scholarly journals Punching Shear Behavior of Reinforced Concrete Slabs under Fire using Finite Elements

2020 ◽  
Vol 26 (5) ◽  
pp. 106-127
Author(s):  
Athraa H. Gharbi ◽  
Akram S. Mahmoud
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Shear Failure ◽  
Punching Shear ◽  
Concrete Slabs ◽  
Mechanical And Thermal Properties ◽  
Element Analysis ◽  
Reinforced Concrete Slabs ◽  
Fire Condition ◽  
Increasing Temperature

The main aim of this paper is studied the punching shear and behavior of reinforced concrete slabs exposed to fires, the possibility of punching shear failure occurred as a result of the fires and their inability to withstand the loads. Simulation by finite element analysis is made to predict the type of failure, distribution temperature through the thickness of the slabs, deformation and punching strength. Nonlinear finite element transient thermal-structural analysis at fire conditions are analyzed by ANSYS package. The validity of the modeling is performed for the mechanical and thermal properties of materials from earlier works from literature to decrease the uncertainties in data used in the analysis. A parametric study was adopted in this study,  it has many factors such as the ratios of length to thickness, fire temperature, time exposed to fire, concrete compressive strength, area exposed to fires and type of support. It can be concluded from this research the significant factors that affect the punching shear strength. However, the increasing ratio of length to thickness may be lead to increasing the deflection more than 123% at fire condition. Also, the increasing temperature leads to increasing the deflection about 40% at fire condition.

scholarly journals Nonlinear finite element analysis of punching shear strength of reinforced concrete slabs supported on L-shaped columns

2020 ◽  
Vol 19 (4) ◽  
pp. 125-138
Author(s):  
Qing Zhang ◽  
Graeme J. Milligan ◽  
Maria Anna Polak
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Reinforced Concrete ◽  
Nonlinear Finite Element ◽  
Punching Shear ◽  
Shear Behaviour ◽  
Concrete Slabs ◽  
Shear Stresses ◽  
Element Analysis ◽  
Reinforced Concrete Slabs

Most current concrete design codes include provisions for punching shear of reinforced concrete slabs supported on columns with L, T, and cruciform shapes. Reference studies verifying the accuracy of these code provisions are typically not provided. Empirical data of punching failures of slabs supported on columns with L, T, and cruciform shapes are limited due to the cost and time required to test specimens with slab thicknesses and column sizes commonly used in practice. In this paper, the punching shear behaviour of five interior L-shaped slab-column connections, one without a slab opening and four with slab openings, subjected to static concentric loading are analyzed using a plasticity-based nonlinear finite element model (FEM) in ABAQUS. The FEM is similar to models previously calibrated at the University of Waterloo and are calibrated considering nine slabs that are tested to study the impact of column rectangularity on the punching shear behaviour of reinforced concrete slabs. The finite element analysis results indicate that shear stresses primarily concentrate around the ends of the L, and that current code predictions from ACI 318-19 and Eurocode 2 may be unconservative due to the assumed critical perimeters around L-shaped columns.

scholarly journals Deformations of R.C.Circular Slabs in Fire Condition

2018 ◽  
Vol 4 (4) ◽  
pp. 712 ◽  
Author(s):  
Abdelraouf Tawfik Kassem
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Slenderness Ratio ◽  
High Surface ◽  
High Surface Area ◽  
Concrete Slabs ◽  
Finite Element Models ◽  
Reinforced Concrete Slabs ◽  
Fire Condition ◽  
In Fire

Reinforced concrete slabs are elements in direct contact with superimposed loads, having high surface area and small thickness. Such a condition makes slabs highly vulnerable to fire conditions. Fire results in exaggerated deformations in reinforced concrete slabs, as a result of material deterioration and thermal induced stresses. The main objective of this paper is to deeply investigate how circular R.C. slabs, of different configurations, behave in fire condition. That objective has been achieved through finite element modelling. Thermal-structural finite element models have been prepared, using "Ansys". Finite element models used solid elements to model both thermal and structural slab behaviour. Structural loads had been applied, representing slab operational loads, then thermal loads were applied in accordance with ISO 843 fire curve. Outputs in the form of deflection profile and edge rotation have been extracted out of the models to present slab deformations. A parametric study has been conducted to figure out the significance of various parameters such as; slab depth, slenderness ratio, load ratio, and opening size; regarding slab deformations. It was found that deformational behaviour differs significantly for slabs of thickness equal or below 100 mm, than slabs of thickness equal or above 200 mm. On the other hand considerable changes in slabs behaviour take place after 30 minutes of fire exposure for slabs of thickness equals or below 100 mm, while such changes delay till 60 minutes for slabs of thickness equals or above 200 mm.

Numerical Analysis of Punching Shear Failure of Self-Compacting Fiber Reinforced Concrete (SCFRC) Ribbed Slabs

2019 ◽  
Vol 972 ◽  
pp. 93-98
Author(s):  
Nurulain Hanida Mohamad Fodzi ◽  
M.H. Mohd Hisbany
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Shear Failure ◽  
Nonlinear Finite Element ◽  
Fiber Reinforced Concrete ◽  
Punching Shear ◽  
Nonlinear Finite Element Method ◽  
Fiber Reinforced ◽  
Element Analysis ◽  
Abaqus Software

This paper deals with behavior and capacity of punching shear resistance for ribbed slabs produce from self-compacting fiber reinforced concrete (SCFRC) by application of nonlinear finite element method. The analysis will be achieved by using ABAQUS software. The nonlinear finite element analysis by ABAQUS will be compare with the experimental results. Results and conclusions may be useful for establishing recommendation and need to be acknowledged.

Effect of Column Dimensions on the Punching Shear of Flat Slab

2019 ◽  
pp. 378-393
Author(s):  
Hamid Abdulmahdi Faris ◽  
Lubna Mohammed Abd
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Concrete Slab ◽  
The Other ◽  
Punching Shear ◽  
Concrete Slabs ◽  
Reinforced Concrete Slab ◽  
Flat Slab ◽  
Interior Edge ◽  
Reinforced Concrete Slabs

The "flat slab" is a reinforced concrete slab bolstered, by a number of columns. Punching, shear is a category for collapse for reinforced concrete slabs exposed to great confined forces. In "flat slab" constructions the shear failure happens, at column bolster joints. To avoid this, collapse two methods are used, first method is increasing the column dimensions and, the other is to use drop panel if the first method leads to uneconomical, design. Two examples are used to find the effect, of column dimensions, increase on the punching shear failure of "flat slab". The first example, is a "flat slab" of span (5 by 5) m and the other is of span (6 by 6) m. The column which examined is the interior, edge and corner columns, and the interior column is the most dangerous case. It is concluded that, the increase of column dimensions are lead to avoid of punching shear failure in "flat slab" and the drop panel is enlarge the area of the critical shear perimeter and this avoiding punching shear failure.

Nonlinear finite element analysis of tests of reinforced concrete slabs

2021 ◽  
Author(s):  
G. I. Zarate Garnica ◽  
Y. Yang ◽  
E. O. L. Lantsoght
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Reinforced Concrete ◽  
Nonlinear Finite Element Analysis ◽  
Nonlinear Finite Element ◽  
Concrete Slabs ◽  
Load Testing ◽  
Element Analysis ◽  
Concentrated Load ◽  
Reinforced Concrete Slabs

<p>In the Netherlands, many existing reinforced concrete slab bridges were built more than 50 years ago. Upon assessment with the new codes, a large number of this type of bridge rate insufficiently. Since many of these existing bridges present complex material properties and boundary conditions, proof load testing is considered an effective method to assess their capacity. However, to be able to safely apply proof load testing on slab bridges, verification in the laboratory is necessary. Therefore, experiments on reinforced concrete slabs of 5 m × 2,5 m × 0,3 m under a concentrated load with varying shear span to depth ratios are carried out in the laboratory of Delft University of Technology. Additionally, nonlinear finite element analysis is used to simulate the experiments following the guidelines of nonlinear finite element analysis published by the Dutch ministry of infrastructure and water management. The results from the finite element and experimental analyses are compared in terms of peak load, failure mode, and crack pattern. A good agreement between the experimental and numerical investigations is observed.</p>

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