• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.1
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• pp.23-29
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• 2017

In this study, a post-correlation analysis for shaking table test of square water storage tank is presented for the use of advances in earthquake-resistant design of liquid storage tank. For this purpose, the ANSYS CFX program is selected for the CFD analysis. Sensitivity analysis for resonant sloshing motion in terms of grid size and turbulence model suggested that (1) horizontal grid size as well as vertical grid size is a key variable in the sloshing analysis, and (2) the SST turbulence model is best for the sloshing analysis. Finally, correlation analyses for a non-resonant harmonic input and scaled earthquake excitation of the El Centro (1940) NS component are carried out using the grid and turbulence model established through the post-correlation analysis for the resonant motion. As a result, sloshing time histories by the CFD analysis agreed very well with the test results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.59-66
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• 2017

In the case of fluid storage structure, hydrostatic pressure acts on the structure due to fluid surge during an earthquake. At this time, hydrodynamic pressure of the fluid charge not only by the strength of the earthquake but also by the sloshing height of the fluid. Factors affecting the change of load include the size, width and height of the fluid storage structure and height of fluid, time-history shape, etc. This paper wanted to identify the relationship between the earthquake shape and fluid free surface shape. The sloshing height measured the height of the fluid by applying earthquake to a tank whose width 500mm and comparison of the experiment and analysis. In addition, the shape of the fluid free surface was measured while varying the shape of earthquake and effective of the shape of earthquake of the fluid was analyzed.

• Journal of the Korean GEO-environmental Society
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• v.7 no.6
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• pp.133-143
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• 2006

A fully coupled effective stress dynamic analysis procedure for modeling seismic liquefaction on slope is presented. An elasto-plastic formulation is used for the constitutive model UBCSAND in which the yield loci are radial lines of constant stress ratio and the flow rule is non-associated. This is incorporated into the 2D version of Fast Lagrangian Analysis of Continua (FLAC) by modifying the existing Mohr-Coulomb model. This numerical procedure is used to simulate centrifuge test data from the Rensselaer Polytechnic Institute (RPI). UBCSAND is first calibrated to cyclic direct simple shear tests performed on Nevada sand. Both pre- and post-liquefaction behaviour is captured. The centrifuge test is then modeled and the predicted accelerations, excess porewater pressures, and displacements are compared with the measurements. The results are shown to be in general agreement. The procedure is currently being used in the design of liquefaction remediation measures for a number of dam, bridge, tunnel, and pipeline projects in Western Canada.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.4
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• pp.389-403
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• 2004

This study presents the structural model modification based on the modal data such as natural frequencies and mode shapes. Preliminary structural model can be obtained using design drawings and field measurement, and therefore the deteriorated stiffness of a structure and the effect of the boundary conditions are difficult to be evaluated in preliminary analysis model, and the preliminary model can be modified using structural response data including static and/or dynamic characteristics. In this study, the structural model is modified based on the structural modal data using genetic algorithm. Modal testing were carried out for Imjin River Bridge and Hangjoo Bridge, the modal properties were estimated using modal identification techniques, and finally the structural models were updated using genetic algorithm. The modified structural model could give us more reliable structural analysis results and therefore those can be used for structural performance evaluation such as load carrying capacity and seismic capacity.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.1 s.47
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• pp.33-39
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• 2006

Parameters including the seismic sources and the elastic wave propagation characteristics were analysed using the observed ground motions from 3 Kyoungju region earthquakes. The Levenberg-Marquardt algorithm was applied to invert all the variables non-linearly and simultaneously with S wave energy In frequency domain. Average stress drop of 3 events and local attenuation parameter ${\kappa}$ were estimated to about 48-bar and 0.0312 respectively. Regional attenuation parameter, Qo and ${\eta}$, were also estimated to be about 417 and 0.83. ${\kappa}$ values are much higher than that of EUS, even though smaller than that of WUS. All these values resultant from this study show that there are differences in some parameters of other studios due to differences in the governing equation. of acceleration motions

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.2
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• pp.35-45
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• 2012

Pseudo static analysis using the Mononobe-Okabe method and numerical analysis considering a small strain nonlinearity from the soil were performed to determine the bearing pressure changes of the inverted T-type retaining wall subjected to earthquake motions. In many cases, an inverted 'T' type retaining wall of more than 10 m shows bearing capacity failure under earthquake conditions, despite showing sufficient bearing capacity during normal conditions. The most important reason for this is the change of the effective base area during an earthquake. In this paper, the change of the effective base area of an inverted 'T' type wall is analyzed by using finite difference element code (FLAC). In addition, the effect of dynamic bearing capacity coefficients (which has been suggested by several researchers but not adopted in current design codes and procedures) was verified.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.7_spc
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• pp.443-451
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• 2016

A Gyeongju earthquake in the magnitude of 5.8 on the Richter scale (the moment magnitude of 5.4), which was recorded as the strongest earthquake in Korea, occurred in September 12, 2016. Compared with the 2011 Virginia earthquake, the moment magnitude was slightly smaller and its duration was 3 seconds, much shorter than 10 seconds of the Virginia earthquake, resulting in relatively minor damage. But the two earthquakes are quite similar in terms of the overall scale, unexpectedness, and social situation. The North Anna Nuclear Power Plant, which is a nuclear power plant located at 18 km away from the epicenter of the Virginia earthquake, had no damage to nuclear reactors because the reactors were automatically shut down as the design basis earthquake value was exceeded. Ground accelerations of the 2016 Gyeongju earthquake did not exceed the threshold value but the manual shutdown was carried out so that Wolsong Nuclear Power Site was not damaged. Damaged historic homestead house and masonry structures due to the Virginia earthquake have been repaired, reinforced, and rebuilt based on a long-term earthquake recovery project. Likewise, it will be necessary to carefully carry out an earthquake recovery planning program to improve overall seismic performance and to reconstruct the historic buildings and structures damaged as a result of the Gyeongju earthquake.

• Journal of the Korean Society for Railway
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• v.20 no.4
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• pp.500-511
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• 2017

Recently, as earthquakes have occurred in Gyeongju, interest in the stability of structures against vibration from earthquakes has increased. In Korea, the capacity of load resistance is mainly considered in the design of anchors. However, the vibration resistance characteristics of anchors have not been fully elucidated. The traditional type of anchor, which is a frictional resistance anchor, is often reported to fail due to vibration in construction procedures, such as blasting. The expansion type of anchor, on the other hand, could have more resistance to vibration but its capability of demonstrating vibratory resistance has to be investigated. In order to verify the vibratory resistance characteristics of expansion anchors against blasting and earthquake vibration, field tests and numerical analyses for seismic wave were performed. Field blasting test results show that the expansion anchor has better capability against vibratory load than does the frictional type anchor. Numerical analysis to earthquake also show that the expansion type anchor provides more resistance than does the frictional type anchor.

• Journal of the Korea Concrete Institute
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• v.14 no.4
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• pp.467-473
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• 2002

The purpose of this study is to investigate the inelastic behavior and ductility capacity of reinforced concrete frame subjected to cyclic lateral load and to provide result for developing improved seismic design criteria. 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. The strength increase of concrete due to the lateral confining reinforcement has been taken into account to model the confined concrete. In boundary plane at which each member with different thickness is connected local discontinuous deformation due to the abrupt change in their stiffness can be taken into account by introducing interface element. The effect of number of load reversals with the same displacement amplitude has been also taken into account to model the reinforcing steel. The proposed numerical method for the inelastic behavior and ductility capacity of reinforced concrete frame subjected to cyclic lateral load is verified by comparison with reliable experimental results.

• Journal of the Korea Concrete Institute
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• v.14 no.3
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• pp.365-372
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• 2002

This experimental investigation was conducted to examine the behavior of eight a third scale columns made of high-strength concrete(HSC). The columns were subjected to constant axial load corresponding to target value of 30 percent of the column axial load capacity and a cyclic horizontal load-inducing reversed bending moment. The variables studied in this research are the volumetric ratio of transverse reinforcement(Ps=1.58, 2.25 ％), tie configuration(hoop-type, cross-type, diagonal-type) and tie yield strength(fy=5,600, 7,950 kgf/$\textrm{cm}^2$). Test results indicated that the flexural strength of all the columns did not exceed calculated flexural capacities based on the equivalent concrete stress block used in current design code. Columns with 42 percent higher amounts of transverse reinforcement than that required by seismic provisions of ACI 318-99 were shown ductile behavior. With axial load of 30 percent of the axial load capacity, the use of high-strength steel as transverse reinforcement may lead to equal or higher ductility than would be achieved with low-strength steel.