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        검색결과 412

        61.
        2017.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Current seismic design provisions such as ASCE 7-10 provide criteria for selecting ground motions for conducting response history analysis. This study is the sequel of a companion paper (I – Ground Motion Selection) for assessment of the ASCE 7-10 criteria. To assess of the ASCE 7-10 criteria, nonlinear response history analyses of twelve single degree of freedom (SDF) systems and one multi-degree of freedom (MDF) system are conducted in this study. The results show that the target seismic demands for SDF can be predicted using the mean seismic demands over seven and ten ground motions selected according to the proposed method within an error of 30% and 20%, respectively
        4,000원
        62.
        2017.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        For estimating the seismic demand of buildings, most seismic design provisions permit conducting linear and nonlinear response history analysis. In order to obtain reliable results from response history analyses, a proper selection of input ground motions is required. In this study, an accurate algorithm for selecting and scaling ground motions is proposed, which satisfies the ASCE 7-10 criteria. In the proposed algorithm, a desired number of ground motions are sequentially scaled and selected from a ground motion library without iterations.
        4,000원
        63.
        2017.04 구독 인증기관·개인회원 무료
        In this study, we suggested the jacking method of small diameter sewer pipe for improving workability of the pipe at the weak ground. The jacking method minimizes the space and time in constructing small diameter sewer pipe. In addition, to use this method do not cause road restrictions during the construction period. In this study, the construction process of the small diameter sewer pipe is explained. In addition, to ensure the safety during construction, the design consideration such as earth pressure and the jacking force of the steel pipe, and safety against boiling of the ground were examined. For verify the safety of this jacking method, it is necessary to carry out an experiment to estimate the safety of main pipe under construction.
        64.
        2017.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        관측된 지반진동은 지진원, 지각감쇠 및 지반의 증폭특성 등 3가지 주요 인자로 구성되어 있고 특히 지반증폭 특성은 지진원 및 감쇠특성을 평가할 때 필요하다. 또한 지진재해도를 분석하기 위해 지반의 증폭 특성에 정보가 내진 공학 뿐만 아니라 암반공학적 특성 분석에서 필수적이다. 지반의 증폭특성 분석을 위해 분석대상 관측소와 기준 관측소 지반진동의 수평/수직 비를 이용하는 방법을 적용하였다. 기존의 기준관측소의 수직성분 방법에 더하여 새로이 기준관 측소의 수평성분 방법을 새로이 시도하였다. 본 연구는 예당저수지 인근에 설치한 4개의 관측소에서 관측된 6개의 가 속도 지반진동을 이용하여 각 지반진동의 S파, Coda파 및 배경잡음 각각을 분석한 지반증폭 특성을 상호 비교하였다. 4개 관측소 공통적으로 S파와 Coda파를 이용한 결과는 상호 유사한 지반증폭 특성을 보였다. 다만 배경잡음은 다른 2 개 지진 에너지와 비교할 때 전혀 다른 지반증폭 특성을 보였고 이는 배경잡음의 발생 원인이 관측소 마다 서로 다르 기 때문으로 입증되었다. 4개 각각의 지진 관측소마다 저주파수 및 고주파수 증폭특성과 관측소 고유의 우월주파수가 서로 상이하여 관측소 고유의 증폭특성을 보여주었다. 또한 본 연구의 결과와 다른 방법의 결과와 비교하면 지반의 동 적특성 및 지반분류 연구에 많은 정보를 제시할 수 있다.
        4,200원
        65.
        2017.04 구독 인증기관 무료, 개인회원 유료
        SSG(self-healing smart grouting) method, has the characteristics such as an improvement of durability and waterproofing, prevention of leaching and pollution. In this study, several tests were performed such as gel-time measurement, uniaxial compression test, permeability test, chemical resistance test to compare the engineering properties of SSG with the other chemical grouting method(LW, SGR). As results of tests, the SSG method has low possibility of groundwater and ground pollution caused by leaching, furthermore, it has advantages like long/short term waterproofing, strength and durability. Therefore the SSG method can be applicable in the fields as an alternative method where is the problems of existing chemical grouting method.
        3,000원
        66.
        2017.04 구독 인증기관 무료, 개인회원 유료
        Since the settlement of the underground ground occurred in Seok-Chon Underground Roadway in Seoul from August 2014, the social interest of ground stability has increased. Thus, in this paper, We introduce not only the legal counterplan about the ground settlement but also a result of study on how many new materials can be used in the repairing of ground settlement.
        3,000원
        67.
        2017.04 구독 인증기관 무료, 개인회원 유료
        최근 도심지에서 지중매설관의 구조적 결함에 의한 토사 유실로 인해 지하 공동이 빈번하게 발생하고 있다. 본 연구에서는 이러한 지하 공동을 파악하는데 있어 현장 실험 수행 결과 전기비저항 탐사와 공압콘관입시험이 지반 조건의 이상 징후를 탐지하는데 효율적임을 확인하였다. 또한, 이미지 분석을 통한 전기비저항 실험 측정값을 정량화 하여 평균 비저항 값을 산정하는 방법을 제안하였다. 실대형 실험 결과, 평균 비저항 값이 감소할수록 위험도가 증가하였고, 공압콘관입시험 결과, N치가 작을수록 위험도가 높다는 것을 확인하였으며, 제한적인 측정 데이터 수를 토대로 평균 비저항 값과 공압콘관입시험의 결과를 토대로 상관관계를 나타내었을 때, 지반의 지하공동 발생과 관련된 위험 수준을 제한적으로 평가할 수 있을 것으로 판단된다.
        3,000원
        71.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The simplified plate theory is presented for static and free vibration analysis of power-law(P) and sigmoid(S) Functionally Graded Materials(FGM) plates. This theory considers the parabolic distribution of the transverse shear stress, and satisfies the condition that requires the transverse shear stress to be zero on the upper and lower surfaces of the plate, without the shear correction factor. The simplified plate theory uses only four unknown variables and shares strong similarities with classical plate theory(CPT) in many aspects such as stress-resultant expressions, equation of motion and boundary conditions. The material properties of the plate are assumed to vary according to the power-law and sigmoid distributions of the volume fractions of the constituents. The Hamilton’s principle is used to derive the equations of motion and Winkler-Pasternak elastic foundation model is employed. The results of static and dynamic responses for a simply supported FGM plate are calculated and a comparative analysis is carried out. The results of the comparative analysis with the solutions of references show relevant and accurate results for static and free vibration problems of FGM plates. Analytical solutions for the static and free vibration problems are presented so as to reveal the effects of the power law index, elastic foundation parameter, and side-to-thickness ratio.
        4,000원
        72.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In recent years, urban areas occurred several times a sinkhole. In Korea, this limestone area where the sink hole sink holes occur based on not much was seen as a very rare phenomenon. However, the occurrence of accidents in recent Subsidence and urban areas is occurring in the limestone sinkhole may yet see another one called artificial Subsidence phenomenon. Subsidence in urban areas can have various causes, such as depression groundwater level changes due to the influence of soil, underground, etc. underground utilities by anthropogenic actions. But a lot of research on natural sinkhole by geological experts continued steadily since the past Subsidence that occurred in recent years the city has become an urgent problem to formulate a countermeasure to be very concerned about the human and material damage. In this study, the city by analyzing existing research on the causes and countermeasures of Subsidence recently released look at the announced sinkhole, published statistics and cases of Subsidence data, and overseas corresponding practices in each relevant agencies and to suggest measures for local Subsidence.
        4,000원
        73.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study dealt with truck crash performance evaluation of new guardrails made of PosMac steels considering the ground bearing capacity effect. Subsequent crash simulation results for SB2 and SB4 grades present that the developed model performs much better in containing and redirecting the impacting vehicle in a stable manner. In this paper, the existing finite element crash analysis of guardrails using the LS-DYNA program is further extended to study the nonlinear dynamic response of the guardrail structures with new type poles supported by external stiffeners. The numerical results for various parameters are verified by comparing different grades with displacements occurred in the barrier from the crash simulation.
        4,000원
        74.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In low to moderate seismic regions, there are limited earthquake ground motion data recorded from past earthquakes. In this regard, th e Gyeongju earthquake (M=5.8)occurred on September 12, 2016 produces valuable information on ground motions. Ground motions w ere recorded at various recording stations located widely in Korean peninsula. Without actual recoded ground motions, it is impossible t o make a ground motion prediction model. In this study, a point source model is constructed to accurately simulate ground motions rec orded at different stations located on different soil conditions during the Gyeongju earthquake. Using the model, ground motions are ge nerated at all grid locations of Korean peninsula. Each grid size has 0.1°(latitude)x0.1°(longitude). Then a contour hazard map is constr ucted using the peak ground acceleration of the simulated ground motions
        4,000원
        75.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, effectiveness of seismic retrofitting methods using passive damping devices was investigated through numerical analyses of short-period structures under earthquakes which have short-duration and high-frequency impulse characteristics similar to Geyongju earthquakes. Displacement spectra of elastic systems and ductility demand of inelastic systems were evaluated by increasing viscous or friction damping. The damping devices could reduce responses of the structures with shorter structural period than 0.2s. The earthquakes similar to impulse load did not induce the responses of the structures with longer period than 0.4s, and the effects of the damping devices which generates damping forces proportional to structural responses became insignificant.
        4,000원
        76.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, time and frequency domain characteristics of Gyeong-ju earthquakes were investigated, and nonlinear time history analyses were conducted for bi-linear hysteretic structures excited by short-duration ground accelerations. Previous studies showed that larger inelastic displacements than the peak displacement of the corresponding elastic system were observed especially for the structures with structural period shorter than 0.3s, and the similar results could be obtained when long-duration ground accelerations were used as excitation loads. For the short-duration earthquakes, however, the inelastic displacements were not so large and almost identical to the peak elastic displacements.
        4,000원
        77.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Korean peninsula has known as a minor-to-moderate seismic region. However, some recent studies had shown that the maximum possible earthquake magnitude in the region is approximately 6.3-6.5. Therefore, a seismic vulnerability assessment of the existing infrastructures considering ground motions in Korea is necessary. In this study, we developed seismic fragility curves for a continuous steel box girder bridge and two typical transmission towers, in which a set of seven artificial and natural ground motions recorded in South Korea is used. A finite element simulation framework, OpenSees, is utilized to perform nonlinear time history analyses of the bridge and a commercial software, SAP2000, is used to perform time history analyses of the transmission towers. The fragility curves based on Korean ground motions were then compared with the fragility curves generated using worldwide ground motions to evaluate the effect of the two ground motion groups on the seismic fragility curves of the structures. The results show that both non-isolated and base-isolated bridges are less vulnerable to the Korean ground motions than to worldwide earthquakes. Similarly to the bridge case, the transmission towers are safer during Korean motions than that under worldwide earthquakes in terms of fragility functions.
        4,000원
        78.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigates important parameters used to determine an effective peak ground acceleration (EPGA) based on the characteristics of response spectra of historical earthquakes occurred at Korean peninsula. EPGAs are very important since they are implemented in the Korean Building Code for the seismic design of new structures. Recently, the Gyeongju earthquakes with the largest magnitude in earthquakes measured at Korea took place and resulted in non-structural and structural damage, which their EPGAs should need to be evaluated. This paper first describes the basic concepts on EPGAs and the EPGAs of the Gyeongju earthquakes are then evaluated and compared according to epicentral distances, site classes and directions of seismic waves. The EPGAs are dependant on normalizing factors and ranges of period on response spectrum constructed with the Gyeongju earthquake records. Using the normalizing factors and the ranges of period determined based on the characteristics of domestic response spectra, this paper draw a conclusion that the EPGAs are estimated to be about 30 % of the measured peak ground accelerations (PGA).
        4,000원
        79.
        2016.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study intends to evaluate the conservativeness of the fixed-base analysis as compared to the soil-structure interaction (SSI) analysis for the seismically isolated model of a nuclear power plant in Korea. To that goal, the boundary reaction method (BRM), combining frequency-domain and time-domain analyses in a twofold process, is adopted for the SSI analysis considering the nonlinearity of the seismic base isolation. The program KIESSI-3D is used for computing the reaction forces in the frequency domain and the program MIDAS/Civil is applied for the nonlinear time-domain analysis. The BRM numerical model is verified by comparing the results of the frequency-domain analysis and time-domain analysis for the soil-structure system with an equivalent linear base isolation model. Moreover, the displacement response of the base isolation and the horizontal response at the top of the structure obtained by the nonlinear SSI analysis using BRM are compared with those obtained by the fixed-base analysis. The comparison reveals that the fixed-base analysis provides conservative peak deformation for the base isolation but is not particularly conservative in term of the floor response spectrum of the superstructure.
        4,200원
        80.
        2016.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        이 연구에서는 p-version 동적무한요소법을 도입함으로써 FE-IE 기법에 기반한 KIESSI-3D 프로그램의 속도향상에 역점 을 두었다. KIESSI-3D의 성능을 평가하기 위해 8가지 실규모 SSI 문제에 대한 수치해석을 수행하였다. 이를 위해 근역지반 모델의 반경( r0 )이 구조물기초 반경(R)의 1.2배, 1.5배, 3.0배인 KIESSI-3D 해석모델을 고려하였다. 또한 SASSI2010 프로그 램을 이용한 SSI 해석을 수행하였으며, 이 결과를 KIESI-3D에 의한 결과와 정확성 및 계산속도를 비교하였다. 수치해석 결 과, 인 KIESI-3D 모델을 사용하면 정확한 해석을 수행할 수 있음을 알 수 있었다. 계산속도 측면을 보면, 새로운 KIESSI-3D의 해석속도는 기존 KIESSI-3D에 비해 최대 25배 빠른 것으로 나타났다.
        4,300원
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