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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
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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
Damage Probabilities according to the Structural Characteristics of Bridges and the Determination of Target Ductilities
Sun, Chang-Ho ; Lee, Jong-Seok ; Kim, Ick-Hyun ;
Journal of the Earthquake Engineering Society of Korea, volume 14, issue 3, 2010, Pages 1~10
DOI : 10.5000/EESK.2010.14.3.001
The target performance of a current seismic design code is to achieve collapse-prevention in order to minimize casualties. Existing structures are also being retrofitted to meet this target performance. This seismic performance seems to have been achieved in recent great overseas earthquakes, but the accompanying enormous economic loss is pointed out as a new problem. A new seismic design concept over the current target performance is required to reduce economic loss, in which a target performance is determined by the damage probability in order to control the damage levels of structures. In this study, the seismic behavior of bridges having different characteristics was investigated by nonlinear seismic analyses, and fragility curves with respect to a reference damage level were derived. Based on these results, the characteristics of target ductilities satisfying a target damage probability were investigated.
Direct Time Domain Method for Nonlinear Earthquake Response Analysis of Dam-Reservoir Systems
Lee, Jin-Ho ; Kim, Jae-Kwan ;
Journal of the Earthquake Engineering Society of Korea, volume 14, issue 3, 2010, Pages 11~22
DOI : 10.5000/EESK.2010.14.3.011
An analysis method is proposed for the transient linear or nonlinear analysis of dynamic interactions between a flexible dam body and reservoir impounding compressible water under earthquake loadings. The coupled dam-reservoir system consists of three substructures: (1) a dam body with linear or nonlinear behavior; (2) a semi-infinite fluid region with constant depth; and (3) an irregular fluid region between the dam body and far field. The dam body is modeled with linear and/or nonlinear finite elements. The far field is formulated as a displacement-based transmitting boundary in the frequency domain that can radiate energy into infinity. Then the transmitting boundary is transformed for the direct coupling in the time domain. The near field region is modeled as a compressible fluid contained between two substructures. The developed method is verified and applied to various earthquake response analyses of dam-reservoir systems. Also, the method is applied to a nonlinear analysis of a concrete gravity dam. The results show the location and severity of damage demonstrating the applicability to the seismic evaluation of existing and new dams.
Effects of the Excitation Level on the Dynamic Characteristics of Electrical Cabinets of Nuclear Power Plants
Cho, Sung-Gook ; Kim, Doo-Kie ; Go, Sung-Hyuk ;
Journal of the Earthquake Engineering Society of Korea, volume 14, issue 3, 2010, Pages 23~30
DOI : 10.5000/EESK.2010.14.3.023
Seismic qualification (SQ) is required prior to the installation of safety related electrical cabinets in nuclear power plants (NPPs). Modal identification of the electrical equipment is one of the most significant steps to perform SQ, and is an essential process to construct a realistic analytical model. In this study, shaking table tests were conducted to identify a variation of the dynamic characteristics of a seismic monitoring system cabinet installed in NPPs according to the excitation level. Modal identification of the cabinet has been performed by a frequency domain decomposition method. The results of this study show that the dynamic properties of the cabinet are nonlinearly varied according to the excitation level and the specimen behaves significantly in a nonlinear manner under safe shutdown earthquake motion in Korea. The main sources of the nonlinear behavior of the specimen have been judged by friction forces and geometrical nonlinearity rather than material nonlinearity. The nonlinear variation of the dynamic characteristics of the electrical cabinet might be accepted as an important fact that should be considered during the SQ of safety related equipment.
Seismic Performance of Gravity-Load Designed Post-Tensioned Flat Plate Frames
Han, Sang-Whan ; Park, Young-Mi ; Rew, Youn-Ho ;
Journal of the Earthquake Engineering Society of Korea, volume 14, issue 3, 2010, Pages 31~38
DOI : 10.5000/EESK.2010.14.3.031
The purpose of this study is to evaluate the seismic performance of gravity-designed post tensioned (PT) flat plate frames with and without slab bottom reinforcement passing through the column. In low and moderate seismic regions, buildings are often designed considering only gravity loads. This study focuses on the seismic performance of gravity load designed PT flat plate frames. For this purpose, 3-, 6- and 9-story PT flat plate frames are designed considering only gravity loads. For reinforced concrete flat plate frames, continuous slab bottom reinforcement (integrity reinforcement) passing through the column should be placed to prevent progressive collapse; however, for the PT flat plate frames, the slab bottom reinforcement is often omitted since the requirement for the slab bottom reinforcement for PT flat plates is not clearly specified in ACI 318-08. This study evaluates the seismic performance of the model frames, which was evaluated by conducting nonlinear time history analyses. For conducting nonlinear time history analyses, six sets of ground motions are used as input ground motions, which represent two different hazard levels (return periods of 475 and 2475 years) and three different locations (Boston, Seattle, and L.A.). This study shows that gravity designed PT flat plate frames have some seismic resistance. In addition, the seismic performance of PT flat plate frames is significantly improved by the placement of slab bottom reinforcement passing through the column.
Characteristics of the Stress-strain Relationship of Square Sectional Concrete Confined by Hoop Reinforcement with Cross-ties
Jeong, Hyeok-Chang ; Cha, Soo-Won ; Kim, Ick-Hyun ;
Journal of the Earthquake Engineering Society of Korea, volume 14, issue 3, 2010, Pages 39~48
DOI : 10.5000/EESK.2010.14.3.039
Improved seismic performances of RC bridges can be attained by sufficient ductilities of piers, which can be obtained by providing sufficient lateral confinements to the plastic hinge regions of piers. The cross sectional shape and the amount of lateral reinforcements are key parameters in the determination of effective confinements. Even though identical amounts of lateral reinforcement are provided, the effective confinement differs due to different spacing, arrangements, hook details and so on. Unlike circular sections in which confinement is exerted by mere hoop reinforcements, cross-ties are arranged in square or rectangular sections to enhance the effective confinements. The stress-strain relationship of confined concrete is varied by how to consider these cross-ties. In this study, the stress-strain relationships of confined concrete with cross-ties are investigated experimentally and their mechanical characteristics are estimated by comparison with other empirical equations.
A Study on the Relationship between the Eccentricity and the Level of Damage in the Seismic Response of Buildings with Plan Irregularities
Jeong, Seoung-Hoon ; Lee, Kwang-Ho ;
Journal of the Earthquake Engineering Society of Korea, volume 14, issue 3, 2010, Pages 49~57
DOI : 10.5000/EESK.2010.14.3.049
Most previous research on the seismic response of structures with plan irregularities have focused on the relationship between the eccentricity and the amount of torsion. This approach cannot provide the direct relationship between the irregularity and the damage. Therefore, an investigation on the relationship between the eccentricities of buildings with plan irregularities and the damage index was performed. Inelastic dynamic time-history analyses were performed on one-story buildings with various eccentricities. For the damage assessment, a 3D damage index was adopted to reflect the effect of the bi-directional response and torsion. Based on the analysis results, buildings with eccentricities of 10%, 20% and 30% will suffer 3~5%, 13~18%, and 33~47% more damage than their regular counterparts, respectively.
Seismic Vulnerabilities of a Multi-Span Continuous Bridge Considering the Nonlinearity of the Soil
Sun, Chang-Ho ; Lee, Jong-Seok ; Kim, Ick-Hyun ;
Journal of the Earthquake Engineering Society of Korea, volume 14, issue 3, 2010, Pages 59~68
DOI : 10.5000/EESK.2010.14.3.059
Seismic performances of existing structures should be assessed with more accuracy for cost-effective retrofits. Existing bridges are assessed by the current guidelines in which a simple method has been adapted considering the technical level of engineers of the historical time of construction. Recently many probabilistic approaches have been performed to reflect the uncertainties of seismic input motions. Structures are modeled frequently with the neglection of soil foundations or modeled occasionally with elastic soil spring elements to consider the effect of the soil on the structural response. However, soil also shows nonlinearity under seismic events, so this characteristic should be reflected in order to obtain a more accurate assessment. In this study, a 6-span continuous bridge has been analyzed under various seismic events, in which the soil was represented by equivalent linear spring elements having different properties according to the intensities of the input motions experienced. The seismic vulnerabilities with respect to the failure of piers and the dropping of the super-structure were evaluated on the basis of the analysis results.