Punching shear capacity of RC slab-CFT column connections

<div><p><em>This research is to study the mechanical properties of Self Compacting Concrete (SCC) as well as punching shear failure of SCC slabs. Self compacting concrete was first invited in 1988 to achieve durable concrete structures .Design of Reinforced concrete slab is often compromised by their ability to resist shear stress at punching shear surface area. The connection between slabs and supporting columns could be susceptible to high shear stress and might cause sudden and brittle failure. Punching shear failure takes the form of truncated pyramid shape. This program includes investigating the effect of SCC, slab thickness on the punching shear behaviour in terms of load-deflection response and ultimate failure load, failure characteristic of punching shear failure (shape of failure zone and size of failure zone) of simply supported slabs of 1000 x 1000 x 50 and 75mm under concentrated load at centre of slab. The slabs are made with both SCC and Conventional concrete (CC). Investigation included two way specimens with different thickness to evaluate the performance of specimen with different thickness and the effect of thickness on punching shear capacity and performance</em>.</p></div>

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Analysis on Punching Shear Behavior of the Raft Slab Reinforced with Steel Fibers

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.400-402.335 ◽

2008 ◽

Vol 400-402 ◽

pp. 335-340

Author(s):

Xiao Wei Wang ◽

Wen Ling Tian ◽

Zhi Yuan Huang ◽

Ming Jie Zhou ◽

Xiao Yan Zhao

Keyword(s):

Reinforced Concrete ◽

Concrete Slab ◽

Shear Behavior ◽

Shear Capacity ◽

Steel Fibers ◽

Punching Shear ◽

Concrete Slabs ◽

Mass Concrete ◽

Reinforced Concrete Slab ◽

The Common

The thickness of the raft slab is determined by punching shear. The raft slab is commonly thick, which causes concrete volume is large. Mass concrete can bring disadvantage to the foundation. In order to increase the bearing capacity and reduce the thickness, it is suggested that the raft slab to be reinforced by steel fibers. There are five groups of specimens in this paper. S1 is the common reinforced concrete slab. S2 and S3 are concrete slabs reinforced by steel fibers broadcasted layer by layer when casting specimen. S4 and S5 are concrete slabs reinforced by steel fibers mixed homogeneously when making concrete. The punching shear tests of these slabs were done. The test results indicate that the punching shear capacity of the slab reinforced with steel fibers is higher than that of concrete slab, the stiffness and crack resistance of the steel fibers reinforced concrete slab are better than those of the common concrete slab and the punching shear of the slabs with different construction methods of steel fibers is similar. It analyses the punching shear behavior of the slab reinforced with steel fibers and suggests the ultimate bearing formula. The calculative values are coincided with the measured values well.

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Numerische Untersuchungen zur Durchstanztragfähigkeit von Flachdeckensystemen/Numerical investigations on punching shear capacity of continuous flat slabs

Bauingenieur ◽

10.37544/0005-6650-2018-04-57 ◽

2018 ◽

Vol 93 (04) ◽

pp. 141-151

Author(s):

D. Kueres ◽

P. Schmidt ◽

S. Bosbach ◽

M. Classen ◽

M. Herbrand ◽

...

Keyword(s):

Shear Capacity ◽

Punching Shear ◽

Numerical Investigations ◽

Flat Slabs ◽

Finite Elemente

Das Durchstanztragverhalten von Stahlbetonplatten wird seit mehreren Jahrzehnten experimentell erforscht. Aufgrund des hohen Kosten- und Arbeitsaufwandes von Durchstanzversuchen an Flachdeckensystemen wurde der Großteil der vorhandenen Durchstanzversuche an isolierten Flachdeckenausschnitten durchgeführt. Die Geometrie der Versuchskörper wurde dabei mit dem Ziel gewählt, den Stützmomentbereich um die jeweils betrachtete Decke-Stütze-Verbindung zu simulieren. Günstige Einflüsse, die sich in Flachdeckensystemen zum Beispiel aus Momentenumlagerungen oder Druckmembrantragwirkung ergeben, können in diesen Versuchen nicht auftreten. Daher eignen sich die vorhandenen Versuche in erster Linie zur sicheren Abschätzung der Durchstanztragfähigkeit.   Aufbauend auf theoretischen und experimentellen Untersuchungen aus der Literatur, wird in diesem Beitrag die Durchstanztragfähigkeit von Flachdeckensystemen anhand von nicht-linearen Finite-Elemente-Simulationen genauer untersucht. Das verwendete numerische Modell wird zunächst anhand von Durchstanzversuchen validiert. Nachfolgend wird das Modell für weiterführende Parameterstudien verwendet, um die Unterschiede zwischen Flachdeckensystemen und –ausschnitten genauer zu analysieren. Die Ergebnisse der numerischen Untersuchungen werden abschließend dafür genutzt, einen praxistauglichen Ansatz zur Bestimmung der Durchstanztragfähigkeit von Flachdeckensystemen im Bereich von Innenstützen abzuleiten.

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Punching shear behaviour of flat slabs with different reinforcement schemes: openings and rectangularity effects

International Journal of Structural Integrity ◽

10.1108/ijsi-08-2020-0079 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Donia Salman ◽

Rabab Allouzi ◽

Nasim Shatarat

Keyword(s):

Structural Engineering ◽

Experimental Tests ◽

Shear Capacity ◽

Punching Shear ◽

Shear Behaviour ◽

Cross Sectional ◽

Content Type ◽

Flat Slabs ◽

Reinforced Concrete Slabs ◽

Rectangular Columns

PurposeThe main goal is to investigate the effect of size and location of opening and column size on the punching shear strength. Openings are often needed in order to install mechanical and electrical services. This process takes away part of the concrete volume which is responsible for resisting the shear forces and any unbalanced moment. Furthermore, the application of rectangular columns in flat slabs is commonly used in practice as they provide lateral stiffness to the building. They are also utilised in garages and multi-storey buildings where these elongated cross-sectional columns reduce the effective span length between adjacent columns.Design/methodology/approachThis research is a numerical-based investigation that is calibrated based on a thirteen previously tested and numerically calibrated slab specimens with no openings. A parametric study is conducted in this study to consider the effect of other parameters, which are the size and location of opening and the rectangularity ratio of column in order to evaluate their effect on the punching shear capacity. A total of 156 models are developed to study these factors. Additionally, the predicted shear carrying capacity of the simulated slabs is calculated using the ACI318–19 and Eurocode (EC2-04) equation.FindingsThe presence of openings reduced the punching shear capacity. The small opening's location and orientation have almost no effect except for one slab. For slabs of large openings, the presence of openings reduced the punching capacity. The punching capacity is higher when the openings are farther from the column. The numerically obtained results of slabs with rectangular columns show lower punching capacity compared to slabs of squared columns with the same length of the punching shear control perimeter. The punching capacity for all slabs is predicted by ACI318–19 and Eurocode (EC2-04) and it is found that Eurocode (EC2-04) provided a closer estimation.Originality/valueThe slabs considered for calibration were reinforced with four different punching shear reinforcement configurations, namely; ordinary closed rectangular stirrups, rectangular spiral stirrups, advanced rectangular spiral stirrups and circular spiral. Generally, there has been limited research on concrete flat slabs with openings in comparison with other subjects related to structural engineering (Guan, 2009) and no research on punching shear with openings of slabs reinforced with these reinforcement schemes. The available research focussed on the effects of openings on the flexural behaviour of reinforced concrete slabs includes Casadei et al. (2003), Banu et al. (2012) and Elsayed et al. (2009). In addition, experimental tests that examined slabs supported on rectangular columns are very limited.

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