• Journal of Navigation and Port Research
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• v.33 no.1
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• pp.27-33
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• 2009

Estimation of the buckling and ultimate strength of a continuous stiffened plate subjected to combined transverse compression and lateral pressure is of high importance to ensure the safety of ship structures, particularly for the bottom plating under a deep draft condition For example, bottom plating of bulk carriers is subjected to transverse thrust caused by the bending of double bottom structure and the direct action of pressure on the side shells. Most of experimental tests, theoretical approach and numerical researches have been performed on the buckling and ultimate strength behaviour of plates or stiffened plates under combined compression and lateral pressure. With regard to stiffened panels, however, most of studies have been concerned with the load conditions of combined longitudinal thrust and lateral pressure, while fewer studies have been performed for the combined transverse thrust and lateral pressure. In addition, the previous researches are mainly concerned with an isolated rectangular plate simply supported along the all edges, whereas actual ship plating is continuous across the transverse frames and heavy girders. In the present paper, a series of elastoplastic large deflection FEA on a continuous stiffened plate is performed and then clarify the characteristic of collapse mode and explain the effect of transverse compression.

• Journal of Korean Society of Steel Construction
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• v.18 no.3
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• pp.301-310
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• 2006

If arches are braced by lateral restraints, the ultimate strength of arches is determined by in-plane buckling and plastic bending collapse. This paper is conducted to investigate the in-plane nonlinear elastic and inelastic buckling behavior and the strength of fixed parabolic arches in uniform compresion, as well as to study arch behaviors against non-uniform in-plane compression and bending. As shown by the results, the limit slenderness ratio is suggested to classify the bucklingmode. Buckling strength of fixed parabolic arches under uniform compresion are evaluated using buckling curve for a straight column. Finally, an interaction e quation for arches under combined axial compresion and bending action is proposed.

• Journal of the Korean Ceramic Society
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• v.52 no.1
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• pp.13-18
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• 2015

The fabrication method used for mineral hydrate is similar to that of ALC (autoclaved lightweight concrete), but the fabrication of normal slurry with a considerable amount of a foaming agent is difficult due to material separation and collapse of the slurry. Therefore, the development of fabrication methods for normal slurry is necessary. The final product, mineral hydrate insulation, has excellent thermal properties but poor strength characteristic given the many pores. In this study, in order to fabricate normal slurry, the viscosity and foaming time of the slurry were controlled. The mixing ratio of the starting material and the polypropylene fiber was controlled to improve the strength. Mineral hydrate with polypropylene fiber showed a higher strength than that without this type of fiber. Specifically, the compressive strength of mineral hydrate with 2% polypropylene fiber added to it was more than 40% higher than that without the fiber.

• Journal of Korea Foundry Society
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• v.23 no.5
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• pp.235-243
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• 2003

The collapsibility of sodium silicate-bonded sands mixed with the L.D converter slag powder to form a hardener were investigated. Five to six percent sodium silicate on the basis of silica sand and 30-40% L.D converter slag powder on the basis of sodium silicate, were mixed and the compressive strength, surface stability index(SSI), bench time, retained strength of the standard sand specimens were measured. The properties were similar to those of general inorganic bonded self-setting molds. The compressive strength and surface stability index were increased and the retained strength and bench time were decreased with increased amount of the L.D converter slag powder. The retained strength of sodium silicate-bonded self-setting molds with the L.D converter slag powder were decreased than $CO_2$ sand molds. The collapsibility of sodium silicate-bonded self-setting molds with the L.D converter slag powder were superior in comparison with $CO_2$ sand molds. The L.D converter slag powder could be used as hardener and collapse agent for the sodium silicate-bonded self-setting molds.

• Journal of The Korean Digital Architecture Interior Association
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• v.12 no.4
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• pp.59-66
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• 2012

This study is interested in identifying the effectiveness of alkali-activated fire protection material compounds including the alkali-activator such as potassium hydroxide, sodium silicate and fly ash as the fire resistant finishing materials. Also, this paper is concerned with change in compressive strength and pore structure of the alkali-activated fire protection material at high temperatures. The testing methods of fire protection materials in high temperature properties are make use of TG-DSC and mercury intrusion porosimetry measurements. This study results show that compressive strength is rapidly degraded depending on a rise of heating temperature. Porosity showed a tendency to increase irrespective of specimen types. This is due to both the outbreak of collapse of gel comprising the cement and a micro crack by heating. However, alkali-activated fire protection material composed of potassium hydroxide, sodium silicate and fly ash has the thermal stability of the slight decrease of compressive strength and porosity at high temperature. These thermal stability is caused by the ceramic binding capacity induced by alkali activation reaction by the reason of the thermal analysis result not showing the decomposition of calcium hydrate.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.421-424
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• 2006

This study, in order for perceiving the mechanical attribute followed by the explosive spalling of high strength concrete material under high temperature and evaluating capacity of endurance of material, targets understanding capacity of endurance of material such as explosive spalling in high temperature, temperature by thickness of clothing, transformation extent, transformation speed and displacement, stocking the maximum load based on the Allowable Stress Design Method. As a result of experimenting the explosive spalling attribute of high strength concrete material, the one possibly causing serious damage is the 50 MPa concrete. In all aspects of 60 MPa concrete, explosive spalling happens. Especially, it is hazardous enough to reveal all the iron bar. All explosive spalling is intensively concentrated on the surface of concrete for the first $5{\sim}25$ minutes, which urges for the explosive spalling protection action. As a result of evaluating the structural safety by the transformation of high strength concrete, while beam assures the fire safety meeting regulation, 60 MPa shows the dramatic increase of transformation, which only counts 84% of safety. In a column, both the concrete exclusion and excessive explosive spalling are concentrated upper part of column, which brings about the dramatic transformation, so it only meets the 50% of safety regulation. Likewise, in 80, 100 MPa concrete which was never experimented considering the condition of domestic structural endurance stocking devices, the faster collapse is expected.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.509-512
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• 2003

Dehydration and micro crack thermal expansion occur in cement hydrates of concrete structure heated by fire for a long time. The characteristic of concrete exposed to high temperature can be analyzed from distribution of porosity and pore size. Porosity showed a tendency to increase irrespective of specimen types. This is due to both the outbreak of collapse of gel comprising the cement and a micro crack by heating. Porosity did not affect the variety of specimen and increased with the same tendency throughout every specimen. In addition, the deteriorate of compressive strength resulted from increase in porosity

• Steel and Composite Structures
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• v.21 no.3
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• pp.589-604
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• 2016

Kenya has recently experienced worrying collapse of buildings during construction largely attributable to the poor quality of in-situ concrete and poor workmanship. The situation in the country is further compounded by rapid deterioration of infrastructure, hence necessitating the development of alternative structural systems such as concrete filled unplasticized poly vinyl chloride (UPVC) tubes as columns. The work herein adds on to the very limited and scanty work on use of UPVC tubes in construction. This study presents the findings of experimental and analytical work which investigated the structural response of composite concrete filled UPVC tubes under compressive load regime. UPVC pipes are cheaper than steel tubes and can be used as formwork during construction and thereafter as an integral part of column. Key variables in this study included the strength of infill concrete, the length to diameter ratio (L/D) of the plastic tube, as well as the diameter to thickness ratio (D/2t) of the plastic tube. Plastic tubes having varying diameters and heights were used to confine concrete of different strengths. Results obtained in the study clearly demonstrate the effectiveness of UPVC tubes as a confining medium for infill concrete, attributable to enhanced composite interaction between the UPVC tube and infill concrete medium. It was determined that compressive strength of the composite column specimens increased with increased concrete strength while the same decreased with increased column height, albeit by a small margin since all the columns considered were short columns. Most importantly, the experimental confined concrete strength increased significantly when compared to unconfined concrete strength; the strength increased between 1.18 to 3.65 times the unconfined strength. It was noted that lower strength infill concrete had the highest confined strength possibly due to enhanced composite interaction with the confining UPVC tube. The study further proposes an analytical model for the determination of confined strength of concrete.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2007.12a
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• pp.25-26
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• 2007

Ship are typically thin-walled structures and consists of stiffened plate structure by purpose of required design load and weight reduction etc. Also, a hull structural characteristics are often used in structures with curvature at deck plating with camber, side shell plating at fore and aft parts and bilge circle parts, It have been believed that these structures can be modelled fundamentally by a part of cylinder. Structural component with curvature subjected to combined loading regimes and complex boundary conditions, which can potentially collapse due to buckling. Hence, for more rational and safe design of ship structures, it is crucial importance to better understand the interaction relationship of the buckling and ultimate strength for cylindrically curved plate under these load components. In this study, the ultimate strength characteristic of curved plate under combined load(lateral pressure load + axial compressive load) are investigated through using FEM series analysis with varying geometric panel properties.

• Journal of Korean Society of Steel Construction
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• v.27 no.3
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• pp.281-288
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• 2015

Seismic members like damper do not have any treatment of preventing story stiffness reduction after elastic yielding of stories causing story collapse. This paper suggests a method able to prevent story stiffness reduction using high-strength steel. This paper suggests these also : (1) High-strength steel stud column reinforcing story stiffness reduction until story drift 0.02rad can be designed in small area without adjusting layout. (2) Suggested seismic member installing at lowest level shows effects to preventing deformation concentration under huge seismic waves.