• 한국강구조학회 논문집
• /
• 제20권1호
• /
• pp.151-163
• /
• 2008

본 논문에는 KTX (Korean eXpres Train)을 위한 3차원 관절대차의 차량-교량 동적 상호작용의 해석모델의 공식이 제안되었다. 궤도틀림의 반주기적 파형이 FRA의 레일틀림 최대허용기준을 사용하여 제안되었고, 레일 이음매와 침목의 간격 또한 포함되었다. 궤도틀림은 수준, 구배, 수평 및 궤간틀림을 포함하고 있다. 결과적으로 나타나는 차량-교량 시스템 행렬은 매우 적은 요소를 포함하기 때문에 1차원의 배열에 저장할 수 있으며, 시간절약적인 해법을 창출한다. 반복기법을 포함하는 차량-교량 작용 계산의 수치적 알고리즘 또한 공식화하였으며, 차량-교량 상호작용을 모사하고 새로운 알고리즘에 의해서 이 문제를 풀기 위한 프로그램이 'XFINAS'라고 불리는 프로그램에 모듈로서 내포되었다. 새로운 프로그램에 의해서 계산된 결과가 검증된 2차원의 차량-교량 상호작용 모델의 결과에 의해서 검증되었다. 본 연구에서 제시한 3차원 해석은 차량의 보다 상세한 응답을 제공한다. 예를 들면, 회전운동-롤링, 요잉 및 피칭- 및 수평 및 수직운동에 대한 가속도를 제공할 수 있으며, 이러한 응답은 승객의 승차감 평가에 유용한 자료로 활용될 수 있다. 차량의 안정성과 차륜의 탈선 또한 본 프로그램에서 계산되는 차륜의 상대변위를 이용하여 직접적으로 계산이 가능하다.

• Structural Engineering and Mechanics
• /
• 제76권3호
• /
• pp.293-310
• /
• 2020

This study derives the differential equations of free vertical bending and torsional vibrations for two- and three-pylon suspension bridges using d'Alembert's principle. The respective algorithms for natural vibration frequency and vibration mode are established through the separation of variables. In the case of the three-pylon suspension bridge, the effect of the along-bridge bending vibration of the middle pylon on the vertical bending vibration of the entire bridge is considered. The impact of torsional vibration of the middle pylon about the vertical axis on the torsional vibration of the entire bridge is also analyzed in detail. The feasibility of the proposed method is verified by two engineering examples. A comparative analysis of the results obtained via the proposed and more intricate finite element methods confirmed the former feasibility. Finally, the middle pylon stiffness effect on the vibration frequency of the three-pylon suspension bridge is discussed. It is found that the vibration frequencies of the first- and third-order vertical bending and torsional modes both increase with the middle pylon stiffness. However, the increase amplitudes of third-order bending and torsional modes are relatively small with the middle pylon stiffness increase. Moreover, the second-order bending and torsional frequencies do not change with the middle pylon stiffness.

• Wind and Structures
• /
• 제23권3호
• /
• pp.191-209
• /
• 2016

Wind tunnel tests of a 1/2200-scale mountainous terrain model have been carried out to investigate local wind characteristics at a bridge location in southeast Tibet, China. Flows at five key locations on the bridge at deck level were measured for 26 directions. It was observed that wind characteristics (including mean wind velocity and overall turbulence intensity) vary significantly depending on the approaching wind direction and measurement position. The wind inclination angle measured in the study fluctuated between $-18^{\circ}$ and $+16^{\circ}$ and the ratio of mean wind velocity to reference wind velocity was small when the wind inclination angles were large, especially for positive wind inclination angles. The design standard wind speed and the minimum critical wind speed for flutter rely on the wind inclination angle and should be determined from the results of such tests. The variation of wind speed with wind inclination angles should be of the asymmetry step type. The turbulence characteristics of the wind were found to be similar to real atmospheric flows.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
• /
• pp.501-504
• /
• 2004

This paper proposes degree of hydration based shrinkage prediction model of 40MPa HPC. This model shows degree of hydration which is defined as the ratio between the hydrated cement mass and the initial mass of cement is very closely related to shrinkage deformation. In this study, degree of hydration was determined by CEMHYD-3D program of NIST. Verification of the predicted degree of hydration is performed by comparison between test results of compressive strength and estimated one by CEMHYD-3D. Proposed model is determined by statistical nonlinear analysis using the program Origin of Origin Lab. Co. To get coefficients of the model, drying shrinkage tests of four specimen series were followed with basic material tests. Testes were performed in constant temperature /humidity chamber, with difference moisture curing ages to know initial curing time effect. Verification with another specimen, collected construction field of FCM bridge, was given in the same condition as pre-tested specimens. Finally, all test results were compared to propose degree of hydration based model and other code models; AASHTO, ACI, CEB-FIP, JSCE, etc.

• 전자공학회논문지 IE
• /
• 제44권1호
• /
• pp.27-32
• /
• 2007

본 논문에서는 차량 이용이 많은 도심지역 편도 2차선의 도로 상에서 차량과 차량 사이에 통신이 이루어지는 경우 송.수신 차량 좌, 우측 반사체와 인접한 차량들에 의해 발생하는 다중경로파의 영향을 고려한 전파예측모델을 제안하였다. 이 때 곡선 도로의 반경을 600[m], 곡선도로의 거리는 $5.24\sim471.2[m]$, 도로교각은 $5o\sim45o$, 곡선도로에 위치한 수신차량은 도로교각과 곡선도로의 거리변화에 대응하여 최소 3.3[m]에서 최대 29.5[m]간격으로 변화시키면서 시뮬레이션 하였다. 그 결과 도로교각이 $5o\sim15o$인 경우 전파경로손실의 경우 수신 차량의 곡선도로 위치에 관계없이 1[dB]이내였고, $15o\sim45o$인 경우 도로교각이 변화함에 따라 대략 $1\sim8[dB]$이었다. 그리고 전파경로의 경우에는 도로교각의 변화에 따라 $0.4\sim120[m]$까지 변화함을 알 수 있었다. 이 때 전파경로 차가 120[m] 발생함에 따른 전파지연시간은 400[nsec]이다.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 1999년도 봄 학술발표회 논문집
• /
• pp.159-168
• /
• 1999

In seismic analysis, there are two main ways - uniform load method and dynamic analysis, dynamic analysis can be divided into response spectrum analysis and time history analysis. In case of which get the complexion of the vibration with 3-axis of coordinate direction in each mode of free vibration mode happened owing to complication of the shape, 3-dimensional dynamic analysis is recommended to perform as multi-mode spectral analysis in standard specification for highway bridge. The purpose of this study is to understand the dynamic behavior by performing multi-mode seismic analysis according to responses analysis and time history anal)'sis in using record of earthquake. In accordance with the criterion of seismic design as defined in standard specification for highway bridge by using modified records of the El Centre and Coyote Lake earthquake, response spectrum was constructed by using the tripartite logarithmic plot. The 3-span continuous space truss bridge was selected as model of numerical analysis. As the result performed time history analysis and analysis of response spectrum for the model of numerical analysis, the result of time history analysis was slightly larger than that of response spectrum analysis. This coincide with the tendency of the result came from the analysis when using a jagged response spectrum analysis, This coincide with the tendency of the result came from the analysis when using a jagged response spectrum for a single excitation. In the Process of performing these two analysis. response spectrum analysis is more effective than time history analysis in saving times in analyzing data.

• Wind and Structures
• /
• 제9권2호
• /
• pp.125-146
• /
• 2006

Stonecutters Bridge of Hong Kong is a cable-stayed bridge with two single-column pylons each 298 m high and an aerodynamic twin deck. The total length of the bridge is 1596 m with a main span of 1018 m. The top 118 m of the tower will comprise structural steel and concrete composite while the bottom part will be of reinforced concrete. The bridge deck at the central span will be of steel whilst the side spans will be of concrete. Stonecutters Bridge has adopted a twin-girder deck design with a wide clear separation of 14.3 m between the two longitudinal girders. Although a number of studies have been conducted to investigate the aerodynamic performance of twin-girder deck, the actual real life application of this type of deck is extremely limited. This therefore triggered the need for conducting the present studies, the main objective of which is to investigate the performance of Stonecutters Bridge against flutter at its in-service stage as well as during construction. Based on the flutter derivatives obtained from the 1:80 scale rigid section model experiment, flutter analysis was carried out using 3-D finite element based single parameter searching method developed by the second author of this paper. A total of 6 finite element models of the bridge covering the in-service stage as well as 5 construction stages were established. The dynamic characteristics of the bridge associated with these stages were computed and applied in the analyses. Apart from the critical wind speeds for the onset of flutter, the dominant modes of vibration participating in the flutter vibration were also identified. The results indicate that the bridge will be stable against flutter at its in-service stage as well as during construction at wind speeds much higher than the verification wind speed of 95 m/s (1-minute mean).

• 대한토목학회논문집
• /
• 제40권2호
• /
• pp.239-245
• /
• 2020

최근 BIM (Building Information Modeling)이 건설 산업계에서 폭넓게 활용되고 있다. 하지만 과거에 시공이 된 구조물에 경우 대부분 BIM이 구축되어 있지 않다. BIM이 구축되지 않은 구조물의 경우, 카메라로부터 얻은 2D 이미지에 SfM (Structure from Motion) 기법을 활용하면 3D 모델의 점군 데이터(Point cloud)를 생성하고 BIM을 구축할 수 있다. 하지만 이렇게 생성된 점군 데이터는 의미론적 정보가 포함되어 있지 않기 때문에, 수작업으로 구조물의 어떤 요소인지 분류해 주어야 한다. 따라서 본 연구에서는 구조물 구성요소를 분류하는 과정을 자동화하기 위하여 딥러닝을 적용하였다. 딥러닝 네트워크 구축에는 CNN (Convolutional Neural Network) 구조의 Inception-ResNet-v2를 사용하였고, 전이학습을 통하여 교량 구조물의 구성요소를 학습하였다. 개발된 시스템을 검증하기 위하여 수집한 데이터를 이용하여 구성요소를 분류한 결과, 교량의 구성요소를 96.13 %의 정확도로 분류할 수 있었다.

• Geomechanics and Engineering
• /
• 제8권6호
• /
• pp.801-810
• /
• 2015

The ultimate pullout capacity under inclined dynamic loading is an important measure of the destruction degree of vertical screw piles (anchors) under dynamic actions. Based on the static and dynamic tests on two kinds of model screw piles, the ultimate bearing capacity was researched considering different distance-width ratio of blade (D/W) and preloading ratio. The results compared well with other experimental data available in the literature. This research reveals that D/W might determine the failure model of the piles (anchors), for example D/W = 3.14 or 5; a critical dynamic-static loading ratio (DSLR) existed in the experiments. The critical DSLR was reached under the conditions of 40%~60% preloading (D/W = 3.14) or 20%~40% preloading (D/W = 5), respectively.

• 해양환경안전학회지
• /
• 제6권1호
• /
• pp.1-9
• /
• 2000

The paper describes system design of next-generation Ship Simulator using Virtual Reality (VRSS), well known as human-computer interaction. VRSS system is required to have special condition that comprises multiple user participants such as captain, officer, pilot, and quartermaster. To cope with that condition, core technologies were explored and proposed multi-networking system with broker server. The evaluation of the proposed system was done with PC-based immersion-type VR device, constituted with HMD (Head Mounted Display), Head Tracking Sensor, Puck, Headphone, and Microphone. Using the VR device, assessment test was carried out in a virtual bridge with 3D objects, which are created by VRML (Virtual Reality Model Language) program. As results of tests, it is shown that the cybernetic 3D objects were act as if real things in a real ship's bridge. Therefore, interesting interaction with participants can be obtained in the system, Thus, we found that the proposed system architecture can be applicable to VRSS system construction.