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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Earthquake Engineering Society of Korea
Journal Basic Information
Journal DOI :
Earthquake Engineering Society of Korea
Editor in Chief :
Volume & Issues
Volume 14, Issue 6 - Dec 2010
Volume 14, Issue 5 - Oct 2010
Volume 14, Issue 4 - Aug 2010
Volume 14, Issue 3 - Jun 2010
Volume 14, Issue 2 - Apr 2010
Volume 14, Issue 1 - Feb 2010
Selecting the target year
Optimal design of nonlinear seismic isolation system by a multi-objective optimization technique integrated with a stochastic linearization method
Kwag, Shin-Young ; Ok, Seung-Yong ; Koh, Hyun-Moo ;
Journal of the Earthquake Engineering Society of Korea, volume 14, issue 2, 2010, Pages 1~13
DOI : 10.5000/EESK.2010.14.2.001
This paper proposes an optimal design method for the nonlinear seismic isolated bridge. The probabilities of failure at the pier and the seismic isolator are considered as objective functions for optimal design, and a multi-objective optimization technique is employed to efficiently explore a set of multiple solutions optimizing mutually-conflicting objective functions at the same time. In addition, a stochastic linearization method is incorporated into the multi-objective optimization framework in order to effectively estimate the stochastic responses of the bridge without performing numerous nonlinear time history analyses during the optimization process. As a numerical example to demonstrate the efficiency of the proposed method, the Nam-Han river bridge is taken into account, and the proposed method and the existing life-cycle-cost based design method are both applied for the purpose of comparing their seismic performances. The comparative results demonstrate that the proposed method not only shows better seismic performance but also is more economical than the existing cost-based design method. The proposed method is also proven to guarantee improved performance under variations in seismic intensity, in bandwidth and in the predominant frequency of the seismic event.
Development of a Precast Concrete Structural Wall Adopting Improved Connections in the Plastic Hinge Region
Kang, Su-Min ; Oh, Jae-Keun ; Kim, Ook-Jong ; Lee, Do-Bum ; Park, Hong-Gun ;
Journal of the Earthquake Engineering Society of Korea, volume 14, issue 2, 2010, Pages 15~26
DOI : 10.5000/EESK.2010.14.2.015
The purpose of this study is to develop a precast concrete structural wall system that can assure reliable seismic performance. In previous studies, the connections of precast concrete structural walls have had some problems in their seismic performance. Therefore, this research proposes precast concrete structural walls which have an improved seismic performance. One is a hybrid precast concrete structural wall that is composed of a reinforced concrete component and a precast concrete component, and another is a precast concrete wall whose reinforcements have a partially reduced section and are partially unbonded from the surrounding concrete. To evaluate the seismic performance of the proposed precast concrete structural walls, the behavior of three specimens, including a reinforced concrete wall, were subjected to reversed cyclic combined flexure and shear. According to the test results, the proposed precast concrete structural walls have reliable seismic performance.
Characteristics of the shear behavior of RC rectangular sectional columns and initial shear strength considering the ratio of longitudinal bars
Lee, Jong-Seok ; Sun, Chang-Ho ; Kim, Ick-Hyun ;
Journal of the Earthquake Engineering Society of Korea, volume 14, issue 2, 2010, Pages 27~36
DOI : 10.5000/EESK.2010.14.2.027
It is well known that the shear strength of an RC column subjected to a lateral force decreases with the increase of the displacement ductility of column. This decreasing rate of shear strength is quite dependent on the initial shear strength. Therefore, the evaluation of the initial shear strength is important to predict the shear strength with reasonable accuracy. The shear behavior is complex because many parameters, such as the sectional shape, aspect ratio, axial force, longitudinal bars and ductility, are mutually interactive. In this study, the initial shear strength has been investigated by experiments varying parameters such as the aspect ratios, void ratios, ratio of longitudinal bars and sectional types. A new empirical equation for the initial shear strength, considering the ratio of the longitudinal bars, has been proposed and its validity has been assessed.
The shear strength of RC rectangular sectional columns considering displacement ductility
Sun, Chang-Ho ; Kim, Ick-Hyun ;
Journal of the Earthquake Engineering Society of Korea, volume 14, issue 2, 2010, Pages 37~47
DOI : 10.5000/EESK.2010.14.2.037
In order to attain enhanced seismic performance of RC bridges, premature shear failure prior to the achievement of target ductilities of the piers should be prevented. For this purpose, a reliable shear strength evaluation is required. The shear strength of an RC column subjected to a lateral force decreases with an increase in ductility. Many empirical equations for the shear strength have been proposed by many researchers. However, there are many discrepancies in the initial shear strength in the low ductility range, and in the decrease rate according to the ductility. In this study, a new empirical equation of shear strength considering the displacement ductility effect has been proposed, in which the initial shear strength equation proposed by the authors was revised on the basis of the investigation of many other researchers' test results. The resulting improvement in accuracy is confirmed by comparison with other empirical equations.
Application of the JMA instrumental intensity in Korea
Kim, Hye-Lim ; Kim, Sung-Kyun ; Choi, Kang-Ryong ;
Journal of the Earthquake Engineering Society of Korea, volume 14, issue 2, 2010, Pages 49~56
DOI : 10.5000/EESK.2010.14.2.049
In general, the seismic intensity deduced from instrumental data has been evaluated from the empirical relation between the intensity and the PGA. From the point of view that the degree of earthquake damage is more closely associated with the seismic intensity than with the observed PGA, JMA developed the instrumental seismic intensity (JMA instrumental intensity) meter that estimate the real-time seismic intensity from the observed strong motion data to obtain a more correct estimate of earthquake damage. The purpose of the present study is to propose a practical application of the JMA instrumental intensity in Korea. Since the occurrence of strong earthquakes is scarce in the Korean Peninsula, there is an insufficiency of strong motion data. As a result, strong motion data were synthesized by a stochastic procedure to satisfy the characteristics of a seismic source and crustal attenuation of the Peninsula. Six engineering ground motion parameters, including the JMA instrumental intensity, were determined from the synthesized strong motion data. The empirical relations between the ground motion parameters were then analyzed. Cluster analysis to classify the parameters into groups was also performed. The result showed that the JMA acceleration (
) could be classified into similar group with the spectrum intensity and the relatively distant group with the CAV (Cumulative Absolute Velocity). It is thought that the
or JMA intensity can be used as an alternative criterion in the evaluation of seismic damage. On the other hand, attenuation relation equations for PGA and
to be used in the prediction of seismic hazard were derived as functions of the moment magnitude and hypocentral distance.
Modal Testing of Arches for Plastic Film-Covered Greenhouses
Cho, Soon-Ho ;
Journal of the Earthquake Engineering Society of Korea, volume 14, issue 2, 2010, Pages 57~65
DOI : 10.5000/EESK.2010.14.2.057
To determine the static buckling loads and evaluate the structural performance of slender steel pipe-arches such as for greenhouse structures, a series of modal tests using a fixed hammer and roving sensors was carried out, by providing no load, then a range of vertical loads, on an arch rib in several steps. More attention was given to an internal arch where vertical and horizontal auxiliary members are not placed, unlike an end arch. Modal parameters such as natural frequencies, mode shapes and damping ratios were extracted using more advanced system identification methods such as PolyMAX (Polyreference Least-Squares Complex Frequency Domain), and compared with those predicted by commercial FEA (Finite Element Analysis) software ANSYS for various conditions. A good correlation between them was achieved in an overall sense, however the reduction of natural frequencies due to the existence of preaxial loads was not apparent when the vertical load level was about up to 38% of its resistance. Some difficulties related to the field testing and parameter extraction for a very slender arch, as might arise from the influences of neighboring members, are carefully discussed.
Estimation of Modal Parameters for Plastic Film-Covered Greenhouse Arches
Cho, Soon-Ho ;
Journal of the Earthquake Engineering Society of Korea, volume 14, issue 2, 2010, Pages 67~74
DOI : 10.5000/EESK.2010.14.2.067
To a series of vibration records obtained from experimental modal testing using a fixed hammer and roving accelerometers for greenhouse arch structures, modal parameters such as natural frequencies, damping ratios and mode shapes are extracted by applying the two most advanced system identification methods in the frequency-domain up to now, so-called PolyMAX and FDD. The former involves both input and output data, while the latter utilizes only the output data. The possibility of determining the static buckling load, detecting damages, etc., for very slender steel-pipe arches by means of a non-destructive testing method based on vibration measurements is primarily investigated. The extracted modal parameters generally correlated well with those obtained using finite element analysis, demonstrating promising results for further on-going research.
Seismic Response Prediction of a Structure Using Experimental Modal Parameters from Impact Tests
Cho, Sung-Gook ; Joe, Yang-Hee ; So, Gi-Hwan ;
Journal of the Earthquake Engineering Society of Korea, volume 14, issue 2, 2010, Pages 75~84
DOI : 10.5000/EESK.2010.14.2.075
An in-cabinet response spectrum should be generated to perform the seismic qualification of devices and instruments mounted inside safety-related electrical equipment installed in nuclear power plants. The response spectrum is available by obtaining accurate seismic responses at the device mounting location of the cabinet. The dynamic behavior of most of electrical equipment may not be easily analyzed due to their complex mass and stiffness distributions. Considering these facts, this study proposes a procedure to estimate the seismic responses of a structure by a combination of a test and subsequent analysis. This technique firstly constructs the modal equations of the structure by using the experiment modal parameters obtained from the impact test. Then the seismic responses of the structure may be calculated by a mode superposition method. A simple steel frame structure was fabricated as a specimen for the validation of the proposed method. The seismic responses of the specimen were estimated by using the proposed technique and compared with the measurements obtained from the shaking table tests. The study results show that it is possible to accurately estimate the seismic response of the structure by using the experimental modal parameters obtained from the impact test.