scholarly journals Design of punching shear for prestressed slabs with unbonded tendons on internal columns

2017 ◽  
Vol 10 (4) ◽  
pp. 788-825
Author(s):  
L. A. R. Luchi ◽  
J. C. C. Leite Jr
Keyword(s):  
Reinforced Concrete ◽  
Inclination Angle ◽  
Shear Resistance ◽  
Punching Shear ◽  
Design Codes ◽  
Total Load ◽  
Unbonded Tendons ◽  
Significant Difference

ABSTRACT This paper is related to the punching shear in prestressed slabs with unbonded tendons for interior columns calculated by the codes ABNT NBR 6118:2007, ABNT NBR 6118:2014, EN 1992-1-1:2004 e ACI 318-11. To calculate the punching shear resistance the formulations of the NBR 6118:07, effective until April/2014, did not consider the compression of the concrete in the plane of the slab, due to prestressing. Just the inclined components of some tendons were considered for total load applied relief, but this fact did not generate a significant difference, compared to reinforced concrete, because the inclination angle is very close to zero. The American and European provisions consider a portion related to the compression of the concrete in the planeof the slab. Differences in the results obtained by the four design codes will be exposed, showing that the EC2:04 and the NBR6118:14 achieved the best results.

Parametric analysis on punching shear resistance of reinforced-concrete continuous slabs

2019 ◽  
Vol 71 (20) ◽  
pp. 1083-1096
Author(s):  
Beatrice Belletti ◽  
Aurelio Muttoni ◽  
Simone Ravasini ◽  
Francesca Vecchi
Keyword(s):  
Reinforced Concrete ◽  
Parametric Analysis ◽  
Shear Resistance ◽  
Punching Shear

scholarly journals Experimental verification of punching shear resistance of flat slab fragments

2021 ◽  
Vol 30 (4) ◽  
Author(s):  
Simona Šarvaicová ◽  
Viktor Borzovič
Keyword(s):  
Reinforced Concrete ◽  
Experimental Verification ◽  
Shear Resistance ◽  
Linear Analysis ◽  
Punching Shear ◽  
Test Results ◽  
Loading Test ◽  
Design Models ◽  
Flat Slab ◽  
Standard Design

The paper deals with the loading test results of an experimental reinforced concrete flat slab fragment, which was supported by an elongated rectangular column. The slab specimens were 200 mm thick and were designed without any shear reinforcement. By experimentally obtained punching shear resistance, the accuracy of the standard design models for prediction punching resistance was compared. The results of the experiments were also compared with the results of a numerical non-linear analysis performed in the Atena program.

scholarly journals Punching shear resistance of reinforced concrete footings: evaluation of design codes

2018 ◽  
Vol 11 (2) ◽  
pp. 432-454
Author(s):  
D. F. A. SANTOS ◽  
A. F. LIMA NETO ◽  
M. P. FERREIRA
Keyword(s):  
Reinforced Concrete ◽  
Progressive Collapse ◽  
Shear Resistance ◽  
Test System ◽  
Shear Capacity ◽  
Experimental Results ◽  
Punching Shear ◽  
Complex Method ◽  
Shear Design ◽  
Eurocode 2

Abstract Punching is a possible failure mode for slender footings and it may lead a structure to ruin through progressive collapse. Although footing present different geometric characteristics, their punching shear design is based on the empirical methods used for flat slabs. This paper uses experimental results from 216 tests to evaluate the performance of design code recommendations presented by ACI 318 (2014), ABNT NBR 6118 (2014) and Eurocode 2 (2010) to estimate the punching shear resistance of reinforced concrete footings. Great dispersion between theoretical and experimental results was observed, being evident that the test system affects the punching shear capacity of footings. The more complex method proposed by Eurocode 2 resulted in a better correlation with experimental results.

Effective Critical Section Evaluation of a Reinforced Concrete Flat-Plate Slab with Openings for its Punching Shear Strength Estimation

2015 ◽  
Vol 764-765 ◽  
pp. 1164-1169
Author(s):  
Dae Jin Kim ◽  
Jong Hwan Park ◽  
Tae Hun Ha
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Flat Plate ◽  
Numerical Algorithm ◽  
Critical Section ◽  
Direct Application ◽  
Punching Shear ◽  
Design Codes ◽  
Critical Sections ◽  
Section Evaluation

Most of current concrete design codes require that critical sections should be reduced in the presence of openings near columns to consider their effects on the punching shear strength of reinforced concrete flat-plate slabs. For example, ACI 318-11 stipulates that a part of the perimeter enclosed by two projection lines from the centroid of the column to the boundaries of the openings shall be considered ineffective. However, the direct application of this rule to practical cases may be rather complicated depending on the geometrical layout and shape of columns and openings. In this paper, simple mathematical formulations are proposed to evaluate the ineffective part of critical sections due to openings. This approach can be applied to the design of reinforced concrete flat-plate slabs based on ACI 318-11. A numerical algorithm is also developed to handle general cases where the ineffective parts of multiple openings overlap with each other.

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 Punching shear in flat slabs by strut and tie model

2021 ◽  
Vol 14 (5) ◽  
Author(s):  
Ricardo José Carvalho Silva ◽  
Dênio Ramam Carvalho de Oliveira ◽  
Nívea Gabriela Benevides de Albuquerque ◽  
Thiago Andrade Gomes ◽  
Aaron Kadima Lukanu Lwa Nzambi
Keyword(s):  
Shear Resistance ◽  
Punching Shear ◽  
Strength Prediction ◽  
Design Codes ◽  
Test Results ◽  
Main Design ◽  
Strut And Tie ◽  
Flat Slabs ◽  
The One ◽  
Strut And Tie Model

Abstract Research on behavior of flat slabs under punching shear, performed by Kinnunen, Regan and Muttoni influenced the main design recommendations. Meanwhile, studies about strut and tie model developed by Schlaich for beams, deep beams and corbels also influenced these design codes. This work aimed to adapt the strut and tie model for the punching shear resistance analysis in flat slabs. The punching shear resistance of 30 flat slabs verified through strut and tie model was compared to the one designed following Brazilian, American and European codes recommendation. Subsequently, this same model was validated by comparing the test results of 32 flat slabs. The strut and tie model results, when compared with the test results, showed a better average than those from codes, and the modified strut and tie model can become an alternative for punching shear strength prediction.

scholarly journals Slabs strengthened for punching shear with post-installed steel and CFRP connectors

2019 ◽  
Vol 12 (3) ◽  
pp. 445-478
Author(s):  
M. J. M. PEREIRA FILHO ◽  
M. V. P. FREITAS ◽  
D. F. A. SANTOS ◽  
A. J. C. NASCIMENTO ◽  
M. P. FERREIRA
Keyword(s):  
Shear Resistance ◽  
Experimental Results ◽  
Punching Shear ◽  
Design Codes ◽  
Shear Reinforcement ◽  
Shear Strengthening ◽  
Flat Slab ◽  
Design Recommendations ◽  
Eurocode 2 ◽  
Shear Failures

Abstract Structural accidents due to punching shear failures have been reported in flat slab buildings. Design recommendations presented by codes can lead to entirely different punching shear resistance estimates for similar situations. Furthermore, design codes do not present guidelines for the design of punching shear strengthening of existing slabs. This paper uses a database with 118 experimental results to discuss the performance of theoretical estimates of punching shear resistance using ACI 318, Eurocode 2 and ABNT NBR 6118 in the case of slabs without shear reinforcement. Another database with results of 62 tests on slabs strengthened with post-installed steel and CFRP dowels is used to evaluate the performance of these strengthening techniques and to propose adaptations in codes to allow their use in punching shear strengthening situations of existing slab-column connections.

scholarly journals Reinforced concrete flat slabs with openings at different distances from the column

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Diego da Silva Lourenço ◽  
Elyson Andrew Pozo Liberati ◽  
Marília Gonçalves Marques ◽  
Luiz Carlos de Almeida ◽  
Leandro Mouta Trautwein
Keyword(s):  
Reinforced Concrete ◽  
Failure Load ◽  
Shear Resistance ◽  
Punching Shear ◽  
Structural Behaviour ◽  
Flat Slabs

abstract: The increase in the use of flat slabs and the need of the openings for the passage of installations, such as hydraulic and electrical, which significantly reduces the punching shear resistance capacity of the slab, makes the understanding of the influence of openings in this type of structure extremely necessary. The influence in the structural behaviour of flat slabs with openings at different distances from the column was investigated through five square slabs (1,800 mm x 1,800 mm x 130 mm) supported on square columns (150 mm x 150 mm) tested until failure. The results obtained experimentally were compared with results available in the literature, as well as with responses predicted from the normative instructions. The results confirm high stresses concentration in the region between the column and the opening and that opening situated at 3d from the column have no influence on the failure load for the tested slabs.

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