• 한국철도학회논문집
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• 제19권6호
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• pp.755-764
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• 2016

이 논문에서는, 변위-변형률 관계로부터 변위를 추정하는 선행 연구의 현장 적용성을 검토하기 위하여 실교량에 대한 현장재하실험을 실시하고, 그 결과에 대해 고찰하였다. 3경간 연속 IPC 거더 도로교 및 강합성 박스거더 경량전철 교량에 변위계 및 변형률 게이지를 부착하고, 재하차량에 의한 응답을 측정하였다. 현장재하실험을 통해 얻어진 실측 변형률을 변위로 변환시키기 위해 변위와 변형률의 관계를 이용하였다. 해석적인 방법으로 변위-변형률 관계를 도출하기 위해 연구대상 교량을 격자구조로 모형화하고 구조해석을 수행하였다. 연구결과, 사전 구조해석에 의해 얻어진 변위-변형률 관계와 실측 변형률을 이용하여 변위를 추정하여도 실용상 만족할 만한 결과를 도출할 수 있었다. 이 연구 결과는 향후 계측이 어려운 환경하에 놓여 있는 교량의 변위 측정에 널리 활용될 수 있을 것으로 기대된다.

• 한국구조물진단유지관리공학회 논문집
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• 제23권4호
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• pp.120-130
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• 2019

본 연구에서는 2006년도의 교량 유지관리 빅데이터를 이용하여 선행연구에서 개발된 차종별 교통량 데이터와 연직 변위 데이터의 상관관계를 바탕으로 광안대교의 차종별 교통량 데이터를 이용한 연직 변위 추정 모델에 대하여 10여년이 경과한 현재적 적용성을 각각의 업데이트 방법으로 개발된 모델의 변위 추정 성능을 비교 분석하였다. 개발된 모델의 현재적 적용성은 추정된 변위는 실측 변위와 유사한 것으로 분석되었으며, 구조화 회귀 분석에 기반한 모델과 주성분 분석에 기반한 모델의 변위 추정 성능은 상호간에 큰 차이가 없다는 것을 알 수 있었다. 결론적으로 본 연구에서 개발한 차종별 교통량 데이터를 이용한 연직 변위 추정 모델은 광안대교의 교통하중에 따른 거동 분석 등에 유효하게 활용될 수 있을 것으로 사료된다.

• 대한원격탐사학회지
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• 제36권4호
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• pp.527-534
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• 2020

This study aims to monitor the displacement of the bridges using Stanford Method for Persistent Scatterers (StaMPS) time-series Persistent Scatterer Interferometric Synthetic Aperture Radar analysis. For case study bridges: Kimdaejung bridge and Deokyang bridge, we acquired 60 and 33 Cosmo-Skymed Synthetic Aperture Radar (SAR) data over the Mokpo region and Yeosu region, respectively from 2013 to 2019. With single-look interferograms, we estimated the long-term time-series displacements over the bridges. The time-series displacements were estimated as -8.8 mm/year and -1.34 mm/year at the mid-span over the selected bridges: Kimdaejung and Deokyang bridge, respectively. This time-series displacement provides reliable and high spatial resolution information to monitor the structural behavior of the bridge for preventing structural behaviors.

• Steel and Composite Structures
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• 제12권5호
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• pp.413-426
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• 2012

In this paper, nonlinear static analysis of three-dimensional cable stayed bridges is performed for the time dependent materials properties such as creep, shrinkage and aging of concrete and relaxation of cable. Manavgat Cable-Stayed Bridge is selected as an application. The bridge located in Antalya, Turkey, was constructed with balanced cantilever construction method. Total length of the bridge is 202 m. The bridge consists of one $\ddot{e}$ shape steel tower. The tower is at the middle of the bridge span. The construction stages and 3D finite element model of bridge are modeled with SAP2000. Large displacement occurs in these types of bridges so geometric nonlinearity is taken into consideration in the analysis by using P-Delta plus large displacement criterion. The time dependent material strength and geometric variations are included in the analysis. Two different finite element analyses carried out which are evaluated with and without construction stages and results are compared with each other. As a result of these analyses, variation of internal forces such as bending moment, axial forces and shear forces for bridge tower and displacement and bending moment for bridge deck are given with detailed. It is seen that construction stage analysis has a remarkable effect on the structural behavior of the bridge.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 심포지엄 논문집 정보 및 제어부문
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• pp.284-296
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• 2005

Bridge displacement measurement system using image processing is developed to overcome the contact type system inefficiencies such as heavy, expensive property and temporary construction necessity. The system is composed of tablet PC with IEEE1394 digital camera, telescope lens and a designed target mark. The key is projection algorithm where all pixels are added up for each row(column) to find out the center line. The experimental results are shown compared with a contact type system.

• 대한토목학회논문집
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• 제34권6호
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• pp.1655-1665
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• 2014

구조물의 변위이력은 구조물의 전체적인 거동을 나타내는 인자의 시간에 대한 이력이므로 이를 추정하는 것은 매우 중요하며, 일반적으로 구조물의 상태를 평가하는데 있어 직관적으로 신뢰할 수 있는 물리량이다. 특히, 교량의 경우 차량 하중에 의해 발생되는 수직 변위를 알아내는 것은 교량에 발생할 수 있는 문제점을 미연에 확인할 수 있어 매우 중요한 부분이다. 하지만 시공된 교량의 수직 변위를 측정하는 것은 실험여건 및 장비의 제약조건 등으로 인해서 직접적으로 측정하는 것이 매우 힘든 실정이다. 본 연구에서는 대상 교량들에 대한 제약조건을 극복하고 변위응답을 추정할 수 있는 방안을 제시하기 위해 임의의 차량하중에 의해서 측정되는 변형률과 변위를 인공신경망에 적용하였다. 인공신경망에 적용하는 축방향 변형률과 수직방향 변위에 대한 학습 자료를 획득하기 위해서 수치해석을 수행하였으며, 실제 교통 상황을 반영하기 위해서 교량을 통과하는 차량의 종류와 차간 거리에 대한 차량이동하중 시나리오를 작성하여 시공된 교량의 실제 교통상황에 따른 차량 이동 하중이 가해지도록 모델링하였다. 인공신경망을 이용한 학습 결과에 따라 임의의 하중에 의해 발생되는 교량의 변형률에 대한 변위를 추정하였고, 인공신경망을 사용하여 추정된 변위 결과가 수치해석을 통한 변위를 잘 표현하는 것을 확인하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.109-117
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• 2008

In this study, a method predicting the displacement responseof structures from the measured dynamic strain signal is proposed by using a mode decomposition technique. Dynamic loadings including wind and seismic loadings could be exerted to the bridge. In order to examine the bridge stability against these dynamic loadings, the prediction of displacement response is very important to evaluate bridge stability. Because it may be not easy for the displacement response to be acquired directly on site, an indirect method to predict the displacement response is needed. Thus, as an alternative for predicting the displacement response indirectly, the conversion of the measured strain signal into the displacement response is suggested, while the measured strain signal can be obtained using fiber optic Bragg-grating (FBG) sensors. To overcome such a problem, a mode decomposition technique was used in this study. The measured strain signal is decomposed into each modal component by using the empirical mode decomposition(EMD) as one of mode decomposition techniques. Then, the decomposed strain signals on each modal component are transformed into the modal displacement components. And the corresponding mode shapes can be also estimated by using the proper orthogonal decomposition(POD) from the measured strain signal. Thus, total displacement response could be predicted from combining the modal displacement components.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(II)
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• pp.1065-1073
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• 2002

A new damage identification technique using static displacement data is developed to assess the structural integrity of bridge structures. In the conventional damage assessment techniques using dynamic response, it is usually difficult to obtain a significant natural frequencies variation from the measured data because the natural frequencies variation is intrinsically not sensitive to the damage of a bridge. In this proposed identification method, the stiffness reduction of the bridges can be estimated using the static displacement data measured periodically and a specific loading test is not required. The static displacement data due to the dead load of the bridge structure can be measured by devices such as a laser displacement sensor. In this study, structural damage is represented by the reduction in the elastic modulus of the element. The damage factor of the element is introduced to estimate the stiffness reduction of the bridge under consideration. Finally, the proposed algorithm is verified using various numerical simulation and compared with other damage identification method. Also, the effect of noise and number of damaged elements on the identification are investigated. The results show that the proposed algorithm is efficient for damage identification of the bridges.

• Earthquakes and Structures
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• 제9권3호
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• pp.455-480
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• 2015

In the last decade, displacement-based (DB) methods have become established design procedures for reinforced concrete (RC) structures. They use strain and displacement measures as seismic performance control parameters. As for other simplified seismic design methods, it is of great interest to prove if they are usually conservative in respect to more refined, nonlinear, time history analyses, and can estimate design parameters with acceptable accuracy. In this paper, the current Direct Displacement-Based Design (DDBD) procedure is evaluated for designing simple single degree of freedom (SDOF) systems with specific reference to simply supported RC bridge piers. Using different formulations proposed in literature for the equivalent viscous damping and spectrum reduction factor, a parametric study is carried out on a comprehensive set of SDOF systems, and an average error chart of the method is derived allowing prediction of the expected error for an ample range of design cases. Following the chart, it can be observed that, for the design of actual RC bridge piers, underestimation errors of the DDBD method are very low, while the overestimation range of the simplified displacement-based procedure is strongly dependent on design ductility.

• Interaction and multiscale mechanics
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• 제5권3호
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• pp.187-210
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• 2012

Cable-stayed bridges are commonly used in modern bridge engineering for covering long spans. In some special cases, the designer is obliged to build such a bridge over an existing fault. Activation of this fault is possible to bring about a relative displacement or separation movement between two neighboring pylons of the bridge built on opposite sides of the fault. In this work, the effect of such a fault-induced pylon displacement on bridge's deformations and on cables' strength is thoroughly studied for several types of cable-stayed bridges and useful conclusions are drawn aiming the design. The influence of a possible earthquake and traffic loads crossing the bridge when the pylons are moving away from each other is not examined.