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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 8, Issue 6 - Dec 2004
Volume 8, Issue 5 - Oct 2004
Volume 8, Issue 4 - Aug 2004
Volume 8, Issue 3 - Jun 2004
Volume 8, Issue 2 - Apr 2004
Volume 8, Issue 1 - Feb 2004
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Maximum Control Force for Sliding Mode Controller with Saturation Problem
Journal of the Earthquake Engineering Society of Korea, volume 8, issue 2, 2004, Pages 1~8
DOI : 10.5000/EESK.2004.8.2.001
Sliding mode control (SMC), which is one of active control algorithms showing remarkable control performance, requires the excessive control force for control of seismically excited civil structures. Therefore, controller saturation should be considered in design of SMC. In this study, a method for determining the maximum control force is developed in terms of the fraction of the lateral restoring force using a design response spectrum. Numerical analyses of MDOF structures with one or multiple control devices verify the effectiveness of the proposed method for the control of seismically excited civil structures with saturation problem.
Improvement of Seismic Performance of Existing Bridges using Isolation
Journal of the Earthquake Engineering Society of Korea, volume 8, issue 2, 2004, Pages 9~17
DOI : 10.5000/EESK.2004.8.2.009
The seismic performance evaluation and retrofit process are very important in old existing bridges. If the result is not appropriate. then a retrofit process are required. Among various retrofit methods, the seismic isolation is a very useful method. because it can be applied by replacing old bridge bearings. In this study, the effectiveness of seismic isolation is rationally verified. For this purpose, two seismic isolations used widely are selected and non-linear static and dynamic analyses are performed. The responses of existing bridges are compared with those of retrofited bridges by seismic isolation bridge for earthquake of target level. and seismic performances are evaluated.
Finite Element Formulation for the Finite Strain Thermo-Elasto-Plastic Solid using Exponential Mapping Algorithm : Model and Time Integration Scheme
Journal of the Earthquake Engineering Society of Korea, volume 8, issue 2, 2004, Pages 19~25
DOI : 10.5000/EESK.2004.8.2.019
The linear analysis for the balance of linear momentum of a structure is relatively easy to perform, but the error becomes large when the structure experiences large deformation. Therefore, the material and geometric nonlinearity need to be considered for the precise calculations in that case. The plastic flow of a ductile steel-like metal mainly transforms its dissipated mechanical energy into heat, which transfers under the first and second law of thermodynamics. This heat increases the temperature of the material and the strength of the material decreases accordingly, which affects mechanical behavior of the given structure. This paper presents a finite-strain thermo-elasto-plastic steel model. This model can handle large deformation and thermal load simultaneously, which is common during earthquake periods. Two 3-dimensional finite element analyses verify this formulation.
Dynamic Analysis of Floating Bridge Subject to Earthquake Load Considering Multi-Support Excitation
Journal of the Earthquake Engineering Society of Korea, volume 8, issue 2, 2004, Pages 27~33
DOI : 10.5000/EESK.2004.8.2.027
Dynamic response analysis is conducted for a floating bridge subjected to multiple support earthquake excitation. The floating bridge used in this study is supported by discrete floating pontoons and horizontal pretension cables supported at both ends of the bridge. The bridge is modeled with finite elements and the hydrodynamic added mass and added damping due to the surrounding fluid around pontoons are obtained using boundary elements. During the analysis the concept of retardation function is utilized to consider the frequency dependency of the hydrodynamic coefficients. Multiple support excitation is introduced at both ends of the bridge and the time history response is compared to that of a simultaneous excitation. The results show that the multiple support excitation yields larger values in some responses. for example in cable tensions. than the sumultaneous excitation.
Evaluation of Capacity Spectrum Methods for Estimating the Peak Inelastic Responses
Journal of the Earthquake Engineering Society of Korea, volume 8, issue 2, 2004, Pages 35~44
DOI : 10.5000/EESK.2004.8.2.035
In the capacity spectrum method(CSM) using a linear response spectrum, the peak response of an inelastic system under a given earthquake load is estimated transforming the system into the equivalent elastic one. The CSM for estimating the peak inelastic response is evaluated in this paper. The equivalent period and damping ratio are calculated using the ATC-40, G lkan, Kowalsky, and Iwan methods, and the performance points are obtained according to the procedure B of ATC-40. Analysis results indicate that the ATC-40 method generally underestimates the peak response resulting in the unsafe design, while the G lkan and Kowalsky methods overestimate the responses. The Iwan method produces the values between those by the ATC-40 method and the G lkan and Kowalsky methods, and estimates the responses relatively closer to the exact ones. Further, it is found that the Kowalsky method gives the negative equivalent damping ratios depending on the hardening ratios, and thereby can not be used to estimate the responses in some cases.
Identification of Stiffness and Damping Matrix of Building Structures using Modal Characteristics
Journal of the Earthquake Engineering Society of Korea, volume 8, issue 2, 2004, Pages 45~53
DOI : 10.5000/EESK.2004.8.2.045
In this paper, the stiffness and damping matrix are experimentally constructed using the structural modal information on frequencies, damping ratio and modal vectors, which are obtained by shaking table tests. Free vibration, harmonic and white noise vibration tests are performed. The acceleration of the shaking table was used as the input signal, and the corresponding accelerations of each floor were measured as output signals. The characteristics and limitations of modal information from each test are compared. The results of this study would be a basic resource of the analytical and experimental studies on the system identification of structures.
An Experimental Study on the Structural Vibration Control Using Semi-Active Orificed Fluid Dampers
Journal of the Earthquake Engineering Society of Korea, volume 8, issue 2, 2004, Pages 55~62
DOI : 10.5000/EESK.2004.8.2.055
In general, control performance of the active control system is superior to that of the passive control devices. However, the active system require a large amount of external energy to operate the actuators. Semi-active control systems maintain the reliability of the passive control systems while taking advantage of the adjustability of the active control system. In this research, a semi-active orificed fluid damper having the capacity of about 2 tons was designed and fabricated. It is a two-stage damper with normally open solenoid valve. A series of tests was performed to grasp its performance characteristics. It was also applied to a 6-story steel structure subjected to random and seismic excitations for the confirmation of its validity on structural vibration absorption.
Seismie Performance Evaluation of Reinforced Concrete Bridge Piers Supported by Laminated Rubber Bearings
Journal of the Earthquake Engineering Society of Korea, volume 8, issue 2, 2004, Pages 63~72
DOI : 10.5000/EESK.2004.8.2.063
The purpose of this study is to evaluate seismic performance of reinforced concrete bridge piers supported by laminated rubber bearings. A computer program, named RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. Seismic isolator element is developed to predict behaviors of laminated rubber bearings. The proposed numerical method for seismic performance evaluation of reinforced concrete bridge piers supported by laminated rubber bearings is verified by comparison with reliable experimental results.
New Technique on the Improvement of Earthquake-Resistant Performance for the Retrofitting of Existing Reinforced Concrete Beam-Column Joints
Journal of the Earthquake Engineering Society of Korea, volume 8, issue 2, 2004, Pages 73~81
DOI : 10.5000/EESK.2004.8.2.073
In this study, experimental research was carried out to improve earthquake-resistant performance for the retrofitting of reinforced concrete beam-column joints using carbon fiber materials in existing reinforced concrete building. Six reinforced concrete beam-column joints were constructed and tested to evaluate the retrofitting effect of test variables, such as the retrofitting materials and retrofitting region(plastic hinge, beam-column joint) under load reversals. Test results show that retrofitting specimen(RPC-CP2, RPC-CR, RJC-CP, RJC-CR), using new materials(carbon fiber plate, carbon fiber rod and carbon fiber sheet), designed by the improvement of earthquake-resistant performance and ductility, attained more load-carrying capacity and stable hysteretic behavior.
Modification of Response Displacement Method for Seismic Design of Underground Structures under Domestic Conditions
Journal of the Earthquake Engineering Society of Korea, volume 8, issue 2, 2004, Pages 83~93
DOI : 10.5000/EESK.2004.8.2.083
In this study. the Modified Response Displacement Method(MRDM) for seismic design of underground box-type structures is proposed. Firstly, to investigate the applicability of the conventional RDM, various parametric studies are performed according to buried depth and soil conditions. Results from the conventional RDM are compared with those of time history analysis in terms of the maximum bending moment and relative displacement. The comparison shows that the velocity response spectrum and the determination method of foundation modulus which significantly influence the accuracy of RDM should be modified. Thus, the modified velocity response spectrum and the new determination method of foundation modulus are proposed under consideration of domestic conditions. In order to demonstrate the accuracy and validity of the proposed MRDM numerical analyses are performed according to different parameters such as depth of base rock, height and width of box, buried depth and soil condition. the comparison with the results of the time history analysis verifies the feasibility of the proposed MRDM for the seismic analysis.