• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.2
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• pp.1-8
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• 1999

The present paper describes an approximation for estimation of earthquake-induced hydrodynamic loads in rigid storage tank which accelerated in horizontal direction. The storage tank is vertically cylindrical, and the sectional shape may be circular, rectangular or irregular. The solution for harmonic excitation is studied based on velocity potential theory, and then the time domain solution for earthquake is obtained by using design response spectrum. As a result, earthquake load is influenced primarily by the inertia force of high frequency effective mass of the storage tank, responding to the characteristics of design response spectrum, tank sectional shape, and the ratio of tank base length to depth. Earthquake-induced hydrodynamic loads in rigid storage tank can be effectively obtained by using the high frequency approximation method in case of quite large, or small ratio of the tank base length to water depth.

• Structural Engineering and Mechanics
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• v.43 no.4
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• pp.503-526
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• 2012

Pounding between closely located adjacent buildings is a serious issue of dense cities in the earthquake prone areas. Seismic responses of adjacent buildings subjected to earthquake induced pounding are numerically studied in this paper. The adjacent buildings are modeled as the lumped mass shear buildings subjected to earthquake acceleration and the pounding forces are modeled as the Kelvin contact force model. The Kelvin model is activated when the separation gap is closed and the buildings pound together. Characteristics of the Kelvin model are extensively explored and a new procedure is proposed to determine its stiffness. The developed model is solved numerically and a SDOF pounding case as well as a MDOF pounding case of multistory adjacent buildings are elaborated and discussed. Effects of different separation gaps, building heights and earthquake excitations on the seismic responses of adjacent buildings are obtained. Results show that the seismic responses of adjacent buildings are affected negatively by the pounding. More stories pound together and pounding is more intense if the separation gap is smaller. When the height of buildings differs significantly, the taller building is almost unaffected while the shorter building is affected detrimentally. Finally, the buildings should be analyzed case by case considering the potential earthquake excitation in the area.

• Journal of the Society of Disaster Information
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• v.17 no.4
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• pp.694-709
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• 2021

Purpose: In this study, earthquake-induced landslide risk assessment was conducted to provide basic data for efficient and preemptive damage prevention by selecting the erosion control work before the earthquake and the prediction and restoration priorities of the damaged area after the earthquake. Method: The study analyzed the previous studies abroad to examine the evaluation methodology and to derive the evaluation factors, and examine the utilization of the landslide hazard map currently used in Korea. In addition, the earthquake-induced landslide hazard map was also established on a pilot basis based on the fault zone and epicenter of Pohang using seismic attenuation. Result: The earthquake-induced landslide risk assessment study showed that China ranked 44%, Italy 16%, the U.S. 15%, Japan 10%, and Taiwan 8%. As for the evaluation method, the statistical model was the most common at 59%, and the physical model was found at 23%. The factors frequently used in the statistical model were altitude, distance from the fault, gradient, slope aspect, country rock, and topographic curvature. Since Korea's landslide hazard map reflects topography, geology, and forest floor conditions, it has been shown that it is reasonable to evaluate the risk of earthquake-induced landslides using it. As a result of evaluating the risk of landslides based on the fault zone and epicenter in the Pohang area, the risk grade was changed to reflect the impact of the earthquake. Conclusion: It is effective to use the landslide hazard map to evaluate the risk of earthquake-induced landslides at the regional scale. The risk map based on the fault zone is effective when used in the selection of a target site for preventive erosion control work to prevent damage from earthquake-induced landslides. In addition, the risk map based on the epicenter can be used for efficient follow-up management in order to prioritize damage prevention measures, such as to investigate the current status of landslide damage after an earthquake, or to restore the damaged area.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.10a
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• pp.157-162
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• 1998

Dynamic loads may arise from rotating parte of pump if they are insufficiently balanced. The magnitude of pump induced vibrations varies according to the weight, eccentricity, and unbalanced mass of pump. This is a study to estimate the pump induced vibration in time and frequency domain by transfer function. The transfer function has real and imaginary information of signals, and response function has also real and imaginary information. So the vibration force can be obtained from the response and transfer function by complex calculation. The amplitudes and components of 50Hp pump vibration force are suggested.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.04a
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• pp.85-92
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• 1999

Blasting induced damage boundary was determined by measuring vibrations adjacent to charging holes. the criterion adopted to define damages is that blasting-induced strains exceeding tension-crack strain level cause damages. The blasting vibrations were measured in terms of acceleration and converted to strains. The tension-crack strain level was determined with tensile strengths and elastic moduli of rock cores. The damage zone was found to be extended radially about 1 meter from the blasthole detonated with 250 to 700 grams of explosives. The comparison of shear wave velocity profiles before and after blasting shows that the damage boundary of 1 meter seems to be reliable.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.133-143
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• 2018

Liquefaction is one of secondary damages after earthquake and has been rarely reported until earthquake except Mw = 5.4 15 November 2017 Pohang earthquake in Korea. In recent years, Mw = 5.8 12 September 2016 Gyeongju earthquake and Mw = 5.4 15 November 2017 Pohang earthquake, which induced liquefaction, occurred in fault zone of Yangsan City located at south-eastern part of Korea. This explains that Korea is not safe against liquefaction induced by earthquake. In this study, the distance between the centroid of administrative district and the epicenter located at Yangsan fault, peak ground velocity (PGA) induced by both Mw = 5.0 and 6.5, and liquefaction potential index (LPI), which is calculated by using groundwater level and standard penetration test results of 274 in the area of Gimhae city located in adjacent to Nakdong river and across Yangsan fault, have been estimated and then kriging method using geographical information systems has been used to evaluate liquefaction effects on the damage of facilities. This study presents that Mw = 5.0 earthquake induces a small and low level of liquefaction resulting in slight damage of facilities but Mw = 6.5 earthquake induces a large and high level of liquefaction resulting in severe damage of facilities.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.7
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• pp.884-891
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• 2018

In this paper, we propose an automatic earthquake P-wave detection algorithm based on the variations of the impact momentum derived from the seismic acceleration signals. The amount of change in the impact momentum induced by the acceleration refers to the influence of buildings or facilities on the earthquake, The proposed algorithm can effectively detect the seismic P-wave by simultaneously considering the amplitude and the frequency change of the seismic wave when the earthquake occurs. Computer simulations using the observed seismic signals were performed to evaluate the validity of the induced impact momentum variation and the superiority of the proposed algorithm.

• Earthquakes and Structures
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• v.6 no.3
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• pp.251-266
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• 2014

Dynamic analyses for a suite of ground of motions were conducted on concrete gravity dam sections to examine the earthquake induced stresses and effective damping. For this purpose, frequency domain methods that rigorously incorporate dam-reservoir-foundation interaction and time domain methods with approximate hydrodynamic foundation interaction effects were employed. The maximum principal tensile stresses and their distribution at the dam base, which are important parameters for concrete dam design, were obtained using the frequency domain approach. Prediction equations were proposed for these stresses and their distribution at the dam base. Comparisons of the stress results obtained using frequency and time domain methods revealed that the dam height and ratio of modulus of elasticity of foundation rock to concrete are significant parameters that may influence earthquake induced stresses. A new effective damping prediction equation was proposed in order to estimate earthquake stresses accurately with the approximate time domain approach.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1206-1213
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• 2009

Earthquake had occurred in the Korean Peninsula about 2,100 times is not well known in the world. With the true liquefaction judgment is well used to in Korea. Through liquefaction judgements were compared with specifications between Korea and Japan, it would be offered some suggestions for liquefaction judgement used in Korea. The proposals were as 1) It can be known that what kind of earthquake will make unstable state between long-term and short-term earthquake if the natural period of ground turned out. In that case, Hachinohe and Ofunato Earthquake wave will need no more. 2) Liquefaction-induced lateral flow or damage for structure should be estimate but it had not performed in Korea. 3) Heavy rain and ocean wave-induced liquefaction also should be examined thoroughly in slope or ocean, respectively.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.5
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• pp.261-269
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• 2018

This study examines earthquake-induced sloshing effects on liquid storage tanks using computation fluid dynamics. To achieve this goal, this study selects an existing square steel tank tested by Seismic Simulation Test Center at Pusan National University as a case study. The model validation was firstly performed through the comparison of shaking table test data and simulated results for the water tank subjected to a harmonic excitation. For a realistic estimation of the wall pressure response of the water tank, three recorded earthquakes with similar peak ground acceleration are applied:1940 El Centro earthquake, 2016 Gyeongju earthquake, and 2017 Pohang earthquake. Wall pressures monitored during the dynamic analyses are examined and compared for different earthquake motions and monitoring points, using power spectrum density. Finally, the maximum dynamic pressure for three earthquakes is compared with the design pressure calculated from a seismic design code. Results indicated that the maximum pressure from the El Centro earthquake exceeds the design pressure although its peak ground acceleration is less than 0.4 g, which is the design acceleration. On the other hand, the maximum pressure due to two Korean earthquakes does not reach the design pressure. Thus, engineers should not consider only the peak ground acceleration when determining the design pressure of water tanks.