• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.903-906
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• 2001

The objective of this experimental study was to understand the effect of horizontal shear bar on the shear behavior of R.C. deep beams. Therefore, in the test program, the horizontal shear bar ratio($\rho_{sh}$) and shear span-to-overall depth ratio(a/h) are considered as two main variables. Test results indicate that for deep beams with a/h equal to 1.0, horizontal shear bar is less efficient in restricting the diagonal crack width development and enhancing the ultimate shear strength. So, it can be concluded that shear resistance of horizontal shear bar is related to a/h rather than clear span-to-effective depth ratio($l_{n}$/d) recommended in ACI code.

• 콘크리트학회논문집
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• 제12권4호
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• pp.23-30
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• 2000

The purpose of this paper is to study on the shear strength of high strength concrete beams with steel fibrous. In general, the shear strength of reinforced concrete beams is affected by the compressive strengths of concrete( c), the shear span-depth ratio(a/d), the longitudinal steel ratio($\rho$ $\omega$), and shear reinforcement. An experimental investigation of the shear strength of high strength concrete beams with steel fibrous was conducted. In each series the shear span-depth ratio(a/d) was held constant at 1.5, 2.8, or 3.6, while concrete strengths were varied from 320 to 520, to 800kgf/$\textrm{cm}^2$. To verify the proposed equations the experimental results were compared with those from other researches such as equation of ACI code 318-95 or equation of Zsutty. To deduce equation for shear strength from experimental data carried out MINITAP program. According to the experimental results, the addition of steel fibrous has increased the deflection and strain at failure load, improving the brittleness of the high strength concrete.

• Smart Structures and Systems
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• 제14권5호
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• pp.785-809
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• 2014

In this paper, an Adaptive nerou-based inference system (ANFIS) is being used for the prediction of shear strength of high strength concrete (HSC) beams without stirrups. The input parameters comprise of tensile reinforcement ratio, concrete compressive strength and shear span to depth ratio. Additionally, 122 experimental datasets were extracted from the literature review on the HSC beams with some comparable cross sectional dimensions and loading conditions. A comparative analysis has been carried out on the predicted shear strength of HSC beams without stirrups via the ANFIS method with those from the CEB-FIP Model Code (1990), AASHTO LRFD 1994 and CSA A23.3 - 94 codes of design. The shear strength prediction with ANFIS is discovered to be superior to CEB-FIP Model Code (1990), AASHTO LRFD 1994 and CSA A23.3 - 94. The predictions obtained from the ANFIS are harmonious with the test results not accounting for the shear span to depth ratio, tensile reinforcement ratio and concrete compressive strength; the data of the average, variance, correlation coefficient and coefficient of variation (CV) of the ratio between the shear strength predicted using the ANFIS method and the real shear strength are 0.995, 0.014, 0.969 and 11.97%, respectively. Taking a look at the CV index, the shear strength prediction shows better in nonlinear iterations such as the ANFIS for shear strength prediction of HSC beams without stirrups.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회논문집(II)
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• pp.567-572
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• 1998

Structural behavior of R/C deep beams was investigated and compared to those of specimens with CFRP Grids. Test results show that the crushing of compression strut for the unstrengthened R/C deep beams is changed to the group of several diagonal cracks at mid-depth within the sheat span. Strengthened specimens grow to be more ductile after the redistribution of internal force on the CFRP Grids. The failure mode and variations of strains in the specimens are dependent on the shear span-to-depth ratio. The lower the shear span-to-depth ratio, the bigger failure load and the less variations in strain are observed. Additional anchorage of CFRP Grids does not only cause the improvement in the internal resistance, but also control the brittle shear failure of specimen after reaching the maximum loads.

• 한국전산구조공학회논문집
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• 제24권1호
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• pp.23-31
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• 2011

본 연구는 섬유 보강 폴리머(Fiber Reinforced Polymers, 이하 FRP) bar로 보강된 콘크리트 깊은보의 전단강도을 평가하기 위하여 전단경간비, 보강비, 유효깊이, 주근의 종류를 변수로 총 15개의 시험체에 대한 전단 실험을 수행하였다. 전단 실험을 토대로 FRP bar로 보강된 콘크리트 깊은보의 균열 및 처짐에 대한 거동 조사를 수행하였으며, ACI 318-08의 스트럿-타이 모델(이하 STM)을 이용한 전단강도와 아치작용을 고려한 기존 제안식에 의한 전단강도를 비교 평가하였다. 그 결과 FRP bar로 보강한 경우가 Steel bar로 보강한 경우보다 전단강도가 증가하는 것으로 나타났으며, 전단강도 산정에 있어 ACI 318-08 STM을 이용한 방법이 경험식에 의한 방법보다 상대적으로 정확했다.

• 콘크리트학회지
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• 제6권2호
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• pp.118-128
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• 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.

• Earthquakes and Structures
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• 제14권3호
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• pp.261-271
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• 2018

Fiber reinforced cementitious composites (FRCC) materials that exhibit strain-hardening and multiple cracking properties under tension were recently developed as innovative building materials for construction. This study aims at exploring the use of FRCC on the seismic performance of coupling beams with conventional reinforcement. Experimental tests were conducted on seven FRCC precast coupling beams with small span-to-depth ratios and one ordinary concrete coupling beam for comparison. The crack and failure modes of the specimens under the low cycle reversed loading were observed, and the hysteretic characteristics, deformation capacity, energy dissipation capacity and stiffness degradation were also investigated. The results show that the FRCC coupling beams have good ductility and energy dissipation capacities compared with the ordinary concrete coupling beam. As the confinement stirrups and span-to-depth ratio increase, the deformation capacity and energy dissipation capacity of coupling beams can be improved significantly. Finally, based on the experimental analysis and shear mechanism, a formula for the shear capacity of the coupling beams with small span-to-depth ratios was also presented, and the calculated results agreed well with the experimental results.

• Structural Engineering and Mechanics
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• 제37권1호
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• pp.39-59
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• 2011

Results of an experimental investigation on the behavior and ultimate shear capacity of 27 reinforced concrete Transfer (deep) beams are summarized. The main variables were percent longitudinal(tension) steel (0.28 to 0.60%), percent horizontal web steel (0.60 to 2.40%), percent vertical steel (0.50to 2.25%), percent orthogonal web steel, shear span-to-depth ratio (1.10 to 3.20) and cube concrete compressive strength (32 MPa to 48 MPa).The span of the beam has been kept constant at 1000 mm with100 mm overhang on either side of the supports. The result of this study shows that the load transfer capacity of transfer (deep) beam with distributed longitudinal reinforcement is increased significantly. Also, the vertical shear reinforcement is more effective than the horizontal reinforcement in increasing the shear capacity as well as to transform the brittle mode of failure in to the ductile mode of failure. It has been observed that the orthogonal web reinforcement is highly influencing parameter to generate the shear capacity of transfer beams as well as its failure modes. Moreover, the results from the experiments have been processed suitably and presented an analytical model for design of transfer beams in high-rise buildings for estimating the shear capacity of beams.

• Smart Structures and Systems
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• 제16권3호
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• pp.497-519
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• 2015

This study discusses the use of Adaptive-Network-Based-Fuzzy-Inference-System (ANFIS) in predicting the shear strength of reinforced-concrete deep beams. 139 experimental data have been collected from renowned publications on simply supported high strength concrete deep beams. The results show that the ANFIS has strong potential as a feasible tool for predicting the shear strength of deep beams within the range of the considered input parameters. ANFIS's results are highly accurate, precise and therefore, more satisfactory. Based on the Sensitivity analysis, the shear span to depth ratio (a/d) and concrete cylinder strength ($f_c^{\prime}$) have major influence on the shear strength prediction of deep beams. The parametric study confirms the increase in shear strength of deep beams with an equal increase in the concrete strength and decrease in the shear span to-depth-ratio.

• 한국구조물진단유지관리공학회 논문집
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• 제6권4호
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• pp.233-242
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• 2002

This study is to investigate experimentally the shear capacity of high-strength lightweight-aggregate reinforced concrete beams subjected to monotonic loading. Ten beams made of fly-ash artificial lightweight high-strength concrete were tested to determine their diagonal cracking and ultimate shear capacities. The variables in the test program were longitudinal reinforcement ratio; which variabled (between 0.83 and 1.66 percent), shear span-to-depth ratio (a/d=1.5, 2.5 and 3.5), and web reinforcement(0, 0.137, 0.275 and 0.554 percent). Six of the test beams had no web reinforcement and the other six had web reinforcement along the entire length of the beam. Most of beams failed brittly by distinct diagonal shear crack, and have reserved shear strength due to the lack of additional resisting effect by aggregate interlocking action after diagonal cracking. Test results indicate that the ACI Building Code predictions of Eq. (11-3) and (11-5) for lightweight concretes are unconservative for beams with tensile steel ratio of 1.66, a/d ratios greater than 2.5 without web reinforcement. Through a more rational approach to compute the contribution of concrete to the shear capacity, a postcracking shear strength in concrete is observed.