASTRAN & MSC/PATRAN software is used.

• Journal of the Korean institute of surface engineering
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• v.49 no.1
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• pp.32-39
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• 2016

In this study, Al and Zn arc thermal spray coatings were carried out onto the substrate of SS400 steel to improve corrosion resistance and durability of hull structural steel for ship in marine environment. Therefore cavitation-erosion test was conducted to evaluate the durability of painted and thermal spray coated specimens. And then the damaged surface morphology and weight loss were obtained to compare with each other, respectively. As a result, the painted specimen was the poorest cavitation resistance characteristics because surface damage behavior appeared to be exfoliated in bulk shape during the cavitation experiment. And Zn thermal spray coating layer presented the significant surface damage depth due to relatively low surface hardness and local cavitation damage tendency. On the other hand, as a result of the weight loss analysis, the painting layer presented the poorest cavitation resistance and the Al thermal spray coating layer relatively showed the best results after cavitation experiment.

• Corrosion Science and Technology
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• v.6 no.3
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• pp.120-127
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• 2007

In any developing nation major investment goes for infrastructure and it is not exception in India. Good numbers of buildings, bridges, shopping malls, car parks etc. are coming up with steel for sustainable development. Thus protecting the structures from corrosion are the challenges faced by professionals for all types of steel structures. About 3% of GDP is accounted for loss due to corrosion. To combat this up to date corrosion map is called for as the country has wide variation of climatic zones with vastcoastline. Logically organic paint system can be prescribed based on the corrosion rate on bare steel with respect to environment. Present paper will emphasis on the study conducted on two types of structural steel coated with organic paint located in twomarine environment having been exposed for three years, Test coupons made from steels both bare and coated are deployed at two field stations having marine (Digha) and industrial marine (Channai) environments. Various tests like AC impedance DC corrosion, polarisation, salt spray test, $SO_2$ chamber and Raman spectroscopy were carried out both in laboratory on fresh as well as coupons collected from exposure sites. Rust formed on the bare and scribed coated coupons are investigated. It is found that normal marine environment at Digha exhibits higher corrosion rate than polluted marine environment in Channai. Rust analysis indicates formation of ${\propto}$-FeoOH protects or reduces corrosion rate at Channai and formation of non-protective ${\gamma}$-FeoOH increases corrosion rate at Digha. The slower corrosion rate in Channai than at Digha is attributed due to availability of $SO_2$, in the environment, which converts non‐protective rust ${\gamma}$-FeoOH to protective rust ${\propto}$-FeoOH. While comparing the damage on the coated panels it is found that low alloy structural steel provides less damage than plain carbon steel. From the experimentations a suitable paint system specification is drawn for identical environments for low medium and high durability.

• Structural Engineering and Mechanics
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• v.82 no.2
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• pp.133-149
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• 2022

This study investigates the resistance of sustainable ultra-high performance concrete (UHPC) on steel reinforcement corrosion. For enhancing the sustainability of UHPC, concrete mixes were prepared with ordinary Portland cement main binder, and mixes with moderate to high percentages of blast furnace cement (CEM III), fly ash (FA), and slag cement as partial replacements of the full quantity of the used cement. Linear polarization resistance technique was employed to estimate the electrochemical behavior of the concrete specimens. Results showed that the compressive strength and the resistance of steel to corrosion in marine environments can be enhanced by improving the sustainability of UHPC through incorporation of CEM III, FA, and slag cement. FA replacement of up to 50% with the addition of 15% SF content produced better compressive strength and steel corrosion resistance than slag cement whether with the use of ordinary Portland cement or blast furnace cement as the main binder.

• Journal of Welding and Joining
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• v.19 no.2
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• pp.182-190
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• 2001

A marine structural material was well known to have high tensile strength, good weldability and proper corrosion resistance. Cu-containing high strength low alloy(HSLA) steel was recently developed for their purposes mentioned above. And the steel is free about preheating for welding, therefore it is reported that shipbuilding cost by using it can be saved more or less. However the marine structural materials like Cu-containing HSLA steel are being generally adopted with cathodic protection method in severe corrosive environment like natural sea water but the high strength steel may give rise to Hydrogen Embrittlement due to over protection at high cathodic current density for cathodic protection. In this study Cu-containing HSLA steel using well for marine atructure was investigated about the susceptibility of Hydrogen Embrittlement as functions of tensile strength, strain ratio, fracture time, and fracture mode, etc. and an optimum cathodic protection potential by slow strain rate test(SSRT) method as well as corrosion properties in natural sea water. And its corrosion resistance was superior to SS400 steel, but Hydrogen Embrittlement susceptibility of Cu-containing HSLA steel was higer than that of SS400 steel. However Hydrogen Embrittlement of its steel by SSRT method was showed with pheonomena such as decreasing of fracture time, strain ratio and fracture mode of QC(quasi-cleavage). Eventually it is suggested that an optimum cathodic protection potential not presenting Hydrogen Embrittlement of Cu-containing of HSLA steel by SSRT method was from-770mv(SCE) to - 900mV(SCE)under natural sea water.

• International Journal of Highway Engineering
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• v.15 no.1
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• pp.1-9
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• 2013

PURPOSES: The purpose of this study is to evaluate physical properties, durability, fatigue resistance, and long-term performance of poly-urethane concrete (PU) which can be possible application of thin layer on long-span orthotropic steel bridge and to check structural stability of bridge structure. METHODS : Various tests of physical properties, such as flexural strength, tensile strength, bond strength and coefficient of thermal expansion tests were conducted for physical property evaluation using two types of poly urethane concrete which have different curing time. Freezing and thawing test, accelerated weathering test and chloride ion penetration test were performed to evaluate the effect of exposed to marine environment. Beam fatigue test and small scale accelerated pavement test were performed to assess the resistance of PU against fatigue damage and long-term performance. Structural analysis were conducted to figure out structural stability of bridge structure and thin bridge deck pavement system. RESULTS: The property tests results showed that similar results were observed overall however the flexural strength of PUa was higher than those of PUb. It was also found that PU materials showed durability at marine environment. Beam fatigue test results showed that the resistances of the PUa against fatigue damage were two times higher than those of the PUb. It was found form small scale accelerated pavement test to evaluate long-term performance that there is no distress observed after 800,000 load applications. Structural analysis to figure out structural stability of bridge structure and thin bridge deck pavement system indicated that bridge structures were needed to increase thickness of steel deck plate or to improve longitudinal rib shape. CONCLUSIONS: It has been known that the use of PU can be positively considered to thin layer on long-span orthotropic steel bridge in terms of properties considered marine environment, resistance of fatigue damage and long-term performance.

• Journal of Welding and Joining
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• v.25 no.4
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• pp.72-78
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• 2007

Aluminized steel sheet is a material with excellent heat resistance, thermal reflection and corrosion resistance. It has wide applications, owing to its low cost and excellent performance, in the petrochemical industry, electric power and other energy conversion systems, etc and has attracted the attention of many investigators. But the welding of aluminized steel sheet has a problem of decreasing tensile-shear strength, caused by mixed Al in the weld. This study investigated behavior of Al and its structural properties to resolve this problem. Several analysis equipment(SEM, EDX, EPMA) were used to investigate Al element in the weld. Also microhardness tester and TEM equipment were used to find the intermetallic compound. As a result of this study, Al-rich zones existed in the weld and Fe-Al intermetallic compounds were found in these zones. At the same time, the weldability of aluminized stainless steel sheet was investigated and compared with that of aluminized steel sheet. Although there is a difference between the base metal of the low carbon steel and stainless steel, it is interpreted that a behavior of Al element in the weld is similar.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.5
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• pp.712-720
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• 1998

The effect of H2:N2 gas ratio on the case thickness hardness and nitrides formation in the sur-face of SCM440 machine structural steel have been studied by micro-pulse plasma process. The thickness of compound layer increased with the increase of nitrogen content in the gas com-position. The maximum thickness of compound layer the maximum case depth and the maximum surface hardness were about 15.8${\mu}m$, 400${\mu}m$ and Hv765 respectively in the nitriding condition of 250Pa and 70% nitrogen content at $520^{\circ}C$ for 7hrs. Generally only nitride phases such as ${\'{\gamma}}$($Fe_4N$)$\varepsilon(Fe_2}{_3N}$ phases were detected in compound and diffusion layer by XRD analysis. The amount of $\varepsilon(Fe_2}{_3N}$ phase increased with the increase of nitrogen content. The relative amounts and kind of phases formed in the nitrided case changed with the change of nitrogen content in the gas composition.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.348-356
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• 2003

Recently, the buckling is easy to happen a thin plate and High Tensile Steel is used at the steel structure and marine structure so that it is wide. Especially, the post-buckling is becoming important design criteria in the ship structure to use especially the High Tensile Steel. Consequently, it is important that we grasp the conduct post-buckling behaviour accurately at the stability of the ship structure or marine structure. In this study, examined closely about conduct and snap-through behaviour after initial buckling of thin plate structure which apply compressive load according to various kinds initial deflection shape under all edges simply supported condition that make by buckling formula in each payment in advance rule to place which is representative construction of hull. Analysis method is F.E.M in used ANSYS program and complicated nonlinear behaviour to analyze such as secondary buckling with snap-through behaviour. Nonlinear buckling control is applied between newton-raphson method and arc-length method in this study