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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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Displacement Ductility Ratio of Reinforced Concrete Bridge Piers with Lap-splices
Park, Kwang-Soon ; Ju, Hyeong-Seok ; Shin, Hyun-Mock ; Kim, Moon-Kyum ;
Journal of the Earthquake Engineering Society of Korea, volume 12, issue 6, 2008, Pages 1~12
DOI : 10.5000/EESK.2008.12.6.001
As internal and external seismic experiment results, the seismic performance of RC bridge piers is largely dependent on the ratio of lap-spliced bars to all longitudinal reinforcing bars in plastic hinge regions, and confining effects of transverse reinforcements. Capacity and displacement ductility of non-seismically designed existing RC piers are reduced by lap splices in plastic hinge regions. The provision for the lap splice of longitudinal reinforcing bars was not specified in KBDS (Korean Bridge Design Specifications) before the implementation of 1992 seismic design code, but the ratio of lap-spliced bars to all longitudinal reinforcing bars in plastic hinge regions is restricted to 50% in the 2005 version of KBDS. This paper presents a seismic assessment of RC piers at lap-splicing ratios of 0%, 50%, and 100%. Through a comparison of experimental and analytic results of RC piers, we introduce an appropriate ultimate strain of confined concrete in plastic hinge regions with lap-splices, and propose a method for estimating displacement ductility ratios of non-seismically designed existing RC piers using fiber element analysis.
FE Model Updating on the Grillage Model for Plate Girder Bridge Using the Hybrid Genetic Algorithm and the Multi-objective Function
Jung, Dae-Sung ; Kim, Chul-Young ;
Journal of the Earthquake Engineering Society of Korea, volume 12, issue 6, 2008, Pages 13~23
DOI : 10.5000/EESK.2008.12.6.013
In this study, a finite element (FE) model updating method based on the hybrid genetic algorithm (HGA) is proposed to improve the grillage FE model for plate girder bridges. HGA consists of a genetic algorithm (GA) and direct search method (DS) based on a modification of Nelder & Mead`s simplex optimization method (NMS). Fitness functions based on natural frequencies, mode shapes, and static deflections making use of the measurements and analytical results are also presented to apply in the proposed method. In addition, a multi-objective function has been formulated as a linear combination of fitness functions in order to simultaneously improve both stiffness and mass. The applicability of the proposed method to girder bridge structures has been verified through a numerical example on a two-span continuous grillage FE model, as well as through an experimental test on a simply supported plate girder skew bridge. In addition, the effect of measuring error is considered as random noise, and its effect is investigated by numerical simulation. Through numerical and experimental verification, it has been proven that the proposed method is feasible and effective for FE model updating on plate girder bridges.
Proposal and Implementation of Emergency Response System of Gas Shut-off in Earthquake
Jung, Hyo-Soon ; Kim, Ick-Hyun ; Lee, Jong-Seok ;
Journal of the Earthquake Engineering Society of Korea, volume 12, issue 6, 2008, Pages 25~33
DOI : 10.5000/EESK.2008.12.6.025
Fires that result from the excessive leakage of gas due to earthquakes cause enormous loss of property as well as numerous human casualties. To prevent such disasters, an emergency gas shut-off system is considered to be one of the effective and rational methods. Considering the seismicity, the earthquake frequency and the gas-supply system of Korea, mass gas shut-off by a gas company is determined to be more cost-effective than individual gas shut-off by customers. In this study, an emergency response system was proposed that would shut off the gas supply immediately. Two different reference seismicities were proposed, to specify rapid response according to the measured seismicity. The gas supply area was divided into several gas shut-off blocks in order to facilitate the shut-off of gas supply in damaged blocks. This proposed system was implemented in the actual gas supply area with reference seismicities on the basis of seismic damage analysis.
Evaluation of Seismic Response of Multi-Story Frames for Multiple Ground Excitations
Choi, Hyun-Hoon ; Christopoulos, C. ; Kim, Jin-Koo ;
Journal of the Earthquake Engineering Society of Korea, volume 12, issue 6, 2008, Pages 35~45
DOI : 10.5000/EESK.2008.12.6.035
To investigate the effects of residual displacement, the structural responses of buckling-restrained braced frames (BRBF) and special moment-resisting frames (SMRF) were evaluated for design-based excitations following an application of initial residual drift. The initial residual drift was applied to the structure in two ways. The first way was to simply apply the same earthquake record to the structure twice, with an appropriate pause between applications to allow the structural response from the first record to return to zero. The second way to apply the initial residual drift was to apply a pushover to the structure until it arrives at the desired residual drift value. According to the analysis results, the initial residual drifts had a significant effect on the responses of steel BRBF and SMRF. The responses of BRBF were more highly dependent on the initial residual deformation than the responses of SMRF. Therefore, in order to minimize the post-event repair cost, a reduction of residual drift is required.
Retrofit Prioritization of Highway Network considering Seismic Risk of System
Na, Ung-Jin ; Park, Tae-Won ; Shinozuka, Masanobu ;
Journal of the Earthquake Engineering Society of Korea, volume 12, issue 6, 2008, Pages 47~53
DOI : 10.5000/EESK.2008.12.6.047
This research focuses on the issue of seismic retrofit prioritization based on the Caltrans` highway network serving Los Angeles and Orange counties. Retrofit prioritization is one of most important problems in earthquake engineering, and it is a problem that most decision makers face in the process of resource allocation. This study demonstrates the methods of prioritized resource allocation in the process of retrofitting a regional highway network. For the criteria of a retrofit ranking, seismic vulnerability and the importance of network link are first introduced. Subsequently, link-based seismic retrofit cases are simulated, investigating the effects of the seismic retrofit in terms of seismic performance, such as driver`s delay. In this study, probabilistic scenario earthquakes are used to perform a probabilistic seismic risk analysis. The results show that the retrofit prioritization can be differently defined and ranked depending on the stakeholders. This study provides general guidelines for prioritization strategy for the effective retrofitting of a highway network system.
Seismic Response Analysis for Three Dimensional Soil-structure Interaction System using Dynamic Infinite Elements
Seo, Choon-Gyo ; Ryu, Jeong-Soo ; Kim, Jae-Min ;
Journal of the Earthquake Engineering Society of Korea, volume 12, issue 6, 2008, Pages 55~63
DOI : 10.5000/EESK.2008.12.6.055
This paper presents a seismic analysis technique for a 3D soil-structure interaction system in a frequency domain, based on the finite element formulation incorporating frequency-dependent infinite elements for the far field soil region. Earthquake input motions are regarded as traveling P, SV and SH waves which are incident vertically from the far-field soil region, and then equivalent earthquake forces are calculated using impedances of infinite soil by dynamic infinite elements and traction and displacement from free field response analysis. For verification and application, seismic response analyses are carried out for a multi-layered soil medium without structure and a typical nuclear power plant in consideration of soil-structure interaction. The results are compared with the free field response using a one-dimensional analytic solution, and a dynamic response of an example structure from another SSI package.
Cyclic Hardening and Degradation Effects on Site Response during an Earthquake
Lee, Jin-Sun ;
Journal of the Earthquake Engineering Society of Korea, volume 12, issue 6, 2008, Pages 65~71
DOI : 10.5000/EESK.2008.12.6.065
A one-dimensional site response analysis program (KODSAP) was developed using cyclic soil behavior model by using the modified parallel IWAN model. The model is able to predict the cyclic hardening and degradation of soil through the adjustment of the internal slip stresses of its elements beyond the cyclic threshold, and satisfies Bauschinger`s effect and the Masing rule in terms of its own behavior characteristics. The program (KODSAP) used the direct integration method in the time domain. The elasticity of the base rock was considered as a viscous damper boundary condition. The effects of cyclic hardening or degradation of soil on site response analysis were evaluated through parametric studies. Three types of analyses were performed to compare the effect of analysis and cyclic parameter on site response. The first type was equivalent linear analysis, the second was nonlinear analysis, and a third was nonlinear analysis using the cyclic hardening or degradation model.