• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.89-96
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• 2000

Landslide damage comprise most part of the damages from the earthquake and it only causes the damage to lives and structures directly but also cease the operation of social system by road or lifeline failure. For these reasons hazard assesment on the landslides has been recognized very important. And hazard maps have been used to visualize the hazard of the landslide. In this study as first step for application of hazard map to domestic cases hazard maps are made for the Ul-Joo Ul-san Korea, Where the Yan-san faults are located. For building hazard maps the degree of hazard are evaluated based on Newmark displacement and the resulting maps are constructed by GIS technique. In hazard assesment maximum ground acceleration obtained from attenuation equation of wave propagation and design earthquake acceleration suggested by Ministry of construction are used for acceleration term. Hazard maps are made by GIS programs Arc/Info and Arc/View based on the digital maps and data from lab tests and elastic wave surveys The maps show the possible landslide regions significantly and the displacements of slide are proportional to the slope angles.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.110-117
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• 2005

This paper deals the shaking table tests with 1/100 scaled model followed by Scott & Iai(1989)'s similitude law for OO dam main desging section to understand nonlinear behavior characteristics of concrete dam body by earthquake wave. As earthquake wave, Hachinohe and Elcentro waves were used and acceleration and displacements are measured to analyze behaviors of dam body. For ground maximum acceleration range ($0.3^{\sim}0.9g$), the results showed linear behavior regardless of ground maximum acceleration and secured safety of structure. To analyze the behavior of dam after tension cracking, 3cm-notch was placed at the critical section of over-flowing section. As results of applying Hachinohe wave(0.8g), Even though tension cracks were formed at over-flowing section by Hachinohe wave(0.8g), it showed that the dam is stable for supporting upper stream part of water tank of dam.

• Geotechnical Engineering
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• v.1 no.1
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• pp.13-20
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• 1985

In this paper, earthquake response of the Bangkok area in Thailand was analyzed in terms of the acceleration response spectrum and maximum acceleration of the computed surface motions. The program SHAKE was employed to analyse the ground motion. With increasing the maximum acceleration and predominant period of given base rock motion, the computed maximum ground surface acceleration increases. but converges on a maximum value of about 0.39. The characteristics of earthquake response spectrum in the Bangkok area are also discussed and illustrated.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.529-535
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• 2005

This paper presents a system identification (SI) scheme in time domain using measured acceleration data. The error function is defined as the time integral of the least squared errors between the measured acceleration and the calculated acceleration by a mathematical model. Damping parameters as well as stiffness properties of a structure are considered as system parameters. The structural damping is modeled by the Rayleigh damping. A new regularization function defined by the L1-norm of the first derivative of system parameters with respect to time is proposed to alleviate the ill-posed characteristics of inverse problems and to accommodate discontinuities of system parameters in time. The time window concept is proposed to trace variation of system parameters in time. Numerical simulation study is performed through a two-span continuous truss subject to ground motion.

• Structural Engineering and Mechanics
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• v.59 no.4
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• pp.719-737
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• 2016

The present study investigated the earthquake behavior of R/C structures considering the vertical earthquake motion with the help of a comparative study. For this aim, the linear time-history analyses of a high-rise R/C structure designed according to TSC-2007 requirements were conducted including and excluding the vertical earthquake motion. Earthquake records used in the analyses were selected based on the ratio of vertical peak acceleration to horizontal peak acceleration (V/H). The frequency-domain analyses of the earthquake records were also performed to compare the dominant frequency of the records with that of the structure. Based on the results obtained from the time-history analyses under the earthquake loading with (H+V) and without the vertical earthquake motion (H), the value of the overturning moment and the top-story vertical displacement were found to relatively increase when considering the vertical earthquake motion. The base shear force was also affected by this motion; however, its increase was lower compared to the overturning moment and the top-story vertical displacement. The other two parameters, the top-story lateral displacement and the top-story rotation angle, barely changed under H and H+V loading cases. Modal damping ratios and their variations in horizontal and vertical directions were also estimated using response acceleration records. No significant change in the horizontal damping ratio was observed whereas the vertical modal damping ratio noticeably increased under H+V loading. The results obtained from this study indicate that the desired structural earthquake performance cannot be provided under H+V loading due to the excessive increase in the overturning moment, and that the vertical damping ratio should be estimated considering the vertical earthquake motion.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.37-44
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• 1999

Spectral characteristic of Kyeongju earthquake occurred on the June 2, 1999 with magnitude 3,4 is analyzed. It is guessed that the stress energy release of source within relatively short period caused the ground near the epicenter to vibrate with large amplitude for the magnitude and predominantly high frequency. The cumulative absolute velocity and average spectrum acceleration are 0.034 gsec and 0.118g, respectively lower than threshold values of potential earthquake damage which is consistent with the investigation of damage in field. The analysis of the acceleration records of Kyeongju earthquake shows the need to develop the ration criterion for the determining the operating basis earthquake of nuclear power plant.

• Geomechanics and Engineering
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• v.4 no.1
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• pp.39-53
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• 2012

Due to strong ground motion of earthquake, the material in the landslide can travel a significant distance from the source. A new landslide model called Multiplex Acceleration Model (MAM) has been proposed to interpret the mechanism of long run-out movement of this type of landslide, considering earthquake behaviors on slope and landslide materials. In previous study, this model was verified by a shaking table test. However, there is a scale limitation of shaking table test to investigate MAM in detail. Thus, numerical simulation was carried out in this study to validate MAM under full scale. A huge rock ejected and A truck threw upwards by seismic force during Wenchuan Earthquake (Ms. 8.0) was discussed based on the simulation results. The results indicate that collisions in P-phase of earthquake and trampoline effect are important behaviors to interpret the mechanism of long run-out and high velocity. The results show that MAM is acceptable and applicable.

• Earthquakes and Structures
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• v.18 no.2
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• pp.163-170
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• 2020

Floor acceleration plays a major role in the seismic design of nonstructural components and equipment supported by structures. Large floor acceleration may cause structural damage to or even collapse of buildings. For precision instruments in high-tech factories, even small floor accelerations can cause considerable damage in this study. Six P-wave parameters, namely the peak measurement of acceleration, peak measurement of velocity, peak measurement of displacement, effective predominant period, integral of squared velocity, and cumulative absolute velocity, were estimated from the first 3 s of a vertical ground acceleration time history. Subsequently, a new predictive algorithm was developed, which utilizes the aforementioned parameters with the floor height and fundamental period of the structure as the new inputs of a support vector regression model. Representative earthquakes, which were recorded by the Structure Strong Earthquake Monitoring System of the Central Weather Bureau in Taiwan from 1992 to 2016, were used to construct the support vector regression model for predicting the peak floor acceleration (PFA) of each floor. The results indicated that the accuracy of the predicted PFA, which was defined as a PFA within a one-level difference from the measured PFA on Taiwan's seismic intensity scale, was 96.96%. The proposed system can be integrated into the existing earthquake early warning system to provide complete protection to life and the economy.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.2
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• pp.35-44
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• 1998

Because of the continual occurrence of minor and moderate earthquakes in Korean peninsula, it is generally considered that Korean is not located in a safe region against probable earthquake any more, even though being recognized as a safe country in earthquake. It is in particular noted that nowadays there has been much concern about unexpected tragedy due to probable earthquake since the disaster of 1995 kobe earthquake. Thus, the objective of this research is to develop appropriate design spectrum which could be practicably used in seismic design of important structures taking into consideration of local physical characteristics. Particularly, we have to keep in mind the lessons from 1985 Mexico earthquake which had disregarded deep research on local ground conditions, being a possible magnification phenomena of ground motions in weak soil layer. Various spectra has been described based on the analysis of historical earthquakes, and generate the artificial ground acceleration. Also, rational numbers of artificial ground acceleration is investigated by the seismic analysis for skew slab bridges.

• Earthquakes and Structures
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• v.1 no.2
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• pp.147-162
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• 2010

The ground acceleration measured at a point on the earth's surface is composed of several waves that have different phase velocities, arrival times, amplitudes, and frequency contents. For instance, body waves contain primary and secondary waves that have high frequency content and reach the site first. Surface waves are composed of Rayleigh and Love waves that have lower phase velocity, lower frequency content and reach the site next. Some of these waves could be of more damage to the structure depending on their frequency content and associated amplitude. This paper models critical earthquake loads for single-degree-of-freedom (SDOF) inelastic structures considering evolution of the seismic waves in time and frequency. The ground acceleration is represented as combination of seismic waves with different characteristics. Each seismic wave represents the energy of the ground motion in certain frequency band and time interval. The amplitudes and phase angles of these waves are optimized to produce the highest damage in the structure subject to explicit constraints on the energy and the peak ground acceleration and implicit constraints on the frequency content and the arrival time of the seismic waves. The material nonlinearity is modeled using bilinear inelastic law. The study explores also the influence of the properties of the seismic waves on the energy demand and damage state of the structure. Numerical illustrations on modeling critical earthquake excitations for one-storey inelastic frame structures are provided.