Comparison and Review of Concrete-to-Concrete Interface Shear Resistance According to Major Design Codes

2016 ◽  
Vol 249 ◽  
pp. 166-172
Author(s):  
Đorđe Čairović ◽  
František Girgle ◽  
Vojtěch Kostiha ◽  
Jaroslav Kadlec ◽  
Petr Stepanek
Keyword(s):  
Cross Section ◽  
Shear Test ◽  
Shear Resistance ◽  
Design Codes ◽  
Adhesive Failure ◽  
Type Specimens ◽  
Interface Shear ◽  
Model Code ◽  
Model Code 2010 ◽  
Slant Shear

The paper focuses on interface shear behavior, more precisely on shear resistance of the interface between lightweight and regular concrete layers cast at different times without shear reinforcement crossing the interface. Different approaches according to most of major design codes (Eurocode, ACI and Model Code 2010 among other) are briefly reviewed, with emphasis on difference between variables resp. material and cross-section characteristics, on which interface resistance depends. Furthermore, two sets of experiments were carried out: direct shear test on Z-type specimens and slant shear test slightly modified to enforce adhesive failure. Obtained results are compared with theoretical values.

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 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 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.

scholarly journals Uncertainty in Shear Resistance of Reinforced Concrete Beams With Stirrups – Comparison of EN 1992-1-1 and fib Mc 2010 Approaches

2014 ◽  
Vol 14 (1) ◽  
pp. 48-56 ◽  
Author(s):  
Jan Krejsa ◽  
Milan Holicky ◽  
Miroslav Sykora
Keyword(s):  
Reinforced Concrete ◽  
Model Uncertainty ◽  
Concrete Beams ◽  
Shear Resistance ◽  
Reinforced Concrete Beams ◽  
Test Results ◽  
Model Code ◽  
Probabilistic Description ◽  
Model Code 2010 ◽  
The Mean

Abstract The submitted contribution is focused on the model uncertainty related to shear resistance of reinforced concrete beams with stirrups. Using available test results, effects of basic variables on the model uncertainty are analysed. Considering the section-oriented models provided in EN 1992-1-1 and in the new fib Model Code 2010 are critically compared. Proposed probabilistic description of the model uncertainty consists of the lognormal distribution having the mean and coefficient of variation dependent on the considered model. Strength of shear reinforcement seems to be the most important basic variable for most of the considered models.

scholarly journals Analysis of the Shear Resistance in the Indented Interface Between Two Concrete Parts of Concrete Composite Beam

2021 ◽  
Vol 31 (1) ◽  
pp. 93-105
Author(s):  
Grzegorz Sadowski ◽  
Piotr Wiliński ◽  
Anna Halicka
Keyword(s):  
Composite Beam ◽  
Correlation Method ◽  
Shear Resistance ◽  
Image Correlation ◽  
Actual Behavior ◽  
Construction Joint ◽  
Model Code ◽  
Eurocode 2 ◽  
Model Code 2010 ◽  
Calculation Results

Abstract This paper presents a comparative analysis of shear resistance in the interface between two concrete parts of concrete composite beam. The construction joint was performed as indented one in accordance with Eurocode 2 and fib Model Code 2010. The numerical calculation results were confronted with the actual results of tests of a composite beam subjected to 4-point bending. The displacement values of tested element were obtained using dial sensors and the digital image correlation method (DIC). The analysis shows that the recommendations of Eurocode 2-1-1 and fib Model Code 2010 do not reflect the actual behavior of concrete composite beam with indented surface.

A modified slant shear test designed to enforce adhesive failure

2013 ◽  
Vol 41 ◽  
pp. 673-680 ◽  
Author(s):  
Rui Saldanha ◽  
Eduardo Júlio ◽  
Daniel Dias-da-Costa ◽  
Pedro Santos
Keyword(s):  
Shear Test ◽  
Adhesive Failure ◽  
Slant Shear

fib Bulletin 65. Model code 2010 Volume 1

2012 ◽  
Author(s):  
Walraven ◽  
Bigaj-van Vliet ◽  
Balazs ◽  
Cairns ◽  
Cervenka ◽  
...  
Keyword(s):  
Model Code ◽  
Model Code 2010

scholarly journals Modeling of Drag Finishing—Influence of Abrasive Media Shape

2021 ◽  
Vol 5 (2) ◽  
pp. 41
Author(s):  
Irati Malkorra ◽  
Hanène Souli ◽  
Ferdinando Salvatore ◽  
Pedro Arrazola ◽  
Joel Rech ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Material Removal ◽  
Direct Shear Test ◽  
Shear Test ◽  
Shear Resistance ◽  
Arbitrary Lagrangian Eulerian ◽  
Eulerian Model ◽  
Drag Forces ◽  
Drag Finishing ◽  
Surrounding Liquid

Drag finishing is a widely used superfinishing technique in the industry to polish parts under the action of abrasive media combined with an active surrounding liquid. However, the understanding of this process is not complete. It is known that pyramidal abrasive media are more prone to rapidly improving the surface roughness compared to spherical ones. Thus, this paper aims to model how the shape of abrasive media (spherical vs. pyramidal) influences the material removal mechanisms at the interface. An Arbitrary Lagrangian–Eulerian model of drag finishing is proposed with the purpose of estimating the mechanical loadings (normal stress, shear stress) induced by both abrasive media at the interface. The rheological behavior of both abrasive slurries (media and liquid) has been characterized by means of a Casagrande direct shear test. In parallel, experimental drag finishing tests were carried out with both media to quantify the drag forces. The correlation between the numerical and experimental drag forces highlights that the abrasive media with a pyramidal shape exhibits a higher shear resistance, and this is responsible for inducing higher mechanical loadings on the surfaces and, through this, for a faster decrease of the surface roughness.

scholarly journals Long-Term Concrete Shrinkage Influence on the Performance of Reinforced Concrete Structures

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 254
Author(s):  
Alinda Dey ◽  
Akshay Vijay Vastrad ◽  
Mattia Francesco Bado ◽  
Aleksandr Sokolov ◽  
Gintaris Kaklauskas
Keyword(s):  
Reinforced Concrete ◽  
Reinforced Concrete Structures ◽  
Tension Stiffening ◽  
Model Code ◽  
Concrete Shrinkage ◽  
Time Period ◽  
Governing Factor ◽  
Model Code 2010 ◽  
Mathematical Process

The contribution of concrete to the tensile stiffness (tension stiffening) of a reinforced concrete (RC) member is a key governing factor for structural serviceability analyses. However, among the current tension stiffening models, few consider the effect brought forth by concrete shrinkage, and none studies take account of the effect for very long-term shrinkage. The present work intends to tackle this exact issue by testing multiple RC tensile elements (with different bar diameters and reinforcement ratios) after a five-year shrinking time period. The experimental deformative and tension stiffening responses were subjected to a mathematical process of shrinkage removal aimed at assessing its effect on the former. The results showed shrinkage distinctly lowered the cracking load of the RC members and caused an apparent tension stiffening reduction. Furthermore, both of these effects were exacerbated in the members with higher reinforcement ratios. The experimental and shrinkage-free behaviors of the RC elements were finally compared to the values predicted by the CEB-fib Model Code 2010 and the Euro Code 2. Interestingly, as a consequence of the long-term shrinkage, the codes expressed a smaller relative error when compared to the shrinkage-free curves versus the experimental ones.

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