• Steel and Composite Structures
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• v.45 no.1
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• pp.101-118
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• 2022

The seismic performance of the reinforced concrete (RC) special-shaped column to steel beam connections with steel jacket used in the RC column to steel beam fabricated frame structures was investigated in this study. The three full-scale specimens were subjected to cyclic loading. The failure mode, ultimate bearing capacity, shear strength capacity, stiffness degradation, energy dissipation capacity, and strain distribution of the specimens were studied by varying the steel jacket thickness parameters. Test results indicate that the RC special-shaped column to steel beam connection with steel jacket is reliable and has excellent seismic performance. The hysteresis curve is full and has excellent energy dissipation capacity. The thickness of the steel jacket is an important parameter affecting the seismic performance of the proposed connections, and the shear strength capacity, ductility, and initial stiffness of the specimens improve with the increase in the thickness of the steel jacket. The calculation formula for the shear strength capacity of RC special-shaped column to steel beam connections with steel jacket is proposed on the basis of the experimental results and numerical simulation analysis. The theoretical values of the formula are in good agreement with the experimental values.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.54
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• pp.285-307
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• 2012

This study analyses the transformation of Asian steel trade and the change of corporate strategy. The purpose of this paper is to examine the circumstances of Asian steel industrial policies, and considering the feature of each nation's steel industrial policies, and the effect of the corporate strategy. In China, mighty steel productive capacity had already formed under original planned economy and industrial policy. In 2003, crude steel production have exceeded 220 million ton in China and that is 23.2% of the steel production share in the world. On the other hand, not only the amount but also the quality becomes an important point in the steel industry in the future. I consider, on researching Asian steel industry, it is important to build up partnership in Korea and Japan for achieve strategic alliance in the steel industry policies and understanding the change of corporate strategy.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.48-53
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• 2003

The steel slag, a by-product which is produced on the process of manufacturing steel by refining pig iron is mainly used as road materials after aging it. It is necessary to age steel slag for long time in air because the reaction with water and free-CaO in steel slag could make the volume expanded. Due to this reason it prevents steel slag from being used as aggregate of concrete. But steel slag used in this study is controled by a air-jet method which rapidly cools substance melted at a high temperature. Rapid cooling prevents from generating of free-CaO in steel slag. In this study, it was investigated that steel slag manufactured by air-jet method affects on concrete in the freezing and thawing. As results of this study, concrete mixed with steel slag was worse in the freezing and thawing than concrete mixed with sand in spite of using air entraining agent. To obtain durability of concrete in the freezing and thawing, it is desirable to mix 50% of steel slag in concrete per unit weight of volume.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.210-214
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• 1995

Research on concrete-filled steel columns has been conducted. It is also well known that the load and deformation capacity of concrete-filled steel columns are considerable larger than those of widely used reinforced concrete columns and steel encased concrete columns because the concrete core in the steel is confined laterally by the steel. But, most of these works focused on columns with strength enhancement by the confinement effect, so that no local buckling prevented by the concrete. columns because the concrete core in the steel is confined laterally by the steel. But, most of these works focused on columns with strength enhancement by the confinement effect, so that no local buckling prevented by the concrete. This paper, therefore, presents on the stress-strain relation of a concrete filled rectangular steel tube under axial compression. As the results, the axial load verse average axial strain relationship of concrete-filled rectangular steel columns were very stable. The small B/t ratios in concrete-filled rectangular steel columns aren't affected prevention of local buckling but strength enhancement by confinement effect.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.6
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• pp.736-743
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• 2007

Laser welding has the advantage of high welding speed and Provides low heat distortion Thus laser welding is a very attractive process for joining thin steel sheet and surface treated steel sheet. And the major item in market for surface treated steel sheet is zinc coated steel. However. the laser welding of zinc coated steel is very difficult because of its low boiling point. Compared with zinc, on the other hand, aluminum has a high boiling point. Thus, laser weldability of aluminized steel is better than that of zinc coated steel. Moreover aluminized steel sheet is a material with excellent heat resistance, thermal reflection and corrosion resistance. The results of laser weldability of the aluminized steel for the full penetration welding will be described in this paper We focused on the investigation of the phenomenons caused by coating condition and behavior of aluminum in weld.

• Corrosion Science and Technology
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• v.9 no.1
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• pp.16-19
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• 2010

Application of ultra-high strength steel sheets is one of the most important methods to satisfy weight reduction and crash safety of a vehicle. Recently, there has been a trend to apply ultra-high strength steel sheets widely to underbody parts in which corrosion resistance is required. In this work, ultra-high strength galvannealed steel sheets with a tensile strength of 1180 MPa were developed. Newly developed ultra-high strength galvannealed steel sheets have comparable properties, such as mechanical properties, spot weldability, crashworthiness and adhesion of coatings, to conventional steel sheets.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.144-145
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• 2006

A developed molybdenum hybrid-alloyed steel powder is based on a molybdenum prealloyed steel powder to which molybdenum powder particles are diffusion bonded. The sintered compact made of this powder has a finer pore structure than that of the conventional molybdenum prealloyed steel powder, because the ferritic iron phase $({\alpha}-phase)$ with a high diffusion coefficient is formed in the sintering necks where molybdenum is concentrated resulting in enhanced sintering. The rolling contact fatigue strength of the sintered and carburized compacts made of this powder improved by a factor of 3.6 compared with that of the conventional powder due to the fine pore structures.

• Structural Engineering and Mechanics
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• v.87 no.1
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• pp.69-84
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• 2023

The use of steel pipe dampers (SPD) as fuses or interchangeable elements in the steel moment-resisting frames (MRF) is one of the newest methods for improving seismic performance. In the present study, the performance of steel pipe dampers in MRF has been investigated. Evaluation of MRF with and without SPD models were performed using the finite element method by ABAQUS. For validation, an MRF and MRF with steel pipe dampers were modeled that had been experimentally tested and reported in previous experimental research and a good agreement was observed. The behavior of these dampers in frames of 3, 6, and 9 stories was studied by modeling the damper directly. Nonlinear time history dynamic analysis was used. It was observed that by increasing the number of stories in the buildings, steel pipe dampers should be used to perform properly against earthquakes. The installation of steel pipe dampers in steel moment-resisting frames shows that the drift ratio between the floors is reduced and the seismic performance of these frames is improved.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.5
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• pp.381-388
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• 2012

In this study, a seismic risk analysis performed for an applicability assessment of steel fiber in containment structures. Steel fiber can increase tensile properties of concrete structures moreover compressive and shear capacity. But many of researches about steel fiber reinforced concrete structures are now only focused in axial load condition. Also it is very difficult to find an effort for application to containment structures in NPP. Therefore, in this study, seismic fragility assessment for a steel fiber reinforced concrete containment structure. As a result, a seismic fragility capacity improved according to increase of shear and ductile capacity of concrete. In the case of 1.0% of steel fiber volume fraction, seismic capacity increases as 10%. But very limited previous experimental results were used in this study, so various element tests were needed for more accurate investigation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.35-44
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• 2017

In this study, steel fiber-reinforced concrete beams with ordinary steel reinforcements, that are below minimum steel reinforcement amount specified in domestic concrete structure design code, were tested in flexure until failure. Steel reinforcement ratio considered were 44%, 66%, 78% and 100% of the minimum steel reinforcement. Considered steel fiber volume fractions were 0.25%, 0.50%, 0.75% and 1.00%. In results, it is confirmed that steel fibers greatly improve crack performance. Also, the steel fibers contributed to increment in yield load not in ultimate load. But the increment was not greater than the reduction by steel reinforcement reduction. The use of steel fibers in RC beams lightly reinforced below the minimum reinforcement ratio specified design code reduced ductility greatly. Consequently, steel reinforcement ratio in steel fiber-reinforced beams lightly reinforced below the minimum steel reinforcement should be increased in order to enhance proper ductility.