scholarly journals INFLUENCE OF LONGITUDINAL REINFORCEMENT ON THE PUNCHING SHEAR RESISTANCE OF REINFORCED CONCRETE SLABS

2009 ◽  
Vol 1 (2) ◽  
pp. 73-79 ◽  
Author(s):  
Dainius Šakinis ◽  
Povilas Vainiūnas
Keyword(s):  
Reinforced Concrete ◽  
Mean Value ◽  
Transverse Force ◽  
Reinforcement Ratio ◽  
Concrete Slabs ◽  
Longitudinal Reinforcement ◽  
Compression Zone ◽  
Reinforced Concrete Slabs ◽  
Dowel Action ◽  
The Mean

This work presents the results of experimental tests on reinforced concrete slabs with different longitudinal reinforcement ratio ρ under concentrated load. Five series of specimen were made and tested, a total of ten slabs. The measurements of the specimens were 2135×2135×140 mm (Fig. 3). Longitudinal reinforcement ratio ρ = 0,449–1,90 %, the diameter of reinforcing bars was 8–16 mm, reinforcement bore yield stresses, spacing between bars was 100 mm. The protective concrete layer of the longitudinal reinforcement in all slabs was 20 mm. The cubic compressive strength of concrete fc,cube = 33,4–46,6 MPa. In the course of the experiment the measurements of the collapsing punching force, the radial and tangential deformations of the compression zone were made, the curves of their expansion were given, displacements of the column head were measured. The surface of the punching cone, irrespective of the longitudinal reinforcement ratio ρ, makes a ˜35° angle with the bottom (compression zone) surface of the slab. Deformations of radial and tangential directions in the compression zone during the course of cracking of the slab do not reach the ultimate compressive strains of concrete (3,50 ‰), the mean value of deformations in the radial direction is 1,6 ‰, the mean value of deformations in the tangential direction is 1,8 ‰, which allows to make a conclusion that the slab is punched-through under transverse collapsing force. The strength criterion of biaxial stress state proposed by Zalesov et al. (1973) and the expression of the resultant transverse force of the dowel action of the longitudinal reinforcement ratio ρ as proposed by Theodorakopoulos et al. (2002), were used to get the expression of the collapsing transverse force Vu which is given in equation (2). The factor of the influence of longitudinal reinforcement ratio ρ expressed through the resultant transverse force Vd of the dowel action makes 40–50 % of the collapsing force, Vd increases with increasing of the longitudinal reinforcement ratio ρ. The resultant transverse force Vc of the compression zone of concrete in the critical section makes 50–60 % of the collapsing force, Vc increases with increasing of the longitudinal reinforcement ratio ρ.

Calculation of Ultimate Loads of Two-Way Reinforced Concrete Slabs

2012 ◽  
Vol 256-259 ◽  
pp. 850-854
Author(s):  
Yong Wang ◽  
Yu Li Dong
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Load ◽  
Failure Criteria ◽  
Reinforcement Ratio ◽  
Concrete Slabs ◽  
Test Results ◽  
Simple Method ◽  
Simply Supported ◽  
Reinforced Concrete Slabs

This paper presents the latest developments of a simple method used to determine the ultimate load of two-way simply supported reinforced concrete slabs. Based on the reinforcement ratio, two failure criteria are proposed in the paper. The effectiveness of the developed model is validated through satisfactory comparison with from test results.

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 Flexural Behavior of Composite Concrete Slabs Made with Steel and Polypropylene Fibers Reinforced Concrete in the Compression Zone

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3616 ◽  
Author(s):  
Barbara Sadowska-Buraczewska ◽  
Małgorzata Szafraniec ◽  
Danuta Barnat-Hunek ◽  
Grzegorz Łagód
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Load Capacity ◽  
Fiber Reinforced Concrete ◽  
Concrete Slabs ◽  
Polypropylene Fibers ◽  
Compression Zone ◽  
Fiber Reinforced ◽  
Reinforced Concrete Slabs ◽  
Fiber Concrete

The paper presented aimed at examining the effect of a fiber-reinforced concrete layer in the compressed zone on the mechanical properties of composite fiber-reinforced concrete slabs. Steel fibers (SF) and polypropylene fibers (PP) in the amount of 1% in relation to the weight of the concrete mix were used as reinforcement fibers. The mixture compositions were developed for the reference concrete, steel fiber concrete and polypropylene fiber concrete. The mechanical properties of the concrete obtained from the designed mixes such as compressive strength, bending strength, modulus of elasticity and frost resistance were tested. The main research elements, i.e., slabs with a reinforced compression zone in the form of a 30 mm layer of concrete with PP or SF were made and tested. The results obtained were compared with a plate made without a strengthening layer. The bending resistance, load capacity and deflection tests were performed on the slabs. A scheme of crack development during the test and a numerical model for the slab element were also devised. The study showed that the composite slabs with fiber-reinforced concrete with PP in the upper layer achieved 12% higher load capacity, with respect to the reference slabs.

Flexural Behaviors of Concrete Slab Reinforced with GFRP Bars

2011 ◽  
Vol 243-249 ◽  
pp. 567-572
Author(s):  
Hao Sheng Gu ◽  
Da Yu Zhu
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Load ◽  
Concrete Slab ◽  
Reinforcement Ratio ◽  
Parameter Analysis ◽  
Concrete Slabs ◽  
Test Results ◽  
Gfrp Bars ◽  
Reinforced Concrete Slabs ◽  
Steel Bars

This paper attempts to reveal the flexural behaviors of concrete slab reinforced with GFRP bars. Through flexural test, the deformation process and failure mode of concrete slabs reinforced with GFRP bars and steel bars are examined, respectively. The deflection, cracking load, ultimate load and concrete strain are compared between two kinds of concrete slabs. From the test results, it is clarified that the moment-deflection curve of GFRP reinforced concrete slab can be divided into two stages. Before concrete cracks the behaviors of two kinds of concrete slabs are almost the same. However, the deflection of concrete slabs reinforced with GFRP bars increases much faster after cracking and the stress-strain diagram is linear up to rupture with no discernible yield point. The ultimate load of concrete slabs reinforced with GFRP bars is 1.2 times of that of concrete slabs reinforced with steel bars. Based on the test results, finite element analysis is performed in order to study the influence of reinforcement ratio. Parameter analysis shows that the flexural rigidity of GFRP reinforced concrete slabs increases with the reinforcement ratio after cracking.

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.

Numerical Modeling of Reinforced Concrete Slabs under Impact Loading

2020 ◽  
Vol 857 ◽  
pp. 99-108
Author(s):  
Enas Mabrook Mouwainea ◽  
Abdul Muttalib I. Said
Keyword(s):  
Reinforced Concrete ◽  
Impact Force ◽  
Impact Load ◽  
Time History ◽  
Reinforcement Ratio ◽  
Concrete Slabs ◽  
Slab Thickness ◽  
Central Deflection ◽  
Reinforced Concrete Slabs ◽  
The Impact

This paper aims to provide a numerical model able to represent the behavior of reinforced concrete slabs subjected to impact loads. The nonlinear finite element analysis adopted by ABAQUS/Explicit Software was used in this study. A parametric study was conducted to provide a comprehensive understanding of the behavior of reinforced concrete slabs subjected to impact load. Two parameters were varied amongst the slabs which classified in to two groups. In the first groups, the thickness of slabs is variable, which was equal to (75, 100, 150 mm). In the second group, the thickness of the slab is constant and the variable was the reinforcement ratio, which ranged from (0.58 to 1%), per layer. In dynamic analysis, the load-time history and deflection-time relation were investigated. For the first group, obviously, as the slab thickness increased, the maximum central deflection of the slabs decreased by (48 – 84 %). Also, the impact force of the slabs increased by (40 – 106%) as the thickness of the slab increased by (33 – 100%). For the second group, the maximum central deflection of the slabs decreased by (6.6 – 8.8 %) as the steel reinforcement increased by (0.58 – 1 %). It was observed in the second group that the change in the value of the impact force was very limited. This lead to a fact that the impact force was not affected by the change of the reinforcement ratio, but mainly affected by the change of the slab thickness.

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