• Journal of the Korean Society of Hazard Mitigation
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• v.3 no.1 s.8
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• pp.123-131
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• 2003

An experiment was carried out to investigate the mechanical behaviour of the circular hollow section reinforced concrete member with internal corrugated steel tube. A specimen, 50cm in diameter and 340cm in length, was made and tested by 3 points bending. The test load was increased slowly (quasi static) to the failure or unacceptable deformation. During the test, lateral displacement at mid point and longitudinal displacement of extreme fiber on compressive and tensile side of the specimen were measured. The measured data were analysed and compared with calculated results for the equivalent member without inserted corrugated steel tube. The comparison shows that the flexural strength and ductility of hollow section reinforced concrete members can be improved by inserting corrugated steel tubes inside.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.31-39
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• 2013

The ultimate behavior of high-strength concrete beams is studied with respect to their strength. Thirteen beams were analyzed and the results are presented herein. The variable parameters were the concrete's compressive strength, from 57 to 184 MPa and the amount of lateral torsional reinforcement, from 0.35 to 1.49%. The ultimate torsional strengths from tests were compared with those by this proposed theory and by the ACI code. As a consequence, The ultimate torsional strengths by this proposed theory show the better results than those by the ACI code.

• Journal of the Korean Society for Railway
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• v.12 no.4
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• pp.574-581
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• 2009

Displacement of the bridge and additional rail stress due to interaction between track and bridge should be limited to the design criteria. Interaction analysis was conducted to investigate the displacement and additional rail stress on CWR in railway bridge of conventional line. Particularly, various parameters affecting interaction phenomena were taken into account in the analysis to enhance an applicability. These parameters included configuration of structure, stiffness of deck and support, steel/concrete bridge, ballast/concrete track and FM/MFM type etc. The results were presented in the form of the design chart which could be useful in preliminary design of the bridge.

• Journal of the Korean Society for Railway
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• v.12 no.4
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• pp.565-573
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• 2009

Displacement of the bridge and additional rail stress due to interaction between track and bridge should be limited to the design criteria. Interaction analysis was conducted to investigate the displacement and additional rail stress on CWR in high speed railway bridge. Particularly, various parameters affecting interaction phenomena were taken into account in the analysis to enhance an applicability. These parameters included configuration of structure, stiffness of deck and support, steel/concrete bridge, ballast/concrete track and FM/MFM type etc. The results were presented in the form of the design chart which could be useful in preliminary design of the bridge.

• Journal of the Korean Society for Advanced Composite Structures
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• v.2 no.3
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• pp.25-29
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• 2011

Some laminate orientations have decreasing values of $D_{16}$, $B_{16}$, $D_{26}$ and $B_{26}$ stiffnesses as the ply number increases. For such plates, the fiber orientations given above behave as specially orthotropic plates and simple formulas developed by the senior author. Most of the bridge and building slabs on girders have large aspect ratios. For such cases further simplification is possible by neglecting the effect of the longitudinal moment terms(Mx) on the relevant partial differential equations of equilibrium. In this paper, the result of the study on the subject problem is presented.

• Journal of Korean Society of Steel Construction
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• v.15 no.1
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• pp.77-85
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• 2003

The lifting and lowering supports method makes up for the weak points in the classical method and provides makes construction economical effect to construction. The application of pre-compression to continuous steel box girder bridges makes it possible to reduce the amount of steel, the height of girders and consequently, the cost consequentlyof the bridges' construction by through the process of concrete filling- up and the lifting-lowering of the inner supports. The lifting and lowering supports method is apt to cause local buckling in the lower flange and web plates by due to the process of the lifting of the inner supports. Therefore iln this study, therefore, the possibility of local buckling could be decreased, in consideration of the lifting force and the buckling strength of stiffened plates, by increasing the number of longitudinal stiffeners and the installation of extended longitudinal stiffeners on the lower flange and the web plates in the range of positive moment.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.136-149
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• 2011

Large portion of the domestic bridges are slab bridges reflecting the geographical characteristic of the country, where exists lots of inclines and small winding brooks. Many of the slab bridges are damaged and superannuated as they become obsolete. Deterioration is accelerated when the traffic density becomes large and heavy vehicles pass frequently. A strengthening method for deteriorated slab bridges was studied in this work. The examined net-type strengthening method uses both longitudinal and transverse prestressing for strengthening. In this way, the deflection at the center of the slab can be better controlled, and consequently, the slab is more efficiently strengthened. Three slab specimens were fabricated for the experimental test and subjected to three different loading conditions, and the load bearing capacities and deflections of slabs were examined. Flexural stiffness of slabs increased by 30.7~107.3%, and deflection of slabs decreased by 27.6~52.2% after net-type strengthening. The net-type prestressing is efficient to the strengthening for the center of a slab, and its efficiency is also valid under eccentric loadings. Since extra prestress forces can be added in the future, if necessary, the net-type strengthening system is advantagous for the maintenance and repair of slab bridges.

• Journal of the Korean Geotechnical Society
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• v.35 no.5
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• pp.21-30
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• 2019

While the study of the shallow tunnel has been mainly on the longitudinal load transfer and horizontal surface conditions, the study of the ground behavior of shallow tunnel under the slope is not sufficient. Therefore, in this study on the ground behavior around a tunnel due to the sidewall deformation of shallow tunnel under the slope that is excavated in longitudinal direction, a scale-down model test has been performed. The model tunnel has the dimension of 320 mm wide, 210 mm high and 55 mm long with enough material strength in aluminum and the model ground has the uniform ground conditions by 3 types of carbon rods. The model test has been performed with the variables of slopes and the cover depths by controlling the tunnel sidewall deformation, and the change of sidewall-load, load transfer, ground subsidence was monitored and analyzed. According to the increase of the slope, the maximum ground subsidence increased by 20~39% compared to the horizontal surface. The load ratio increased by maximum 20% in the tunnel crown and decreased in sidewall according to the surface slope. The load transfer shows maximum 128% of increase at the cover depth of 1.0D, while at the 1.5D cover depth it shows non-critical difference from horizontal surface. The slope has major effects on load transfer at the cover depth of 1.0D.

• Journal of the Korea Concrete Institute
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• v.26 no.2
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• pp.109-116
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• 2014

The flexural behavior test of UHPC segmental box girder which has 160 MPa compressive strength and 15.4 m length was carried out. The effect of steel fibers in combination with reinforcing bars on improving the ductile performance of UHPC box girder was evaluated by comparing the flexural behavior of the UHPC segmental box girders made by the two kinds of mixing portion. The test variables are volume fraction of steel fibers and the arrangement of reinforcing bars. The behavior of UHPC box girder BF2 composed of 1% volume fraction of steel fibers and longitudinal reinforcing bars in web and upper flange with stirrup showed the similar ductile behavior with the girder BF1 composed of 2% volume fraction without stirrup in elastic stress region. But BF1 had the better stiffness and showed the more ductile behavior in inelastic stress region. Segmental interfaces of UHPC box girder have not any crack and slide until the final flexural collapse load.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.261-267
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• 2011

This study reveals the longitudinal vibration mechanism of tendon embedded in a prestressed concrete. The extensional and torsional displacements of the strand are coupled, and the applied prestress level of tendon affects not only axial rigidity but also torsional rigidity. Measuring the elastic wave velocity of tendon, the applied prestress level of tendon could be evaluated. This is because the elastic wave velocity is a function of extensional and torsional rigidity. Using the experimental results for the six prsteressed concrete beams with different prestress levels, the longitudinal vibration mechanism and the effect of prestress level have been examined. To estimate the system ridigities of tendon, a system identification algorithm has been newly developed. The estimated system rigidities have been compared with the available results of related previous study.