scholarly journals NUMERICAL STUDY OF THE PUNCHING SHEAR MECHANISM FOR THIN AND THICK REINFORCED CONCRETE SLABS

2021 ◽  
Vol 17 (4) ◽  
pp. 91-105
Author(s):  
Oleg Kabantsev ◽  
Sergey Krylov ◽  
Sergey Trofimov
Keyword(s):  
Reinforced Concrete ◽  
Experimental Studies ◽  
Great Influence ◽  
Shear Capacity ◽  
Punching Shear ◽  
Concrete Slabs ◽  
Longitudinal Reinforcement ◽  
Shear Mechanism ◽  
Reinforced Concrete Slabs ◽  
The Difference

The assessment of the punching shear capacity for reinforced concrete slabs, carried out according to the regulatorydocuments of a number of countries, leads to significantly various results. At the same time, the results of thecalculated forecast may have great differences from the experimental data. A great influence on the accuracy of the resultsof the calculated forecast is exerted by the thickness of the examined slabs, as well as the value of longitudinal reinforcement.These parameters determine the features of the mechanisms of destruction of slabs in case of the punching shearmechanism, as indicated by individual interpretations of the results of experimental studies. In order to determine thefeatures of the punching shear mechanism of reinforced concrete slabs of various thicknesses, numerical studies of theprocess of cracking and destruction of slabs of different thicknesses have been performed. Differences in the mechanismof formation and development of cracks in thin and thick slabs are revealed. The paper shows that the behavior of thinand thick slabs has qualitative distinctions at the initial stages of formation and development of the cracks leading todestruction. The authors have also shown the difference between stress-strain state of thick and thin slabs before destruction.In conclusion, it was established that the influence of longitudinal reinforcement on the strength during punching inthick slabs is much less than in thin ones.When evaluating the punching shear capacity of reinforced concrete slabs, the regulatory documents of different countries give significantly different results. In this case, the calculation results may differ significantly from the experimental data. The deterioration of the thickness of the calculated slabs, as well as the value of the longitudinal reinforcement has a great influence on the accuracy of the calculation results. These parameters determine the features of the destruction mechanisms of slabs under punching. This fact is indicated by some interpretations of the results of experimental studies. In order to establish the peculiarities of the punching shear mechanism of reinforced concrete slabs of different thicknesses, a numerical investigation of the cracking and destruction of slabs of different thicknesses have been performed. Differences in the mechanism of formation and development of cracks in thin and thick slabs have been revealed. The paper shows that the behavior of thin and thick slabs has qualitative differences at the initial stages of the cracks formation and development that leads to destruction. The difference between stress-strain state of thick and thin slabs before breaking have been shown. It was found that the effect of longitudinal reinforcement on the punching shear strength in thick slabs is much less than in thin ones.

scholarly journals Prediction of Punching Shear Capacity of Two-Ways FRP Reinforced Concrete Slabs

2017 ◽  
Vol 5 (2) ◽  
pp. 1-7
Author(s):  
Ilker Kara ◽  
Besian Sinani
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Shear Capacity ◽  
Reinforced Concrete Beams ◽  
Punching Shear ◽  
Concrete Slabs ◽  
Design Standards ◽  
Concrete Members ◽  
Reinforced Concrete Slabs ◽  
Frp Reinforcement

An innovative solution to the corrosion problem is the use of fiber-reinforced polymer (FRP) as an alternative reinforcing material in concrete structures. In addition to the non corrodible nature of FRP materials, they also have a high strength-to-weight ratio that makes them attractive as reinforcement for concrete structures. Extensive research programs have been carried out to investigate the flexural behavior of concrete members reinforced with FRP reinforcement. On the other hand, the shear behavior of concrete members, especially punching shear of two-way slabs, reinforced with FRP bars has not yet been fully explored. The existing provisions for punching of slabs in most international design standards for reinforced concrete are based on tests of steel reinforced slabs. The elastic stiffness and bonding characteristics of FRP reinforcement are sufficiently different from those of steel to affect punching strength. In the present study, the equations of existing design standards for shear capacity of FRP reinforced concrete beams have been evaluated using the large database collected. The experimental punching shear strengths were compared with the available theoretical predictions, including the CSA S806 (CSA 2012), ACI-440.1R-15 (ACI 2015), BS 8110 (BSI 1997), JSCE (1997) a number of models proposed by some researchers in the literature. The existing design methods for FRP reinforced concrete slabs give conservative predictions for the specimens in the database. This paper also presents a simple yet improved model to calculate the punching shear capacity of FRPreinforced concrete slabs. The proposed model provides the accurate results in calculating the punching shear strengths of FRP-reinforced concrete slender slabs.

scholarly journals Resisting punching shear stress in reinforced concrete slabs

2018 ◽  
Vol 162 ◽  
pp. 04025
Author(s):  
Ebada Ahmed ◽  
Boshra Eltaly ◽  
Fatma El-Zhraa ◽  
Magdy Tayel
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Shear Capacity ◽  
Punching Shear ◽  
Shear Reinforcement ◽  
Reinforcement System ◽  
Strength Concrete ◽  
Reinforced Concrete Slabs ◽  
The Difference ◽  
Compact Strength

Punching shear failure is a major problem encountered in the design of reinforced concrete flat slabs. The utilization of shear reinforcement via shear studs or other means has become a choice for improving the punching shear capacity. In this study, a new alternative of reinforcement modalities were tested and demonstrated the effect of self-compact concrete on the punching shear capacity, beside that compared between the difference codes to identify the suitable one for determining the position of critical section of punching shear. Nevertheless, in this investigation, the proposed reinforcement system is examined for interior columns only. An experimental work consisting of six specimens: five of them were cast with normal reinforced concrete and one was cast with self-compact strength concrete. The obtained results indicate that the proposed shear reinforcement system has a positive effect in the enhancement of the punching shear capacity of interior slab–column connection of self-compact strength concrete.

scholarly journals Evaluation of punching shear strength of flat slabs supported on rectangular columns

2018 ◽  
Vol 33 ◽  
pp. 02007 ◽  
Author(s):  
Valery Filatov
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Concrete Slab ◽  
Structural Parameters ◽  
Experimental Studies ◽  
Punching Shear ◽  
Design Solution ◽  
Concrete Slabs ◽  
Reinforced Concrete Slabs ◽  
Rectangular Columns

The article presents the methodology and results of an analytical study of structural parameters influence on the value of punching force for the joint of columns and flat reinforced concrete slab. This design solution is typical for monolithic reinforced concrete girderless frames, which have a wide application in the construction of high-rise buildings. As the results of earlier studies show the punching shear strength of slabs at rectangular columns can be lower than at square columns with a similar length of the control perimeter. The influence of two structural parameters on the punching strength of the plate is investigated - the ratio of the side of the column cross-section to the effective depth of slab C/d and the ratio of the sides of the rectangular column Cmax/Cmin. According to the results of the study, graphs of reduction the control perimeter depending on the structural parameters are presented for columns square and rectangular cross-sections. Comparison of results obtained by proposed approach and MC2010 simplified method are shown, that proposed approach gives a more conservative estimate of the influence of the structural parameters. A significant influence of the considered structural parameters on punching shear strength of reinforced concrete slabs is confirmed by the results of experimental studies. The results of the study confirm the necessity of taking into account the considered structural parameters when calculating the punching shear strength of flat reinforced concrete slabs and further development of code design methods.

Punching shear provisions for reinforced and presfressed concrete flat slabs

1996 ◽  
Vol 23 (2) ◽  
pp. 502-510 ◽  
Author(s):  
N. J. Gardner
Keyword(s):  
Reinforced Concrete ◽  
Correction Factor ◽  
Prestressed Concrete ◽  
Shear Capacity ◽  
Punching Shear ◽  
Concrete Slabs ◽  
Flat Slabs ◽  
Reinforced Concrete Slabs ◽  
Unbonded Tendons ◽  
Effective Depth

The validity of the CSA A23.3-94 code provisions for punching shear were compared with the punching shear results of 142 reinforced concrete flat slabs, 16 prestressed concrete flat slabs with unbonded tendons, and 17 flat slabs with unbonded prestressed and supplementary bonded reinforcement. The code prediction equations are not capable of direct verification against experimental results without using a correction factor. Using a justifiable correction factor, the CSA A23.3-94 provisions are appropriately conservative for reinforced concrete slabs but the scatter is large. However, it was concluded that the CSA A23.3-94 provisions are not conservative for prestressed concrete flat slabs. An equation is proposed to calculate the punching shear capacity of reinforced concrete and prestressed concrete slabs, which has a smaller coefficient of variation than the punching shear provisions of CSA A23.3-94, for symmetrically loaded interior columns. The critical section of the proposed method is the perimeter of the column, which is easier to justify than an arbitrary critical perimeter half the effective depth of slab from the column. Key words: reinforced concrete, prestressed concrete, flab slabs, punching shear.

scholarly journals Investigation of longitudinal reinforcement contribution in shear punching of reinforced concrete flat slabs without transverse reinforcement

2019 ◽  
Vol 279 ◽  
pp. 02005
Author(s):  
Vladimir Alekhin ◽  
Alexander Budarin ◽  
Maxim Pletnev ◽  
Liubov Avdonina
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Load Capacity ◽  
Punching Shear ◽  
Concrete Slabs ◽  
Transverse Reinforcement ◽  
Longitudinal Reinforcement ◽  
Factors Affecting ◽  
Codes Of Practice ◽  
Reinforced Concrete Slabs

The shear punching of the reinforced concrete slabs is a complex process occurring when considerable force is concentrated on the relatively small area of a column-slab connection. An incorrect assessment of load capacity of slab under the punching shear may lead to an accident. One of the most significant factors affecting the slab capacity is longitudinal reinforcement. In this article much attention is given to the analysis of the longitudinal rebar impact on the maximum loading capacity of reinforced concrete slabs without transverse reinforcement affected by punching shear force using the finite element method. The results obtained via the finite element simulation are compared with laboratory tests and manual calculations carried-out using various methods represented in different national building Codes of practice.

scholarly journals Complete “stress-strain” diagrams of rolled steal beams

2018 ◽  
Vol 230 ◽  
pp. 02008
Author(s):  
Stanislav Fomin ◽  
Yuriy Izbash ◽  
Yuriy Bondarenko ◽  
Serhii Butenko ◽  
Iryna Plakhotnikova
Keyword(s):  
Reinforced Concrete ◽  
Composite Structures ◽  
Experimental Studies ◽  
Concrete Slabs ◽  
Steel Beams ◽  
Rolled Steel ◽  
Stress Strain ◽  
Reinforced Concrete Slabs ◽  
The Difference ◽  
The Web

This paper covers features of rolled steel beams used in composite structures. Composite structures consist of reinforced concrete slabs and rolled steel beams. To calculate its fire resistance it is necessary to know their complete “stress-strain” diagrams. Steel girders, which work together with reinforced concrete slabs, are widely used in bridge building. The tests on samples cut from web and a rack of an I-beam were conducted. The results of experimental studies of the “stress-strain” diagrams of rolled beams indicate the difference in the physicalmechanical characteristics of steel in the web and flanges of the beams. The experimental studies of diagrams were carried out at temperatures of 20, 400, 500, 600, 700 and 800 °C. The properties of the steel were significantly affected by the temperature. The “stress-strain” diagrams of rolled beams and table of results of experimental studies were obtained. The complete “stress-strain” diagrams of the rolled beams were studied. Experimental studies have been conducted using a newly developed patented installation. The differences of diagrams in the web and flanges of the steel I-beams were found.

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