• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 추계학술대회 논문집
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• pp.73-78
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• 2000

This paper describes the effect of span-to-depth ratio, which describes aspect of cell formed with top diaphragm steel plate, on capacity in composite steel-concrete structure of sandwich system. The span-to-depth ratio \ulcorner load-carrying mechanism and load-distribution capacity of structure. Therefore, stress levels of members and load-resis\ulcorner of system vary according to span-depth ratio. In this study, numerical nonlinear analysis was performed to various ratio for two types(MA, MB) composite structure of sandwich system to analyze the influence of span-to-depth ratio or, behavior. The difference of load-carrying mechanism and stress of members results from analysis results, then bas\ulcorner differences, the effects of span-to-depth ratio on shear capacity, flexural capacity and load-resistance capacity were analyze effects on failure mode and ductility were briefly. As a results of this study, as span-to-depth ratio increases, \ulcorner bottom steel plate and concrete lower. This implies an increase in effective flexural and shear capacity. Therefore lo\ulcorner capacity of structure improves as span-to-depth ratio increases, Especially, the effect is greate in shear than flexural span-to-depth ratio increases, this difference between flexural and shear capacity may change failure mode and ductility. span-to-depth ratio increases capacity increases more than flexural capacity, we should expect that structural behavior mode gradually change from shear to flexural and ductility of structure gradually improves.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.890-895
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• 2003

The purpose of this experimental study is to investigate the influence of shear span-to-depth ratio on the minimum shear reinforcement ratio of reinforced concrete beams. In this study, 7 reinforced concrete beam specimens were tested. The parameters of experiment are shear span-to-depth ratio(a/d=2.0, 3.0, 4.0) and shear reinforcement ratio($p_v$=0%, 0.183%, and 0.233%). The section of all secimens was 350mm width and 450mm depth. The observed results were compared with the calculated results by the current ACI 318-02 Building Code and the proposed equation. The safety rate of the specimens, L5S2A, L5S3A, L5S4A, and L5S4P specimens were 1.80, 1.25, 1.38, and 1.56 respectively. The test results indicated that the shear behavior of reinforced concrete beams with the minimum shear reinforcement was influenced by the shear span-to-depth ratio.

• 한국구조물진단유지관리공학회 논문집
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• 제4권1호
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• pp.93-100
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• 2000

The purpose of this study is to investigate the shear behavior of reinforced concrete beams according to small shear span-depth ratio between a/d=1.5, 2.8, 3.6. In general, shear strength of reinforced concrete beams is dependent on the compressive strength of concrete the longitudinal steel ratio, the shear span-depth ratio and shear reinforcement. The static test was carried out to measure the ultimate load, the initial load of flexural and diagonal cracking, crack patterns, fracture modes. The load versus strain and load versus deflection relations were obtained from the static test. The test results on shear strength were compared with results obtained by the formulas of ACI code 318-95. The shear strength of reinforced concrete beams exceeded those predicted following present ACI code 318-95(11-6).

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.897-902
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• 2001

The purpose of this experimental study is to investigate the shear behavior of high-strength concrete deep beam and to grasp the conservatism of ACI Building Code. Experimental results on 12 deep beams under two equal symmetrically placed point loads are reported. Main variables are vertical and horizontal web reinforcement and shear span-to-overall depth ratio. Test results indicated that web reinforcement dose not affect on formation of inclined cracks but shear span-to-overall depth ratio affect on inclined shear cracks and ultimate shear strength. Addition of vertical web reinforcement improves ultimate shear strength of H.S.C. deep beams that shear span-to-overall depth ratio is 1.0. Considerable increase in ultimate shear strength of H.S.C. deep beams with increasing horizontal web reinforcement that shear span-to-overall depth ratio is 0.5. Especially with increasing concrete strength($f_{ck}$) the ACI code is conservative in estamating the ultimate shear strength of deep beams.

• 콘크리트학회논문집
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• 제16권6호
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• pp.795-803
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• 2004

현행 구조설계기준식에서는 취성적으로 파괴하는 최소전단보강철근 파괴를 방지하기 위하여 철근콘크리트 보에 최소전단보강철근을 배근하도록 규정하고 있다. 최소전단철근비는 콘크리트의 압축강도와 함께 주인장철근비와 전단경간비에 영향을 받는다. 이 연구에서는 주인장철근비와 전단경간비가 철근콘크리트 보의 최소전단철근비에 미치는 영향을 파악하기 위하여 14개의 철근콘크리트 보를 실험하였다. 실험에 의하면 전단 여유율은 주인장철근비가 증가할수록 증가하였고, 전단경간비가 증가할수록 감소하였다. 실험 결과는 ACI 318-02 기준식과 선행 연구의 제안식과 비교되었다.

• Structural Engineering and Mechanics
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• 제53권1호
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• pp.41-55
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• 2015

In this paper, a model for the evaluation of shear strength of fibre reinforced polymer (FRP)-reinforced concrete beams is given. The survey of literature indicates that the FRP reinforced beams tested with shear span to depth ratio less than or equal to 1.0 is limited. In this study, eight concrete beams reinforced with GFRP rebars without stirrups are cast and tested over shear span to depth ratio of 0.5 and 1.75. The concrete compressive strength is varied from 40.6 to 65.3 MPa. The longitudinal reinforcement ratio is varied from 1.16 to 1.75. The experimental shear strength and load-deflection response of the beams are determined and reported in this paper. A model is proposed for the prediction of shear strength of beams reinforced with FRP bars. The proposed model accounts for compressive strength of concrete, modulus of FRP rebar, longitudinal reinforcement ratio, shear span to depth ratio and size effect of beams. The shear strength of FRP reinforced concrete beams predicted using the proposed model is found to be in better agreement with the corresponding test data when compared with the shear strength predicted using the eleven models published in the literature. Design example of FRP reinforced concrete beam is also given in the appendix.

• 대한토목학회논문집
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• 제29권3A호
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• pp.259-266
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• 2009

본 연구에서는 전단보강이 없는 FRP 보강근을 사용한 콘크리트 보의 제작 및 파괴실험을 통하여 FRP bar와 철근의 탄성계수비, 휨보강근비 및 전단지간비의 영향을 동시에 고려하여 콘크리트 전단강도를 평가할 수 있는 수식을 제안하였다. 실험변수로서 2종류의 FRP bar, 3종류의 전단지간비 및 3종류의 휨보강근비를 사용하였으며, 총 36개의 FRP 보강근을 사용한 콘크리트 보를 제작하고 4점 휨 실험을 수행하였다. 전단지간비의 영향을 상세히 분석하기 위하여 앞서 연구된 2종류의 전단지간비에 대한 실험결과를 인용하였다. 실험자료들을 회귀분석하여 콘크리트 전단강도 계산에 필요한 전단강도보정계수를 구하는 수식을 제안하였다. 제안된 수식의 검증을 하기 위하여 여러 문헌으로부터 조사된 31개의 실험결과에 대하여 본 연구의 제안식과 다른 연구자들이 제안한 수식들을 함께 적용하여 비교 분석하였다. 그 결과, 본 연구에서 제안된 수식은 실험결과에 가장 근접하는 결과를 주는 것을 알 수 있었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.205-208
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• 2005

A single span-to-depth ratio function is proposed for control of deflection in one-way concrete construction. The equation can be applied to one-way slabs, beams, and flat plates. Effects of cracking, time-dependent deformation, boundary conditions, applied loading, and target deflection-to-span ratio are taken into account.

• Journal of the Korean Wood Science and Technology
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• 제43권2호
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• pp.177-185
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• 2015

The goal of this study is to evaluate the limitation of ASTM D 198 bending and ASTM D 3044 in determination of elastic modulus and shear modulus. Different material properties and span to depth ratios were used to analyze the effects of material property and testing conditions. The ratio of true elastic modulus to apparent elastic modulus evaluated from ASTM D 198 bending sharply decreased with increment of span to depth ratio. Shear modulus evaluated from ASTM D 198 bending decreased with increment of depth, whereas shear modulus evaluated from ASTM D 3044 was hardly influenced by increment of depth. Poisson's ratio influenced shear modulus from ASTM D 198 bending but did not influence shear modulus from ASTM D 3044. Different shearing factor was obtained for different depths of beams to correct shear modulus obtained from ASTM D 198 bending equivalent to shear modulus from theory of elasticity. Equivalent shear modulus of materials could be obtained by applying different shearing factors associated with beam depth for ASTM D 198 bending and correction factor for ASTM D 3044.

• International Journal of Concrete Structures and Materials
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• 제18권2E호
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• pp.111-116
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• 2006

The purpose of this study is to investigate the relations between unbonded tendon stress and its influential parameters, i.e. bonded reinforcement ratio, span/depth ratio, and loading type. To this end, the influence of such parameters was examined with twenty eight test results of previous studies. Afterwards, an experimental study was carried out with twenty one test specimens. The investigation of previous and current experiments revealed the followings; (1) The bonded reinforcement ratio and prestressing ratio were proved to be important variables on the unbonded tendon stress. (2) The ratio of span to depth and the type of loading affected the unbonded tendon stress partially although their effects varied with bonded reinforcement ratio. (3) AASHTO LRFD Code and Moon/Lim's design equations predicted the experimental results well with the safety margin.