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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 12, Issue 6 - Dec 2008
Volume 12, Issue 5 - Oct 2008
Volume 12, Issue 4 - Aug 2008
Volume 12, Issue 3 - Jun 2008
Volume 12, Issue 2 - Apr 2008
Volume 12, Issue 1 - Feb 2008
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Seismic Response of R/C Structures Subjected to Artificial Ground Motions Compatible with Design Spectrum
Jun, Dae-Han ; Kang, Ho-Geun ;
Journal of the Earthquake Engineering Society of Korea, volume 12, issue 1, 2008, Pages 1~9
DOI : 10.5000/EESK.2008.12.1.001
In seismic response analysis of building structures, the input ground accelerations have considerable effect on the nonlinear response characteristics of structures. The characteristics of soil and the locality of the site where those ground motions were recorded affect on the contents of earthquake waves. Therefore, it is difficult to select appropriate input ground motions for seismic response analysis. This study describes a generation of artificial earthquake wave compatible with seismic design spectrum, and also evaluates the seismic response values of multistory reinforced concrete structures by the simulated earthquake motions. The artificial earthquake wave are generated according to the previously recorded earthquake waves in past major earthquake events. The artificial wave have identical phase angles to the recorded earthquake wave, and their overall response spectra are compatible with seismic design spectrum with 5% critical viscous damping. The input ground motions applied to this study have identical elastic acceleration response spectra, but have different phase angles. The purpose of this study is to investigate their validity as input ground motion for nonlinear seismic response analysis. As expected, the response quantifies by simulated earthquake waves present better stable than those by real recording of ground motion. It was concluded that the artificial earthquake waves generated in this paper are applicable as input ground motions for a seismic response analysis of building structures. It was also found that strength of input ground motions for seismic analysis are suitable to be normalize as elastic acceleration spectra.
Failure Probability of Nonlinear SDOF System Subject to Scaled and Spectrum Matched Input Ground Motion Models
Kim, Dong-Seok ; Koh, Hyun-Moo ; Choi, Chang-Yeol ; Park, Won-Suk ;
Journal of the Earthquake Engineering Society of Korea, volume 12, issue 1, 2008, Pages 11~20
DOI : 10.5000/EESK.2008.12.1.011
In probabilistic seismic analysis of nonlinear structural system, dynamic analysis is performed to obtain the distribution of the response estimate using input ground motion time histories which correspond to a given seismic hazard level. This study investigates the differences in the distribution of the responses and the failure probability according to input ground motion models. Two types of input ground motion models are considered: real earthquake records scaled to specified intensity level and artificial input ground motion fitted to design response spectrum. Simulation results fir a nonlinear SDOF system demonstrate that the spectrum matched input ground motion produces larger failure probability than those of scaled input ground motion due to biased responses. Such tendency is more remarkable in the site of soft soil conditions. Analysis results show that such difference of failure probability is due to the conservative estimation of design response spectrum in the range of long period of ground motion.
Flexural strength of high-strength concrete filled steel tube columns strengthened by carbon fiber sheets
Park, Jai-Woo ; Hong, Young-Kyun ; Hong, Gi-Soup ;
Journal of the Earthquake Engineering Society of Korea, volume 12, issue 1, 2008, Pages 21~28
DOI : 10.5000/EESK.2008.12.1.021
The CFT (Concrete Filled Steel Tube) columns became popular in high rise building construction due to not only its composite effect but also economic advantage. However, it has been pointed out in various previous researches that the current practice in CFT columns may lead the steel tube to probable local buckling at critical sections of the columns right after yielding. To resolve such a problem, the TR-CFT (Transversely Reinforced Concrete Filled Steel Tube) column is proposed to control or at least delay the local buckling state at the critical section by wrapping the CFT columns with carbon fiber sheet. The validity of the proposed column system is validated through the present paper by observing the experimental performance and comparing it with the analytical prediction of the TR-CFT columns with hish strength concrete. It is also shown that the current design code provisions such as ACI-318, in which the contribution of concrete confining effect filled in steel tube is not appropriately accounted for, may contain too much conservatism.
The effects of End Platens on Effective Stresses in Resonant Column (RC) Specimens during Consolidation
Bae, Yoon-Shin ;
Journal of the Earthquake Engineering Society of Korea, volume 12, issue 1, 2008, Pages 29~42
DOI : 10.5000/EESK.2008.12.1.029
The objective of this study is to investigate the effects of rigid end platens on effective stresses in soil mass during consolidation. The friction between the teeth of top cap/base pedestal and the specimen during consolidation decreases the radial and tangential effective stresses in RC specimens. However, it is unpractical to measure the effective stresses in the soil specimen. Two approaches were used to evaluate the state of stress in RC specimens during consolidation. First, careful measurements were made of small strain shear modulus,
in specimens with carefully controlled void ratios and stress histories, to infer the state of stress. And second, a finite element analysis was performed to analytically evaluate the effect of various soil parameters on the state of stress in RC specimens during consolidation. By combining these experimental and analytical results, an example was performed to predict the average state of stress in RC specimens during consolidation.
Identifying Strain Associated with Damping Ratio from Tosional Test Using a Combined Damping Model
Bae, Yoon-Shin ;
Journal of the Earthquake Engineering Society of Korea, volume 12, issue 1, 2008, Pages 43~55
DOI : 10.5000/EESK.2008.12.1.043
The complexity of determining strain associated with shear modulus and damping ratio in torsional tests has been resolved by means of several approaches. Particularly, the modified equivalent radius approach is adequate to when generating the plots of equivalent radius ratio versus strain more effectively over any range of strains in resonant column and torsional shear (RC/TS) tests. The modified equivalent radius approach was applied for hyperbolic, modified hyperbolic, and Ramberg-Osgood models in evaluating damping ratio. Results showed that using a single value of equivalent radius ratio based on conventional equivalent radius approach is not appropriate. A new model was developed to consider the soil damping behavior at small strains as well as hysteretic damping and it was attempted to determine adjustments are required in evaluating strain associated damping when combining the two damping components.
Shaking Table Experimental Study on 3-Dimensional Floor Isolation in Main Control Room of Nuclear Power Plant
Lee, Kyung-Jin ; Ham, Kyung-Won ; Suh, Yong-Pyo ; Yoon, Hyun-Do ;
Journal of the Earthquake Engineering Society of Korea, volume 12, issue 1, 2008, Pages 57~66
DOI : 10.5000/EESK.2008.12.1.057
An experimental study was performed to evaluate seismic reduction performance and applicability of 3-dimensional floor isolation system to the main control room of nuclear power plant. A friction pendulum system(FPS) and air spring were designed and fabricated for 3-dimensional floor isolation system. Two kind of the partial experimental model of a main control room attached to the FPS and air spring were tested on the shaking table. The experimental model consisted of a control panel, a
access floor, four FPS and air springs. The artificial time histories based on the vertical and horizontal floor response spectrums(OBE, SSE) of the main control room were used as the earthquake input signals in the test. Compared to non-isolated system, the seismic response of experimental models using 3-dimensional floor isolation system were shown considerable seismic reduction performance.
An Experimental Study for the Shear Property and the Temperature Dependency of Seismic Isolation Bearings
Cho, Chang-Beck ; Kwahk, Im-Jong ; Kim, Young-Jin ;
Journal of the Earthquake Engineering Society of Korea, volume 12, issue 1, 2008, Pages 67~77
DOI : 10.5000/EESK.2008.12.1.067
Seismic isolation has been studied continuously as a solution of the seismic engineering to reduce the sectional forces and the damages of structures caused by earthquakes. To certify reliable design and installation of the seismic isolation systems, seismic isolation bearings should be fabricated under well planned quality control process, and proper evaluation tests for their seismic performance should be followed. In this study, shear property evaluation tests for the lead rubber bearings(LRB) and the rubber bearings(RB) were implemented and the temperature dependency tests were also implemented to evaluate the changes of shear properties according to the changes of temperature. After evaluation tests, the measured shear properties were compared to their design values and their deviation was analyzed comparing with the allowable error ranges specified in Highway Bridge Design Specifications. These results showed that a considerable number of isolation bearings have so large deviations from their design values that their error ranges were over or very close to the allowable ranges. And the test results for temperature dependency showed that the shear properties of isolation bearings would be changed in great degree by the change of temperature during their service period. If these two types of changes in their shear properties are superposed, it would possible that the changes of shear properties from their original design values are over than 50%.
Comparison of Approximate Nonlinear Methods for Incremental Dynamic Analysis of Seismic Performance
Bae, Kyeong-Geun ; Yu, Myeong-Hwa ; Kang, Pyeong-Doo ; Kim, Jae-Ung ;
Journal of the Earthquake Engineering Society of Korea, volume 12, issue 1, 2008, Pages 79~87
DOI : 10.5000/EESK.2008.12.1.079
Seismic performance evaluation of structure requires an estimation of the structural performance in terms of displacement demand imposed by earthquakes on the structure. Incremental Dynamic Analysis(IDA) is a analysis method that has recently emerged to estimate structural performance under earthquakes. This method can obtained the entire range of structural performance from the linear elastic stage to yielding and finally collapse by subjecting the structure to increasing levels of ground acceleration. Most structures are expected to deform beyond the limit of linearly elastic behavior when subjected to strong ground motion. The nonlinear response history analysis(NRHA) among various nonlinear analysis methods is the most accurate to compute seismic performance of structures, but it is time-consuming and necessitate more efforts. The nonlinear approximate methods, which is more practical and reliable tools for predicting seismic behavior of structures, are extensively studied. The uncoupled modal response history analysis(UMRHA) is a method which can find the nonlinear reponse of the structures for ESDF from the pushover curve using NRHA or response spectrum. The direct spectrum analysis(DSA) is approximate nonlinear method to evaluate nonlinear response of structures, without iterative computations, given by the structural linear vibration period and yield strength from the pushover analysis. In this study, the practicality and the reliability of seismic performance of approximate nonlinear methods for incremental dynamic analysis of mixed building structures are to be compared.
Characteristic Investigation of the Bedrock Earthquake Records for the Structural Time-History Seismic Analyses
Kim, Yong-Seok ;
Journal of the Earthquake Engineering Society of Korea, volume 12, issue 1, 2008, Pages 89~95
DOI : 10.5000/EESK.2008.12.1.089
Until recently lots of time-history seismic analyses were performed with the earthquake motions recorded at the soft soil surface without taking into account the effects of the soft soil amplification. However, it is important to utilize the bedrock seismic motions for the rational seismic analyses of a structure considering the site soil conditions. In this study, 26 bedrock earthquake records were selected from publicly available 1557 seismic records provided by the Pacific Earthquake Engineering Research Center (PEER) for the study, and the characteristics of them were investigated. Study results showed that it is not reasonable to estimate earthquake acceleration intensity from the magnitude of an earthquake without considering the site soil conditions and it is also hard to draw any general relationships between earthquake acceleration intensity, earthquake magnitude and epicenter distance with bedrock earthquake records in the PEER database. However, 26 bedrock earthquake records selected in this study can be utilized for the time-history seismic analyses of a structure-soil system as bedrock earthquake ones, and it is also confirmed that it is necessary to take into account acceleration intensity, magnitude, epicenter distance and site conditions simultaneously for the proper use of those selected earthquake records.