• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.7_spc
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• pp.425-434
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• 2016

This study investigates important parameters used to determine an effective peak ground acceleration (EPGA) based on the characteristics of response spectra of historical earthquakes occurred at Korean peninsula. EPGAs are very important since they are implemented in the Korean Building Code for the seismic design of new structures. Recently, the Gyeongju earthquakes with the largest magnitude in earthquakes measured at Korea took place and resulted in non-structural and structural damage, which their EPGAs should need to be evaluated. This paper first describes the basic concepts on EPGAs and the EPGAs of the Gyeongju earthquakes are then evaluated and compared according to epicentral distances, site classes and directions of seismic waves. The EPGAs are dependant on normalizing factors and ranges of period on response spectrum constructed with the Gyeongju earthquake records. Using the normalizing factors and the ranges of period determined based on the characteristics of domestic response spectra, this paper draw a conclusion that the EPGAs are estimated to be about 30 % of the measured peak ground accelerations (PGA).

• Geomechanics and Engineering
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• v.24 no.1
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• pp.67-79
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• 2021

The influence of ground motions on the seismic response of utility tunnels was investigated. A series of small-scale shaking table model tests were carried out under uniform excitation in the transverse direction. Different peak accelerations of EL-Centro and Taft earthquake waves were applied. The acceleration responses, earth pressure, seismic strain, bending moment and structure deformations were measured and discussed. The results showed that the types of earthquake waves had significant influences on the soil-structure acceleration responses. However, the amplitude of the soil acceleration along the depth showed consistent variation regardless of the types of earthquake waves and tunnels. The horizontal soil pressure near the top and bottom slabs showed obviously larger values than those at other depths. In general, the strain response in the outer surface was more significant than that on the inner surface, and the peak strain in the end section of the model was larger than that in the middle section. Moreover, the bending moment at the corner points was much larger than that at middle point, and the bending moment was greatly affected by both input accelerations and seismic wave types. The opposite direction of shear deformation on the top and bottom slabs presented a rotation trend of the model structure.

• Earthquakes and Structures
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• v.17 no.6
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• pp.599-609
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• 2019

After an earthquake, a quick seismic assessment of a structure can facilitate the recovery of operations, and consequently, improve structural resilience. Especially for facilities that play a key role in rescue or refuge efforts (e.g., hospitals and power facilities), or even economically important facilities (e.g., high-tech factories and financial centers), immediately resuming operations after disruptions resulting from an earthquake is critical. Therefore, this study proposes a prompt post-earthquake seismic evaluation method that uses displacement and acceleration measurements taken from real structural responses that resulted during an earthquake. With a prepared pre-earthquake capacity curve of a structure, the residual seismic capacity can be estimated using the residual roof drift ratio and stiffness. The proposed method was verified using a 6-story steel frame structure on a shaking table. The structure was damaged during a moderate earthquake, after which it collapsed completely during a severe earthquake. According to the experimental results, a reasonable estimation of the residual seismic capacity of structures can be performed using the proposed post-earthquake seismic evaluation method.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.458-467
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• 2000

The standard of performance-based seismic design accepted by Ministry of Construction and Transport requires to install and manage earthquake instruments for the facilities of seismic category I and to acquire earthquake response data of these facilities at earthquake events. So detailed standard and guideline for installation and management of earthquake instruments for each facilities according to the seismic design standard are getting ready. This paper presents the part of installation locations of sensors in that detaile standard and guideline.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.10a
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• pp.27-32
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• 2000

Microearthquake records with magnitude 2.6~3.1 recorded in the southeastern part of the Korean peninsula during 1994~1998 are analyzed. Total of 42 records consisted of 12 events instrumented at 7 stations. The response spectra with the above data shows that the frequency range of the dominant response is about 10~25Hz and are compared with the standard response spectrum. The result implies that the characteristics of the microearthquake ground motion differ from those of standard response spectrum presented in US NRC Reg. Guide 1.60 especially at higher frequencies.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.4
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• pp.179-190
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• 1998

All brick masonry buildings are constructed without any structural limitation under earthquake load, in Korea. However, it is necessary to evaluate response for seismic loads since the number of earthquake occurances in Korea is increasing. In this paper, the load resisting capacities of brick masonry buildings are investigated by finite element analysis method and the response due to seismic load are analyzed by applying 0.12g earthquake load. It was observed that the two story masonry building is not safe under the 0.12g earthquake load, especially at the first floor. The cracks were occurred under the bond beam and around the openings due to the stress concentration.

• Earthquakes and Structures
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• v.11 no.4
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• pp.649-664
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• 2016

A seismic damaged bridge may be hit again by a strong aftershock or another earthquake in a short interval before the repair work has been done. However, discussions about the impact of the unrepaired damages on the residual earthquake resistance of a steel bridge are very scarce at present. In this paper, nonlinear time-history analysis of a steel arch bridge was performed using multi-scale hybrid model. Two strong historical records of main shock-aftershock sequences were taken as the input ground motions during the dynamic analysis. The strain response, local deformation and the accumulation of plasticity of the bridge with and without unrepaired seismic damage were compared. Moreover, the effect of earthquake sequence on crack initiation caused by low-cycle fatigue of the steel bridge was investigated. The results show that seismic damage has little impact on the overall structural displacement response during the aftershock. The residual local deformation, strain response and the cumulative equivalent plastic strain are affected to some extent by the unrepaired damage. Low-cycle fatigue of the steel arch bridge is not induced by the earthquake sequences. Damage indexes of low-cycle fatigue predicted based on different theories are not exactly the same.

• Nuclear Engineering and Technology
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• v.53 no.4
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• pp.1345-1356
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• 2021

Damage to nuclear power plants causes human casualties and environmental disasters. There are electrical facilities that control safety-related devices in nuclear power plants, and seismic performance is required for them. The 2016 Gyeongju earthquake had many high-frequency components. Therefore, there is a high possibility that an earthquake involving many high frequency components will occur in South Korea. As such, it is necessary to examine the safety of nuclear power plants against an earthquake with many high-frequency components. In this study, the shaking table test of electrical facilities was conducted against the design earthquake for nuclear power plants with a large low-frequency components and an earthquake with a large high-frequency components. The response characteristics of the earthquake with a large high-frequency components were identified by deriving the amplification factors of the response through the shaking table test. In addition, safety of electrical facility against the two aforementioned types of earthquakes with different seismic characteristics was confirmed through limit-state seismic tests. The electrical facility that was performed to the shaking table test in this study was a motor control center (MCC).

• Structural Engineering and Mechanics
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• v.33 no.2
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• pp.179-191
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• 2009

This paper is aimed at combining wavelet multiresolution analysis and nonstationary Kanai-Tajimi model for the simulation of earthquake accelerograms. The proposed approach decomposes earthquake accelerograms using wavelet multiresolution analysis for the simulation of earthquake accelerograms. This study is on the basis of some Iranian earthquake records, namely Naghan 1977, Tabas 1978, Manjil 1990 and Bam 2003. The obtained results indicate that the simulated records preserve the significant properties of the actual accelerograms. In order to investigate the efficiency of the model, the spectral response curves obtained from the simulated accelerograms have been compared with those from the actual records. The results revealed that there is a good agreement between the response spectra of simulated and actual records.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1210-1215
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• 2002

The spent fuel handling tool is used to handle the refuel bundle and treated by hoist rope on the bridge crane. The new developed handling tool of NPP(Nuclear Power Plant) should be conformed the structural stability under earthquake condition. In this study, the stress and seismic analysis of the handling tool are performed by finite element method. Using the Floor Response Spectrum(FRS) obtained through the time history analysis, the modal and seismic analysis under Operating Basis Earthquake(OBE) and Safe Shutdown Earthquake(SSE) load conditions are carried out. Total 4 cases of different locations of the trolly and the hook are investigated. With the spring-damper element, the tension analysis of hoist rope is conducted. The stability of handling tool under earthquake load condition is conformed with regulatory guide.