scholarly journals Performance of Shear Reinforcement against Punching Shear Loads

2019 ◽  
Vol 9 (2) ◽  
pp. 841-850
Keyword(s):  
Numerical Study ◽  
Shear Capacity ◽  
Punching Shear ◽  
Slab Thickness ◽  
Test Results ◽  
Shear Reinforcement ◽  
Concentrated Load ◽  
Flat Slab ◽  
Flat Slabs ◽  
Strength Formula

This research targets to maximize the ductility and strength of the reinforced concrete flat slabs. However, to be efficient, the shear reinforcement must be anchored well in the tension and compression zones of the slab. The test results on the slab-column connection models which provided with shear reinforcement are introduced in this study. The benefits of using shear reinforcement are to reduce the slab thickness, and to minimize both the cost and the total weight of the structure. Twelve flat slab specimens have been tested to study the effect of different types of steel RFT on the punching shear of the flat slab. The experimental parameters include no shear reinforcement which study the advantage of using tension RFT ONLY against punching shear, no shear reinforcement which study the advantage of using compression RFT against punching shear, shear RFT (Vertical Stirrups) which study the effect of using shear RFT with constant distribution 0.5d, and a new distribution of shear stirrups which study the effect of using new different width & spacing of vertical stirrups. The twelve specimens were loaded with concentrated load at the mid span until failure. The general behavior of the deformation of the tested slab specimens was examined and recorded (cracking, deflection, and strain in both steel and concrete). A comparison established between the experimental and the numericaltheoretical results obtained from applying the punching shear strength formula given in design codes, and finite element modeling analysis; ABAQUS 2017 software package was used for this analysis. A total of six building codes were examined with regard to their provisions concerning the punching shear. A comparison had been made between the research test results and the codes equations to improve the methods of the analysis about the flat slabs. This study aimed to improve the punching shear capacity of flat slab which leads to more accurate results compared with the codes predictions. To achieve this aim, an experimental and numerical study was carried out for this investigation.

scholarly journals PERILAKU PUNCHING SHEAR PADA HUBUNGAN KOLOM BULAT DENGAN FLAT SLAB AKIBAT BEBAN TEKAN AKSIAL

2019 ◽  
Vol 1 (1) ◽  
pp. 1-14
Author(s):  
Muhammad Zardi
Keyword(s):  
Concrete Strength ◽  
Load Condition ◽  
Maximum Load ◽  
Shear Capacity ◽  
Punching Shear ◽  
Shear Reinforcement ◽  
Eccentric Load ◽  
Flat Slab ◽  
Circular Column ◽  
Flat Slabs

The aim of the tests was to investigate the influence of concrete strength, the eccentricity of the column and the use of shear reinforcement in flat slabs on punching shear. The research specimens are 8 units of flat slabs. Flat slab size 1400 x 1400 mm2 with thickness of 120 mm. Flat slabs were connected with circular column with dimension 225 mm  of diameter and 200 mm of height. Flat slabs were made in to 2 variations of concrete strength, e.i. 30 MPa and 60 MPa, 2 variations of shear reinforcement, e.i. without shear reinforcement and with shear reinforcement and 2 variations of eccentricity that, e.i. without eccentricity and with eccentricity. Each treatment has 1 specimen. Each specimen has 6 cylinder specimens. Cylinder specimens used as a concrete strength control for main specimen (flat slab). The tests showed that the concrete strength had a strong influence on punching shear strength. This is shown by capacity increase of 42.78%; 54.00%; 46.59% and 0.02%. The value is ratio between the maximum load of the specimens with 60 MPa and 30 MPa at the same eccentricity and the same shear reinforcement. The eccentricity of column reduce the capacity of punching shear. This is shown by 3 specimens decrease in capacity of 3.70%; 36.75% and 7.30%. Only 1 specimen that increase in capacity of 9.27%. The value is ratio between the maximum load of the specimens with 40 mm eccentricity and 0 mm eccentricity at the same compressive strenght and the same shear reinforcement. The use of shear reinforcement does not always increase the punching shear capacity. There are 2 observations that increased capacity (52.07% and 65.37% at the centric load) and 2 observations decreased capacity (0.12% and 4.92% at the eccentric load). The value is ratio between the maximum load on the specimens using shear reinforcement with the specimens that do not use shear reinforcement at the same compressive strenght and the same eccentricity.The use of shear reinforcement increase punching shear capacity of flat slab at the centric load condition. The use of shear reinforcement decrease punching shear capacity of flat slab at the eccentric load condition.

scholarly journals An Analytical and Numerical Investigation on Punching Shear Behaviour of SCC Slab

2016 ◽  
Vol 3 (3) ◽  
Author(s):  
V. Kavinkumar ◽  
R. Elangovan
Keyword(s):  
Shear Stress ◽  
Shear Failure ◽  
Shear Capacity ◽  
Punching Shear ◽  
Shear Behaviour ◽  
Slab Thickness ◽  
Failure Zone ◽  
Self Compacting Concrete ◽  
Concentrated Load ◽  
Different Thickness

<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>

scholarly journals Investigation of the effects of opening size and location on punching shear resistance of flat slabs using Abaqus

2021 ◽  
Vol 15 (4) ◽  
pp. 136-147
Author(s):  
Nguyen Tuan Trung ◽  
Pham Thanh Tung
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Numerical Study ◽  
Shear Resistance ◽  
Design Principles ◽  
Numerical Results ◽  
Punching Shear ◽  
Shear Reinforcement ◽  
Flat Slabs ◽  
Abaqus Model

The paper presents a numerical study on the effects of opening size and location on punching shear resistance of flat slabs without drop panels and shear reinforcement using ABAQUS. The study proposes an ABAQUS model that is enable to predict the punching shear resistance of flat slabs with openings. The model is validated well with the experimental data in literature. Using the validated numerical model, the effects of opening size and location on the punching shear resistance of flat slabs are then investigated, and the numerical results are compared with those predicted by ACI 318-19 and TCVN 5574:2018. The comparison between experimental and numerical results shows that the ABAQUS model is reliable. The punching shear resistances calculated by ACI 318-19 and TCVN 5574:2018 with different opening sizes and locations are agreed well to each other, since the design principles between two codes now are similar.

scholarly journals New Methods to Resisting Punching Shear Stress in Reinforced Concrete Flat Slabs

2018 ◽  
Vol 8 (02) ◽  
Author(s):  
Fatma M. Eid ◽  
Tayel Magdy ◽  
Ebada Ahmed
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Shear Capacity ◽  
Punching Shear ◽  
Shear Reinforcement ◽  
Reinforcement System ◽  
Strength Concrete ◽  
Flat Slabs ◽  
The Difference ◽  
Compact Strength

Punching shear failure is a major problem encountered in the design of reinforced concrete flat slabs. The utilization of shear reinforcement via shear studs or other means has become a choice for improving the punching shear capacity. In this study, a new alternative of reinforcement modalities were tested and demonstrated the effect of self-compact concrete on the punching shear capacity, beside that compared between the difference codes to identify the suitable one for determining the position of critical section of punching shear. Nevertheless, in this investigation, the proposed reinforcement system is examined for interior columns only. An experimental work consisting of six specimens: five of them were cast with normal reinforced concrete and one was cast with self-compact strength concrete. The obtained results indicate that the proposed shear reinforcement system has a positive effect in the enhancement of the punching shear capacity of interior slab–column connection of self-compact strength concrete.

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.

The Effect of Anchorage Strength with Anchorage Capacity in Flat Plate

2014 ◽  
Vol 627 ◽  
pp. 245-248
Author(s):  
Hyun Ki Choi
Keyword(s):  
Shear Strength ◽  
Flat Plate ◽  
Shear Failure ◽  
Punching Shear ◽  
Slab Thickness ◽  
Shear Reinforcement ◽  
Strength Formula ◽  
Test Result ◽  
Plate System ◽  
Structure Test

The punching shear on the flat plate slab-column connection can bring about the reason of the brittle punching shear failure which may result of collapsing the whole structure. From the development of residential flat plate system, the shear reinforcement is developed for preventing the punching shear. This study proposed 3 reinforcements that are increased to bond capacity using lateral bar, the structure test is performed. As performed test result, because slabs not keep enough bond length, slab is failed before shear reinforcement's yield strength duo to anchorage of slip. According to result, FEM analyzed an effect of slab thickness and concrete compressive. The study suggests shear strength formula that possible a positive shear reinforcement in slab-column connection.

Optimization of a flat slab with different type of punching reinforcement

2021 ◽  
Vol 16 (1) ◽  
pp. 52-57
Author(s):  
Petra Bujňáková ◽  
Jakub Mečár
Keyword(s):  
Shear Failure ◽  
Punching Shear ◽  
Shear Reinforcement ◽  
Flat Slab ◽  
Flat Slabs ◽  
Extreme Load ◽  
New Construction ◽  
New Type ◽  
Shear Reinforcements ◽  
Conventional Type

AbstractSeveral types of punching shear reinforcements are available for increase of the maximum resistance against punching shear failure of flat slabs. Conventional punching shear reinforcement in form of stirrups or double headed studs are in use for decades. They are well known due to their simplicity and good performance. A new type of punching reinforcement has been developed for the case, where the flat slab exposed to extreme load and resistance of conventional type of punching shear reinforcement is not sufficient. Another designs point out that new construction system can reduce the amount of CO2. This paper presents some results of parametric study focused on design of the flat slab using different types of punching shear reinforcement and considering the concrete consumption.

Screw Anchors Used as Post-Installed Shear Reinforcement in Flat Slabs

2018 ◽  
Vol 272 ◽  
pp. 53-63 ◽  
Author(s):  
Ondrej Keseli ◽  
Juraj Bilčík ◽  
Ivan Hollý
Keyword(s):  
Punching Shear ◽  
Slab Thickness ◽  
Shear Reinforcement ◽  
Lower Face ◽  
Existing Structures ◽  
Flat Slabs ◽  
Parking Garages ◽  
Upper Face ◽  
Deformation Level ◽  
The Moment

More restrictive requirements of new codes, increasing of imposed loads connected with usage change of the existing structures, errors in design process or during execution can lead to necessity of the strengthening of the existing buildings. In paper, the new and modern strengthening system of flat slabs against punching shear using screw anchors is presented. Screw anchors are installed from lower face of the slab into vertically drilled boreholes. After the installation, the screw anchors operate as punching shear reinforcement. The advantages of the system are significant resistance and deformation capacity increment of the flat slab as well as easy and fast installation with no need to drill through the whole slab thickness and access the upper face of the slab. System is suitable for strengthening of office buildings, since removal of the flooring is not needed or in parking garages, where the water resistance is not disturbed by the system. Moreover, paper deals with special problems that are connected with design of the presented strengthening system e.g. considering of load (deformation) level of the slab at the moment of strengthening, performance of the screw anchors in cracked and non-cracked concrete and anchorage conditions improvement of the screw anchors by application of glue or mortar into the borehole prior the screw installation.

Review of the Punching Shear Behavior of Concrete Flat Slabs in Ambient and Elevated Temperature

2013 ◽  
Vol 4 (4) ◽  
pp. 259-280 ◽  
Author(s):  
Mehrafarid Ghoreishi ◽  
Ashutosh Bagchi ◽  
Mohamed Sultan
Keyword(s):  
Elevated Temperature ◽  
Shear Failure ◽  
Shear Behavior ◽  
Shear Capacity ◽  
Punching Shear ◽  
Ambient Conditions ◽  
Flat Slab ◽  
Flat Slabs ◽  
Analytical Studies ◽  
In Fire

There are a number of benefits associated with two-way concrete flat slab construction for office buildings, parking garages and apartments - for example, reduced formwork, prompt erection, flexibility of partitions, and minimal increase in story heights. However, concrete flat slabs could be quite vulnerable to punching shear failure in the event of a fire. The objective of the present article is to provide a state of the art review of the existing research and the issues associated with concrete flat slabs in fire and elevated temperature. There are a number of experimental and analytical studies on the punching shear behavior of concrete flat slabs in ambient conditions, available in the literature. Based on these studies, it is found that punching shear capacity in ambient condition is affected by many factors, which may not remain constant during a fire exposure. Only a limited number of studies on concrete flat slabs for punching shear failure in fire are available. This paper reviews the available experimental and analytical studies, standards and codes to address the research gap in estimating of punching shear strength of concrete flat slab-column connections without shear reinforcement.

scholarly journals A Comparative Study of Flat Slabs Using Different Shear Reinforcement Parameters

2018 ◽  
Vol 7 (2.20) ◽  
pp. 321
Author(s):  
N Girish ◽  
N Lingeshwaran
Keyword(s):  
Reinforced Concrete ◽  
Brittle Failure ◽  
Shear Failure ◽  
Crack Pattern ◽  
Steel Plates ◽  
Punching Shear ◽  
Shear Reinforcement ◽  
Flat Slab ◽  
Flat Slabs ◽  
Four Corners

Punching shear failure is a brittle failure and it is one of the most important types of failure to be considered while designing a reinforced concrete flat slab. This paper aims to study the performance of reinforced concrete flat slabs equipped with different punching shear reinforcement parameters. Three flat slab specimens were cast where two specimens contain punching shear reinforcement in the form of shear stirrups and structural shearbands. The test specimens have length and width of 1000mm and thickness of 185mm for the slabs. The slabs are connected to a column at the center with length and breadth of 300mm and a depth of 700mm. The test specimens were supported by steel plates with length and breadth of 150mm and a thickness of 25mm at the four corners of the slab. The test specimens are loaded on the column face at the top. The deflection, strain and crack pattern were observed and recorded.   

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