• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
• /
• pp.979-984
• /
• 2001

The Sang-Jin bridge constructed by the Free Cantilever Method in 1985 is 4-span concrete rahmen bridge with a hinge at midspan. Due to the effect of creep, shrinkage of concrete and relaxation of tendon, the Sang-Jin bridge exposed the excessive displacement at midspan with the passage of time. In order to improve the load-carrying-capacity and durability of the bridge, needs to repair and rehabilitate the structure emerged. New rehabilitation methods were applied such as external prestressing of concrete box, application of pier pre-camber and steel truss jacking. Structural analysis and several tests including static load test, dynamic load test and ambient vibration test were executed to verify the improvement. The test result showed that the displacement of the midspan was improved by 10mm and it was verified that the stiffness of the bridge was increased. Totally, the load-carrying-capacity of Sang-Jin bridge was increased at least 1.56times which was attributed to the new rehabilitation method.

• Computers and Concrete
• /
• 제12권2호
• /
• pp.169-186
• /
• 2013

The aim of this paper is to determine the effect of soil-structure interaction and time dependent material properties on behavior of concrete box-girder highway bridges. Two different finite element analyses, one stage and construction stage, have been carried out on Komurhan Bridge between Elazi$\breve{g}$ and Malatya province of Turkey, over Fırat River. The one stage analysis assume that structure was built in a second and material properties of structure not change under different loads and site conditions during time. However, construction stage analysis considers that construction time and time dependent material properties. The main and side spans of bridge are 135 m and 76 m, respectively. The bridge had been constructed in 3 years between 1983 and 1986 by balanced cantilever construction method. The parameters of soil-structure interaction (SSI), time dependent material properties and construction method are taken into consideration in the construction stage analysis while SSI is single parameter taking into consideration in the one stage analysis. The 3D finite element model of bridge is created the commercial program of SAP2000. Time dependent material properties are elasticity modulus, creep and shrinkage for concrete and relaxation for steel. Soft, medium, and firm soils are selected for evaluating SSI in both analyses. The results of two different finite element analyses are compared with each other. It is seen that both construction stage and SSI have a remarkable effect on the structural behavior of the bridge.

• 한국전산구조공학회논문집
• /
• 제29권3호
• /
• pp.219-227
• /
• 2016

이 연구에서는 현장타설 캔틸레버공법(free cantilever method)을 적용한 PSC(prestressed concrete) 교량에 콘크리트의 장기거동을 고려한 시공 중 계측분석 방법을 제안하였다. 콘크리트 박스 거더의 장기 거동에 따른 응력을 확인하기 위해 온도센서와 변형률계를 함께 설치하고 계측된 데이터를 이용하여 크리프계수를 산출하였다. 또한 크리프계수를 적용한 콘크리트 박스 거더의 시공 중 응력을 분석하고 설치된 온도 센서의 변화 데이터를 비교하여 세그먼트 시공에 따른 연직변위를 분석하였다. 연구결과, 교량의 장기 거동을 고려한 FCM 교량의 시공 중 계측은 레이저 변위계나 처짐계를 사용하지 않고 온도와 변위 데이터만을 이용하여 효율적인 분석이 가능한 것으로 나타났다.

• 한국강구조학회 논문집
• /
• 제19권2호
• /
• pp.191-199
• /
• 2007

본 연구에서는 캔틸레버 공법으로 가설되는 사장교의 최종단계에서 초기평형상태를 구현하기 위한 폐합 방법을 제안하였다. 캔티레버식 가설에 의한 사장교에서 초기평형상태의 구현을 위해서는 거더 폐합단계에서 폐합단면 양측의 연직 처짐, 회전각 및 축방향 변위에 대한 적합조건을 만족시켜야 하는데, 본 연구에서는 실제 시공시 적용 가능한 데릭 크레인의 인양력과 케이블의 장력, 그리고 주탑부에 설치된 유압잭을 이용하여 적절한 폐합이 가능함을 제시하였다. 제안된 방법을 예제 교량의 시공단계 해석에 적용하여 그 타당성을 검증하였으며, 폐합시 축방향 변위에 관한 적합조건의 고려 여부가 주탑의 결과에 큰 영향을 끼치는 것으로 나타났다.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2008년도 정기 학술대회
• /
• pp.203-208
• /
• 2008

Recently, high-rise building structures connected by a sky-bridge are frequently constructed. To predict accurate dynamic responses of structures connected a sky-bridge, time history analysis is required. Repetitive analyses are required in the design process. If the entire structure model is employed in the repetitive time history analysis, it would take a lot of computational time and engineers' efforts. Therefore, an equivalent model for high-rise building structures connected by a sky-bridge was proposed in this study. The proposed model consists of cantilever having original structure's stiffnesses and masses. Based on the analytical results, it has been shown that the equivalent model can reduce the analysis time and provide similar seismic responses to the original model.

• Interaction and multiscale mechanics
• /
• 제3권4호
• /
• pp.373-387
• /
• 2010

This study is intended to assess low frequency sound radiated from a viaduct under normal traffic. The bridge comprises steel box girders and wide cantilever decks on which vehicles pass. The low frequency sound and the acceleration response of the bridge under normal traffic are measured to investigate how bridge vibrations affect the low frequency sound observed near the bridge. Observations demonstrate that strong relationships exist between frequency characteristic of bridge's acceleration response and the sound pressure level of low frequency sound. A noteworthy point is that the dynamic feature of the sound pressure level is mostly affected by dynamic feature of the span locating near the observation point.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
• /
• pp.285-286
• /
• 2007

This paper presents a robust controller in order to handle the guide rail vibrations of Bridge Inspection System. While a Bridge Inspection Robot moves on guide rails with vibration by weight occurs. Therefore, Guide rail as structure like cantilever beam appears vibration by weight of Bridge Inspection Robot. The Z axis of Bridge Inspection Robot operates with Scissors structure. Bridge Inspection Robot is used 'PID Controller based on Sliding Mode control' for position control with Z axis. At the result of, this paper is applied to simulation about position control regarding vibration to occur with Z axis.

• 콘크리트학회논문집
• /
• 제18권6호
• /
• pp.711-720
• /
• 2006

FCM 교량 상부구조의 거동은 콘크리트의 크리프와 건조수축 등에 의해 시간 의존적 거동을 나타내며, 이에 의해 하부구조 즉, 교각에는 시간에 따른 추가의 과도한 모멘트가 발생할 수 있다. 본 연구에서는 FCM 공법으로 시공되는 콘크리트 교량의 크리프와 건조수축에 의한 교각의 모멘트를 감소시킬 수 있는 기법을 제안하였다. 제안 기법은 교량의 체계적인 시간의존적 거동 해석과 교량 시공중의 제어하중 재하로 이루어진다. 제어하중의 크기 및 교각 유연도에 따른 교각의 거동 분석을 수행하였다. 교각 유연도에 따른 수치해석 결과는 교각의 유연도가 작을수록 시간에 따른 교각 모멘트 값은 증가하여 설계시 불리한 측면을 나타내고 있다. 제어하중을 도입하지 않은 경우에 비해 제어하중을 도입한 경우의 모멘트는 감소하고 있다. 또한, 실제 교량에 대한 수치해석 분석을 통하여 제안기법의 효용성을 제시하였다. 따라서, FCM 공법으로 시공되는 교량에서, 유연도가 작은 교각의 시간에 따른 모멘트 변화를 효율적으로 제어할 수 있다고 판단된다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1996년도 추계학술대회 논문집
• /
• pp.721-725
• /
• 1996

The microfabricated test structures were used in order to evaluate the stress characteristics in films. The test structures were fabricated using surface micromachining technique, including HF vapor phase etching as an effective release method. The fabricated structures were micro strain gauge, cantilever-type vernier gauge and bridge for stress measurement, and cantilever for stress gradient measurement. The strain was measures by observing the deformation of the structures occurred after release etching and the amount of deformation can be detected by micro vernier gauge, which has gauge resolution of 0.2${\mu}{\textrm}{m}$. The detection principles and the degree of precision for the measured strain were also discussed. The characteristics of residual stress in LPCVD polysilicon films were studied using these test structures. The stress gradient due to the stress variation through the film thickness was calculated by measuring the deflection at the cantilever free end.

• Journal of Periodontal and Implant Science
• /
• 제28권2호
• /
• pp.273-280
• /
• 1998

This study was to compare the patients wearing comfortable distally extending cantilever bridges (DECBs) with those having discomfortable ones, in the aspect of the periodontal condition & prosthodontic status. The subjects in the present study were 164 patients appointed to Seoul National University Dental Hospital. One group was consisted of 101 patients wearing comfortable DECBs and the other group were made of 64 patients who had felt discomfort. On clinical parameters, there were no significant difference between 2 groups in plaque index, tooth mobility & probing depth, but gingival index was higher in group wearing discomfortable DECBs. In prosthodontic status, the ratio of pontic oversize was higher in the group of discomfortable DECBs, but there were no significant difference in the view of crown overcontour, overhanging margin & interproximal space closure between 2groups. This study failed to clarify causal factors of discomfortable DECBs.