Punching Resistance of Flat Slabs without Shear Reinforcement

2015 ◽  
Vol 1106 ◽  
pp. 213-216
Author(s):  
Ján Hanzel ◽  
Lucia Majtánová ◽  
Jaroslav Halvonik
Keyword(s):  
Statistical Evaluation ◽  
Experimental Tests ◽  
National Standard ◽  
Structural Members ◽  
Shear Reinforcement ◽  
Safety Level ◽  
Model Code ◽  
Flat Slabs ◽  
Eurocode 2 ◽  
Model Code 2010

RC flat slabs are frequently used structural members in building construction. Safety verification and avoidance of failure due to punching in the vicinity of a column is currently performed using empirical model which is introduced in Eurocode 2. However extensive discussions are held about replacement of the EC2 model by more refined mechanical model which is presented in Model Code 2010. The paper deals with statistical evaluation of the safety level above mentioned models for punching resistance without shear reinforcement. Evaluation is supplemented by third model from already cancelled Czechoslovak national standard ČSN 731201. Database which includes results of more than 400 experimental tests of flat slab specimens has been used for the statistical evaluation.

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.

A Method to Predict the Punching Shear Strength of Flat Slabs with Shear Reinforcement Using a Strut-and-Tie Model

2017 ◽  
Vol 738 ◽  
pp. 25-35
Author(s):  
Lukáš Lyčka ◽  
Petr Štěpánek
Keyword(s):  
Shear Failure ◽  
Complex Problem ◽  
Punching Shear ◽  
Shear Reinforcement ◽  
Model Code ◽  
Strut And Tie ◽  
Flat Slabs ◽  
Model Code 2010 ◽  
Strut And Tie Model ◽  
Critical Aspects

The use of flat slabs in constructions due to its many functional and economic advantages is wide-spread. Behavior of flat slabs in shear and flexure is a fairly complex problem. Therefore, the punching shear failure belongs to one of the most critical aspects in the design of concrete buildings.The purpose of this paper is to describe a framework of the proposed method for predicting the punching shear of flat slabs with shear reinforcement. Most of the current codes in force are mainly based on empirical formulation. The proposed method is based on a strut-and-tie model and therefore could be considered as an analytical approach. For the purpose of demonstrating the effectiveness of the proposed method, the method is compared with some of the main methods currently in use, such as Eurocode EC2, ACI 318 and Model Code 2010. The comparison consists of results of more than 90 experiments on flat slabs with shear reinforcement, gathered from publications from all around the world.

Strut-and-Tie Model for Predicting the Punching Shear of Flat Slabs with Shear Reinforcement

2017 ◽  
Vol 259 ◽  
pp. 178-183
Author(s):  
Lukáš Lyčka ◽  
Petr Štěpánek
Keyword(s):  
Physical Models ◽  
Punching Shear ◽  
Empirical Equations ◽  
Shear Reinforcement ◽  
Model Code ◽  
Strut And Tie ◽  
Flat Slabs ◽  
The World ◽  
Model Code 2010 ◽  
Strut And Tie Model

The purpose of this paper is to describe a framework of the proposed method for predicting the punching shear of flat slabs with shear reinforcement. The proposed method is based on a strut-and-tie model. Current methods of predicting the punching shear strength of flat slabs could be divided into these categories: models based on empirical equations, physical models, analytical methods and finite element methods. Most of the current codes in force would be best described as empirical formulations. Physical model for prediction of punching shear is described in Model Code 2010. Proposed method for flat slabs with shear reinforcement is based mainly on a strut-and-tie model and therefore could be considered as an analytical method.For the purpose of demonstrating the effectiveness of the proposed method, the method is compared with some of the main methods currently in use, such as Eurocode EC2, American code ACI 318 and Model Code 2010. The comparison consists of results of more than 98 experiments of punching shear on the flat slabs with shear reinforcement, gathered from publications from all around the world.

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 Influence of the supplementary reinforcement on the shear strength of beams with prefabricated truss stirrups

2022 ◽  
Vol 15 (1) ◽  
Author(s):  
Rosângela Silva Pinto ◽  
Vanessa Carolaine Sousa ◽  
Luamim Sales Tapajós ◽  
Maurício de Pina Ferreira ◽  
Aarão Ferreira Lima Neto
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Experimental Tests ◽  
Experimental Results ◽  
Shear Reinforcement ◽  
Theoretical Shear Strength ◽  
Safety Level ◽  
Eurocode 2 ◽  
Wide Beams ◽  
Concrete Elements

abstract: This paper presents the results of seven experimental tests in reinforced concrete wide beams, aiming to investigate their performance when subjected to shear, using prefabricated truss stirrups as shear reinforcement, as well as a supplementary reinforcement to control cracks by delamination. The main analysed variables were: position of the supplementary reinforcement, inclination of the shear reinforcement, and spacing between stirrups. Results showed that strength increments of up to 142% were obtained using the prefabricated truss stirrups. Furthermore, the experimental results were compared with the theoretical shear strength estimates of the tested beams, following the recommendations of NBR 6118 (2014), Eurocode 2 (2004), and ACI 318 (2014), in order to evaluate the safety level of these codes when designing concrete elements subjected to shear with the reinforcement used in this paper.

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 Estudo comparativo entre valores teóricos e resultados experimentais de módulo de elasticidade de concretos produzidos com diferentes tipos de agregado graúdo

2017 ◽  
Vol 17 (3) ◽  
pp. 281-294 ◽  
Author(s):  
Antonio Carlos dos Santos ◽  
Angela Maria de Arruda ◽  
Turibio José da Silva ◽  
Paula de Carvalho Palma Vitor
Keyword(s):  
Model Code ◽  
Eurocode 2 ◽  
Model Code 2010

Resumo O módulo de elasticidade do concreto é uma propriedade importante para os profissionais envolvidos na indústria da construção civil, uma vez que seu valor é determinante para o controle das deformações. Este trabalho avaliou o módulo de elasticidade de três classes distintas de concreto (C20, C30 e C40) produzidas com dois tipos litológicos de rochas, basalto e dolomito, de diferentes jazidas da região do Triângulo Mineiro. Como parte do estudo experimental, foram moldadas 324 amostras cilíndricas de 10 cm × 20 cm. Os valores de módulo de elasticidade obtidos foram comparados com seis formulações propostas em quatro normas, institutos e códigos do concreto: ABNT NBR 6118 versão 2007 e 2014, ACI 318, EUROCODE 2 and FIB Model Code, Ibracon 2003. Dentre as formulações propostas pelas normas, as indicadas pela FIB Model Code (2010) e ABNT NBR 6118 (2014) apresentaram valores mais próximos aos resultados experimentais deste estudo.

scholarly journals Behaviour of recycled aggregate concrete under combined compression and shear stresses

2018 ◽  
Vol 68 (331) ◽  
pp. 162
Author(s):  
K. Liu ◽  
J. Yan ◽  
C. Zou
Keyword(s):  
Failure Criterion ◽  
Coarse Aggregate ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Shear Stresses ◽  
Aggregate Concrete ◽  
Model Code ◽  
Eurocode 2 ◽  
Model Code 2010 ◽  
Normal Strength

To investigate the behaviour of recycled aggregate concrete (RAC) under combined compression and shear stresses, 75 hollow cylinder specimens prepared with various replacement ratios of recycled coarse aggregate (RCA) were tested with a self-designed loading device. The results showed that the failure pattern was similar for RAC with different replacement ratios of RCA. The ultimate shear stress improved with an increasing axial compression ratio of less than 0.6 and declined after exceeding 0.6. A modified failure criterion for RAC with normal strength under combined compression and shear stresses was proposed. A new procedure to predict the shear strength for RAC beams without stirrups was developed based on the proposed failure criterion, showing a better correlation with the experimental results than the predictions calculated by GB50010, Eurocode 2, fib Model Code 2010 and ACI 318-11.

Reconstruction Effectiveness of Locally Supported Flat Slabs to Increase in Shear Resistance

2020 ◽  
Vol 309 ◽  
pp. 246-251
Author(s):  
Mária Bolešová ◽  
Katarína Gajdošová ◽  
Marek Čuhák
Keyword(s):  
Shear Stress ◽  
Numerical Models ◽  
Shear Resistance ◽  
Reconstruction Method ◽  
Detailed Calculation ◽  
Shear Reinforcement ◽  
Flat Slab ◽  
Advantages And Disadvantages ◽  
Flat Slabs ◽  
Eurocode 2

The most used horizontal load-bearing systems in concrete buildings are flat slabs. The effective and economic reconstruction of a locally supported flat slab of an existing building creates a complex task. Shear stress arises near the column and it becomes critical in design with increasing slab slenderness and requires a more detailed calculation. Increasing in the shear resistance of the flat slab can be achieved in various ways. Each method brings different effectiveness, advantages and disadvantages. The most widely used methods of the reconstruction are the increase in the size of the column (therein increasing the control perimeter for displaying the shear stress), the increase in the thickness of the flat slab or reinforcing the slab with shear reinforcement. Bolts and screw anchors (using different mounting angles) can be used as shear reinforcement. Each mentioned reconstruction method should be subjected to numerical calculations and verification of its efficiency. The parametric study presented in this paper is focused on the reconstruction techniques and their verification according to various numerical models. The results from Eurocode 2, fib Model Code 2010 and the new generation of Eurocode 2 are compared to show the differences between them. The aim of this paper is to bring a demonstration of the reconstruction methods that will increase in the shear resistance of the locally supported flat slabs and trying to choose the most effective one.

Sign in / Sign up

Export Citation Format

Share Document