Flat Slab Punching Shear Design

The slab is for an offi ce where the specifi ed load is 1. the slabs supported directly on columns, without beams between columns. flat slabs subjected to flexure-induced punching. Ancon Shearfix is installed within a concrete slab to reinforce column heads against punching shear. Direct design method: (Cl. This paper compares design provisions for punching shear at internal columns in the superseded British Standard BS 8110, Eurocode 2 (EC2) and fib Model Code 2010 (MC2010). FLAT SLAB DESIGN IN SAFE - Duration: How we resist the punching shear around the columns | Drawing plan of Shear reinforcement - Duration: 3:37. The punching shear strength is an extremely significant parameter for the design of flat slabs, i. The following features are supported in term of punching shear checks and design. Punching Shear in Post-Tensioned Flat Slabs with Stud Rail Shear Reinforcement by Alessandra L. Flexural and Punching Shear Design of FRP RC Flat Slabs Flexural and Punching Shear Design of FRP RC Flat Slabs Dr Abdel Wahab El-Ghandour Lecturer (Ain Shams Univ. 1, IS456-2000). Flat-slab construction has been widely used in construction today because of many advantages that it offers. Therefore, a stress demand/stress approach is assumed. 8√fcu or 5 N/mm 2 where u0 is the perimeter of the load area 2. Steps involved in the design of flat. The story height is 3. - If punching shear is the governing design criterion for flat slabs, the live load can be increased for a given thickness of the slab if shear reinforcement is provided. 1) One-way (beam) shear 2) Two-way (punching) shear. The following features are supported in term of punching shear checks and design. Verification of the shear capacity at the control perimeters around a rectangular column. The development of high-performance materials and advanced computational tools has allowed the building of relatively thin concrete slabs supported on columns. 0-nHiiameter column capitals. Τhe LSF on top of the upper FLAT SLAB TESTING. Ancon® Shearfix Punching Shear Reinforcement. Punching shear calculations are provided for columns/pedestals that land on concrete slabs. For the flat slab, funnel-shaped punching shear preventer shown in Figure 1(a) is sometimes used to increase the punching shear strength of flat slab-to-column connection. Flat slab is a reinforced concrete slab supported directly by concrete columns without the use of beams. From the above discussion we can see that the providing the shear reinforcement is the best method to solve the problem of punching shear. The punching shear design according to EN 1992-1-1 checks that the acting shear force vEd does not exceed the resistance vRd. Design Considerations. The openings (one or two) were adjacent to the shorter. Good Question! There are generally 4 methods used to overcome shear failure in general. A flat slab may come in the form of solid slab or contain recesses developed on the soffit in order that the soffit contains a series of ribs in two directions. used as a basis for refinement of existing punching shear models and further development of modern design provisions in this field. Factored footing pressure is used to determine footing depth and reinforcement. 1, IS456-2000). Behavior of flat slabs in shear and flexure is a fairly complex problem. Around the columns, the shear stresses create a high risk for punching shear. These materials are originally located at different websites. The effects of flexural reinforcement and shear reinforcement on the punching shear strength of slab-column connections are analyzed in this study. For the flat slab with the general arrangement as shown below, let us design the punching shear for column B1 given the following design information; Ultimate axial force on column V Ed = 400 kN Thickness of slab = 250 mm. Description. Methods adopted to enhance the punching shear strength of flat slabs are also discussed. Abstract Flat slab system is becoming widely popular for multistory buildings due to its several advantages. , see Moehle, 1989). Capping Beam Design. CIVIL ENGINEERING. • Members which fail due to punching are often examined at regions near to the columns, with a pyramid-like diagonal crack occurring at the distance surrounding the column. By simplifying slab reinforcement at column locations and eliminating column capitals, stirrup cages, or I -beam shear heads, they enable efficient design and rapid construction of flat plate concrete floor slabs. PURPOSE: A shear stiffener for a reinforced concrete flat slab is provided to prevent the crack and damage of a slab caused by a vertical shear force. I have trying to verify the punching shear of the columns but for some reason I don't know, SAFE won't calculate the punching shear on the perimeter columns ("N/C" result). A flat slab may come in the form of solid slab or contain recesses developed on the soffit in order that the soffit contains a series of ribs in two directions. simplified yet realistic analytical design expressions for predicting the punching shear strength of hybrid flat slab systems with and without shear reinforcement are proposed. [FIGURE 1 OMITTED] Codes' recommendation Punching strength according to the NBR 6118 The calculation model of resistance to punching in flat slabs without shear reinforcement, according to the Brazilian standard NBR 6118 (ABNT, 2014) suggests the verification of two control perimeters, C and C'. Finite element analysis of reinforced concrete slabs subjected to punching load is evaluated and results are compared with. Loading scheemes 9. Ancon Shearfix is installed within a concrete slab to reinforce column heads against punching shear. The shear stud used is the same type as used in conventional steel or concrete composite beams. The use of flat plate system will be checked. Punching shear may result from a concentrated load or reaction acting on a relatively small area. punching shear and avoid triggering of progressive collapse. Due to the sudden and brittle nature of punching shear failures, slab-column connection design must be conducted with proper safety precautions. to brittle punching shear failure. File name: Punching shear - ACI code. Slide 10 Flat Plate Photo courtesy of the Godden Collection, Earthquake Engineering Library, University of California, Berkeley Slide 11 Slab Drop Panels Column Capitals Flat Slab with Drop Panels & Capitals Drop panels and column capitals. Design of Waffle Slab (without beams) by Direct Design Method Punching shear force in slab 20. Therefore, the punching shear failure belongs to one of the most critical aspects in the design of concrete buildings. 1 Definition and construction The flat slab is defined in Hong Kong Code of Practice: Structural Use of Concrete 2013 (COP2013) as a slab with or without drops, supported generally without beams by columns with or without column heads. Flexural and Punching Shear Design of FRP RC Flat Slabs Flexural and Punching Shear Design of FRP RC Flat Slabs Dr Abdel Wahab El-Ghandour Lecturer (Ain Shams Univ. Long term deflection of the flat plate. Punching shear is a phenomenon where a concentrated force on a slab causes a shear failure cone that "punches" through. This demand may be effectively addressed by changes in dimensions of certain members, or their material strengths (for example, shear walls and column sizes), or provision of shear reinforcement or a combination thereof. Punching Shear in Post-Tensioned Flat Slabs with Stud Rail Shear Reinforcement by Alessandra L. In consequence of limited anchorage conditions of punching shear reinforcement elements in flat slabs depending on the effective depth, only a reduced steel strength may be used in the calculation of the steel contribution. Without Beams, Flat Plates and Flat Slabs Tests of flat plate structures indicate that in most practical cases, the capacity is governed by shear. While in many former codes the punching shear resistance was determined regardless of the type of member, in Eurocode 2 two different design equations for flat slabs and column bases were introduced. Introduction 1Flat slabs used a lot in multi stories structures because. method of providing Punching Shear Reinforcement around columns, and piles with-in flat slabs and post-tensioned slabs, at slab to shearwall junctions, beam to col-umn junctions and within footings and foundation slabs. Punching of flat slabs - design for shear at th e column heads 12. This is done assuming k sys=2. Design of flat plate slab and its Punching Shear Reinf. For the flat slab with the general arrangement as shown below, let us design the. Chapter 2 should be followed except for minimum shear reinforcement. PUNCHING SHEAR BEHAVIOR OF FIBER REINFORCED POLYMERS REINFORCED CONCRETE FLAT SLABS: EXPERIMENTAL STUDY. Punching strength of flat slabs with and without shear reinforcement The punching shear strength is an extremely significant parameter for the design of flat slabs, i. KEYWORDS –ANSYS, Drop Panel, Flat Slab, Punching. In the figure-1, D ped is the depth of the pedestal. Ubani Obinna Ranks on. The different punching shear design provisions are critically reviewed by means of parameter studies and a comparison of the calculated resistances and test results. This study addresses design aspects for the punching shear bolt retrofitting system for reinforced concrete flat slabs supported on columns. 1 - Punching failure surfaces of flat slab Fig. Concrete flat slabs and footings: Design method for punching and detailing for ductility Broms, Carl Erik KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges. Introduction Punching of reinforced concrete (RC) slabs is investigated [1, 2]. Volume 3, Issue 10, April 2014 138 Abstract— “Flat Slab” is better understood as the slab without beams resting directly on supports (like columns & or walls). The first part of this thesis discusses previous research on the tensile membrane action of reinforced concrete slabs and the use of structural. Later on, Hong. If the design shear vEd exceeds the shear capacity vRd,c the program computes the necessary shear (links) reinforcement. This article presents an alternative method for designing concrete flat slabs subjected to flexure-induced punching. The system consists of double-headed studs welded to flat rails, positioned around the column head or base. ESCRIPTION. 3 of ACI 318 allows the use of shear reinforcement for slabs and footings in the form of bars, as in the vertical legs of stirrups. of Sheffield). Punching shear, or two-way shear, at column supports is often the controlling factor in establishing a slab thickness. 4 A 3 2 1 B C D X Y 0. 4-m-diameter columns with 1. There are two main failure modes of flat slabs: Flexural Failure. reinforcement, bending moment, shear force, span to slab depth ratio and slab thickness. Reasons are several, like design or construction errors, poor quality materials, not complying with new codes provisions, or increase of vertical load. A primary concern in the design of reinforced concrete flat slab structures is that of punching shear at the slab-column connections. Link for download Slab Punching Shear Calculation Spreadsheet. This study addresses design aspects for the punching shear bolt retrofitting system for reinforced concrete flat slabs supported on columns. In flat-plate floors, slab-column connections are subjected to high shear stresses produced by the transfer of axial loads and bending moments between slab and columns. Provisions of the 2004 version of the Canadian standard A23. The total cost represents the cost of concrete, strand tendons, steel, duct, grout, anchorages device and formwork for the slab. (Schedule Of Rates 2008-09). The study was part of a larger national and multidisciplinary project about fire safety of car parks, from which. Punching Shear Design. A flat slab may come in the form of solid slab or contain recesses developed on the soffit in order that the soffit contains a series of ribs in two directions. PUNCHING SHEAR • always a critical consideration in flat plate design around the columns • instead of using thicker section, shear reinforcement in the form of shear heads, shear studs or stirrup cages may be embedded in the slab to enhance shear capacity at the edges of walls and columns. The objective is to cover the design procedure in most practical situations including: interior, edge and corner columns, prestressed and nonprestressed slabs. The potential of punching shear failure of flat-plate structures under combined effects of vertical and horizontal ground motion is examined based on the three design criteria given in ACI 318-14: eccentric shear stress model, story design drift limit for slab-column connections without shear reinforcement, and two-way shear strength for one. Design Example of Punching Shear in Slabs (Eurocode 2) by. Around the columns, the shear stresses create a high risk for punching shear. With new punching shear design guidance in hand, Benmokrane proceeded in 2010 to use GFRP reinforcement in one portion of a large city-owned parking garage that was undergoing rehabilitation at Québec’s city hall. Normal design practice is to always control for punching shear in cases where the structure functions as a flat slab. It can also recognize openings and design for punching shear accordingly. File name: Punching shear - ACI code. for shear in one-way slabs and punching shear (Mut-toni 2003a, 2003b and 2003c) were recently included in the new version of the Swiss code for structural concrete (SIA 262, 2003), which can be considered to be fully based on this theory for the shear design of members without stirrups. Here, we have tried to gather various reading materials available in the web about flat slab floor system in one place. The shear stress distribution in the slab around the column becomes non-. Generalnsideration Co s for use of Flat slab Floor System The following are the main factors to be considered before adopting the use of the concrete flat plate with steel/concrete column system. Description. Direct design method: (Cl. In flat slab system two types of failure occurs namely flexural failure and punching shear failure. On the other hand, a limited number of analytical work is done using self-developed programs, commercial software, or by utilizing mathematical model. A variety of factors can reduce the punching shear design capacity, including openings and construction tolerances. Equivalent frame method. Punching shear may result from a concentrated load or reaction acting on a relatively small area. punching shear capacity in the test specimen with shear stud reinforcement. Flat slab, Punching shear: Design of slab section in punching shear according to Eurocode 2 § 6. (300 mm) reinforced concrete flat slab for the 450,000 square foot (42,000 m2) addition. This type of failure is one of the most critical considerations when determining the thickness of flat slab at the slab-column intersection. Modeling Structure RFEM 5 allows you to perform the punching shear design for both 2D slab and 3D structures. The utilization of shear reinforcement via shear studs or other means has become a choice for improving the punching shear capacity. For ease of reference, the following description of the task solution is based on the punching failure verification model presented in EC2 —see Fig. 1Flat slabs used a lot in multi stories structures because of such advantages as: flat ceiling, low formwork, and reduce story height. It provides a great deal of flexibility in the placement of the structure’s vertical load-carrying elements as could potentially be the case with steel or masonry. A civil engineer should study these lectures and materials for structural engineering acumen. Hence it is necessary to re-examine the applicability of the present punching shear design methods for HSC slabs, using the published data. Let us know if you'd like to see. Design of the shear reinforcem ent vEd ≤ vRd,cs vRd,cs is the design value of the spe- cific punching shear capacity of the slab designed with shear reinforcement along the section investigated (N/mm 2): vRd,cs =0,75 vRd,c+ nA sw fywd,ef sinα u d 1 1 where: n= sr. The purpose of this example is to verify slab punching shear design in SAFE. The increase in load factor compared to slabs according to Eurocode 2 without punching shear reinforcement is αFDBII = 2. An effective shear area factor, γ, is therefore introduced to simulate the loss of shear area and which is the ratio of the projected section area A DEF to A ABC as indicated in the following. Punching Shear Design. In order to. Although generally preceded by flexural failure, punching shear is a brittle failure mode and the risk of progressive collapse requires a higher safety class in structura. of a flat slab structure the application of pure gravity or shear loading may trigger punching failure. The lateral loads are independently resisted by shear walls. Design of slab for punching shear. doc Punching shear stress check and reinforcement design based on ACI code Categorization of columns: Based on the geometry of the floor slab at the vicinity of a column, each column is categorized into to one of the following options: 1. Introduction Punching of reinforced concrete (RC) slabs is investigated [1, 2]. The remaining percentage of the unbalanced bending moment will be converted as shear which is given by equation 11-37. An effective shear area factor, γ, is therefore introduced to simulate the loss of shear area and which is the ratio of the projected section area A DEF to A ABC as indicated in the following. Carvalho, Guilherme S. Slide 10 Flat Plate Photo courtesy of the Godden Collection, Earthquake Engineering Library, University of California, Berkeley Slide 11 Slab Drop Panels Column Capitals Flat Slab with Drop Panels & Capitals Drop panels and column capitals. I am unable to understand what is happening when i import a roof slab. The punching shear design of flat slabs and column bases was revised with the introduction of Eurocode 2. Then, the results are used to determine the failure mode. Flexural and Punching Shear Design of FRP RC Flat Slabs Flexural and Punching Shear Design of FRP RC Flat Slabs Dr Abdel Wahab El-Ghandour Lecturer (Ain Shams Univ. It's a function of column footprint and slab thickness. This is reflected in the codes of practice covering the design of such structural systems where the conservative. In addition, Wenyuan Wang et al. Tekla Structural Designer allows you to check for punching shear in your structural flat slabs. (Schedule Of Rates 2008-09). design problems of slab-column connections in flat plate structures is the punching shear failure at overloads. (Schedule Of Rates 2008-09). Conversely the thickness of the slab (and/or the size of the column) can be diminished - The remarkable increase in ductility enhances safety of flat slabs with transverse. "Punching shear design of earthquake resistant slab column connections" by Sami Megally and Amin Ghali, ACI Structural Journal, Title No. 3 related to punching shear design of reinforced concrete flat plates at their connections with columns are reviewed, with attention to the changes introduced in 2004. Design elevated concrete slabs with or without post-tensioning. This demand may be effectively addressed by changes in dimensions of certain members, or their material strengths (for example, shear walls and column sizes), or provision of shear reinforcement or a combination thereof. Traditionally designed as gravity load carrying systems, flat slabs are found even in earthquake prone areas. The lateral loads are independently resisted by shear walls. The punching shear strength is an extremely significant parameter for the design of flat slabs, i. Ubani Obinna Ranks on. Round slab thickness up to the nearest ¼”. I am trying to do a flat slab design and at the moment I have Dead loads applied straight after construction while concrete slab is supported and Live loads applied at a later stage. Punching shear is a phenomenon in flat slabs caused by concentrated support reactions inducing a cone shaped perforation starting from the top surface of the slab. Τhe LSF on top of the upper FLAT SLAB TESTING. At the same time, the practical applications of. used as a basis for refinement of existing punching shear models and further development of modern design provisions in this field. Keywords: punching shear, flat slab, flat foundation, mini-max principle, reinforced concrete. Nowadays, a considerable number of flat slab buildings requires strengthening against punching. The slabs were tested with four sides rigidly supported, three sides supported and two sides supported. Ancon Shearfix Punching Shear Reinforcement System - Used within a slab to provide additional reinforcement around columns, Ancon Shearfix provides an ideal solution to the design and construction problems associated with punching shear. 318-05 design codes and a guide to the new Decon ® STDESIGN V3. The increase in column diameter at the head flaring of column head takes care of punching shear developed at a distance of d/2 all around the junction between the slab and column head. (long narrow slabs). Mahbub-ul-Alam, Asst. A finite element simulation for experimental punching shear behavior of reinforced concrete slab is presented in this paper. The development of high-performance materials and advanced computational tools has allowed the building of relatively thin concrete slabs supported on columns. However, the system is also prone to brittle shear failures at slab-column connections. Punching shear failure of the slab is usually sudden and leads to a progressive collapse of the flat plate structures. Maximum shear stress at the face of the load: vmax = V / u0 d ≤ 0. Here, we have tried to gather various reading materials available in the web about flat slab floor system in one place. Shear considerations can therefore be the controlling factor in determining the required slab thickness or column size, especially of post-tensioned (PT) flat-plates. Punching shear is a phenomenon in flat slabs caused by concentrated support reactions inducing a cone shaped perforation starting from the top surface of the slab. 2R-10, Guide to. Unbalanced moments, transferred between concrete flat plates and columns due to earthquakes, produce shear stresses that increase the vulnerability to brittle punching failure. These stresses, if sufficient and where additional reinforcement has not been provided, would result in the column 'punching' through the slab. Obtained values were compared with the design punching shear of the same slab without an opening, based on that, the influence of this parameter on the behavior of reinforced concrete slabs was determined. 1, IS456-2000). The punching shear provisions of AS 3600-2009,. The flat plate system may save money on formwork, but it requires the use of a heavier slab than a flat slab system. for analysis and design of the flat slab with staggered column by equivalent frame method. SK 9/14 Moment diagram at an internal column of a flat slab where Vt — calculated shear from analysis — moment transferred to column by frame analysis — length Of side of perimeter considered parallel to axis of bending. The shear stud used is the same type as used in conventional steel or concrete composite beams. Prof, CEN, SUB DESIGN OF THE FLAT PLATE SLAB BY DDM DESIGN OF PUNCHING SHEAR REINFORCEMENT Le. 3 m 8 m 8 m 8 m 0. 2R-10, Guide to. For the flat slab with the general arrangement as shown below, let us design the punching shear for column B1 given the following design information; Ultimate axial force on column V Ed = 400 kN Thickness of slab = 250 mm. Melo, Ronaldo B. The number of truncated pyramid-crack interceptors may be increased for heavy punching shear forces. The increase in load factor compared to slabs according to Eurocode 2 without punching shear reinforcement is αFDBII = 2. This demand may be effectively addressed by changes in dimensions of certain members, or their material strengths (for example, shear walls and column sizes), or provision of shear reinforcement or a combination thereof. 3-14, Design of Concrete Structures, and recommendations of ACI 421. For that reason,. When structure is subjected to high lateral forced coming from seismic events. urthermoreF the e ect of some parameters on the resistance was to be compared. In pad foundations, where weight and depth are not so critical, it's effects are satisfied by providing sufficient depth. It is assumed that the crack forms at about 45 degrees (though it may vary between 25-40 degrees) and the failure is in the form of a tru. Available strengthening methods are, however,. These stresses brings about the cracks in concrete & may provoke the failure. Obtained values were compared with the design punching shear of the same slab without an opening, based on that, the influence of this parameter on the behavior of reinforced concrete slabs was determined. for analysis and design of the flat slab with staggered column by equivalent frame method. urthermoreF the e ect of some parameters on the resistance was to be compared. A total of 17 full-scale interior slab–column specimens measuring 2500 mm × 2500 mm reinforced with GFRP and steel bars were constructed and tested under concentric loads until failure. The behaviour and design of flat slabs structures for gravity loads are well established but their seismic behaviour is not well understood and generally found to be unsatisfactory. conventional beam-slab design Other possible flat slab arrangements Waffle slab Band beam slab Flat slab plan and elevation Typical layout and sectional view As built RC flat plate Refer to photograph Note absence of beams What is punching. The purpose of this example is to verify slab punching shear design in SAFE. The basic philosophy in the design of flat slab is to consider only gravity forces; this method ignores the effect of punching shear due to unbalanced moments at the slab column junction which is critical. Guide: Prefabricated punching shear reinforcement for reinforced concrete flat slabs. Punching Shear Design. PINGYU YAN. Stud rails: prefabricated punching shear reinforcement PAUL EVANS, ANCON BUILDING PRODUCTS The loads on a concrete slab supported on a concrete column induce shear stresses in the slab. The punching shear resistance slab-column connection is one of the most important parameters in the design of flat slabs. Using FEA in studying the effect of using embedded steel shear heads on the enhancement of punching shear capacity and behavior of reinforced concrete flat slabs. New Punching Shear Reinforcement for Flat Slabs •Shear design. Strengthening of slab-column connection against punching shear failure with FRP materials This research investigates the effectiveness of NSM strengthening against punching shear failure in flat slabs with CFRP bars. It provides a great deal of flexibility in the placement of the structure’s vertical load-carrying elements as could potentially be the case with steel or masonry. Maximum shear stress at the face of the load: vmax = V / u0 d ≤ 0. Due to the sudden and brittle nature of punching shear failures, slab-column connection design must be conducted with proper safety precautions. The analysis and design follow the equivalent frame analysis method of the ACI code, which considers a one-bay wide strip of the floor system as a continuous frame. method of providing Punching Shear Reinforcement around columns, and piles with-in flat slabs and post-tensioned slabs, at slab to shearwall junctions, beam to col-umn junctions and within footings and foundation slabs. 1 - Punching failure surfaces of flat slab Fig. 1R-08, Guide to Shear Reinforcement for Slabs, and ACI 421. The numerical example is a flat slab that has three 24-foot-long spans in each direction, as shown in Figure 1. To achieve a sufficient punching shear resistance at. Reasons are several, like design or construction errors, poor quality materials, not complying with new codes provisions, or increase of vertical load. Punching Shear Another important consideration when designing two-way slab systems, whether conventionally reinforced or post-tensioned, is punching shear. doc Punching shear stress check and reinforcement design based on ACI code Categorization of columns: Based on the geometry of the floor slab at the vicinity of a column, each column is categorized into to one of the following options: 1. Barros b, Vítor M. Design for punching shear should allow for the effects of moment transfer at the column/slab junction. If the concrete ’s shear capacity is smaller then the actual shear force: 3. By simplifying slab reinforcement at column locations and eliminating column capitals, stirrup cages, or I -beam shear heads, they enable efficient design and rapid construction of flat plate concrete floor slabs. the problem i am facing is that safe is showing punching shear ratio values of the shear wall on which the slab is resting. The existing methods of detailing for punching shear, which range from stirrups, proprietary prefabricated systems of shear ladders and shear hoops to stud rails, do not provide absolute guarantees of safety. Punching Shear of Reinforced Concrete Flat Plates with Openings by Liana L. Based on the approaches proposed in this paper, for hybrid members without shear reinforcement,. Studs are manufactured in virtually any length to suit the depth of slab, but are normally formed in increments of 5 mm within the 130–1000 mm range. In consequence of limited anchorage conditions of punching shear reinforcement elements in flat slabs depending on the effective depth, only a reduced steel strength may be used in the calculation of the steel contribution. The results of the reinforced concrete floor slab and column junction computer model non‐linear numerical analysis are presented and compared with the results of an experimental study. Appropriate design and detailing of the slab-column joints are essential to prevent such failure. Flat Plate Slab System Slabs may be supported by reinforced concrete beams, by masonry or reinforced concrete walls, by. Column heads:. All panels are supported by 0. F&U-FORYOU 17,265 views. Punching Shear Design. Punching Shear • Can govern the depth of a flat slab • Further research required into the mechanism of punching shear • Punching shear reinforcement in flat slabs increased by introduction of EC2 (in comparison with BS8110) • Further reinforcement/depth likely in next iteration of EC2. Suggestions are given for. several aspects of punching shear previously observed in testing as size effect (decreasing nominal shear strength with increasing size of the member). Punching shear failure of the slab is usually sudden and leads to a progressive collapse of the flat plate structures. For the design of punching shear, code provisions rely mostly on empirical methods derived from the test results on simply supported conventional and thin slab specimens. These factors are the influences on the flat two-way floor slab punching shear strength. restraint from shear walls and stiff columns. Interior column. Slab Punching Shear Design P. RC Punching Shear Design Analysis: Input data for the design is a force and an area over which the force acts, e. the behavior of flat slabs by shear heads. Design of slab for punching shear. Design for punching shear. SCADA Pro Flat Slab module for analysis and design is an advanced finite element solution that can operate independently or fully integrated with SCADA Pro Structural Analysis and Design software. Tests have established that punching shear in slabs can be effectively resisted by reinforcement consisting of vertical rods mechanically anchored at the top and bottom of slabs. Although this punching shear stress. Modeling Structure RFEM 5 allows you to perform the punching shear design for both 2D slab and 3D structures. For the flat slab with the general arrangement as shown below, let us design the. Appropriate design and detailing of the slab-column joints are essential to prevent such failure. The bar used in this system has a characteristic yield strength of 500 N/ mm. Tests have established that punching shear in slabs can be effectively resisted by reinforcement consisting of vertical rods mechanically an chored at top and bottom of slabs. , see Moehle, 1989). Loading scheemes 9. The increase in column diameter at the head flaring of column head takes care of punching shear developed at a distance of d/2 all around the junction between the slab and column head. Flat-slab building structures possesses major advantages over traditional slab-beam-column structures because of the free design of space, shorter construction time, architectural –functional and economical aspects. I have trying to verify the punching shear of the columns but for some reason I don't know, SAFE won't calculate the punching shear on the perimeter columns ("N/C" result). New Punching Shear Reinforcement for Flat Slabs •Shear design. This study addresses design aspects for the punching shear bolt retrofitting system for reinforced concrete flat slabs supported on columns. For enhancing the effect of punching shear either we have to increase the thickness of slab or optimizing the thickness by designing punching shear reinforcement. Punching Shear Design. Punching stresses generally arises when a concentrated load is applied to a small area of slab. Two-Way Flat Slab (Concrete Floor with Drop Panels) System Analysis and Design Design the concrete floor slab system shown below for an intermediate floor considering partition weight = 20 psf, and unfactored live load = 60 psf. These can be placed at columns or point loads anywhere along the slab. Prof, CEN, SUB DESIGN OF THE FLAT PLATE SLAB BY DDM DESIGN OF PUNCHING SHEAR REINFORCEMENT Le. To avoid punching shear failure drop panels, column heads or shear reinforcement are used. PUNCHING SHEAR • always a critical consideration in flat plate design around the columns • instead of using thicker section, shear reinforcement in the form of shear heads, shear studs or stirrup cages may be embedded in the slab to enhance shear capacity at the edges of walls and columns. For the design of punching shear, code provisions rely mostly on empirical methods derived from the test results on simply supported conventional and thin slab specimens. This failure mechanism occurs when the column below the slab literally. European Commission Joint Research Centre Institute for the Protection and Security of the Citizen Contact information Address: Joint Research Centre, Via Enrico Fermi 2749, TP 480, 21027 Ispra (VA), Italy. PUNCHING SHEAR BEHAVIOR OF FIBER REINFORCED POLYMERS REINFORCED CONCRETE FLAT SLABS: EXPERIMENTAL STUDY. So don’t rejoice just yet that you only have a small percentage of the unbalanced moment resisted as bending moment in the slab. Hello guys, I have a model of a flat plate, with a couple of shear walls on the perimeter. Punching shear stress may cause a slab sudden failure at the. com/public/qlqub/q15. The slab is for an offi ce where the specifi ed load is 1. The flat plate system may save money on formwork, but it requires the use of a heavier slab than a flat slab system. Melo, and Ronaldo B. Link for download Slab Punching Shear Calculation Spreadsheet. For carrying out this project an interior panel of a flat slab with dimensions 6. Description. punching shear resistance can be verified through a simple mechanical model. The scope of work will be as below. CIVIL ENGINEERING. the slabs supported directly on columns, without beams between columns. 3 of ACI 318 allows the use of shear reinforcement for slabs and footings in the form of bars, as in the vertical legs of stirrups. Two methods of design are available for flat slabs: 1. The basic philosophy in the design of flat slab is to consider only gravity forces; this method ignores the effect of punching shear due to unbalanced moments at the slab column junction which is critical. The punching shear resistance can thus be increased by. php(143) : runtime-created function(1) : eval()'d code(156) : runtime-created. Study Design: Parametric study is carried out by varying the repair and strengthening number of stirrups rows and the stirrups materials. The shear resistance at a column after punching can be very low unless. Concrete flat slabs and footings: Design method for punching and detailing for ductility Broms, Carl Erik KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges. If it were only BS like the equations shown above, the additional punching shear brought about by the unbalanced bending moment in the columns of a flat slab or flat plate would have been chicken bit. The method is based on the assumption that the punching shear strength is controlled by the inclination of a unique punching shear crack that produces a conical failure surface. Verification of the shear capacity at the control perimeters around a rectangular column. Melo, Ronaldo B. Punching, unbuttoning and perforation 11. In flat slab structures this occurs at column support points. Slab with and without punching shear reinforcement is used for the analysis. the problem i am facing is that safe is showing punching shear ratio values of the shear wall on which the slab is resting. These slabs which are directly supported by columns are called Flat Slabs. 1R-08, Guide to Shear Reinforcement for Slabs, and ACI 421. Nowadays, a considerable number of flat slab buildings requires strengthening against punching. The system consists of double-headed studs welded to flat rails, positioned around the column head or base. I have trying to verify the punching shear of the columns but for some reason I don't know, SAFE won't calculate the punching shear on the perimeter columns ("N/C" result). Punching shear failure occurs with almost no warning signs, because deflections are small and cracks at the top side of the slab is usually not visible [2]. The potential of punching shear failure of flat-plate structures under combined effects of vertical and horizontal ground motion is examined based on the three design criteria given in ACI 318-14: eccentric shear stress model, story design drift limit for slab-column connections without shear reinforcement, and two-way shear strength for one. The design values of the punching shear for the slabs with openings were obtained according to EC 2. The first way is verification of the concrete strut capacity at the column periphery defined as VRd,max. The Punching Strength of High-Strength Flat Slabs: Experimental Study Qi Zhang - 9 - shear punching strength and the flexural punching strength are calculated.