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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
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Sensitivity Analysis of Rockfill Input Parameters Influencing Crest Displacement of CFRD Subjected to Earthquake Loading
Ha, Ik-Soo ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 1, 2007, Pages 1~9
DOI : 10.5000/EESK.2007.11.1.001
The purpose of this study is to carry out the quantitative sensitivity analysis on rockfill material influencing the dam crest displacement of CFRD(Concrete-Faced Rockfill Dam) subjected to earthquake loading. The total 105 dynamic numerical analyses (2 input earthquake, 2 magnitudes for each earthquake. 27 rockfill material property combinations obtained from large triaxial tests) on CFR type "D" dam in operation were conducted. The global sensitivity analysis was carried out using the results of numerical analysis. From the results of sensitivity analysis, It was found that the crest settlement of the CFR type dam subjected to earthquake was absolutely affected by the shear modulus of rockfill material irrespective of the input earthquakes and the maximum acceleration of each earthquake. Also, it was found that the horizontal displacement of the dam crest was highly affected by the shear modulus of rockfill material though the extent of effect on that was smaller than the settlement and the extent of effect depended on the input earthquakes and the maximum acceleration of each earthquake. On the contrary, it was found that the effect of friction angle was negligible.
GA-Based Optimal Design for Vibration Control of Adjacent Structures with Linear Viscous Damping System
Ok, Seung-Yong ; Kim, Dong-Seok ; Koh, Hyun-Moo ; Park, Kwan-Soon ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 1, 2007, Pages 11~19
DOI : 10.5000/EESK.2007.11.1.011
This paper proposes an optimal design method of distribution and capacities of linear viscous dampers for vibration control of two adjacent buildings. The previous researches have dealt with suboptimal design problem under the assumption that linear viscous dampers are distributed uniformly or proportionally to the sensitivity of the modal damping ratio according to floors, whereas this study deals with global optimization problem in which the damping capacities of each floor are independently selected as design parameters. For this purpose, genetic algorithm to effectively search multiple design variables in large searching domains is adopted and objective function leading to the global optimal solutions is established through the comparison of several optimal design values obtained from different objective functions with control performance and damping capacity. The effectiveness of the proposed method is investigated by comparing the control performance and total damping capacity designed by the proposed method with those of the previous method. In addition, the time history analyses are performed by using three historical earthquakes with different frequency contents, and the simulation results demonstrate that the proposed method is an effective seismic design method for the vibration control of the adjacent structures.
The Pseudo-Dynamic Test for the Seismic Retrofit System Utilizing Existing Bridge Bearings
Kwahk, Im-Jong ; Cho, Chang-Beck ; Kim, Young-Jin ; Kwark, Jong-Won ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 1, 2007, Pages 21~27
DOI : 10.5000/EESK.2007.11.1.021
In this study, an approach that installs seismic isolation bearings was proposed for the seismic retrofit of the existing bridges. The method that replaces all existing bearings with seismic isolators was proposed already. However, in this study, we recommend to utilize the existing bearings for the benefit of safety and cost. According to our proposal, the seismic isolators do not support vertical loads but they Just function as the period shifter and the horizontal damper. To verify this approach experimentally, the real scale bearings and lead rubber bearings far the real highway bridges were designed and fabricated. And the responses of this isolated bridges to the assumed earthquakes were determined by the pseudo dynamic test scheme. The test results were also compared to the responses computed by the well known structural analysis software to check the reliability of the test. From the test results, we found that the retrofitted bridges using the proposed method showed stable performances under earthquakes.
Capacity of Concrete Filled Carbon Tube Columns Based on the Comparison of Ductility and Energy Dissipation Capacity
Lee, Kyoung-Hun ; Hong, Won-Kee ; Lee, Young-Hak ; Kim, Hee-Cheul ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 1, 2007, Pages 29~35
DOI : 10.5000/EESK.2007.11.1.029
Flexural capacity estimation test of concrete filled carbon tube (CFCT) column under the cyclic lateral load was carried out in this study. Thickness of carbon tube and winding angles of carbon fiber were chosen as test parameters and two types of column with square and circular sections were manufactured. To act axial and lateral load, three dynamic actuators were used and all specimens were made with actual size. Flexural stiffness, ability of deformation, energy dissipation capacity and ductility behavior. of CFCT column were analyzed with test data.
Experimental Study on Flexural Capacity of Circular Concrete Beam Confined by Carbon Fiber Tubes
Lee, Kyoung-Hun ; Hong, Won-Kee ; Lee, Young-Hak ; Kim, Hee-Cheul ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 1, 2007, Pages 37~43
DOI : 10.5000/EESK.2007.11.1.037
Experiments for circular unreinforced concrete beams confined by carbon fiber tubes (CFT) made of carbon fiber sheets were performed. Selected test parameter was thickness of carbon fiber tube: 1.5mm (3 layers), 2.0mm (4 layers), 2.5mm (5 layers), and 3.0mm (6 layers). Based on the test results, an equation for estimating moment capacity of the circular beams confined by carbon fiber tubes was proposed. Comparison results showed good agreement up to 2.5mm (5 sheets) of the CFT thickness.
Determination of Mean Shear Wave Velocity to the Depth of 30m Based on Shallow Shear Wave Velocity Profile
Sun, Chang-Guk ; Chung, Choong-Ki ; Kim, Dong-Soo ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 1, 2007, Pages 45~57
DOI : 10.5000/EESK.2007.11.1.045
The mean shear wave velocity to the depth of 30 m (Vs30) derived from the western Vs is the current site classification criterion for determining the design seismic ground motion taking into account the site amplification potential. In order to evaluate the Vs30 at a site, a shear wave velocity (Vs) Profile extending to at least 30 m in depth must be acquired from in-situ seismic test. In many cases, however, the resultant depth of the Vs profile may not extend to 30 m, owing to the unfavorable field condition and the limitation of adopted testing techniques. In this study, the Vs30 and the mean shear wave velocity to a depth shallower, than 30 m (VsDs) were computed from the Vs profiles more than 30 m in depth obtained by performing various seismic tests at total 72 sites in Korea, and a correlation between Vs30 and VsDs was drawn based on the computed mean Vs data. In addition, a method for extrapolating the Vs profile from shallow depth to 30 m was developed by building a shape curve based on the average data of all Vs profiles. For evaluating the Vs30 from the shallow Vs profiles, both the methods using VsDs and shape curve result in less bias than the simplest method of extending the lowermost Vs equally to 30 m in depth, and are usefully applicable particularly in the cases of the Vs profiles extending to at least 10 m in depth.
Study on the Site Classification and Site Coefficients for the Seismic Design Regulations of KBC
Kim, Yong-Seok ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 1, 2007, Pages 59~65
DOI : 10.5000/EESK.2007.11.1.059
Site classification of IBC and KBC is based on the ft-kips unit system and is not friendly for the linear interpolation of the site coefficients due to the implicit relationship between a site class and site coefficients, defining a site class by the range of the soil properties, not by a single soil property. Also, the site class definition of KBC has too wide range of soil properties for each soil class. making the structural engineers difficult to estimate the site coefficients for the diverse soil layers. In this study, a new site classification in SI unit system was proposed for the seismic design codes of KBC etc., and the comparison of the site coefficients of
was also performed to investigate the possibility of the linear interpolation of the site coefficients with the proposed new site classification. According to the study results, it was more reasonable for the linear interpolation of the site coefficients to utilize the proposed new site classification considered the Sl unit system and the soil characteristics of the 30m soil layer beneath the shallow embedded foundation, and the linear interpolation of the acceleration coefficients for the design spectrum can be performed more reasonably defining the site coefficients for the representative shear wave velocities of each site class. With the study results, a new site classification, and the linear interpolation permitted acceleration coefficients fer the design spectrum were proposed for the modification of the seismic design regulations of KBC.
Seismic Response Analyses of the Structure-Soil System for the Evaluation of the Limits of the Site Coefficients
Kim, Yong-Seok ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 1, 2007, Pages 67~77
DOI : 10.5000/EESK.2007.11.1.067
Site coefficients in IBC and KBC codes have some limits to predict the rational seismic responses of a structure, because they take into account only the effect of the soil amplification without the effects of the structure-soil interaction. In this study, upper and lower limits of the site coefficients are estimated through the pseudo 3-D elastic seismic response analyses of structures built on the linear or nonlinear soil layers taking Into account the effects of the structure-soil interaction. Soil characteristics of site classes of A, B and C were assumed to be linear, and those of site classes of D and E were done to be nonlinear and the Ramberg-Osgood model was used to evaluate shear modulus and damping ratio of a soil layer depending on the shear wave velocity of the soil layer, Seismic analyses were performed with 12 weak or moderate earthquake records scaled the peak acceleration to 0.1g or 0.2g and deconvoluted as earthquake records at the bedrock located at 30m deep under the outcrop. With the study results of the elastic seismic response analyses of structures, new standard response spectrum and upper and lower limits of the site coefficients of
at the short period range and the period of 1 second are suggested including the effects of the structure-soil interaction, and new site coefficients for the KBC code are also suggested.
Analytical Study on Joints in Precast Segmental Prestressed Concrete Bridge Piers
Kim, Tae-Hoon ; Jin, Byeong-Moo ; Kim, Young-Jin ; Shin, Hyun-Mock ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 1, 2007, Pages 79~87
DOI : 10.5000/EESK.2007.11.1.079
This paper presents an analysis procedures of Joints in precast segmental prestressed concrete bridge piers. 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. An unbended tendon element based on the finite element method, that can represent the interaction between tendon and concrete of prestressed concrete member, is used. A joint element is newly developed to predict the inelastic behaviors of segmental joints. The proposed numerical method for joints in precast segmental prestressed concrete bridge piers is verified by comparison with reliable experimental results.
A Study on Seismic Source and Propagntion Characteristics using a Series of 12 Fukuoka Earthquakes
Kim, Jun-Kyoung ;
Journal of the Earthquake Engineering Society of Korea, volume 11, issue 1, 2007, Pages 89~97
DOI : 10.5000/EESK.2007.11.1.089
Parameters including the seismic sources and the elastic wave propagation characteristics were analysed using the observed ground motions from 12 Fukuoka region earthquakes. The Levenberg-Marquardt algorithm was applied to invert all the variables non-linearly and simultaneously with S wave energy in fiequency domain. Average stress drop of 12 events and local attenuation parameter
under seismic stations were estimated to about 79.2-bar and 0.043 respectively. Regional attenuation parameter, Qo and
, were also estimated to be about 248.1 and 0.558 respectively. Low value of Qo seems to caused by inhomogeneous tectonic characteristics between Japan island and southern Korean peninsula.
values are much higher than that characterizing EUS (Eastern United States) region, and nearly similar to that of WUS (Western Waited States) region. If the informations on site specific amplification of all the seismic stations are known,
values can be estimated more precisely. All the values including the seismic sources and the site and crustal scale propagation characteristics can be used as seismic design parameters.