Reinforced concrete beams without stirrups considering shear friction and fracture mechanics

2006 ◽  
Vol 33 (2) ◽  
pp. 161-168 ◽  
Author(s):  
M T Kazemi ◽  
V Broujerdian
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Fracture Mechanics ◽  
Shear Failure ◽  
Concrete Beams ◽  
Concrete Strength ◽  
Shear Capacity ◽  
Reinforced Concrete Beams ◽  
Maximum Aggregate Size ◽  
Aggregate Interlock

A new expression for the shear capacity of reinforced concrete beams without stirrups was derived by calculating the aggregate interlock capacity across the major diagonal crack of the beam, a procedure somewhat similar to those based on the modified compression field theory. Two formulas were obtained from the simplification of this expression. All three relations capture the dependence of shear strength on the size of the beam, the ratio of shear span to beam depth, longitudinal reinforcement ratio, maximum aggregate size, and concrete strength. The limits of these formulas agree well with the limit solutions of shear failure load for very small and very large beams based on plastic and fracture mechanics solutions, respectively. The proposed relations were calibrated by least-squares fitting of the existing experimental database (consisting of 398 data points) and resulted in low coefficients of variation. The simplest version is suitable for design codes.Key words: reinforced concrete, shear strength, beams, aggregate interlock, crack opening, size effect.

A Comparative Study of the Shear Strength Prediction for Reinforced Concrete Beams without Shear Reinforcement

2014 ◽  
Vol 584-586 ◽  
pp. 1135-1140
Author(s):  
Leandro Mouta Trautwein ◽  
Luiz Carlos de Almeida ◽  
Ricardo Gaspar
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Concrete Strength ◽  
Shear Capacity ◽  
Reinforced Concrete Beams ◽  
Strength Prediction ◽  
Beam Depth ◽  
Web Reinforcement ◽  
Concrete Elements

This paper focuses on the assessment of the shear strength prediction established in the brazilian concrete code, NBR6118/2007[1], for reinforced concrete beams without web reinforcement. The values obtained by using the brazilian code equation are compared with a significant number of available experimental data and with those predicted by the expressions of other national and international codes, such as CEB-FIP MC90[2] and ACI-318/11[3]. The brazilian concrete code regarding shear capacity of reinforced concrete elements are explicitly assumed to be valid only for concrete strengths up to 50 MPa. It is shown that the code equation may be unconservative in a large number of cases. This discrepancy increases with increasing concrete strength, decreasing longitudinal reinforcement ratio and increasing beam depth.

scholarly journals Influence of Steel Fiber on the Shear Strength of a Concrete Beam

2018 ◽  
Vol 4 (7) ◽  
pp. 1501 ◽  
Author(s):  
Ali Ammar Hameed ◽  
Mohannad Husain Al-Sherrawi
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Concrete Beam ◽  
Shear Failure ◽  
Steel Fiber ◽  
Concrete Beams ◽  
Shear Capacity ◽  
Steel Fibers ◽  
Reinforced Concrete Beams ◽  
Shear Reinforcement

The shear failure in a concrete beam is a brittle type of failure. The addition of steel fibers in a plain concrete mix helps to bridge and restrict the cracks formed in the brittle concrete under applied loads, and enhances the ductility of the concrete. In this research an attempt was made to investigate the behavior and the ultimate shear strength of hooked end steel fiber reinforced concrete beams without traditional shear reinforcement. Four simply-supported reinforced concrete beams with a shear span-to-depth ratio of about 3.0 were tested under two-point loading up to failure. Steel fibers volumetric fractions that used were 0.0, 0.5, 0.75 and 1.0%. Test results indicated that using 1.0% volume fraction of hooked steel fiber led to exclude shear failure and enhanced the use of steel fibers as shear reinforcement in concrete beams. The results also showed that a concrete beam with hooked steel fiber provided higher post-flexural-cracking stiffness, an increase in the shear capacity and energy absorption and an increase in the maximum concrete and steel reinforcement strains.

scholarly journals Shear behavior degradation and failure pattern of reinforced concrete beam with chloride-induced stirrup corrosion

2019 ◽  
Vol 22 (14) ◽  
pp. 2998-3010 ◽  
Author(s):  
Zhao-Hui Lu ◽  
Hai Li ◽  
Wengui Li ◽  
Yan-Gang Zhao ◽  
Zhuo Tang ◽  
...  
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Concrete Strength ◽  
Shear Behavior ◽  
Reinforced Concrete Beams ◽  
Failure Pattern ◽  
Reinforcement Corrosion ◽  
Shear Span ◽  
Depth Ratio

Reinforcement corrosion exhibits an adverse effect on the shear strength of reinforced concrete structures. In order to investigate the effects of chloride-induced corrosion of reinforcing steel on the shear behavior and failure pattern of reinforced concrete beams, a total of 24 reinforced concrete beams with different concrete strength grades and arrangements of stirrups were fabricated, among which 22 beams were subjected to accelerated corrosion to achieve different degrees of reinforcement corrosion. The failure pattern, crack propagation, load–displacement response, and ultimate strength of these beams were investigated under a standard four-point loading test in this study. Extensive comparative analysis was conducted to investigate the effects of the concrete strength, shear span-to-depth ratio, and stirrup type on the shear behavior of the corroded reinforced concrete beams. The results show that increasing the stirrup yielding strength is more effective in improving the shear strength of corroded reinforced concrete beams than that of concrete compressive strength. In terms of three types of stirrups, the shear strength of the beams with deformed HRB-335 is least sensitive to stirrup corrosion, followed by the beams with smooth HPB-235 and the beams with deformed HRB-400. The effect of the different stirrups on the shear strength depends on the corrosion degree of stirrup and shear span-to-depth ratio of the beam. The predicted results of shear strength of corroded reinforced concrete beams by a proposed analytical model are well consistent with the experimental results.

Implication of Unbondedness in Reinforced Concrete Beams

2012 ◽  
Vol 587 ◽  
pp. 36-41 ◽  
Author(s):  
S.F.A. Rafeeqi ◽  
S.U. Khan ◽  
N.S. Zafar ◽  
T. Ayub
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Failure Mode ◽  
Shear Failure ◽  
Concrete Beams ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Flexural Capacity ◽  
Flexural Reinforcement

In this paper, behaviour of nine (09) RC beams (including two control beams) after unbonding and exposing flexural reinforcement has been studied which were intentionally designed and detailed to observe flexural and shear failure. Beams have been divided into three groups based on failure mode and unbounded and exposed reinforcement. Beams have been tested under two-point loading up to failure. Experimental results are compared in terms of beam behaviour with respect to flexural capacity and failure mode which revealed that the exposed reinforcement does not altered flexural capacity significantly and unbondedness positively influences shear strength; however, serviceability performance of beams with unbonded and exposed reinforcement is less.

scholarly journals Shear Performance of Reinforced Concrete Beams Affected by Satisfactory Composite-Recycled Aggregates

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1711
Author(s):  
Changyong Li ◽  
Na Liang ◽  
Minglei Zhao ◽  
Kunqi Yao ◽  
Jie Li ◽  
...  
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Shear Crack ◽  
Shear Capacity ◽  
Reinforced Concrete Beams ◽  
Recycled Aggregates ◽  
Shear Span ◽  
Model Code ◽  
Model Code 2010

This paper is the outcome of experiments on the shear performance of reinforced concrete beams with approved composite-recycled aggregates. The strength grade of composite-recycled aggregate concrete (CRAC) was between 30 MPa and 60 MPa. The shear span-to-depth ratio varied from 1 to 3. The adaptability of HRB400 rebar, with critical yield strength of 400 MPa, used as stirrups was also verified. As the composite technology overcame the shortcomings of recycled coarse aggregate, CRAC had similar mechanical properties with those of conventional concrete. Details on the shear behaviors of test beams under a four-point loading test are presented. The results indicated that the changes of CRAC strain, stirrup strain, and shear-crack width depended on the failure patterns, which are controlled by the shear-span to depth ratio. The stirrups yield at the failure of reinforced CRAC beams. The shear cracking resistance and the shear capacity of reinforced CRAC beams can be predicted by the statistical equations. Based on the design codes GB50010, ACI318-19, Model Code 2010 and DIN-1045-1-2008 for conventional reinforced concrete beams, the shear strengths provided by CRAC and stirrups are statistical analyzed. The rationality of the design equations is examined by the utilization level of shear strength provided by CRAC. The maximum shear-crack widths are extracted from the test data of reinforced CRAC beams at normal service state. Comparatively, by specifying the lower limit of shear strength provided by the CRAC with various shear-span to depth ratios, China code GB50010 gives a rational method for utilizing CRAC. Under the premise that the design of shear capacity would give considerations to meet the normal serviceability, the factored strength of HRB400 rebar should be 360 MPa for the calculation of shear strength provided by stirrups. The design methods in codes of GB50010, ACI318-19 and Model Code 2010 are conservative for the shear capacity of reinforced CRAC beams.

scholarly journals Influence of coarse aggregate on the shear strength of reinforced concrete beams

2020 ◽  
Author(s):  
◽  
Hoosen Ahmed Jajbhay
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Concrete Beam ◽  
Coarse Aggregate ◽  
Concrete Beams ◽  
Shear Capacity ◽  
Reinforced Concrete Beams ◽  
Shear Reinforcement ◽  
Shear Transfer ◽  
Coarse Aggregates

Research to accurately predict the shear capacity of reinforced concrete beams without shear reinforcement has been ongoing since the early 20th century. Aggregate interlock of the coarse aggregates at the shear crack interface is one of the internal mechanisms of shear transfer and a major contributor to the shear capacity of slender beams. It is plausible, therefore, to investigate if the coarse aggregate itself influences the shear capacity of a concrete beam. The influence of the type of coarse aggregate on the shear capacity of beams without shear reinforcement was investigated in this study. From the literature study an understanding of the properties of coarse aggregates was gained, the internal mechanisms of shear transfer in reinforced concrete beams without shear reinforcement were determined, and the parameters influencing shear strength were identified. Based on this information an experimental program was designed. Eighteen reinforced concrete beams without shear reinforcement were cast. The beams were cast from three different types of coarse aggregates commonly used in the Durban area, i.e., dolerite, quartzite and tillite. For each type of coarse aggregate two variations were tested, i.e., 13 mm and 19 mm maximum aggregate sizes. For each size of coarse aggregate, three concrete strengths were tested. The beams were loaded in a beam press, by applying an increasing point load offset from midspan to induce cracking on the shorter side, until shear failure of the beam occurred. For the three concrete strengths, beams cast from dolerite had the highest shear capacity while beams cast from tillite had less shear capacity than beams cast from quartzite coarse aggregate. Furthermore, beams cast from 13 mm maximum size coarse aggregate had higher shear capacity than beams cast from 19 mm aggregate. The conclusion may be drawn that the type and size of coarse aggregate does influence the shear strength of a reinforced concrete beam without shear reinforcement.

scholarly journals Modelling of Shear Strength for Reinforced Concrete Beams Provided with Side-Face Reinforcement in Dependence of Crack Inclination Angle

2019 ◽  
Vol 8 (6) ◽  
pp. 3941-3950
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Inclination Angle ◽  
Concrete Beams ◽  
Concrete Strength ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Shear Design ◽  
Web Reinforcement ◽  
Side Face

Shear behavior of reinforced concrete beams (RCbeams) is proved to be influenced by different parameters such as web reinforcement, beam size, shear span-to-depth ratio, concrete strength, and longitudinal reinforcement. In addition to these parameters, researches acknowledge the significant contribution of side-face reinforcement (SFR) in shear strength of RC-beams. This paper aims at proposing a new model for predicting shear strength of RC-beams that accounts for the contribution of SFR in shear strength along with the other above-mentioned parameters. An explicit formula is derived based on a mechanical conceptual model that considers the variation of the inclination angle of diagonal shear cracking. The derived formula is verified on the basis of numerical analysis results in addition to the available results from relevant experimental researches in literature. Reliability of the proposed formula is investigated compared to design provisions in different codes. Results demonstrates that the proposed formula is more capable of predicting shear strength of RC-beams provided with SFR rather than shear design codes. Consistency of the proposed formula in predicting shear strength implies that the mechanical concept, on which the proposed formula is derived, is in consistent with the actual mechanical behavior.

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