• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.27-33
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• 2010

In this study, a monotonic loading test to estimate structural capacity of 12 meter long full scale precast pre-stressed concrete beam specimen was performed with a 2,000 kN dynamic actuator. A couple of embedded steel plate was installed at the ends of the beam and specimens were connected to steel girder frame with high tension bolts. Nominal compressive strength of pre-stressed concrete beam and slab were 50 MPa and 24 MPa respectively. Two HD25 tensile steel reinforcements were welded on vertical plate of embedded steel plate. Pre-stressed concrete beam specimen was loaded by displacement control method with a certain loading pattern which was repeated loading and unloading with 10mm increment displacement. About 88.34%, 86.97% and 66.83% of displacement restoration ratios were evaluated at elastic, inelastic and plastic behavior region of specimen respectively.

• International Journal of Highway Engineering
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• v.1 no.1
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• pp.85-96
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• 1999

This study was performed to evaluate performance of polymer-modified asphalt mixtures and specially designed reinforcement techniques against reflection cracking of the asphalt pavement overlay. Selected polymers were used for asphalt modification and polyester fiber, a polypropylene film (vinyl) and a grid were used for mixture reinforcement. Using the asphalt mixture with optimum asphalt content, a slab was made and cut into two pieces of specimen. A layer of grid or vinyl was placed at the bottom of specimen to strengthen the pavement layer against crack. A repeated loading was applied to the asphalt mixture specimen which is Placed on a cement concrete with a pseudo-crack. Crack propagation under repeated loading was monitored and effectiveness of the devised crack retarding techniques was evaluated. From the test results. a significant retardation of mode I crack progress was monitored from some of the modified and reinforced asphalt mixtures.

• Journal of the Korea Concrete Institute
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• v.25 no.4
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• pp.447-455
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• 2013

In this study, reinforced concrete slabs with steps were experimentally studied to analyze their structural performance and to suggest reinforcing details in the step. Because the stepped slabs may behave very poorly in terms of bending strength, stiffness, deflection, cracking, etc., the study is aimed to suggest proper reinforcing details such that the same bending strength is obtained as that without steps. The bending strengths of 12 test specimens with a variety of different reinforcing detail types or other parameters were compared with each other. The specimen without any additional reinforcement in the step had a very low bending strength and significant damage, and the specimens with diagonal reinforcements in the step showed substantial early cracks, experienced hinging of the step, and had a substantial loss of the bending strength. In contrast, the specimens with a combination of U-bars, reversed U-bars, L-bars, and reversed L-bars performed very well and almost reached to 100% of the slab bending strength. The U-bars and reversed U-bars were effective in controling the diagonal cracks, while the L-bars and reversed L-bars were effective in preventing from yielding of slab reinforcement near the step.

• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.4
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• pp.434-440
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• 1983

For the determination of stress intensity factors, three methods have been used conventionally; the photoelastic method, the compliance method and the electrical resistance method. These methods, however, have common short coming upon experimental performance; the difficulty of cutting out sharp crack tips and arbitray crack forms similar to the practical one on the specimen. to eliminate this flaw, one of the author previously presented new methods, that is, for the determination of $K_{III}$ mode, the membrane analogy was applied and the slab analogy was used for the determination of $K_{I}$ and $K_{II}$ . The validity of this method was proved through the performance of a series of experiments of which theoretical solution are known.n.n.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03a
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• pp.149-152
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• 1999

The effect of initial orientation on the microstructure and texture evolution of two ferritic stainless steels was investigated. the columnar and equiaxed crystal specimens which were prepared from continuous casting slab were hot rolled annealed cold rolled and annealed respectively. The rolling and recrystallization textures at each process stage were examined by orientation distribution function (ODF) and electron back-scattered diffraction (EBSD); The observation showed that the orientation density of the $\alpha$-fibre of hot rolled band of columnar crystal specimen was more pronounced than that of the equaxed one at the center layer. Nevertheless the cold rolled textures of Type 430 steel have demonstrated a rather similar development . Compared to Type 430 steel the development of the $\alpha$-fibre in the center layer of Type 409L steel was much more pronounced. The relation between texture evolution and ridging behaviour has been discussed.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.799-804
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• 2002

The compatibility of concrete repairs is proposed by D. Cusson et al. and N. K. Emberson et al. But this is the general compatibility of concrete repairs. This study is actualized the general compatibility of concrete repairs on the flexural specimen under bending load. This study is obtained following results. 1) As a results of analysis for repair effects on failure shape, debonding between concrete and repairs, yielding load and ultimate/yielding ratio, the repair effects is ascertained that the repair R3 is much excellent than the repair R7, but on the other hand R7 is very high than R3 on the viewpoint of compressive strength, where repair R7, R3 is a product. 2) Therefore the compatibility of concrete repair proposed by D. Cusson et al. and N. K. Emberson et al. must be reanalyzed for structures types of column, beam, wall, slab et al.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.750-753
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• 2004

In this paper, experimental test on the full scale model of steel and concrete composite plate girder with prefabricated slabs under hogging moments was conducted cautiously and observed in order to study cracking in precast decks. Details of prefabricated slab transverse joints were determined from previous research. A test specimen was overhanging simple support beam, totally 28 meter length. Through the 4-point flexural test, the behaviour of the composite girder under hogging moments was observed. From the test results, crack development and crack widths were observed.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.525-530
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• 2002

This study is peformed to propose the slab deck for the composite bridge with two girders. Considering the characteristics of the long span and the construction conditions in korea, a cast-in-place PSC deck was proposed for that bridge. To examine structural behaviors and safety of the proposed PSC deck, two real scale partitions of deck(12m$\times$3.2m) were tested under the fatigue loading. In the test, the failure mode and behaviors of each specimen, and the ultimate load carrying capacity of the two-girder-bridge deck were identified. Generally, the failure of concrete bridge deck is caused by the local punching shear stress resulting from the moving wheel load. Even though its ultimate flexural capacity is sufficiently larger than the demand, it could be failed by the punching shear fatigue. Therefore, the fatigue safety of the proposed PSC deck should be checked.

• Structural Engineering and Mechanics
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• v.53 no.3
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• pp.455-479
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• 2015

This paper presents a numerical analysis of reinforced concrete slabs under missile impact loading. The specimen used for the numerical simulation was tested by the Technical Research Center of Finland. LS-DYNA, commercial available software, is used to analyze the model. The structural components of the reinforced concrete slab, missile, and their contacts are fully modeled. Included in the analysis is material nonlinearity considering damage and failure. The results of analysis are then verified with other research results. Parametric studies with different longitudinal rebar ratios, shear bar ratios, and concrete strengths are conducted to investigate their influences on the punching behavior of slabs under the impact of a missile. Finally, efficient designs are recommended.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.332-334
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• 2009

This thesis puts forward a suggestion of measuring inner crack and center segregation in steel processing by using scanner and image processing with sulfur printer. This is a system to scan according to the program, to choose the size of the specimen and to press the 'Measurement' button, come to a check result, to send the result to the server, and to save the data and check the measurement result in web. To sum up, there are three points in this system.