• Journal of the Korea Concrete Institute
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• v.12 no.4
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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.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.293-298
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• 1995

The strength of shear connectors embedded in lightweight concrete slab with deck plate is influenced by various factors of deck plate, shear conncetor and concrete. Generally, it is reported that the strength of shear connector in lightweight concrete decreases in comparison with that in normal concrete. So this paper is to use compressive strength of lilghtweight concrete, width-height ratio of deck plate, and cross sectional area of shear conncetor as variables, to evaluate the strength of shear conncetors in composite beam of steel and lilghtweight concrete slabs with deck plate, and then to suggest the reasonable strength equation by comparing the push-out test results with establixhed strength formula. As the result of 24 specimens test, in case of lightweight concrete slab with deck plate, it has showed that in the same strength, the strength of shear connector decreased about 10~20% in comparison with that in normal concrete. In spite of lightweight concrete, the test results were closely approached the established strength formula of shear connector using Fisher's reduction coefficient.

• Proceedings of the Korea Concrete Institute Conference
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• 1990.04a
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• pp.51-56
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• 1990

Investigations on the behavior of steel fiber reinforced high strength concrete beams subjected to predominant shear are accomplished to determine their diagonal shear strength including ultimate shear strength. The parameters varied were the volume fraction(Vf) of the fibers, shear span depth ratio(a/d). The test result show that diagonal shear strength and ultimate shear strength are increased siginificantly due to crack arrest mechanism. Predictive equations are suggested for evaluating the diagonal cracking strength and ultimate shear strength of the fiber reinforced high strength concrete beams.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.220-225
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• 1993

This paper is an experimental study on shear capacity of the high strength lightweight reinforced concrete beams with shear-depth ratio between 1.5 and 2.5. Thirteen T & rectangular beams were tested to determine their diagonal cracking and ultimate shear capacity. The major variables are shear span-depth ratio (a/d=1.5, 2.0, 2.5), concrete compressive strength(f'c=210, 24., 270㎏/㎠) and tensile steel ratio( =0.6, 1.2%). Based on results obtained from experiment of high strength lightweight reinforced concrete Beam & normal concrete, the following conclusions were drawn. (1) The shear capacity of high-strength lightweight concrete is less 15% than that of normal concrete under same condition. (2) As the results of Comparing this experimental datas with other various formulas. It is regarded that ACI 318-89 shear strength formula related tensile strength is proper to design formula of shear strength of high-strength lightweight reinforced concrete using lightweight concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1990.10a
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• pp.83-87
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• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.925-930
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• 2003

Provisions for ACI 318-02 and NZS 3101 pertaining to shear design of shear walls evaluated the applicability of high-strength, concrete shear walls subjected to lateral loads. Results of 73 tests of reinforced concrete shear walls were reviewed. Evaluation of test results conducted in Korea, England, America, Japan, and Australia for low-aspect ratio walls indicates that the nominal unit shear strength($\phi$=1.0) calculated using the provisions of ACI and NZS does not represent the observed shear strength well. Based on the limited database considered in this study, a reasonable lower bound to the shear strength of high-strength concrete shear walls is found to be $\sqrt[0.4]{f_{cu}}$ MPa. Similar to that of normal strength concrete walls, the rate of increase of the measured shear strength with $$\rho$_n/ㆍf_y$ is less than 1.0. Therefore, the rate of increase of shear strength attributable to the web reinforcement in shear walls appears to be overestimated by the modified truss analogy.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.356-361
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• 1994

From the previous experimental test results, it has shown that shear that shear strength in lightweight concrete beams was about 85% on that in normal concrete beams. It is speculated that shear connectors in composite beams of steel and lightweight concrete associated with the longitudinal shear strength decrease more in strength than those in normal concrete. So this paper, as a study on strength of shear connectors in composite beams of steel and lightweight concrete slabs, has a purpose to compare the strength formula resulted from the push-out test of thirteen solid slab and four deck Plate slab with the established ones, and then to suggest a proper strength formula of the shear connectors. The established strength formula of the shear connectors is prescribed for $P_ps = 0.50A_s . \sqrt{f_C . E_C}$by AISC coed, but from the experimental test results the strength values of the shear connectors in lightweignt concrete slabs shows about 70% on those of the shear connectors in normal concrete slabs by AISC code. Therefore, as a strength formula this paper suggests to multiply the established strength formula by reduction factor$(\varphi=0.7)$.

• Structural Engineering and Mechanics
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• v.41 no.3
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• pp.407-420
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• 2012

This study investigated possible ways to replace conventional stirrups used on high-strength concrete members with improved reinforcing materials. Headed bar and high-strength steel were chosen to substitute for conventional stirrups, and an experimental comparison between the shear behavior of high-strength concrete large beams reinforced with conventional stirrups and the chosen stirrup substitutes was made. Test results indicated that the headed bar and the high-strength steel led to a significant reserve of shear strength and a good redistribution of shear between stirrups after shear cracking. This is due to the headed bar providing excellent end anchorage and the high-strength steel successfully resisting higher and sudden shear transmission from the concrete to the shear reinforcement. Experimental results presented in this paper were also compared with various prediction models for shear strength of concrete members.

• Structural Engineering and Mechanics
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• v.53 no.1
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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.

• Structural Engineering and Mechanics
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• v.33 no.3
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• pp.357-371
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• 2009

Test results of thirteen reinforced concrete corbels with shear span-to-depth ratio greater than unity are reported. The main variables studied were compressive strength of concrete, shear span-to-depth ratio and parameter of vertical stirrups. The test results indicate that the shear strengths of corbels increase with an increase in compressive strength of concrete and parameter of vertical stirrups. The shear strengths of corbels also increase with a decrease in shear span-to-depth ratio. The smaller the shear span-to-depth ratio of corbel, the larger the stiffness and the shear strength of corbel are. The higher the concrete strength of corbel, the higher the stiffness and the shear strength of corbel are. The larger the parameter of vertical stirrups, the larger the stiffness and the shear strength of corbel are. The softened strut-and-tie model for determining the shear strengths of reinforced concrete corbels is modified appropriately in this paper. The shear strengths predicted by the proposed model and the approach of ACI Code are compared with available test results. The comparison shows that the proposed model can predict more accurately the shear strengths of reinforced concrete corbels than the approach of ACI Code.