• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.3
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• pp.178-186
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• 2005

In this study, the PSC girder bridge retrofitted with external tendons is tested to verify the strengthening effects. We measure the variations of the displacement and strain at mid-span of each beam as external tendons are removed in sequence. The structural behavior of the bridge are examined using controlled truck load tests for the systems before and after all external tendons were removed. From the test results, the characteristics of structural behavior of the bridge do not change significantly, but the natural frequency is decreased after the external tendons are removed. The strengthening effects of bridges can be exactly estimated by analytical methods some extent. As a result of this study, when a PSC girder bridge is deteriorated, the bridge can be retrofitted effectively by External Prestressing Strengthening Method, and the strengthening effects can be predicted through accurate structural analysis.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.190-198
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• 2011

The precast production has many advantages by fast construction period, labor-saving and high quality. In recent years, the application of the precast product has been increased in the earth retaining wall field. This paper presents the results of the numerical analysis that was carried out to evaluate the dynamic stability of precast and prestressed earth retaining wall under moving train load. The two-dimensional FEM analysis was used to the numerical analyses. The train load to act on trackbed is combined by the real measured roughness phase angle and quasi-static load. The dynamic stability is analysed by the displacement, acceleration and stress under moving train load at each specified location. The results of the analysis show that the precast and prestressed retaining wall has very stable capability for the railway.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.100-108
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• 2010

The axial strength of existing RC columns were experimentally investigated in this paper to understand the strength characteristics of existing structural members and to get a appropriate data in strengthening design of RC members in a remodelling construction. Ten RC columns were prepared by being cut and extracted directly from the demolition site of the apartment housings. Each column was tested under uniaxial loadings with different eccentricities in order to evaluate the axial strength of existing RC columns. From the test results, it was found that axial strength of all the specimens were at least 75% higher than those of the theoretical values required by current code. But member displacement ductility ratio were relatively low ranging from 2.12~5.86.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.142-152
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• 2010

In this study, eleven reinforced concrete beams, without stirrup, using high ductile fiber-reinforced mortar with ground granulated blast furnace slag(SHF Series, SHFSC Series) and standard specimens without or with stirrup(SSS, BSS) were constructed and tested under monotonic loading. Experimental programs were carried out to improve and evaluate the shear performance of such test specimens, such as the load-displacement, the failure mode, the maximum strength, and shear strength. All the specimens were modeled in scale-down size. Test results showed that test specimens(SHF Series, SHFSC Series) was increased respectively the shear strength carrying capacity by 26%, 20% and the ductility capacity by 5.27, 5.75 times in comparison with the standard specimen without stirrup(SSS). And the specimens(SHF Series, SHFSC Series) showed enough ductile behavior and stable flexural failure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.16-24
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• 2017

The purpose of this paper is to search the optimal location of offset outrigger system in high-rise building after a structural schematic design of 80 stories building was conducted, making use of MIDAS-Gen. In this research, the key factors of analysis study were column stiffness, outrigger position in plan and outrigger location in height. For the aim of finding out the optimum position of offset outrigger system in tall building, we studied the lateral displacement in top floor which is the very essential variables in the structural design of high-rise building. The results of study showed that the column stiffness, the outrigger location in plan and outrigger location in height had an effect on the optimal position of outrigger system. Also, it is indicated that the research results can be useful in acquiring the structural design materials for seeking the optimum position of offset outrigger system in tall building.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.3
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• pp.117-127
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• 2012

As increasing number of large-size earthquake around Korean peninsula, many interests have been focused to the earthquake strengthening of existing structures. Fiber reinforced plastic composite material is one of strengthening material widely used to increase seismic performance of structures. It should have high stiffness as well as large ductility to provide best strengthening result. Thus selection of stiffener and fiber in composite is of important. In this study, the optimal combination of fiber and stiffener is selected with variety of tensile tests. In order to investigate performance of chosen composite material, several finite element analyses are performed with proposed FRP composite material for existing RC columns. It is discussed that the seismic performance of strengthened columns through the load-displacement relationship. It is shown that the proposed composite material can increase the strength as well as ductility of exiting RC columns.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.4
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• pp.60-68
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• 2012

This study describes an analytical and experimental investigation of the pedestrian steel-deck truss bridge in the City of Rochester, New York, U.S.A. This investigation was undertaken to provide assurance that this important bridge continues to be functional for this use. An ambient vibration experiment on full-scale structures is a way of assessing the reliability of the various assumptions employed in the mathematical models used in analysis. It is also the most reliable way of determining the structural parameters of major importance in structural dynamics, such as the mode shapes and the associated natural frequencies. Pedestrian-induced vibrations have been measured on the bridge to determine the displacement and the vertical and transverse dynamic characteristics of the steel deck truss. In the analytical modeling, three-dimensional finite element analysis was developed and validated against the ambient tests.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.4
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• pp.35-42
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• 2015

This study analytically reviewed the behavior of Steel Plate Concrete(SC) walls subjected to cyclic loads to investigate the effects of shape and arrangement spacing of studs on the behavior of SC walls. To perform it, 9 cases of finite element analyses considering the different shape and spacing of studs in SC wall were carried out. As the results, the skeleton curves were obtained from the load-displacement history curves and the ultimate and yielding forces were increased as the spacing of studs decrease. In addition, the strength of inclined studs are shown to be bigger compared to that of general studs. The damping ratios are increased as the decrease of strength ratio. Finally, as the decrease of stud spacings, the cumulative dissipated energy was increased and the seismic performance was improved.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.4
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• pp.83-91
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• 2015

Under impact or blast loads, concrete behaves with different mechanical properties comparing to the static loading conditions. In other words, with high strain rate, mechanical properties of concrete vary significantly. To evaluate the compressive characteristics of concrete with high strain rate, SHPB(Split Hopkinson Pressure Bar) test is typically used. However, because SHPB test method has been developed for metallic materials, it is necessary to verify the applicability of SHPB for brittle materials such as concrete. Also, there have been little researches on the evaluations of mechanical characteristics of UHPC under high strain rate conditions. This study has been performed to evaluate and analyse the compressive characteristics of plain concrete and UHPC with SHPB test apparatus. Also, to verify the applicability of SHPB test for concrete, direct displacement image analysis with high speed camera was performed for the comparisons with analytical solutions for SHPB test.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.6
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• pp.1-10
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• 2014

In this study, thirteen reinforced concrete beams, ground granulated blast furnace slag, replacing recycled coarse aggregate with PVA fiber (BSPG series) and recycled coarse aggregate with hybrid fiber ($BSPGR_1$, $BSPGR_2$ series), and standard specimen (BSS) were constructed and tested under monotonic loading. Experimental programs were carried out to improve and evaluate the Structural performance of such test specimens, such as the load-displacement, the failure mode, and the maximum load carrying capacity. All the specimens were modeled in 1/2 scale-down size. Test results showed that test specimens ($BSPGR_1$, $BSPGR_2$ series) was increased the compressive strength by 13%, the maximum load carrying capacity by 4~21% and the ductility capacity by 4~28% in comparison with the standard specimen (BSS). And the specimens ($BSPGR_1$, $BSPGR_2$ series) showed enough ductile behavior and stable flexural failure.