• 대한기계학회논문집A
• /
• 제21권2호
• /
• pp.317-326
• /
• 1997

An investigation was performed to study the matrix cracking and delamination in laminated composite plates due to transverse impact. A model was developed for predicting the initiation of the matrix cracking and the shape and size of impact-induced delamination in laminated composite plates resulting from the ballistic impact. The model consists of a stress analysis and a failure analysis. A transient finite element analysis which was based on the higher-order shear deformation theory was adopted for calculating the stresses inside the laminated composite plates during impact. A failure analysis was used to predict the initial intraply matrix cracking and the shape and size of the interface delamination in the laminates. As a results, a shear matrix cracking which was governed by the transverse interlaminar shear stress occured at the middle layer near the midplane of laminates and a bending matrix cracking which was governed by the transverse inplane stress occured at the bottom layer near the surface of laminates. In a thick laminates, a shear matrix cracking generated first at the middle layer of laminates, but in a thin laminates, a bending matrix cracking generated first at the bottom layer of laminates.

• International Journal of Concrete Structures and Materials
• /
• 제3권1호
• /
• pp.47-56
• /
• 2009

The first diagonal cracking and ultimate shear load of reinforced girder made of ultra high performance fiber reinforced concrete (UHPFRC) were investigated in this paper. Eleven girders were tested in which eight girders failed in shear. A simplified formulation for the first diagonal cracking load was proposed. An analytical model to predict the ultimate shear load was formulated based on the two bounds theory. A fiber reinforcing parameter was constituted based on the random assumption of steel fiber uniform distribution. The predicted values were compared with the conventional predictions and the test results. The proposed equation can be used for the first cracking status analysis, while the proposed equations for computing the ultimate shear strength can be used for the ultimate failure status analysis, which can also be utilized for numerical limit analysis of reinforced UHPFRC girder. The established fiber reinforcing theoretical model can also be a reference for micro-mechanics analysis of UHPFRC.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1990년도 가을 학술발표회 논문집
• /
• pp.83-87
• /
• 1990

The effect of concrete strength on shear cracking strength in reinforced concrete beams is investigated analytically. The quantitative response of reinforced concrete beam-end-part with varing concrete stiffness, which is a function of concrete compressive strength, is examined utilizing a finite element mothod. The result indicates that the severer shear stress localization/concentration takes place in the beam having higher concrete strength. Thus the increase ratio of shear cracking strength with respect to concrete compressive strength decreases as the concrete strength becoms higher.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
• /
• pp.885-890
• /
• 2000

12 RC deep beams with a/d = 1.17 are reported. This paper is to study the effect of vertical and horizontal web reinforcement and web reinforcement arrangement on inclined cracking shear, ultimate shear strength, midspan deflection, and inclined crack width. Test results indicated that web reinforcement produces and arrangement seems to moderately affect inclined cracking shear, ultimate shear strength and crack width. However, addition of horizontal web reinforcement(pv = 0.0085) little or no influence on inclined cracking shear, ultimate shear strength and crack width. The member which vertical and horizontal web reinforcement concentrate on the center web considerably increases in load-carrying capacity.

• 콘크리트학회논문집
• /
• 제11권4호
• /
• pp.43-54
• /
• 1999

Shear tests are performed on four full-scale 12.5 m proto-type models, "least depth double tee," which are resulted from the optimization process. Domestic superimposed live load regulation, domestic material properties which is available to product. Korean building code requirements, construction environments and economy are considered as the main factors to establish the process. All of the specimens tested fully comply with the shear strength requirements as specified by ACI 318-95. The research has shown following results. 1) The development length requirement of ACI 318-95 does not seem a good predictor for the estimation of bond failure in a beam with the strands below the supports. 2) The load required for the first initial coner cracking in the dap end and first web shear cracking does not seem to have any relation with the dimension and shear strength of the section in the test beams. 3) The strand slip has a direct relationship with the web shear cracking. However, the coner cracking in the dap end does not give any help for the slip in anchorage. 4) Use of whole area for bearing steel at the bottom of dap end is desired for safe bearing pressure design in the precast prestressed double tee beams. 5) The deflection of beam influences directly on the amount of strand slip at the anchorage after initiation of it, and relationship between them are very linear.

• 한국구조물진단유지관리공학회 논문집
• /
• 제26권3호
• /
• pp.48-54
• /
• 2022

본 연구는 균열에 의한 콘크리트 전단벽 강성저하 영향 평가를 위해 수행되었으며, 극한 내지진 하중의 60%까지 재하한 비선형 해석 결과, 사전 균열효과에 의해 비손상 대비 진동수의 12%정도 진동수가 감소하였으며 강성 측면에서 23%정도의 감소현상을 나타냈다. 단계적으로 지진하중의 크기를 증가시킨 비선형 해석 결과, 지진하중의 세기가 커짐에 따라 콘크리트 전단벽체에 전단균열이 발생하여 진전함을 파악하고, 반복이력에 의한 에너지 손실과 강성 저하가 뚜렷하게 발생함을 알 수 있었다. 또한 두 가지 콘크리트 강도와 전단벽 제원에 대하여 지진하중의 크기가 극한 내지진 하중에 근접함에 따라 진동수의 감소량은 비손상 대비 10~40%정도로 나타났으며, 강성의 경우 비손상 대비 40%정도 수준까지 감소할 수 있는 것으로 나타났다.

• Computers and Concrete
• /
• 제12권5호
• /
• pp.697-715
• /
• 2013

Numerous studies have been conducted to understand the shear behavior of reinforced concrete (RC) beams since it is a complex phenomenon. The diagonal cracking strength of a RC beam is critical since it is essential for determining the minimum amount of stirrups and the contribution of concrete to the shear strength of the beam. Most of the existing equations predicting the diagonal cracking strength of RC beams are based on experimental data. A powerful computational tool for analyzing experimental data is an artificial neural network (ANN). Its advantage over conventional methods for empirical modeling is that it does not require any functional form and it can be easily updated whenever additional data is available. An ANN model was developed for predicting the diagonal cracking strength of RC slender beams without stirrups. It is shown that the performance of the ANN model over the experimental data considered in this study is better than the performances of six design code equations and twelve equations proposed by various researchers. In addition, a parametric study was conducted to study the effects of various parameters on the diagonal cracking strength of RC slender beams without stirrups upon verifying the model.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
• /
• pp.377-380
• /
• 1999

This paper dscribes an experimental investigation into the cause of flexural-shear failure in RC beams. The experimental variables are bottom flange width and tension bar location. Then these test results were compared and analyzed to deduce the major cause of critical-shear cracking. As a result, it was found that the propagation of the critical shear crack depended exclusively on the intensity of horizontal cracking.

• Structural Engineering and Mechanics
• /
• 제56권2호
• /
• pp.317-340
• /
• 2015

Design codes have specified the minimum shear reinforcement requirement for reinforced concrete (RC) and prestressed concrete (PSC) members to prevent brittle and premature shear failure. They are, however, very different from one another, and particularly, ACI318 code allows the required minimum shear reinforcement to be reduced in PSC members, compared to that in RC members, by specifying the additional equation for PSC members whose basis is not clear. In this paper, the minimum shear reinforcement ratio for PSC members was proposed, which can provide a sufficient reserved shear strength and deformation capacity. The proposed equation was also verified by the test results of PSC specimens lightly reinforced in shear, comparing to design codes and other proposed equations from previous studies.

• 콘크리트학회지
• /
• 제6권2호
• /
• pp.118-128
• /
• 1994

본 논문은 전단철근을 갖지 않는 강섬유보강콘크리트 보의 전단거동을 규명하고 균열전단강도와 극한전단강도를 예측하기 위한 것으로 섬유로 보강된 11개의 보을 포함한 총 14개의 보에 대한 실험을 수행하였다. 실험의 변수는 섬유혼입율과 전단지간 등이며, 실험과정을 통해 파괴형상, 처짐, 균열전단강도 및 극한전단강도를 측정하였다. 실험결과로부터 섬유의 혼입량이 많아지고 전단지간이 짧아질수록 섬유보강콘크리트 보의 균열 및 극한전단강도가 증가됨을 밝혔다. 그리고 실험결과를 희귀분석하여 균열전단겅도와 극한전단강도 추정식을 제안 하였으며, 제안된 식에 의해 강섬유의 혼입으로 얻어지는 전단강도에 대한 섬유의 기여효과를 추정할 수 있었다. 또한, 제안된 추정식에 의해 계산된 값과 실험결과를 비교 검토하여 그 상관성을 확인하였다.