• Structural Engineering and Mechanics
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• 제63권4호
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• pp.447-456
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• 2017

The primary objective of this paper is to study the effectiveness of anchorage on the performance of shear deficient beams externally strengthened with CFRP composites. The overall behavior of the tested beams loaded up to failure, the onset of the cracking, and crack development with increased load and ductility were described. The use of CFRP composites is an effective technique to enhance the shear capacity of RC beams by using CFRP strips anchored into the tension side and from the top by 15-34% based on the investigated variables. Bonded anchorage of CFRP strips with width of 0.1h-0.3h to the beam resulted in a decrease in average interface bond stress and an increase in the effective strain of the FRP sheet at failure, which resulted in a higher shear capacity as compared with that of the U-wrapped beams without anchorage as well as delay or mitigate the sheet debonding from the concrete surface.

• Computers and Concrete
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• 제17권1호
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• pp.67-86
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• 2016

Strengthening as well as correcting unsightly deflections of reinforced concrete (RC) beam may be accomplished by retrofitting. An innovative way to do this retrofitting that is proposed in this study utilizes turnbuckle to apply external post-tensioning. This Turnbuckle External Post-Tensioning (T-EPT) was experimentally proven to improve the serviceability and load carrying capacity of reinforced concrete beams. The T-EPT system comprises a braced steel frame and a turnbuckle mechanism to provide the prestressing force. To further develop the T-EPT, this research aims to develop a numerical scheme to analyze the structural performance of reinforced concrete beams with this kind of retrofitting. The fiber method analysis was used as the numerical scheme. The fiber method is a simplified finite element method that is used in this study to predict the elastic and inelastic behavior of a reinforced concrete beam. With this, parametric study was conducted so that the effective setup of doing the T-EPT retrofitting may be determined. Different T-EPT configurations were investigated and their effectiveness evaluated. Overall, the T-EPT was effective in improving the serviceability condition and load carrying capacity of reinforced concrete beam.

• 한국농공학회논문집
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• 제48권2호
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• pp.27-35
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• 2006

Large dams are managed with operation standard and flood forecasting systems, while small dams do not have management method generally. Shortage of water resources and natural disasters due to drought and flood raised public concerns for management of small dams. Most of small dams are irrigation dams, which need diversified water uses. However, the lack of systematic management of small dams have caused serious water wastage and increased natural disasters. Storage management method and system were developed to solve these problems in small dams. The system was applied to Seongju dam for effective management. The storage management method was established considering hydrology simulation and statistical analysis using the system. This method can bring additional available water, even in the same conditions of the water demand and the supply conditions of watershed. It can improve the flood control capacity and water utilization efficiency by' the flexible operation of storage space.

• Current Optics and Photonics
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• 제2권1호
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• pp.39-46
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• 2018

Visible-light communication (VLC) combined with advanced illumination can be expected to become an integral part of next-generation communication networks. One of the major concerns in VLC implementation is developing resource-allocation schemes in a multi-user scenario. However, the scheduling for heterogeneous quality of service (QoS) traffic has not been studied so far, for the indoor VLC downlink system. In this paper, we creatively introduce effective-bandwidth and effective-capacity theory into the multi-user scheduling (MUS) problem, to guarantee the user's statistical delay QoS. We also take account of the aggregate interference (AI) in the indoor VLC downlink system, and analyze its impact on the user-centric MUS problem for the first time. Simulations show that the AI has a nonnegligible influence on the scheduling result, and that the proposed scheduling scheme could guarantee the user's QoS requirement under the premise of ensuring sum capacity.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.679-684
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• 1997

In this study, compressive strengths of reinforced concrete compression members rehabilitated with C.F.L. were analyzed from the test. Test parameters are spacing, spliced length, and section area of rehabilitation material. Displacement, failure load were measured during test. The failure mode and ultimate load were analyzed from these measured data. Test result shows that closer spacing of C.F.L. is more effective. strengthening with 1-ply C.F.L. is more effective than that of specimen with 2-ply C.F.L. The compressive capacity of specimen spliced ($\pi$.D)/2 shows almost similar strength to that of non-spliced specimen. The ultimate load carrying capacity of specimen strengthened with C.F.L. is increased to 1.11~1.68 times of that of non-rehabilitation specimen.

• 한국자동차공학회논문집
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• 제4권3호
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• pp.83-91
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• 1996

This paper investigates the energy absorption characteristics of thin-walled rectangular tubes. In the compact mode, the crushing process of a thin-walled tube is analyzed into 3 parts by the ratio of outward to inward fold length. The mean crush load and the half-wave folding length are determined by using minimum energy principle. The effective crush distance can be determined when half-wave folding length is known, and the number of folds is derived when crush distance is given. Thus when the crush distance is given, energy absorption capacity can be estimated with mean crush load and number of folds. And the theoretical value is proven experimentally.

• Earthquakes and Structures
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• 제25권4호
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• pp.297-305
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• 2023

The conventional method of structural seismic design was based on increasing structural capacity, which usually didn't reduce earthquake seismic effects. By changing the philosophy of structure design, technologies such as passive seismic control have been used in structures. So far, a large number of seismic isolation systems have been introduced to dissipate earthquake energy that is applied to a structure. These systems act against earthquakes rather than increasing the strength and capacity of the structure. In the present paper, a suspended column called a "pendulum column" is investigated, and a new idea has been considered to improve the performance of the pendulum column isolator by changing the gravity effect by adding a spring under the isolator system. The behavior of the studied isolator system has been researched. Then the isolator system was investigated under different earthquakes and compared with a common pendulum column isolator. The results show that changing the gravity effect has an effective role in the response of the system by reducing the system stiffness. Equations for the system showed that even in a special state, complete isolation is possible. Finally, the tested model verified the theory.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.187-192
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• 2003

Nowadays, It has adapted both Ultimate Strength Design(USD) and Allowable Stress Design(ASD) Method evaluating load-carrying capacity of PSC I Type Girder Bridge. But it has confused because the each method has brought some different results. This study shows some results of loading test of the PSC I type Girder Bridge and analyzed the structural behavior by FEM analysis considering material nonlinear. Parametric study of effective prestress of post tendon is performed and compared to results of loading test.

• 한국관개배수논문집
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• 제6권1호
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• pp.74-80
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• 1999

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.209-212
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• 2008

I형강 접합 절곡 강합성 바닥판은 절곡 바닥판내에 I형강을 매입하여 기존의 현장타설 철근콘크리트바닥판보다 경량화되고 하중저항성능 및 시공성을 향상시킨 강합성 바닥판이다. 현재 일반적인 철근콘크리트 구조물의 유효휨강성에 대한 계산은 도로교설계기준 및 ACI에서 제안하고 있는 방법을 사용하고 있다. 본 논문에서는 도로교설계기준 및 ACI에서 제안된 유효휨강성에 대한 산정 방법과 CEB-FIP MC-90에서 제안하고 있는 방법을 사용해 I형강 접합절곡강합성 바닥판의 유효휨강성을 계산하고 그에 대한 적합성을 평가하였다. 또한 전단연결재의 유 무, 단면의 변화, 부재연결 그리고 일반철근콘크리트보와의 비교등 4가지 실험변수를 두고 총 5개의 실험체를 제작 실험하였고 실험결과와 이론식으로 산정된 휨강성값을 비교,평가하여 실험변수에 따른 휨강성의 변화를 분석하였다. 실험결과 CEB-FIP MC-90에서 제안하고 있는 방법이 ACI에서 제안하고 있는 방법보다 만족스러운 결과를 나타냈으며, 전단연결재가 있고 콘크리트와 바닥판의 부착면적이 많은 경우에 하중저항 성능과 휨강성이 높게 나타났다.