• 한국공간구조학회논문집
• /
• 제4권4호
• /
• pp.85-89
• /
• 2004

A frame element embedded normal to a shear wall or slab (shell element) is common in the structural systems. In that case there is a need for a membrane or shell element to have a normal rotation degree of freedom at each node in order to have a good result of stresses. Even if Many other people studied this area, All man, Cook and Sabir are representative investigators in this area. In this research paper, Sabir's methods of vertex rotation stiffness matrix in a membrane element are studied. New stiffness of vertex rotation are proposed by taking advantage of beam stiffness theory. Rectangular elements stiffness with rotational degree of freedom are compared in accuracy ratio each other.

• KCI Concrete Journal
• /
• 제12권1호
• /
• pp.113-120
• /
• 2000

This paper presents the behavior and strengthening effect of reinforced concrete rectangular beams strengthened using CFRP sheets with different strengthening level. In general, normally strengthened beams are failed by interfacial shear failure (delamination) within concrete, instead of by tensile failure of the CFRP sheets. The delamination occurred suddenly and the concrete cover cracked vertically by flexure was spalled off due to the release energy. The strengthened beams were stiffer than the control beam before and after reinforcement yielding. The ultimate load considerably increased with an increase of strengthening level, while the ultimate deflection significantly decreased. The tensile force of CFRP sheets and average shear stress of concrete at delamination failure were curvilinearly proportional to the strengthening level. Therefore, the increment of ultimate load obtained by strengthening was curvilinearly proportional to the strengthening level. The averaged horizontal shear stress of concrete at the interface ranges between (equation omitted) and (equation omitted) (in kg/$\textrm{cm}^2$) depending on strengthening level.

• Structural Engineering and Mechanics
• /
• 제45권2호
• /
• pp.169-182
• /
• 2013

The mechanical behavior of rectangular foundation plates with perimetric beams and internal stiffening beams of the plate is herein analyzed, taking the foundation design into account. A series of dimensionless parameters related to the geometry of the studied elements were defined. In order to generalize the problem statement, an initial settlements was considered. A numeric procedure was developed for the resolution by means of the Finite Differences Method that takes into account the stiffness of the plate, the perimetric and internal plate beams and the soil reaction module. Iterative algorithms were employed which, for each of the analyzed cases, made it possible to find displacements and reaction percentages taken by the plate and those that discharge directly into the perimetric beams, practically without affecting the plate. To enhance its mechanical behavior the internal stiffening beams were prestressed and the results obtained with and without prestressing were compared. This analysis was made considering the load conditions and the soil reaction module constant.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
• /
• pp.1613-1614
• /
• 2006

In this paper, a $4{\times}4$ rectangular patch array antenna operated at 20 GHz is implemented for the satellite communication. Two $2{\times}2$ subarrays are designed and more efficient $2{\times}2$ subarray is used for the design of $4{\times}4$ patch array. The sixteen patch antennas and microstrip feeding line are printed on the single-layered substrate. The spacing between the array elements is chosen to be $0.736{\lambda}$. HPBW (Half-Power Beam Width) is 17.6 degrees in the E-plane and 18.7 degrees in the H-plane with a gain of 17.2SdBi in the simulation results.

• 한국구조물진단유지관리공학회 논문집
• /
• 제3권3호
• /
• pp.213-222
• /
• 1999

On condition that opening located at high shear strength position in H-shaped steel beams with web opening, beams are structurally to be frailed so necessity and efficiency of vertical reinforcement to add horizontal reinforcement already published ahead study. Up to the present study of web opening beams, limited one opening which located in comparatively small shear strength position. But frequently opening area is enlargement by necessity, so width of opening is larger by limit of depth or increasing number of opening. This study carry out experiment to make efficient reinforcing method about strength and deformation of steel beams with web openings. Parameters of this study are openings location, ratio of opening width within opening height and various reinforcing types.

• Structural Engineering and Mechanics
• /
• 제7권3호
• /
• pp.331-344
• /
• 1999

This paper provides an analysis of the transient behaviour of a right-angled bent cantilever beam subjected to a suddenly applied force at its tip perpendicular to its plane. Based on a rigid, perfectly plastic material model, a double-hinge mechanism is required to complete the possible deformation under a rectangular force pulse (constant force applied for a finite duration) with a four-phase response mode. The kinematics of the various response phases are described and the partitioning of the input energy at the plastic hinges during the motion is evaluated.

• Computers and Concrete
• /
• 제11권5호
• /
• pp.365-382
• /
• 2013

Although shear reinforcement in beams typically consists of steel bars bent in the form of stirrups or hoops, the addition of deformed steel fibres to the concrete has been shown to enhance shear resistance and ductility in reinforced concrete beams. This paper presents a model that can be used to predict the shear strength of fibrous concrete rectangular members without stirrups. The model is an extension of the plasticity-based crack sliding model originally developed for plain concrete beams. The crack sliding model has been improved in order to take into account several aspects: the arch effect for deep beams, the post-cracking tensile strength of steel fibre reinforced concrete and its ability to control sliding along shear cracks, and the mitigation of the shear size effect due to presence of fibres. The results obtained by the model have been validated by a large set of experimental tests taken from literature, compared with several models proposed in literature, and numerical analyses are carried out showing the influence of fibres on the beam failure mode.

• Structural Engineering and Mechanics
• /
• 제77권2호
• /
• pp.273-291
• /
• 2021

The strut-and-tie method (STM) has been widely accepted and used as a rational approach for the design of disturbed regions ('D' regions) of reinforced concrete members such as in corbels and deep beams, where traditional flexure theory does not apply. This paper evaluates the applicability of the equilibrium based STM in strength predictions of deep beams (with rectangular and circular cross-section) and corbels using the available experiments in literature. STM is found to give fairly good results for corbel and deep beams. The failure modes of these deep members are also studied, and an optimum amount of distribution reinforcement is suggested to eliminate the premature diagonal splitting failure. A comparison with existing empirical and semi empirical methods also show that STM gives more reliable results. The nonlinear finite element analysis (NLFEA) of 50 deep beams and 20 corbels could capture the complete behaviour of deep members including crack pattern, failure load and failure load accurately.

• 한국의학물리학회지:의학물리
• /
• 제11권1호
• /
• pp.1-18
• /
• 2000

쐬기인자의 조사면에 따른 변화는 여러 저자들에 의해 보고되었으나, 아직도 정량적인 설명이 이루어지지않고 있다 따라서 본 연구에서는 4 cm $\times$ 4 cm에서부터 25 cm $\times$ 25 cm까지의 조사면에 대해서 10 cm $\times$ 10 cm 기준 조사면에 대한 상대적 쐬기인자를 조사하였다. 조사면의 증가에 따라 쐬기를 통과하는 고에너지 광자선의 선속변화로 인해 쐬기인자는 6MV 광자선에서 최고 8.0%까지 증가하였다. 이러한 증가는 조사면이 10 cm보다 작은 경우를 제외하고는 일반적으로 알려진 바와 같이 광자선이 통과하는 쐬기의 부피와 선형적인 관계를 갖고 있음이 박혀졌다. 그러나 특히 쐬기의 경사면에 평행한 방향으로의 조사면이 증가하는 좁은 조사면의 경우에서는 쐬기의 두께변화로 인해 야기되는 광자선의 선속변화가 상대적으로 작아짐에 따라 10-15 cm까지는 약간의 감소가 나타나고 있다 따라서, 광자선의 중심축의 선량에 기여하는 주광자선의 선속변화로 인해 쐬기인자의 변화원인을 설명할 수 있으며, 그 관자선의 선속변화는 쐬기의 경사방향에 대한 조사면의 크기변화에 영향을 받고 있음을 알 수 있다. 기존에 제안되어진 쐬기인자의 변환 식을 본 연구결과에 잘 맞도록 보정하여 제시하였다.

• 콘크리트학회논문집
• /
• 제24권3호
• /
• pp.225-232
• /
• 2012

이 연구는 순환잔골재를 사용한 콘크리트의 전단거동을 평가하고자 하였다. 추가적으로 순환굵은골재를 현행규준식 및 제안식과 비교/분석하였다. 동일한 압축강도를 갖는 5개의 실험체를 계획하였으며 각 실험체는 순환잔골재치환율(0%, 30%, 60%, 70%, 100%)을 변수로 계획하였으며 전단철근은 보강하지 않았다. 실험에 사용한 순환잔골재는 흡수율과 비중을 만족하는 골재를 사용하였다. 사용한 골재 중 70% 치환한 실험체의 경우 저품질의 순환잔골재를 사용하였다. 실험은 하중-변위관계, 전단변형, 경사균열하중, 균열패턴, 최대전단강도, 파괴모드를 분석하여 평가하였다. 실험 결과 순환잔골재를 사용한 철근콘크리트 보의 전단거동은 천연골재와 비교하여 전반적으로 큰 차이를 보이지 않았으나, 전단에 관한 규준식 및 제안식과 비교한 결과 순환잔골재를 사용한 철근콘크리트 보의 경우 규준식 수정을 통한 새로운 제안식이 필요할 것으로 판단된다.