• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.6
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• pp.41-52
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• 2007

Earthquake time-history analyses have been carried out for a buried gas pipeline of X65 which is of popular use in Korea. Parameters included are shape of a buried gas pipeline, soil characteristics, single and multiple earthquake input ground motions and burial depths. Predicted response of strain and relative displacement are then compared with allowable strain and displacement capacity calculated by Guidelines for the Seismic Design of Buried Gas Pipelines, KOGAS. Comparative studies show that strains are in general affected by the burial depths together with change of soil conditions. Regarding the relative displacement, while axial relative displacement is not influenced by the burial depths, transverse relative displacement is affected by both burial depths as well as soil conditions. In all, the current study is encouraged to give a useful information for healthy earthquake evaluation of a buried pipeline.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.6
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• pp.53-61
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• 2007

This study investigates the effect of site class, post-yield stiffness ratio, damping ratio, yield-strength reduction factor, and natural period on inelastic displacement ratio of bilinear SDF systems located at the sites classified as NEHRP site class B,C,D. The previous studies developed inelastic displacement ratio using equal displacement rule in the intermediate and long period range. But, this approximation overestimates the inelastic displacement ratio. Furthermore, inelastic displacement ratio has not been developed for the systems having a damping ratio less than 5%. This study conducts nonlinear regression analysis for proposing equations for calculating median and deviation of the inelastic displacement ratio of the bilinear SDOF system having damping ratios ranging from 0 to 20%. Using median and deviation of the inelastic displacement ratio, probabilistic inelastic displacement ratio is estimated, which can be used for performance-based seismic evaluation.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.753-760
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• 2020

In this study, the structural safety of the bearing support was analysed by applying the vertical load (bearing design load) and horizontal load (horizontal force generated during an earthquake) using a precise three-dimensional numerical model. The results of stress and displacement of newly-poured concrete and welded rebars were confirmed numerically. Numerical results show that the increase in the horizontal force and the height of the beam causes the concrete cracking and the stress increase of the rebar connections due to the increase of the stress at the new concrete interface. Therefore, it was analyzed that the increase in the height of bearing support is directly related to the horizontal force and it is necessary to apply the bearing support height appropriate for the bearing support capacity. It was proposed that a method of setting the height of the bearing support suitable for the bearing capacity and determining the reinforcement by presenting the guideline with the correlation between the horizontal force acting on the bearing support and its height.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.3 s.55
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• pp.63-72
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• 2007

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.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.6
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• pp.401-412
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• 2016

On Tuesday, January 17, 1995, an earthquake of magnitude 7.2 struck the Port of Kobe. In effect, the port was practically destroyed. After a hazard investigation, researchers reached a consensus to adopt a performance-based design in port and harbor structures in Japan. A residual displacement of geotechnical structures after an earthquake is one of the most important engineering demands in performance-based earthquake-resistant design. Thus, it is essential to provide reliable responses of geotechnical structures after an earthquake through various techniques. Today, a nonlinear explicit response history analysis(NERHA) of geotechnical structures is the most efficient way to achieve this goal. However, verification of the effective stress analysis, including post liquefaction behavior, is difficult to perform at a laboratory scale. This study aims to rigorously verify the NERHA by using well-defined field measurements, existing numerical tools, and constitutive models. The man-made, Port Island, in Kobe provides intensive hazard investigation data, strong motion records of 1995 Kobe earthquake, and sufficient engineering parameters of the soil. Two dimensional numerical analysis was conducted on the caisson quay wall section at Port Island subjected to the 1995 Kobe earthquake. The analysis result matches very well with the hazard investigation data. The NERHA procedure presented in this paper can be used in further studies to explain and examine the effects of other factors on the seismic behavior of gravity quay walls in liquefiable soil areas.

• Journal of the Korean Geotechnical Society
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• v.28 no.9
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• pp.31-45
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• 2012

This study was conducted to estimate the stability of a quay wall in case of wave overtopping under the combined action of an earthquake and tsunami using limit equilibrium method. The tsunami force was calculated by using a numerical program called TWOPM-3D (3-D one-field Model for immiscible TWO-Phase flows). Especially, the wave force acting behind the quay wall after a tsunami wave overtopping was estimated by treating back fill as a permeable material. The stability of the quay wall was assessed for both the sliding and overturning modes under passive and active conditions. The variation in the stability of the quay wall with time was determined by parametric studies, including those for the tsunami wave height, seismic acceleration coefficient, internal friction angle of the soil, wall friction angle, and pore water pressure ratio. When the earthquake and tsunami were considered simultaneously, the tsunami induced wave overtopping increased the stability of the quay wall under the passive condition, but in the active condition, the safety factors decreased.

• Journal of the Korean Geotechnical Society
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• v.34 no.5
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• pp.53-63
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• 2018

Dynamic soil-pile interaction is the main concern in the design of group piles under earthquake loadings. The lateral resistance of the pile group under dynamic loading becomes different from that of a single pile due to the group pile effect. However, this aspect has not yet been properly studied for the pile group under seismic loading condition. Thus, in this study the group pile effect was evaluated by performing a series of dynamic centrifuge tests on $3{\times}3$ group pile in dry loose sand. The multiplier coefficients for ultimate lateral resistance and subgrade reaction modulus were suggested to obtain the p-y curve of the group pile. The suggested coefficients were verified by performing the nonlinear dynamic analyses, which adopted Beam on Nonlinear Winkler Foundation model. The predicted behavior of the pile group showed the reasonable agreement compared with the results of the centrifuge tests under sinusoidal wave and artificial wave.

• Journal of the Korean Geotechnical Society
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• v.33 no.5
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• pp.15-23
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• 2017

The evaluation of earthquake load on the surface is very important factor for the seismic reinforcement of existing building, and the magnitude of earthquake load depends on a shear wave velocity profile of soil under a building. To determine a shear wave velocity profile under a existing building, test method should be able to determine a reliable shear wave velocity profile under conditions such as heavy background noise and the small test area, and be sensitive to the variation of material property. In this research, HWAW (Harmonic Wavelet Analysis of Waves) method is applied to determine a shear wave velocity profile under a existing building. In this paper, through numerical simulations and field tests, the feasibility of the proposed method was shown.

• Journal of the Korean Geotechnical Society
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• v.33 no.5
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• pp.25-35
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• 2017

Liquefaction is one of the major seismic damage, and several methods have been developed to evaluate the possibility of liquefaction. Recently, a probabilistic approach has been studied to overcome the drawback of deterministic approaches, and to consider the uncertainties of soil properties. In this study, the spatial variability of cone penetration resistance was evaluated using CPT data from three locations having different variability characteristics to perform the probabilistic analysis considering the spatial variability of soil properties. Then the random fields of cone penetration resistance considering the spatial variability of each point were generated, and a probabilistic analysis of liquefaction induced settlement was carried out through CPT-based liquefaction evaluation method. As a result, the uncertainty of soil properties can be overestimated when the spatial variability is not considered, and significant probabilistic differences can occur up to about 30% depending on the allowable settlement.

• Steel and Composite Structures
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• v.32 no.1
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• pp.79-90
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• 2019

This study introduces new connections that connect the beam to the column with slit dampers. Plastic deformations and damages concentrate on slit dampers. The slit dampers prevent plastic damages of column, beam, welds and panel zone and act as fuses. The slit dampers were prepared with IPE profiles that had some holes in the webs. In this paper, two experimental specimens were made. In first specimen (SDC1), just one slit damper connected the beam to the column and one IPE profile with no holes connected the bottom flange of the beam to the column. The second specimen (SDC2) had two similar dampers which connected the top and bottom flange of the beam to the column. Cyclic loading was applied on Specimens. The cyclic displacements conditions continued until 0.06 radian rotation of connection. The experimental observations showed that the bending moment of specimen SDC2 increased until 0.04 story drift. In specimen SDC1, the bending moment decreases after 0.03 story drift. Test results indicate the high performance of the proposed connection. Based on the results, the specimen with two slit damper (SDC2) has higher seismic performance and dissipates more energy in loading process than specimen SDC1. Theoretical formulas were extended for the proposed connections. Numerical studies have been done by ABAQUS software. The theoretical and numerical results had good agreements with the experimental data. Based on the experimental and numerical investigations, the high ductility of connection is obtained from plastic damages of slit dampers. The most flexural moment of specimen SDC1 occurred at 3% story drift and this value was 1.4 times the plastic moment of the beam section. This parameter for SDC2 was 1.73 times the plastic moment of the beam section and occurred at 4% story drift. The dissipated energy ratio of SDC2 to SDC1 is equal to 1.51.