scholarly journals Effect of load balancing on punching shear stress and deflection of post tensioning flat slab with different grade of concrete

2018 ◽  
Vol 7 (3.29) ◽  
pp. 157
Author(s):  
Kamal Padhiar ◽  
Dr C. D. Modhera ◽  
Dr A. K. Desai ◽  
Dr S. A. Vasanwala
Keyword(s):  
Shear Stress ◽  
Load Balancing ◽  
Load Balance ◽  
Punching Shear ◽  
Flat Slab ◽  
Flat Slabs ◽  
Equivalent Frame ◽  
Frame Method ◽  
Post Tensioning

Flat slabs are a widely adopted solution now a day for buildings, because of their economic and functional advantages. The main objective of this paper is to analysis of post tensioning flat slab by changing the different parameter such as span of slab, grade of concrete and load balancing and comparing the result such as deflection and punching shear. Grade of concrete and load balance directly influence to the deflection and punching shear of flat slab. So in this paper concrete grade varies M-35 to M-50 is considered and load balance varies from minimum 25% to maximum 100% is considered. The use of ADAPT-PT builder 2015 is recommended because of its friendly use and quick calculation capabilities. Use of the ACI Code equivalent frame method of analysis was performed using said software.  

Internal Force and Deflection Calculation of a Kind of Cellular Hollow Flat Slab Floor

2011 ◽  
Vol 94-96 ◽  
pp. 67-72
Author(s):  
Jin Sheng Han ◽  
Shu Ping Cong
Keyword(s):  
Internal Force ◽  
Thin Wall ◽  
Structural Form ◽  
Flat Slab ◽  
Flat Slabs ◽  
Calculation Results ◽  
Equivalent Frame ◽  
Frame Method

The structural form of a kind of cellular hollow flat slab floor using thin wall plastic boxes was introduced. The equivalent frame method, which was used to analyze the internal force of this kind of cellular hollow flat slab floor, was discussed. Finally, the method to calculate the deflection of cellular hollow flat slab was investigated and some improvements in this method were presented. The effects of the cracks on the stiffness and deflection of hollow flat slabs were taken into account in this method to decrease the error of elasticity calculation results.

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.

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 Design considerations on the influence of slab continuity on punching resistance of flat slabs

2020 ◽  
Vol 13 (6) ◽  
Author(s):  
Fernanda Gabriella Batista Santos Oliveira ◽  
Luis Fernando Sampaio Soares ◽  
Robert Lars Vollum
Keyword(s):  
Shear Crack ◽  
Floor Plate ◽  
Punching Shear ◽  
Fe Modelling ◽  
Flat Slab ◽  
Design Considerations ◽  
Flat Slabs ◽  
Shear Design ◽  
Eurocode 2 ◽  
Modelling Assumptions

abstract: This paper assesses the influence of slab continuity on the punching resistance of a realistically proportioned flat slab floor plate without shear reinforcement. The edge column punching resistance of a symmetric flat slab extending bays in each direction was assessed by means of NLFEA with TNO DIANA, MC2010 levels II, III, IV, Eurocode 2 and NBR 6118. Both Eurocode 2 and NBR 6118 are seen to give similar predictions for punching resistance, while MC2010, which is based on the Critical Shear Crack Theory and depends on how rotations are calculated and FE modelling assumptions, varies significantly with its levels of approximation with Level IV agreeing reasonably well with predictions from NLFEA. Direction for the critical rotations is shown to vary and can also be influenced by the reinforcement over the span. For EC2, NBR 6118 and MC2010 LoA II and III punching shear design are independent of span, unlike the results obtained with MC2010 LoA IV.

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.

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.   

scholarly journals Punching shear in reinforced concrete flat slabs with hole adjacent to the column and moment transfer

2014 ◽  
Vol 7 (3) ◽  
pp. 414-467 ◽  
Author(s):  
D. C. Oliveira ◽  
R. B. Gomes ◽  
G. S. Melo
Keyword(s):  
Reinforced Concrete ◽  
Reinforcement Rate ◽  
Load Test ◽  
Punching Shear ◽  
Test Results ◽  
Flat Slab ◽  
Flat Slabs ◽  
Flexural Reinforcement ◽  
Hole Dimension ◽  
The Moment

The structural behavior and the ultimate punching shear resistance of internal reinforced concrete flat slab-column connections, with one hole adjacent to the column, with or without flexural moment transfer of the slab to the column was investigated. Main variables were: the existence whether or not hole, flexural reinforcement layout and ratio, the direction and sense of the moment transferred and the eccentricity of the load (M (moment transferred to column) / V (shear)) ratio at the connection - 0,50 m or 0,25 m. Seven internal slab-column joining were tested and ultimate loads, cracking, deflections, concrete and reinforcement strains were analyzed. The existence of hole adjacent to the smaller column dimension, the hole dimension, flexural reinforcement rate and placing, the variation of relation Mu/Vu in function of the load, and, than, of eccentricity of the load, influenced the slabs behavior and rupture load. Test results were compared with the estimations from CEB-FIP/MC1990 [7], EC2/2004 [12], ACI-318:2011 [1] and NBR 6118:2007 [5]. ACI [1] and EC2 [12] presented most conservative estimates, although have presented some non conservative estimates. Brazilian NBR [5], even though being partly based in EC2 [12], presented smaller conservative estimates and more non conservative estimates. A modification on all codes is proposed for taking in account the moment caused by the eccentricity at the critical perimeter for slabs with holes.

scholarly journals Fiber Reinforced Polymer Laminates for Strengthening of RC Slabs against Punching Shear: A Review

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 685 ◽  
Author(s):  
Osama Ahmed Mohamed ◽  
Manish Kewalramani ◽  
Rania Khattab
Keyword(s):  
Shear Strength ◽  
Shear Capacity ◽  
Fiber Reinforced Polymer ◽  
Punching Shear ◽  
Fiber Reinforced ◽  
Flat Plates ◽  
Flat Slab ◽  
Flat Slabs ◽  
Reinforced Polymer ◽  
Floor Systems

Reinforced concrete flat slabs or flat plates continue to be among the most popular floor systems due to speed of construction and inherent flexibility it offers in relation to locations of partitions. However, flat slab/plate floor systems that are deficient in two-way shear strength are susceptible to brittle failure at a slab–column junction that may propagate and lead to progressive collapse of a larger segment of the structural system. Deficiency in two-way shear strength may be due to design/construction errors, material under-strength, or overload. Fiber reinforced polymer (FRP) composite laminates in the form of sheets and/or strips are used in structurally deficient flat slab systems to enhance the two-way shear capacity, flexural strength, stiffness, and ductility. Glass FRP (GFRP) has been used successfully but carbon FRP (CFRP) sheets/strips/laminates are more commonly used as a practical alternative to other expensive and/or challenging methods such column enlargement. This article reviews the literature on the methodology and effectiveness of utilizing FRP sheets/strips and laminates at the column/slab intersection to enhance punching shear strength of flat slabs.

scholarly journals Behaviour of Strengthened Flat Slab with Opening at Edge Column under Punching Shear Strength

2020 ◽  
Vol 9 (3) ◽  
pp. 1039-1045
Keyword(s):  
Shear Strength ◽  
Punching Shear ◽  
Shear Behaviour ◽  
Slab Thickness ◽  
Control Specimen ◽  
Flat Slab ◽  
Flat Slabs ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Critical Problems

Flat slab system is widely used because of its architectural flexibility Punching is one of the major and critical problems in flat slab especially for the edge column. There are many traditional ways to increase the punching shear strength of concrete slabs like increasing the slab thickness or column dimensions which is against the architectural desire Using FRP strengthening for the flat slabs against punching shear can be considered as a new application. Sometimes an opening is needed to be punched through existing slabs to install cables, elevators and ventilation systems, etc. This causes weakening due to the cutting of concrete and reinforcing steel and also increases the punching problems especially if the opening beside the edge columns. This research is aimed to evaluate the effects of strengthening with Glass Fiber Reinforced Polymer (GFRP) on the punching shear behaviour of flat slab with an opening varying in location with respect to the edge column. Bearing capacity, deflection, ductility, energy absorption and stiffness obtained from the tested slabs are compared to the control specimen, which was without opening and strengthening. It is observed that, the punching shear capacities of the strengthened specimens significantly increased compared to control specimen. Creating openings in flat slab beside the edge column should be approached with great caution and avoided if possible because of its bad effects. In case of openings are of extreme necessity, it is recommended to be created in the front of the edge column not in the side

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