• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.1095-1102
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• 2010

본 연구에서는 펄스 방전 기술에 의해 확공된 앵커의 인발 거동에 대한 수치해석을 수행하였다. 펄스 방전 현상을 등가의 폭발 현상으로 모델링하여 점성토와 사질토 지반에 대한 확공해석을 수행하였으며 이를 통해 펄스 방전에 의해 개량된 지반 조건을 구현하였다. 확공된 지반에 대해 설치된 압축형 그라우트 앵커의 인발 거동을 시뮬레이션하여 인발력-인발변위 곡선을 산정하였다. 해석 결과, 점성토의 경우에는 확공 정도가 인발 거동과 밀접한 관련을 갖는 반면, 사질토의 경우에는 확공 정도 이외의 추가적인 증가 요인이 확인되는 것으로 나타났으며 펄스 방전 기술이 사질토 지반의 다짐을 통해 앵커의 인발력을 증가시키는 것으로 판단되었다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.381-387
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• 2002

Curved bridges are composed of curved members which have certain curvatures, comparing to straight bridges. Therefore, their behavior is quite different from one of the straight bridges, mainly due to the geometric characteristics of the curved bridges. In this paper, the curved bridges consisted of the single box-girder span are investigated to study the effects of negative reaction forces. The parameters considered in this study are span lengths, angles of curvature, and the number of shoes. Midas/civil computer program was used for the analysis of the curved bridges. The analysis results show that negative reaction forces are not created with one shoe installed. When two shoes are provided, on the other hands, the uplift forces are developed at the inside shoe. It is also concluded that the increasing ratio of negative reaction forces becomes larger, as the angles of curvature increase, and the elongation of span lengths turns out to increase the magnitudes of the uplift forces.

• 문화기술의 융합
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• 제10권3호
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• pp.839-844
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• 2024

본 연구는 인접굴착공사, 지반열화 및 지하수위의 변화에 따른 지하구조물 변위거동이 궤도 손상에 미치는 영향을 해석적으로 분석하였다. 연구대상인 콘크리트궤도는 침목플로팅궤도(STEDEF)와 사전제작형궤도(B2S)를 대상으로 분석하였다. 침목플로팅궤도는 콘크리트 도상과 침목이 분리된 궤도구조이다. 사전제작형궤도는 프리캐스트 슬래브를 이용하여 레일 및 체결장치를 조립하여 레일의 탄성거동을 유도하는 궤도구조이다. 수치해석을 위해 콘크리트 궤도별로 레일부터 콘크리트 도상까지 모두 3차원 요소로 모델링하였다. 또한 지하구조물 변위거동을 변수로 설정하여 콘크리트 도상의 손상영향을 분석하였다. 수치해석을 이용하여 융기 및 침하에 따른 콘크리트 도상 응력을 분석하였으며, 인장강도 및 전단강도와 비교하여 균열 발생 수준을 분석하였다. 분석결과, 동일한 융기 및 침하발생 시 사전제작형궤도보다 침목플로팅궤도가 취약한 것으로 분석되었다. 또한 최대 융기 및 침하부 기준으로 침목플로팅궤도의 균열발생 영향범위가 큰 것으로 분석되었다.

• 한국지반공학회논문집
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• 제18권1호
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• pp.5-16
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• 2002

본 연구에서는 직경 1,000mm의 시험말뚝에 대한 압축정재하시험 수행시 반력말뚝으로 사용된 직경 2,500mm의 대구경 경사반력소켓말뚝의 인발거동을 분석하였다. 경사반력말뚝은 풍화암층과 연암층 10m에 걸쳐서 현장타설말뚝으로 소켓되어졌으며, 강관부는 강관과 속채움콘크리트로, 그리고 소켓부는 콘크리트와 철근으로 구성되었다. 각 구성부재에 작용하는 변형율을 측정하기 위해 센서를 설치하였으며, 반력말뚝두부의 인발량을 측정하기 위하여 LVDT를 설치하였다. 정재하시험중 재하된 최대인발하중은 10MN이었으며 최대인발변위는 7m, 잔류인발변위는 최대 1mm 정도 발생하였다. 인발하중의 83%를 풍화암층에서 그리고 12%를 연암층에서 지지하는 것으로 나타났으며 풍화암에 소켓된 철근콘크리트부와 연암에 소켓된 털근콘크리트부에서 각각 125.3kPa와 61.8kPa의 인발응력이 발생하였다. 따라서, 풍화암층에서도 인발하중을 충분하게 지지하고 있으므로 풍화암층은 마찰력을 크게 발휘하는 지지층으로 사용되었다.

• Earthquakes and Structures
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• 제7권6호
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• pp.1001-1024
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• 2014

The size of spread footings was found to be unnecessarily large from some actual engineering practices constructed in Taiwan, due to the strict design provisions related to footing uplift. According to the earlier design code in Taiwan, the footing uplift involving separation of footing from subsoil was permitted to be only up to one-half of the foundation base area, as the applied moment reaches the value of plastic moment capacity of the column. The reason for this provision was that rocking of spread footings was not a favorable mechanism. However, recent research has indicated that rocking itself may not be detrimental to seismic performance and, in fact, may act as a form of seismic isolation mechanism. In order to clarify the effects of the relative strength between column and foundation on the rocking behavior of a column, six circular reinforced concrete (RC) columns were designed and constructed and a series of rocking experiments were performed. During the tests, columns rested on a rubber pad to allow rocking to take place. Experimental variables included the dimensions of the footings, the strength and ductility capacity of the columns and the intensity of the applied earthquake. Experimental data for the six circular RC columns subjected to quasi-static and pseudo-dynamic loading are presented. Results of each cyclic loading test are compared against the benchmark test with fixed-base conditions. By comparing the experimental responses of the specimens with different design details, a key parameter of rocking behavior related to footing size and column strength is identified. For a properly designed column with the parameter higher than 1, the beneficial effects of rocking in reducing ductility and the strength demand of columns is verified.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.605-614
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• 2010

In this paper, the initial behavior of transmission tower was analyzed. This tower was firstly constructed by rock anchor foundation in domestic 154 kV transmission line and wireless real-time monitoring system was installed to obtain the measured data for analysis of the structure behavior. For this purpose, 16 strain gauges was installed in anchors of foundation and strain gauges, clinometers, anemoscope and settlement sensors was installed at superstructure. As the results, the main factor which influence the behavior of superstructure is wind velocity, wind direction, rainfall and temperature change. Especially, the uplift load at stub of transmission structure revealed about 35.4 percentages of design load. Hereafter the long term stability will be analyzed.

• 산업기술연구
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• 제26권A호
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• pp.109-117
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• 2006

This study is an numerical study of predicting the behavior of anchor embedded in weathered rocks, subjected to uplift loads, about ultimate pullout capacity and the failure mechanism. Factors influencing the behavior of anchors were investigated by reviewing the data about in-situ anchor tests performing numerical modelling with changing the bondage length of anchor, diameter of anchor body and diameter of tenden, and by Correlations between those factors were evaluated to apply them to predict the behavior of anchors. As results of numerical analysis, a linear relationship between bondage length, diameter of anchor body and diameter of tenden with ultimate pullout capacity was obtained on the one hand, from the result of numerical analysis changing the Young's modulus of weathered rock, this parameter was found to inflence to load-displacement and ultimate pullout capacity within the range of 10%, which was mot so significant to affect.

• Earthquakes and Structures
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• 제16권6호
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• pp.691-704
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• 2019

This study simulates the responses of large-scale bridge piers under pseudo-dynamic tests to investigate the performance of four types of numerical models that consider the nonlinear behavior of the pier and the rocking behavior of the footing. In the models, beam-column elements with plastic hinges are used for the pier, two types of foundation models (rotational spring and distributed spring models) are adopted for the footing behavior, and two types of viscous damping models (Rayleigh and dashpot models) are applied for energy dissipation. Results show that the nonlinear pier model combined with the distributed spring-dashpot foundation model can reasonably capture the behavior of the piers in the tests. Although the commonly used rotational spring foundation model adopts a nonlinear moment-rotation property that reflects the effect of footing uplift, it cannot suitably simulate the hysteretic moment-rotation response of the footing in the dynamic analysis once the footing uplifts. In addition, the piers are susceptible to cracking damage under strong seismic loading and the induced plastic response can provide contribution to earthquake energy dissipation.

• 한국지반공학회논문집
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• 제19권6호
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• pp.227-243
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• 2003

강관말뚝의 속채움 콘크리트 B방법에서 미끌림방지턱의 구조적인 특성을 알아보기 위하여, 강관말뚝머리의 내부에 미끌림방지턱을 설치하지 않은 시험체와 2단의 곡률 강편 미끌림방지턱을 강관말뚝내부에 용접한 시험체(시방서 방법), 그리고 미끌림방지턱을 다수의 곡률 강편과 고장력볼트로 체결한 시험체(개발형 방법)에 대하여 실물크기 인발 및 압발 실험을 수행하였다. 그 결과, 미끌림방지턱이 없는 시험체는 최대인발하중 15.6tonf에서, 최대압발하중 27.57tonf에서 콘크리트의 화학적 부착파괴가 발생하였다. 그리고 미끌림방지턱이 있는 시방서 방법과 개발형 방법의 시험체는 없는 시험체보다 최대인발하중의 약 8.9배와 최대압발하중의 6.2배 크게 나타났다. 또한 시방서 방법과 개발형 방법의 하단 미끌림방지턱에 대한 하중분담비율은 거의 동일한 거동을 보인 반면에, 상단 미끌림방지턱은 시방서방법보다 개발형 방법의 하중분담비율이 크게 기여하였다. 그리고 시방서 방법과 개발형 방법의 미끌림방지턱 형상에 의한 합성작용과 구조성능은 거의 동일하였다.

• Steel and Composite Structures
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• 제35권2호
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• pp.261-278
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• 2020

In steel-concrete composite beams, to improve the cracking resistance of the concrete slab in the hogging moment region, a new type of connector in the interface, named uplift-restricted and slip-permitted screw-type (URSP-S) connector has been proposed. This paper focuses on the behavior of steel-concrete composite beams with URSP-S connectors. A total of three beam specimens including a simply supported beam with URSP-S connectors and two continuous composite beams with different connectors arrangements were designed and tested. More specifically, one continuous composite beam was equipped with URSP-S connectors in negative moment region and traditional shear studs in other regions. For comparison, the other one was designed with only traditional shear studs. The failure modes, crack evolution process, ultimate capacities, strain responses at different locations as well as the interface slip of the three tested specimens were measured and evaluated in-depth. Based on the experimental study, the research findings indicate that the larger slip deformation is allowed while using URSP-S connectors. Meanwhile, the tensile stress reduces and the cracking resistance of the concrete slab improves accordingly. In addition, the overall stiffness and strength of the composite beam become slightly lower than those of the composite beam using traditional shear studs. Moreover, the arrangement suggestion of URSP-S connectors in the composite beam is discussed in this paper for its practical design and application.