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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 11, Issue 6 - Dec 2007
Volume 11, Issue 5 - Oct 2007
Volume 11, Issue 4 - Aug 2007
Volume 11, Issue 3 - Jun 2007
Volume 11, Issue 2 - Apr 2007
Volume 11, Issue 1 - Feb 2007
Selecting the target year
Incorporating Genetic Algorithms into the Generation of Artificial Accelerations
Park, Hyung-Ghee ; Chung, Hyun-Kyo ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 2, 2007, Pages 1~9
DOI : 10.5000/EESK.2007.11.2.001
The method of generating the artificial acceleration time histories for seismic analysis based on genetic algorithms is presented. For applying to the genetic algorithms, the frequencies are selected as the decision variables eventually to be genes. An arithmetic average crossover operator and an arithmetic ratio mutation operator are suggested in this study. These operators as well as the typical simple crossover operator are utilized in generating the artificial acceleration time histories corresponding to the specified design response spectrum. Also these generated artificial time histories are checked whether their outward features are to be coincident with the recorded earthquake motion or not. The features include envelope shape, correlation condition between 2 horizontal components of motion, and the relationship of max. acceleration, max. velocity and max. displacement of ground.
Rational Evaluation of Seismic Response Modification Factor of Steel Moment Frame Based on Available Connection Rotation Capacity
Lee, Cheol-Ho ; Kim, Geon-Woo ; Song, Jin-Gyu ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 2, 2007, Pages 11~17
DOI : 10.5000/EESK.2007.11.2.011
In current seismic design practice, the response modification factor (R-factor) is used as a factor to reduce the elastic base shear demand to the design force level. As is well-known, the R-factor is a committee-consensus factor and, as such, highly qualitative and empirical. The relationship between the R-factor and the connection rotation capacity available in a particular structural system has remained a missing link. In this paper, a rational procedure to evaluate the R-factor is proposed. To this end, the relationship between the available connection rotation capacity and the R-factor is defined and quantified using nonlinear pushover analysis. An RRS steel frame designed according to IBC 2000 was used to illustrate and verify the proposed procedure. Nonlinear time history analysis results indicated that the R-factor definition proposed in this study is generally conservative from design perspective.
Mechanical Characteristic Analysis of Coil Spring & Viscous Damper
Kim, Min-Kyu ; Choun, Young-Sun ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 2, 2007, Pages 19~26
DOI : 10.5000/EESK.2007.11.2.019
This paper presents the results of experimental studies of the mechanical characteristics of the Coil Spring and Viscous Damper system. The Coil Spring and Viscous Damper systems were selected for the isolation of Emergency Diesel Generator (EDG) which is located in Nuclear Power Plant (NPP). The Coil Spring and Viscous Damper systems were developed for the operating vibration isolation and seismic isolation for scaled Model EDG System. The damping properties of the viscous damper changes as the variation of velocity. Through this research nonlinear damping characteristics and the effective stiffness of coil spring and viscous damper system were evaluated.
Forced Vibration Testing of a Four-Story Reinforced Concrete Frame Building
Yu, Eun-Jong ; Wallace, John W. ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 2, 2007, Pages 27~38
DOI : 10.5000/EESK.2007.11.2.027
A series of forced vibration tests and ambient vibration measurement was conducted on a four-story reinforced concrete building damaged in the 1994 Northridge earthquake. Both low amplitude broadband and moderate amplitude harmonic excitation were applied using a linear shaker and two eccentric mass shakers, respectively, and ambient vibrations were measured before and after each forced vibration test. Accelerations, interstory displacements, and curvature distributions were monitored using accelerometers, LVDTs and concrete strain gauges. Natural frequencies and the associated mode shapes fur the first 7 modes were identified. Fundamental frequencies determined from the eccentric mass shaker tests were 70% to 75% of the values determined using ambient vibration data, and 92% to 93% of the values determined using the linear shaker test data. Larger frequency drops were observed in the NS direction of the building, apparently due to damage that was induced during the Northridge earthquake.
Seismic Performance Evaluation of a RC Special Moment Frame Building
Kim, Tae-Wan ; Kim, Jin-Koo ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 2, 2007, Pages 39~45
DOI : 10.5000/EESK.2007.11.2.039
In this study the probability and the reliability-based seismic performance evaluation procedure proposed in the FEMA-355F was applied to a reinforced concrete moment frame building. For the FEMA procedure, which was originally developed for steel moment frame structures, to be applied to other structural systems, the capacity should be re-defined and the factors reflecting the uncertainties related to capacity and demand need to be determined. To perform the evaluation procedure a prototype building was designed per IBC 2003, and inelastic dynamic analyses were conducted applying site-specific ground motions to determine the parameters for performance evaluation. According to the analysis results, distribution of the determined capacities turned out to be relative]y smaller than that of the demands, which showed that the defined capacity was reasonable. It was also shown that the prototype building satisfied the target performance since the determined confidence levels exceeded the otjectives for both local and global collapses.
Performance Evaluation of Semi-Active Tuned Mass Damper for Elastic and Inelastic Seismic Response Control
Lee, Sang-Hyun ; Chung, Lan ; Woo, Sung-Sik ; Cho, Seung-Ho ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 2, 2007, Pages 47~56
DOI : 10.5000/EESK.2007.11.2.047
In this study, tile performance of a passive tuned mass damper (TMD) and a semi-active tuned mass damper (STMD) was evaluated in terms of seismic response control of elastic and inelastic structures under seismic loads. First, elastic displacement spectra were obtained for the damped structures with a passive TMD, which was optimally designed using the frequency and damping ratio presented by previous study, and with a STMD proposed in this study. The displacement spectra confirm that STMD provides much better control performance than passive md with less stroke. Also, the robustness or the TMD was evaluated by off-tuning the frequency of the TMD to that of the structure. Finally, numerical analyses were conducted for an inelastic structure of which hysteresis was described by Bouc-Wen model and the results indicated that the performance of the passive TMD of which design parameters were optimized for a elastic structure considerably deteriorated when the hysteretic portion or the structural responses increased, while the STMD showed about 15-40% more response reduction than the TMD.
Vibration Control of Mega Frame Structures using a Semi-active Tuned Mass Damper
Kim, Hyun-Su ; Lee, Dong-Guen ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 2, 2007, Pages 57~68
DOI : 10.5000/EESK.2007.11.2.057
The mega frame system is becoming popular for the design and construction of skyscrapers because this system exhibits structural efficiency by allowing high rigidity of the structure while minimizing the amount of structural materials to be used. Since the mega frame system is usually adopted for super high-rise buildings, the comfort of occupants may be main concerns in the practical application of this system. For the enhancement of the serviceability of mega frame structures, a semi-active tuned mass damper (STMD) is developed in this study. To this end, a Magnetorheological (MR) damper is employed replacing passive damper as a semi-active damper to improve the control effect of a conventional TMD. Since a conventional finite element model of mega frame structures has significant numbers of DOFs, numerical simulation for investigation of control performances of a STMD is impossible by using the full-order model. Therefore, a reduced-order system using minimal DOFs, which can accurately represent the dynamic behavior of a mega frame structure, is proposed in this study through the matrix condensation technique To improve the efficiency of the matrix condensation technique, multi-level matrix condensation technique is proposed using the structural characteristics of mega frame structures. The efficiency and accuracy of the reduced-order control proposed in this study and the control performance of a STMD were verified using example structures.
Damage Detection of Structures using Peak and Zero of Frequency Response Functions
Park, Soo-Yong ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 2, 2007, Pages 69~79
DOI : 10.5000/EESK.2007.11.2.069
In this paper, a technique to detect structural damage and estimate its severity using peaks and zeros of frequency response functions (FRFs) is developed. The peaks in FRFs represent the natural frequencies of the structure and the zeros provide additional information. The characteristics of peaks and zeros are defined and the calculation procedure to obtain the peaks and zeros from the relationship between frequency response function and stiffness and mass matrices are clearly explained. A structural system identification theory which is utilizing the sensitivity of stiffness of a structural member to eigenvalues, i.e., peaks and zeros, is established. The proposed method can identify damage location and its severity, with natural and zero frequencies, by estimating structural stiffness of the structure in the process of making a analytical model The accuracy and feasibility is demonstrated by numerical models of a spring-mass system and a beam structure.
Detailed Investigation on the Dynamic Excess Pore Water Pressure through Liquefaction Tests using Various Dynamic Loadings
Choi, Jae-Soon ; Jang, Seo-Yong ; Kim, Soo-Il ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 2, 2007, Pages 81~94
DOI : 10.5000/EESK.2007.11.2.081
In most experimental researches on the liquefaction phenomenon, an earthquake as a random vibration has been regraded as a sinusoidal wave or a triangular wave with an equivalent amplitude. Together with the development in the part of signal control and data acquisition, dynamic experimental equipments in the soil dynamics have also developed rapidly and further more, several real earthquakes have been simulated in the large model test such as shaking table tests and centrifuge tests. In Korea, several elementary laboratory tests to simulate the real earthquake load were performed. From these test results, it was reported that the sinusoidal wave cannot reliably reflect the soil dynamic behavior under the real earthquake motion. In this study, 4 types of dynamic motions such as the sinusoidal wave, the triangular wave, the incremental triangular wave and several real earthquake motions which were classified with shock-type and vibration-type were loaded to find something new to explain the change of the excess pore water pressure under the real earthquake load. Through the detailed investigation and comparison on all test results, it is found that the dynamic flow is generated by the soil plastic deformation and the velocity head of dynamic flow is changed the pressure head in the un-drained condition. It can be concluded that the change of the excess pore water pressure is related to the pressure head of dynamic flow. Lastly, a new hypothesis to explain such a liquefaction initiation phenomenon under the real earthquake load is also proposed and verified.
Correlation of Experimental ana Analytical Inelastic Responses of 1:12 Scale Irregular High-Rise RC Buildings
Ko, Dong-Woo ; Lee, Han-Seon ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 2, 2007, Pages 95~104
DOI : 10.5000/EESK.2007.11.2.095
Three types of high-rise RC building structures having irregularity in the lower two stories were selected as prototypes and were performed nonlinear static analysis by using OpenSees to verify the analysis technique and to investigate the seismic capacity of those buildings. The first one has a symmetrical moment resisting frame (Model 1), the second has an infilled shear wall in the central frame (Model 2), and the third has an infilled shear wall only in one of exterior frames (Model 3). Fiber model, which consists of concrete and reinforcing bar represented from stress-strain relationship, is adapted used for simulate the nonlinearity of members, and MVLEM(Multi vertical linear element model) is used for simulate the behavior of wall. The analytical results are simulate the behavior of piloti stories well, for example, the stiffness and yield farce of piloti stories, the up-lift of wall and the variation of lateral stiffness of column due to the variation of axial forces. Overstrength of Model 2 and Model 3 are about 2 times larger than that of Model 1. The reason of the high oversttrength and ductility of Model 2 and Model 3 is that the conservative design of Model 2 and Model 3, whose beam and column sections are the same as those of Model 1. The ductilities of Model 1 and Model 3 are slightly larger than that of Model 1 and Model 3. Model 1 and Model 3 reached mechanism condition, whereas Model 2 failed to the shear failure of shear wall and the large axial forces in columns due to large overturning moment.
Development of Performance-Based Seismic Design of RC Column Retrofitted By FRP Jacket using Direct Displacement-Based Design
Cho, Chang-Geun ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 2, 2007, Pages 105~113
DOI : 10.5000/EESK.2007.11.2.105
In the current research, an algorithm of performance-based seismic retrofit design of reinforced concrete columns using FRP jacket has been proposed. For exact prediction of the nonlinear flexural analysis or FRP composite RC members, multiaxial constitutive laws of concrete and composite materials have been presented. For seismic retrofit design, an algorithm of direct displacement-based design method (DDM) proposed by Chopra and Goel (2001) has been newly applied to determine the design thickness of FRP jacket in seismic retrofit of reinforced concrete columns. To compare with the displacement coefficient method (DCM), the DDM gives an accurate prediction of the target displacement in highly nonlinear region, since the DCM uses the elastic stiffness before reaching the yield load as the effective stiffness but the DDM uses the secant stiffness.