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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Earthquake Engineering Society of Korea
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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
Back Analysis Technique for the Estimation of Tension Force on Hanger Cables
Kim, Nam-Sik ; Park, Dong-Uk ; Park, Yong-Myung ; Cheung, Jin-Hwan ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 3, 2007, Pages 1~10
DOI : 10.5000/EESK.2007.11.3.001
In general, the tension forces of hanger cable in suspension bridges play an important role in evaluating the bridge conditions. The vibration method, as a conventional one, has been widely applied to estimate the tension forces by using the measured frequencies on hanger cables. However, the vibration method is not applicable to short hanger cables because the fiequencies of short cables are severely sensitive to flexural rigidity. Thus, in this study, the tension forces of short hanger cables, of which the length is shorter than 10 meters, were estimated through back analysis of the cable fiequencies measured from Gwang-An suspension bridge in Korea. Direct approach to back analysis is adopted using the univariate method among the direct search methods as an optimization technique. The univariate method is able to search the optimal tension forces without regard to the initial ones and has a rapid convergence rate. To verify the feasibility of back analysis, the results from back analysis and vibration method are compared with the design tension forces. From the comparison, it can be inferred that back analysis results are more reasonable agreement with the design tension forces of short hanger cable. Therefore, it is concluded that back analysis applied in this study is an appropriate tool for estimating tension forces of short hanger cables.
Fragility Analysis for Evaluation and Comparison of Seismic Performance of Building Structures
Park, Joo-Nam ; Choi, Eun-Soo ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 3, 2007, Pages 11~21
DOI : 10.5000/EESK.2007.11.3.011
Potential damage and losses associated with structural systems caused by earthquake can be reduced by application of seismic design to the structures. Because the building cost required for seismic design is generally higher than the cost for non-seismic design, the application of seismic design must be justified considering both seismic performance and cost. This paper presents a risk-based fiamework for evaluation and comparison of seismic performance of structures such that necessary data can be supplied for decision making on seismic design. Seismic fragility curve is utilized for seismic risk assessment of structures, and the process for decision analysis on adaptation of seismic design is presented based on the equivalent cost model.
Evaluation of Seismic Performance of Prefabricated Bridge Piers with a Circular Solid Section
Kim, Hyun-Ho ; Shim, Chang-Su ; Chung, Chul-Hun ; Kim, Cheol-Hwan ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 3, 2007, Pages 23~31
DOI : 10.5000/EESK.2007.11.3.023
Fast bridge construction has been increasingly needed according to the changed construction environment. This paper deals with quasi-static tests on precast piers for bridge substructures. One of the most crucial aspect of the design of precast prestressed concrete bridge piers is the seismic performance. Seven precast pier elements were fabricated. The amount of prestressing bars, the prestressing force, and the location and number of the joint between segments were the main test parameters. Test results showed that the introduced axial prestress made the restoration of the deformation under small lateral displacement and minor damage. However, there was no effect of the prestress when the plastic hinge region was damaged severely due to large lateral displacement. Judging from the observed damage, the design of the joints in precast piers should be done for the first joint between the foundation and the pier segment. The amount of the necessary prestressing steel may be designed to satisfy the P-M diagram according to the service loads, not by having the same steel ratio as normal RC bridge piers. In order to satisfy the current required displacement ductility, it is necessary to have the same amount of the transverse reinforcements as RC piers. As the steel ratio increases, the energy absorption capacity increases. The number of joints showed a little influence on the energy absorption capacity.
Shaking Table Test of Isolated EDG Model
Kim, Min-Kyu ; Choun, Young-Sun ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 3, 2007, Pages 33~42
DOI : 10.5000/EESK.2007.11.3.033
In this study, for research on an improvement of the seismic safety of an EDG system, a small scale EDG system was manufactured. For the isolation system, the Coil Spring-Viscous Damper systems were selected. For the shaking table test, 3 kinds of seismic motions were selected which had different frequency contents. In this study, the isolation effects were different and they depended on the input seismic motion. In the case of an NRC earthquake which had low fiequency contents, the isolation effects of the horizontal direction were 20%. But for the seismic motions which had high fiequency contents, the isolation effects were
. In the case of the vertical direction, poor isolation effects were observed. It was because the design properties and the real properties of the isolation system were a little different.
Weighting-Factored Evaluation Method for Determination of Seismic Retrofitting Schemes for Existing Bridges
Ha, Dong-Ho ; Lee, Ji-Hoon ; Park, Kwang-Soon ; Lee, Yong-Jae ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 3, 2007, Pages 43~52
DOI : 10.5000/EESK.2007.11.3.043
This study suggests a method to determine optimal seismic retrofitting schemes for existing bridges based on weighting-factored evaluation. According to the recognition for potential seismic risk, various kinds of retrofitting methods are applied to improve the seismic performance of existing bridges. However, the relevant technique is not available to select optimal retrofitting scheme for bridges now. This suggested method weights five factors, structural compatibility, economic efficacy, environmental factor, consturctability and maintenance, and draws out optimal seismic retrofitting schemes. The application of the developed method to one hundred sixty existing bridges verifies the adaptability of this method. As a result, this study provides an idealized retrofitting schemes, and the suggested method could be a guideline to determine the more cost-effective and optimal retrofitting schemes for existing bridges in Korea.
Improvement of Seismic Performance of Long-span Bridges using Complex Dampers
Ha, Dong-Ho ; Park, Kwan-Soon ; Park, Won-Suk ; Pyeon, Mu-Wook ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 3, 2007, Pages 53~62
DOI : 10.5000/EESK.2007.11.3.053
This paper presents a new vibration control method for long-span bridges using complex damper system. The new system presents simple mechanical configuration with oil and elasto-plastic dampers which have velocity and displacement dependency in vibration energy absorbing. This system can produce various damping forces according to the applied external forces by the velocity and displacement-dependent characteristics of the dampers. The oil damper dissipates vibration energy for relatively frequent and small amplitude like in the case for small to moderate earthquakes, whereas the elasto-plastic damper system works for rare and large amplitude vibration such as high seismic excitation. Thus, the proposed system exhibits the advantage of low cost with high performance since the roles of the two different dampers are effectively separated. A numerical model is established for the complex damper system, and the response characteristics and effectiveness of the proposed system are presented through numerical simulations. Numerical results show that the proposed complex damper system can significantly improve the seismic performance of long-span bridge structures with much more effective damping mechanism than single conventional passive damper systems.
Evaluation of Vibration Characteristics of Operating Rotational Machines Depending of Types of Foundation
Kim, Min-Kyu ; Choun, Young-Sun ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 3, 2007, Pages 63~72
DOI : 10.5000/EESK.2007.11.3.063
The Emergency Diesel Generator (EDG) is a very important equipment for the safety of a Nuclear Power Plant (NPP). In this study, the operating vibration of three kinds of EDG systems was measured. The target EDG systems are Yonggwang 5 unit and Ulchin 2 and 3 units. The Yonggwang 5 and Ulchin 3 unit EDG systems are the same type but the foundation systems are different. One is an anchor bolt type and the other is a spring and viscous-damper type. The purpose of these measurements is for a verification of the vibration isolation effect depending on the foundation system. As a result, It can be said that the spring and viscous damper system of the EDG performed better for the vibration isolation than that of anchor bolt type.
Development of Seismic Analysis Model and Time History Analysis for KALIMER-600
Koo, Gyeong-Hoi ; Lee, Jae-Han ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 3, 2007, Pages 73~86
DOI : 10.5000/EESK.2007.11.3.073
In this paper, a simple seismic analysis model of the KALIMER-600 sodium-cooled fast reactor selected to be the candidate of the GEN-IV reactor is developed. By using this model, the seismic time history analysis is carried out to investigate the feasibilities of a seismic isolation design. The developed simple seismic analysis model includes the reactor building, reactor system,, IHTS piping system, steam generator, and seismic isolators. The dynamic characteristics of the simple seismic model are verified with the detailed 3-dimensional finite element analysis for each part of the KALIMER-600 system. By using the developed simple seismic model, the seismic time history analyses for both cases of a seismic isolation and non-isolation design are performed for the artificial time history of a SSE (Safe Shutdown Earthquake) 0.3g. From the comparison of the calculated floor response spectrum, it is verified that the seismically isolated KALIMER-600 reactor building shows a great performance of a seismic isolation and assures a seismic integrity.
A Study on the Seismic Performance of Energy-Dissipating Sacrificial Devices for Steel Plate Ginder Bridges
Cho, Kwang-Il ; Gwak, Pil-Bong ; Mha, Ho-Seong ; Kim, Sang-Hyo ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 3, 2007, Pages 87~96
DOI : 10.5000/EESK.2007.11.3.087
A new Energy-Dissipating Sacrificial Device (EDSD) is developed for steel plate girders, which can effectively dissipate the energy stored in the structures during seismic actions. To verify the performance of the EDSD, various seismic responses of a sample bridge with the EDSD are analyzed in terms of energy, member forces and deformation. The full scale model tests are conducted to certify the performance of the EDSD when it is applied on existing bridges. Using the improved hysteretic model of the sacrificial member, the seismic analysis for an example bridge is performed. The results show that the proposed EDSD under seismic excitations can significantly decrease the energy stored in the bridge structures and reduce the relative displacements of each superstructure to the ground. The EDSD is also found to function as a structural fuse under strong ground motions, sacrificing itself to absorb the excessive energy. Consequently, economical enhancement of the seismic performance of bridges can be achieved by employing the newly developed energy-dissipating sacrificial device.