Analysis of the crack development and shear transfer mechanisms of reinforced concrete beams with low amounts of shear reinforcement

2020 ◽  
Vol 222 ◽  
pp. 111114
Author(s):  
Nguyen Duc Tung ◽  
Christoph Betschoga ◽  
Nguyen Viet Tue
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Crack Development ◽  
Reinforced Concrete Beams ◽  
Shear Reinforcement ◽  
Shear Transfer ◽  
Transfer Mechanisms

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 Experimental Evaluation on Components of Shear resistance of Reinforced Concrete Beams with Shear Reinforcement Provided

2021 ◽  
Author(s):  
Sreenivasa Prasad Joshi ◽  
Poluraju P
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Shear Resistance ◽  
Transfer Mechanism ◽  
Reinforced Concrete Beams ◽  
Structural Behavior ◽  
Compression Zone ◽  
Shear Reinforcement ◽  
Shear Transfer ◽  
Aggregate Interlocking

Abstract The contribution of aggregate interlocking and dowel force in shear strength of reinforced concrete beams was topic of research for many years. The precise forecasts of shear behavior were challenging to determine due to complication involved. The existing theories had focused on aggregate interlocking force and shear resistance arising due to concrete compression zone, neglecting the contribution of dowel force despite considering as significant constituent in shear transfer mechanism. The present investigation focuses on cogitating all components in shear transfer mechanism by providing shear reinforcement and keeping clear cover and effective span to depth ratio constant. Sixteen specimens were considered for parametric study by employing suitable variables such as increase in strength of concrete and variation in flexural reinforcement. Eight specimens were conventional beams and the remaining eight specimens were provided with preformed cracks. Moment vs. displacement curvature and strain vs. moment curvature were plotted to evaluate shear at uncracked compression zone and accordingly aggregate interlocking force and dowel force were determined based on the empirical formulas proposed. From the result it was confirmed that contribution of aggregate interlocking force and dowel force were insignificant and shear resistance due to uncracked compression zone is the sole contributor in shear transfer mechanism. Structural behavior of concrete beams was also studied and it was confirmed that beams with preformed cracks exhibited better structural behavior when related to conventional beams.

scholarly journals Shear resistance of welded inclined bars in rectangular reinforced concrete beams

2018 ◽  
Vol 250 ◽  
pp. 03003
Author(s):  
Noor Suhaida Galip ◽  
Roslli Noor Mohamed ◽  
Ramli Abdullah
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Concrete Beams ◽  
Shear Resistance ◽  
Reinforced Concrete Beams ◽  
Shear Reinforcement ◽  
Shear Forces ◽  
Distance Ratio ◽  
Effective System ◽  
Horizontal Portion

The bent-up bars have not been used as shear reinforcement in beams since the past 40 years or so. In all cases of design and construction nowadays, shear forces are resisted by vertical links only. Some complications in installing the multiple set of bent-up bars, the less opportunity to have sufficient number of bent-up bars due to small number of flexural reinforcement provided at the mid-span of the beams and also the large anchorage required for the horizontal portion of the bars beyond the upper end of the bend could be the reasons behind this. This paper presents the results of tests on five rectangular reinforced concrete beams in which the effectiveness of welded inclined bars (WIB) as shear reinforcement was studied. Two of the beams were controlled specimens, with no shear reinforcement in one, and full design vertical links in another. The other three beams were provided with three different quantities of WIB, measured in terms of area to distance ratio, Asw / S as shear reinforcement in the shear spans. All beams were tested to failure under two point loads with a shear span to effective depth ratio of 2.34, which would ensure that the failure was due to shear unless their shear capacities were larger than the flexural capacity. The performances of the beams were measured in terms of deflection, crack formation, strains in WIB and on the concrete surfaces in the shear region, ultimate loads and failure modes. The results show that WIB alone is capable of carrying the whole shear forces in the beam, and larger shear capacities are achieved with a larger quantity of WIB, and a higher grade of the bars used. The beam with WIB requires 22% less in the quantity of Asw / S compared to that with vertical links to achieve the same shear resistance. These suggest that WIB can be used as an effective system of shear reinforcement in beams.

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