• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.1159-1164
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• 2005

Seismic analysis methods in use on ground structure are equivalentstatic analysis, response-displacement method and dynamic analysis etc. Equivalentstatic analysis does not considerdynamic effect, and dynamic analysis process is very complex. then 'Urbanrail transit earthquake-resistance design standard (2005.06)' is persuading that analyze by response displacement method that consider enough dynamic effect of ground structure statically. But, It is very complex and difficult to apply response-displacement method in the field. So, modified equivalentstatic analysis or pseudo static analysis that is easy to apply in the field and have rationality of design is practically used. In this study, I try to prescribe the applicable scale of structure and static analysis that have calculative effectiveness about response-displacement method by comparing and analyzing the result of each analysis method according to the scale of urban rail transit' box type concrete structure and by performing seismic analysis that apply modified equivalentstatic analysis, pseudo static analysis and response-displacement method changing the kind of ground, depth of bedrock, size of structure.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.732-737
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• 2005

This paper performed pseudo static analysis and dynamic analysis for CFRD and evaluated reliability with the results of Shaking Table Test. The Seismic coefficient method, modified seismic coefficient method, Newmark method of Pseudo static analysis and frequency domain response analysis, time domain history analysis of dynamic analysis were used. The analysis results were differ between analysis method, but the trends of acceleration and displacement were good agreement with the results of shaking table test.

• 한국산학기술학회논문지
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• 제12권9호
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• pp.4239-4249
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• 2011

일본과 같은 지진 빈발국은 CFRD의 경우 지진시 댐제체 상류부의 Face Slab에 응력이 집중하여 파괴되는 경우를 대부분 상정하여 내진안정성을 평가한다. 그러나 우리나라에서는 현재까지 이에 대한 명확한 해석방법이 확립되어 있지 않다. 본 논문은 CFRD에 대하여 등가정적해석 및 동적해석 수행 후 진동대시험과 비교하여 그 신뢰성을 평가하였다. 등가정적해석은 진도법, 수정진도법, Newmark법을 적용하였고 동적해석은 주파수응답해석, 시간이력 해석법을 적용하였다. 해석결과 해석 방법별 편차는 발생하나 가속도 및 변위의 발생경향은 진동대시험 결과와 잘 일치하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.620-625
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• 2009

The seismic slope stability is most often evaluated by the pseudo-static limit analysis, in which the earthquake loading is simplified as static inertial loads acting in horizontal and/or vertical directions. The transient loading is represented by constant acceleration via the pseudostatic coefficients. The result of a pseudostatic analysis is governed by the selection of the value of the pseudostatic coefficient. However, selection of the value is very difficult and often done in an ad hoc manner without a sound physical reasoning. In addition, the maximum acceleration is commonly estimated from the design guideline, which cannot accurately estimate the dynamic response of a slope. There is a need to perform a 2D dynamic analysis to properly define the dynamic response characteristics. This paper develops the modified one-dimensional seismic site response analysis. The modified site response analysis adjusts the density of the layers to simulate the change in mass and weight of the layers of the slope with depth. Multiple analyses are performed at various locations within the slope to estimate the change in seismic response of the slope. The calculated peak acceleration profiles with depth from the developed procedure are compared to those by the two-dimensional analyses. Comparisons show that the two methods result in remarkable match.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2011년도 정기 학술대회
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• pp.324-327
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• 2011

The design requirement for ground mounted sign structures are fairly well defined in the AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaries, and Traffic Signals and consists of applying an equivalent pseudo-dynamic loading to account for the dynamic effects of wind loads and ignores the dynamic effect due to moving vehicle loads. This design approach, however, should not be applied to the design of bridge mounted sign structures because ignoring the dynamic effects of the moving vehicle loads may produce non-conservative results, since the stiffness of the bridge structure can greatly influence the behavior. Not enough information is available in the literatures which provide guide lines to include the influence of moving vehicles in the design of the bridge mounted sign structures. This paper describes a theoretical methodology, Bridge-Vehicle Interaction Element, which can be utilized to account for the dynamic effect of moving vehicles. A case study is also included where this methodology was successfully applied. It was concluded that the bridge-vehicle interaction finite element developed can provide a more accurate representation of the behavior of bridge mounted sign structures. The result of these analysis enabled development of simple and effective retrofitting scheme for the existing support system of bridge-mounted-structure.

• 한국지반공학회논문집
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• 제36권11호
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• pp.7-20
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• 2020

본 연구에서는 말뚝기초를 대상으로 지반조건을 고려한 동적 수평지반반력계수를 제안하기 위하여 수치해석을 수행하였다. 3차원 유한차분 프로그램을 사용하여, 다양한 지반의 전단파 속도에 따라 동적수치해석을 수행하였다. 수치해석 결과로부터 동적 p-y 곡선을 도출하여 동적 수평지반반력계수를 계산하는 데 필요한 보정계수(α)를 산정하였다. 분석결과, 본 연구에서 산정된 보정계수(α)는 기존 도로교 설계기준(2015)에 제시된 획일적인 값(α=2)이 아니라 지반의 전단파 속도와 구속압에 매우 큰 영향을 받는 것을 알 수 있었으며 이를 고려한 함수식으로 제안하였다. 제안된 α의 적용성 분석을 위해 서로 다른 해석 기법(등가정적해석방법과 동적해석방법)에서의 적용성을 비교하였다. 그 결과, 제안된 보정계수(α)를 사용하는 방법은 기존 동적 수평지반반력계수를 사용하는 방법에 비해 지반-말뚝 시스템의 수평거동 특성을 비교적 적절하게 예측함을 알 수 있었다.

• Earthquakes and Structures
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• 제8권5호
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• pp.1241-1254
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• 2015

Spatially variable ground motions can be significant on the seismic response of a structure due to the incoherency of the incident wave. Incoherence of the incident wave is resulted from wave passage and wave scattering. In this study, wave passage effect on the response spectrum of a building structure built on a soft soil layer was investigated utilizing a finite element program of P3DASS (Pseudo 3-dimensional Dynamic Analysis of a Structure-soil System). P3DASS was developed for the axisymmetric problem in the cylindrical coordinate, but it is modified to apply anti-symmetric input earthquake motions. Study results were compared with the experimental results to verify the reliability of P3DASS program for the shear wave velocity of 250 m/s and the apparent shear wave velocities of 2000-3500 m/s. Studied transfer functions of input motions between surface mat foundation and free ground surface were well-agreed to the experimental ones with a small difference in all frequency ranges, showing some reductions of the transfer function in the high frequency range. Also wave passage effect on the elastic response spectrum reduced the elastic seismic response of a SDOF system somewhat in the short period range.

• 폴리머
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• 제24권3호
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• pp.366-373
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• 2000

본 연구에서는 poly(phenylene sulfide)(PPS)와 ABS의 물성을 상호보완하기 위하여 블렌드를 제조하였다. 각 성분간의 상용성을 증진시키기 위하여 소량의 무수말레인산을 ABS에 반응시켜 MABS (ABS-g-MAH)를 제조하였으며, PPS/ABS 및 PPS/MABS 블렌드는 이축 혼련 압출기를 이용하여 용융 흔합하였다. 블렌드에서 ABS의 화학적 개질이 블렌드의 모폴로지와 열적 성질에 미치는 영향을 관찰하였다. PPS/MABS 블렌드의 경우, 각 성분간에 강한 인력이 형성되는 것을 광학현미경과 SEM을 이용하여 확인하였으며, DMA 분석에서는 단일 유리전이 온도를 확인하였다. 또한 화학적으로 개질된 MABS를 사용한 PPS/MABS의 블렌드는 PPS/ABS보다 향상된 열적 성질을 나타내었다.

• 한국지반환경공학회 논문집
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• 제10권1호
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• pp.49-54
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• 2009

지진동에 대한 사면의 안정성은 일반적으로 지진계수를 이용하여 지진하중을 유사정적 하중으로 단순화하여 한계평형법으로 평가된다. Transient 지진동은 지진계수를 이용하여 정적하중으로 대체된다. 하지만, 유사정적 해석결과에 절대적인 영향을 미치는 지진계수는 합리적인 물리적 근거 없이 산정된다. 또한 내진설계기준에 의거하여 산정되는 최대가속도는 사면의 진동특성을 반영한다고 볼 수 없으며, 이를 정확하게 예측하기 위해서는 2차원 동적해석을 수행해야 한다. 본 연구에서는 수정된 1차원 동적해석과 유사정적해석을 연결한 Hybrid 유사정적 해석법을 제안하였다. 기존의 해석기법은 깊이에 따라서 변이하는 가속도를 고려할 수 없기에 신뢰성 있는 사면의 안정성 예측이 어려운 실정이다. 수정된 1차원 지반응답해석은 깊이에 따른 사면 무게변화를 모델링하기 위하여 층의 밀도를 조정하였으며 위치별 진동가속도를 예측하기 위해서 다수의 해석을 수행하였다. 2차원 유한요소해석과 비교한 결과, 수정된 1차원 해석은 2차원 해석과 일치성이 우수한 것을 확인할 수 있었다. 해석결과를 유사정적해석에 입력하여 깊이에 따라서 변이하는 가속도 주상도를 적용하였으며 기존의 해석방법으로 계산된 안전율과 비교하였다. 비교 결과, 계산된 안전율에는 큰 차이가 발생하는 것으로 나타났으며, 기존의 해석기법으로 안전율을 예측할 경우, 매우 비현실적인 값을 계산할 수 있다. 본 연구에서 개발된 기법은 해석의 신뢰성을 현격하게 향상시키는 것으로 나타났다.

• 한국지반환경공학회 논문집
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• 제24권2호
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• pp.13-24
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• 2023

Tunnels may undergo a larger or a smaller response compared with the free-field soil. In the pseudo-static procedure, the response of the tunnel is most often characterized by a curve that relates the racking ratio (R) with the flexibility ratio (F), where R represents the ratio of the tunnel response with respect to the free-field vibration and F is the relative stiffness of the tunnel and the surrounding soil. A set of analytical and empirical curves that do not account for the depth and the aspect ratio of the tunnel are typically used in practice. In this study, a series of dynamic analyses are conducted to develop a set of F-R_m relations for use in a frame analysis method. R_m is defined as an adjusted R where the rocking mode of deformation is removed and only the racking deformation is extracted. The numerical model is validated against centrifuge test recordings. The influence of aspect ratio, buried depth of tunnel on results is investigated. The results show that R_m increases with the increase of the buried depth and the aspect ratio. The widely used F-R relations are highlighted to be different compared with the obtained results in this study. Therefore, the updated F-R_m relations with proposed equations are recommended to be used in practice design. The rocking response decreases with either the decrease of the difference of stiffness between surrounding soil and tunnel or the larger aspect ratio of the tunnel section.