• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.3
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• pp.295-305
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• 2011

In this study, a seismic behavior of electrical cabinet system in Nuclear Power Plants(NPPs) was evaluated by the shaking table test. A 480V Motor Control Centers(MCCs) was selected for the shaking table test, and a real MCC cabinet for the Korea Nuclear Power Plant site was rented by manufactured company. For the shaking table tests, three kinds of seismic input motions were used, which were a US NRC Reg. guide 1.60 design spectrum, a UHS spectrum and PAB 165' floor response spectrum(FRS). Especially, the UHS input motion was selected for an evaluation of structural seismic amplification effects, three directional accelerations were measured at three points outside on the cabinet system and also that of the incabinet response amplification, accelerations were measure at two points which were mounted in electrical equipment such as relay. Seismic amplification effect is determined at the outside and inside of a cabinet as input seismic motion, and compared to the results which are calculated by analytical method based on NUREG/CR-5203.

• Journal of Korean Society of Steel Construction
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• v.25 no.4
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• pp.389-398
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• 2013

The structural provisions of rectangular CFT (concrete-filled tubular) columns in the 2005/2010 AISC Specification, ACI 318-08, and EC4 were comparatively analyzed as a preliminary study for establishing the unified standards for composite structures. The provisions analyzed included those related to the nominal strength, the effect of confinement, plate slenderness, effective flexural stiffness, and the material strength limitations. Small or large difference can be found among the provisions of AISC, ACI, and EC4. Generally, the 2010 AISC Specification provides the revised provisions which reflect up-to-date test results and tries to minimize the conflict with the ACI provisions. For example, the 2010 AISC Specification introduced a more finely divided plate slenderness limits for CFT columns. In seismic applications, the plate slenderness limits required for highly and moderately ductile CFT columns were separately defined. However, the upper cap limitations on material strengths in both the AISC and EC4 provisions are too restrictive and need to be relaxed considering the high-strength material test database currently available. This study found that no provisions reviewed in this paper provide a generally satisfactory method for predicting the P-M interaction strength of CFT columns under various material combinations. It is also emphasized that a practical constitutive model, which can reasonably reflect the stress-strain characteristics of confined concrete of rectangular CFT columns, is urgently needed for a reliable prediction of the P-M interaction strength.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.2
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• pp.91-99
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• 1985

The acceleration levels and durations of seismic inputs for nuclear power plant design are surveyed. Among those inputs, two artificial acceleration time histories with same acceleration level and duration are selected and their characteristics are studied by calculating response spectra and spectrum intensity. The selected time histories which have the duration of 24 sec. satisfy the design response spectra of US Nuclear Regulatory Commission Regulatory Guide 1. 60. One of the selected time histories is improved to have the duration of 15 sec. without significant changes in the other characteristics. A case study of a plane model with 3 lumped masses is done using three time histories, i.e, two selected and one improved time histories. It is found that the improved curve gives almost the same results as the original one and reduces the computer time by about half, whereas two selected time histories give the results with same trend but much different magnitudes each other. It is claimed, however, that the improved time history is not the optimal one, but very economical in practical applications.

• Journal of the Korean earth science society
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• v.37 no.1
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• pp.52-61
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• 2016

The purpose of the study was to create a probabilistic seismic hazard map using the input data that reflected the seismo-tectonic characteristics of the Korean Peninsula by applying USGS program (Harmsen (2008). The program was partly modified for the purpose of this study. The uncertainty of input parameters given by specialists was reflected in calculating the seismic hazard values by logic tree method. The general pattern of PGA was quite sensitive and similar to the shape of areal source. The probabilistic seismic hazard map showed the contour distribution of peak acceleration (%g) with 10% probability of exceedance in 5, 10, 20, 50, 100, 250, and 500 years. The result showed that the peak ground acceleration (PGA) values of the northern peninsula were almost half values of the southern peninsula except Hwanghae province. The general trend of the hazard map extended in the direction of NW-SE from Whanghae province to south-eastern regions of the peninsula. The values in northern part of Kangwon province were relatively lower than other areas in the southern peninsula. The maps produced through this study are considered valuable in regulating the seismic safety of the major facilities in the Korean Peninsula.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.1
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• pp.13-20
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• 1985

Two Cable-Stayed bridge on south coast in Korea has not constructed until a quarter of a century past since the beginning of it's own era. Our country is about to be interested in such a type of bridge. It has succeeded in constructing the 500 m spanned bridge against wind and earthquake in other several countries. Many contries are striving for designning a long spanned bridge to 1000m. For the realization of such a long spanned bridge in Korea clues to the problems, "How to design it", should be solved one by one. One of difficulties is in analysing the mechanical system because of multi-orter indeterminacy. In this study one of the numerical methods is proposed in order to eliminate the troublesome.

• Journal of Korean Tunnelling and Underground Space Association
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• v.8 no.4
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• pp.365-375
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• 2006

The structural analysis for the secondary lining of tunnels is generally performed by a frame analysis model. This model requires a ground loosening load estimated by some empirical methods, but the load is likely to be subjective and too large. The ground load acting on the secondary lining is due to the loss of the supporting function of the first support members such as shotcrete and rockbolts. Therefore, the equilibrium condition of the ground and the first support members should be considered to estimate the ground load acting on the secondary lining. Ground-lining interaction model, shortly GLI model, is developed on the basis of the concept that the secondary lining supports the ground deformation triggered by the loss of the support capacity of the first support members. Accordingly, the GLI model can take into account the ground load reflecting effectively not only the complex ground conditions but the installed conditions of the first support members. The load acting on the secondary lining besides the ground load includes the groundwater pressure and earthquake load. For the structural reinforcement of the secondary lining based on the ultimate strength design method, the factored load and various load combination should be considered. Since the GLI model has difficulty in dealing with the factored load, introduced in this study is the superposition principle in which the section moment and force of the secondary lining estimated for individual loads are multiplied by the load factors. Finally, the design method of the secondary lining using the GLI model is applied to the case of a shallow subway tunnel.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.3
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• pp.130-139
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• 2016

A frequency of earthquake occurrence in the Republic of Korea is increasing over the past few decades. In this situation, an importance of earthquake prevention comes to the fore because the earthquake does damage to structures and causes severe damage of human life. For the earthquake prevention, a real-time vibration measurement for structures is important. As an example, the United States of America and Japan have already been monitoring real-time earthquake acceleration for the important structures and the measured acceleration data has been managed by forming database. This database could be used for revising the seismic design specifications or predicting the damage caused by earthquake. In Korea, Earthquake Recovery Plans Act and Enforcement Regulations are revised and declared lately. Ministry of Public Safety and Security is constructing a integrated management system for the measured earthquake acceleration data. The purpose of this research is to develop a real-time vibration monitoring and analysis system for structures which links to the integrated management system. The developed system contains not only a monitoring function to show real-time acceleration data but also an analysis system to perform fast fourier transform, to obtain natural frequency and earthquake magnitude, to show response spectrum and power spectrum, and to evaluate structural health. Additionally, this system is designed to be able to link to the integrated management system of Ministry of Public Safety and Security. It is concluded that the developed system can be useful to build a safety management network, minimize maintenance cost of structures, and prevention of the structural damage due to earthquake.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.11-20
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• 2013

In this paper, the quantitative damage index for reinforced concrete (RC) columns with non-seismic details were presented. They are necessary to carry out the postearthquake safety evaluation of RC buildings under 5 stories without seismic details. The static cyclic test of the RC frame sub-assemblage that was an one span and actual-sized was first conducted. The specimen collapsed by the shear failure after flexural yielding of a column, lots of cracks on the surfaces of columns and beam-column joints and the cover concrete splitting at the bottom of columns occurred. The damage levels of these kinds of columns with non-seismic details were classified to five based on the load-displacement relationship by the test result. The residual story drift ratios and crack widths were then adapted as the quantitative index to evaluate the damage limit states because those values were comparatively easy to measure right after earthquakes. The highest one among the residual story drift ratios under the similar maximum story drift ratio decided on the residual story drift ratio of each damage limit state. On the other hand, the lowest and average ones among the respective residual shear and flexural widths under the similar maximum story drift ratio decided on the residual shear and flexural widths of each damage limit state, respectively. These values for each damage limit state resulted in being smaller than those by the international damage evaluation guidelines that are for seismically designed members under the same deformations.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.2 s.54
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• pp.215-222
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• 2009

In this study, steel and FRP jackets are used to confine concrete cylinders. The FRP jacket behaviors compositely with concrete since there is bonding between them. However, the used steel jacket in this study do not behavior compositely with concrete since there is not an adhesive between them. The steel jackets are attached by external forces and the welding. This study suggests the measuring method of the axial strain for the confined concrete cylinders showing noncomposite behavior with the jackets and the correcting method of the measured strain for the composite-behavior jackets. For the noncomposite-behavior steel jacket, the axial strain of the steel surface does not represent the axial strain of the concrete inside. Also, a compressormeter can not be used. Thus, the two rigid plates at the top and bottom of a cylinder are placed and the distance of the two plates are measured and used for estimating the axial strain of the concrete. For the composite-behavior FRP jacket, the vertical strain measured on the FRP surface can be used for estimating the axial strain of the concrete. However, the vertical strain on the FRP surface contains the tensile strain due to the bulge of the concrete and, thus, the tensile strain should be corrected from the vertical strain. The corrected verticals strains compared with the measured strain or a existing constitute model; the result is satisfactory. The uncorrected stress-strain curves have the potential to under estimate the ductile behavior and the energy-dissipation-capacity of the composite-behavior FRP jackets.

• Journal of the Korean Geotechnical Society
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• v.33 no.12
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• pp.81-92
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• 2017

According to the revision of the Housing Act in 2013, it has been possible to carry out an apartment remodeling project involving two to three floor vertical extension. The remodeling project with vertical extension requires foundation reinforcement because structural safety due to additional load and enhanced seismic criteria must be met. In this case, structural analysis is performed to analyze the load distributed to existing PC pile and reinforced additional pile. The vertical stiffness ($K_v$) of the pile is required for structural analysis, but the research on the 20~30 year old PC pile stiffness is very limited. In this paper, the stiffness of the PC pile in accordance with the change of diameter and length was analyzed by examining the results of 38 field pile load tests performed during the construction of the apartments in the 1990's. As a result of the analysis, the pile stiffness decreases with the increase of the length-diameter ratio (L/D). In addition, the results of on-site pile load test are compared with the coefficient 'a' for estimating pile stiffness proposed in Korea Highway Bridge Design Standard (2008) and the Pile Foundation Design Guideline of Korea Railroad Corporation (2012). It shows that 'a' obtained through the estimation of the literature is very similar to the field test results in the range of 10