scholarly journals The Influence of Concrete Strength on Shear Capacity of Reinforced Concrete Members without Shear Reinforcement

2013 ◽  
Vol 12 (1) ◽  
pp. 151-158
Author(s):  
Marta Słowik
Keyword(s):  
Reinforced Concrete ◽  
Concrete Strength ◽  
Shear Capacity ◽  
Shear Reinforcement ◽  
Professional Literature ◽  
Standard Methods ◽  
Model Code ◽  
Concrete Members ◽  
Eurocode 2 ◽  
Model Code 2010

In the paper, dimensioning rules for shear capacity in reinforced concrete members without shear reinforcement given in Eurocode 2, ACI Standard 318 and Model Code 2010 are described. The fib Model Code recommendations are described in more detailed way as they are based on a new concept. The shear strength calculated on the basis of the mentioned codes is later compared to the results of test from professional literature in order to verify standard methods and to analyze the influence of concrete strength on shear capacity in beams without stirrups.

scholarly journals The influence of longitudinal reinforcement on shear capacity of reinforced concrete members without shear reinforcement

2014 ◽  
Vol 13 (3) ◽  
pp. 151-158
Author(s):  
Marta Słowik
Keyword(s):  
Reinforced Concrete ◽  
Shear Capacity ◽  
Longitudinal Reinforcement ◽  
Test Results ◽  
Shear Reinforcement ◽  
Professional Literature ◽  
Model Code ◽  
Concrete Members ◽  
Eurocode 2 ◽  
Model Code 2010

In the paper, the influence of longitudinal reinforcement on shear capacity of reinforced concrete members without shear reinforcement is discussed. The problem is analyzed on the basis of the author’s own test results and tests results reported in the professional literature. It has been concluded that longitudinal reinforcement has an effect on shear capacity especially in members of shear span-to-depth ratio a/d < 2,5. The test results have also been used to verify standard methods of calculating the shear capacity in reinforced concrete members without shear reinforcement given in Eurocode 2, ACI Standard 318 and Model Code 2010.

scholarly journals Punching strength of reinforced concrete flat slabs without shear reinforcement

2012 ◽  
Vol 5 (5) ◽  
pp. 659-691 ◽  
Author(s):  
P. V. P. Sacramento ◽  
M. P. Ferreira ◽  
D. R. C. Oliveira ◽  
G. S. S. A. Melo
Keyword(s):  
Reinforced Concrete ◽  
Shear Crack ◽  
Theoretical Method ◽  
Shear Reinforcement ◽  
Model Code ◽  
Flat Slabs ◽  
Codes Of Practice ◽  
Eurocode 2 ◽  
Model Code 2010 ◽  
Theoretical Results

Punching strength is a critical point in the design of flat slabs and due to the lack of a theoretical method capable of explaining this phenomenon, empirical formulations presented by codes of practice are still the most used method to check the bearing capacity of slab-column connections. This paper discusses relevant aspects of the development of flat slabs, the factors that influence the punching resistance of slabs without shear reinforcement and makes comparisons between the experimental results organized in a database with 74 slabs carefully selected with theoretical results using the recommendations of ACI 318, EUROCODE 2 and NBR 6118 and also through the Critical Shear Crack Theory, presented by Muttoni (2008) and incorporated the new fib Model Code (2010).

scholarly journals Theoretical prediction of punching shear capacity of flat slabs without shear reinforcement strengthened by concrete topping

2021 ◽  
Vol 1203 (2) ◽  
pp. 022108
Author(s):  
Daniel Čereš ◽  
Katarína Gajdošová
Keyword(s):  
Shear Resistance ◽  
Design Guidelines ◽  
Shear Capacity ◽  
Reinforcement Ratio ◽  
Punching Shear ◽  
Shear Reinforcement ◽  
Model Code ◽  
Flat Slabs ◽  
Eurocode 2 ◽  
Model Code 2010

Abstract The main reasons for strengthening flat slabs are the change of the use of a building, increase in the value of loads, degradation of the concrete cover layer, or insufficient reinforcement. This paper is focused on the assessment of punching shear capacity of the strengthened flat slabs without shear reinforcement. One of the possibilities how to enhance punching shear capacity is the addition of reinforced concrete topping. The main goal of this paper is to compare the possibilities for calculation of the increase in the punching shear capacity by investigation of the influence of different thicknesses of concrete toppings and different reinforcement ratio. A reference specimen is represented by a fragment of a flat slab with the thickness of h = 200 mm supported by circular column with the diameter of 250 mm. Three different thicknesses (50 mm, 100 mm, 150 mm) of concrete toppings were considered together with three different reinforcement ratios for each thickness of concrete overlay. Theoretical predictions of the punching shear resistance of flat slabs were evaluated by design guidelines according to the relevant standards: Eurocode 2 (EN 1992-1-1), Model Code 2010 and draft of the second generation of Eurocode 2 (prEN 1992-1-1). The differences in the influence of reinforcement ratio are significant. In Model Code 2010 the reinforcement ratio in concrete topping was considered in equation of moment of resistance. This is unlike in both of the mentioned Eurocodes, where the reinforcement ratio was assumed as a geometric average value of the original reinforcement ratio in the slab before strengthening and of the reinforcement ratio of concrete topping. All the predicted theoretical calculations are based on the perfect connection and bond between the original and new layer of concrete. These predictions should be verified by experimental investigation, which is going to be prepared shortly. By the additional increase in the thickness of concrete topping or in the amount of added reinforcement the attention should be payed to the limitation of the punching shear resistance by the value of the maximum punching shear resistance in the compression concrete strut.

scholarly journals Shear behavior of reinforced concrete wide beams strengthened with CFRP sheet without stirrups

2019 ◽  
Vol 12 (1) ◽  
pp. 80-98
Author(s):  
Ali Laftah Abass
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Load ◽  
Concrete Strength ◽  
Shear Behavior ◽  
Shear Capacity ◽  
Rc Beams ◽  
Shear Reinforcement ◽  
Control Beam ◽  
Cfrp Sheet ◽  
Wide Beams

Reinforced concrete wide beams (WBS) have been used in construction buildings because its provide many advantages; reducing the reinforcement congestion, reducing the quantity of the required formwork, providing simplicity for replication, and decreasing the storey height. The current study presents the results of four full-scale wide RC beams in order to study their shear behavior and investigate the effectiveness of carbon fiber reinforced polymer (CFRP) when using as shear reinforcement to improve the shear capacity of wide RC beams, one these beams was fabricated by (ANSYS) program this beam was unstrengthened with CFRP and without stirrups (control beam), the other two beams was strengthened with vertical and inclined CFRP sheet without stirrups and the last beam reinforced with shear stirrups (WBS). All beams casted with normal concrete strength (30 MPa), simply supported and under two point loads. The performances of these beams were measured in terms of; ultimate load, crack patterns, concrete and steel strains, deflection, and mode of failure. The results showed an increasing in ultimate load of strengthened beams with inclined, vertical CFRP and beam with shear reinforcement by (19.9%), (7.14%) and (39.8%) respectively as compared with the control beam, and this results means possibility of replacing the internal shear reinforcement with externally bonded CFRP.

scholarly journals Reliability-based assessment of the partial factor for shear design of fibre reinforced concrete members without shear reinforcement

2021 ◽  
Vol 54 (5) ◽  
Author(s):  
Jesús Miguel Bairán ◽  
Nikola Tošić ◽  
Albert de la Fuente
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Shear Resistance ◽  
Fibre Reinforced Concrete ◽  
Shear Reinforcement ◽  
Model Code ◽  
Shear Design ◽  
Model Code 2010 ◽  
Partial Factor ◽  
Failure Probabilities

AbstractFibre reinforced concrete (FRC) is increasingly used for structural purposes owing to its many benefits, especially in terms of improved overall sustainability of FRC structures relative to traditional reinforced concrete (RC). Such increased structural use of FRC requires safe and reliable models for its design in ultimate limit states (ULS). Particularly important are models for shear strength of FRC members without shear resistance due to the potential of brittle failure. The fib Model Code 2010 contains a model for the shear strength of FRC members without shear reinforcement and the same partial factor accepted for RC structures is accepted for FRC elements. This approach, however, is potentially on the unsafe side since the uncertainties of some design-determining mechanical properties of FRC (i.e., residual flexural strength) are larger than those for RC. Therefore, in this study, a comprehensive reliability-based calibration of the partial factor γc for the shear design of FRC members without shear reinforcement according to the fib Model Code 2010 model is performed. As a first step, the model error δ is assessed on 332 experimental results. Then, a parametric analysis of 700 cases is performed and a relationship between the target failure probability βR and γc is established. The results demonstrate that the current model together with the prescribed value of γc = 1.50 does not comply with the failure probabilities accepted for the different consequences of failure of FRC members over a 50-year service life. Therefore, changes to the shear resistance model are proposed in order to achieve the target failure probabilities.

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 ON SHEAR REINFORCEMENT DESIGN OF STRUCTURAL CONCRETE BEAMS ON THE BASIS OF THEORY OF PLASTICITY

2009 ◽  
Vol 15 (4) ◽  
pp. 395-403 ◽  
Author(s):  
Bjarne Christian Jensen ◽  
Andrzej Lapko
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Concrete Strength ◽  
Structural Members ◽  
Shear Reinforcement ◽  
Reinforcing Bars ◽  
Shear Design ◽  
Theory Of Plasticity ◽  
Eurocode 2 ◽  
Reinforcement Design

Modern design of reinforced concrete structural members for shear is based on the theory of plasticity. This paper is written to contribute to the understanding of the inclination of the concrete strut in the inclined strut model for design of shear reinforcement in beams, which among others are used in Eurocode 2. The problem of inclination of the compression strut in truss model is analysed depending on shear reinforcement ratio and effectiveness ratio of concrete strength for compression. Also the understanding of necessary ductility in steel reinforcing bars is discussed in the paper and especially the needs of tests on translation capacity of the shear failure are here analysed. To explain these problems the paper gives a short introduction to the theory of plasticity of reinforced concrete in shear and the background for the equations, which are used in shear design according to Eurocode 2. Santrauka Šiuolaikinis gelžbetonio elementų skersinės armatūros skaičiavimas pagrįstas plastiškumo teorijos principais. Straipsnyje pateikti sijų skersinės armatūros skaičiavimo ypatumai, taikant įstrižojo statramsčio modelį, kuris taikomas ir Eurokode 2. Išnagrinėtas gniuždomojo strypo pavertimas santvaros modelyje, atsižvelgiant į skersinės armatūros ir efektyvaus gniuždomojo betono stiprio santykį. Aptartas armatūrinio plieno strypų stamantrumas, akcentuota sijų laikomosios galios šlyčiai eksperimentinių tyrimų būtinybė. Pateiktas gelžbetoninių sijų šlyties skaičiavimas, taikant plastiškumo teorijos principus. Aptartas Eurokode 2 šlyties skaičiavimams taikomų priklausomybių teorinis pagrindas.

scholarly journals Shear Capacity and Behaviour of Bending Reinforced Concrete Beams Made of Steel Fibre-Reinforced Waste Sand Concrete

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2996
Author(s):  
Marek Lehmann ◽  
Wiesława Głodkowska
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Fibre Composite ◽  
Shear Capacity ◽  
Reinforced Concrete Beams ◽  
Fine Aggregate ◽  
Steel Fibres ◽  
Ordinary Concrete ◽  
Model Code ◽  
Model Code 2010

Inthis paper, we report the results of our research on reinforced concrete beams made of fine aggregate fibre composite, with the addition of steel fibres at 1.2% of the composite volume. The fine aggregate fibre composite is a novel construction material, in which the aggregate used is a post-production waste. Twenty reinforced concrete beams with varying degree of shear reinforcement, in the form of stirrups with and without the addition of steel fibres, tested under loading. The shear capacity results of reinforced concrete beams made of the fine aggregate fibre composite being bent by a transversal force, as well as the cracking forces causing the appearance of the first diagonal crack, are discussed. The stages of functioning of such elements are described. Furthermore, the effect of the steel fibres on the reduction of diagonal cracking is analysed. Computation of the shear capacity of the tested elements is performed, based on the Model Code 2010 and RILEM TC-162 TDF standards, for two variants of the compression strut inclination angle θ that measured during testing, and the minimum(in accordance with the Model Code 2010 standard). We found that the SMCFT method part of Model Code 2010 showed the best compatibility with the experimental results. The tests and analyses performed demonstrate that the developed novel fibrecomposite—the properties of which are close to, or better than, those of the ordinary concrete—can be used successfully for the manufacturing of construction elements in the shear capacity aspect. The developed fine aggregate fibrecomposite could serve, in some applications, as an alternative to ordinary concrete.

scholarly journals Strengthening flat slabs without shear reinforcement against punching shear by concrete overlay

2021 ◽  
Vol 1209 (1) ◽  
pp. 012056
Author(s):  
D Čereš ◽  
K Gajdošová
Keyword(s):  
Parametric Study ◽  
Shear Crack ◽  
Shear Resistance ◽  
Shear Capacity ◽  
Reinforcement Ratio ◽  
Punching Shear ◽  
Flat Slab ◽  
Model Code ◽  
Eurocode 2 ◽  
Model Code 2010

Abstract Research in this paper presents a theoretical study of increasing in punching shear capacity of the strengthened flat slab by concrete overlay. The parametric study is based on comparison of three different relevant standards design models and presents results how Eurocode 2 (EN 1992-1-1), Model Code 2010 and draft of second generation of Eurocode 2 (prEN 1992-1-1) take into account strengthening by concrete overlay. A reference specimen is represented by a fragment of a flat slab supported by circular column. Influence of concrete toppings depends on thickness and also on reinforcement ratio. In Eurocode 2 and new generation of Eurocode 2 the increase of punching shear resistance of the slab with concrete topping can be taken into account only by reinforcement ratio and thickness of the slab considering the perfect connection and bond between the original slab and new layer of concrete overlay. Model Code 2010 is based on Critical shear crack theory and the reinforcement ratio in concrete topping was considered in equation of moment of resistance and punching shear resistance is calculated by considering the rotation and deformation of the slab. Estimation of results by parametric study are compared by non-linear model from Atena software.

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