Pdf a new punching shear equation of normal and high. This verification example provides stepbystep calculations which serve as an overview of the punchingshear process. Punchingshear formulation safe computers and structures. The formulation for punching shear is presented in context help, which is available within the safe interface through help documentation verification aci318. This design example provides stepbystep handcalculations and compares various aci methodologies to determine the critical shear perimeter of circular. Punching shear analysis of reinforced concrete flat plates. Punching shear strength of reinforced concrete slabs without. On the other hand, the punching shear strength depends of the column location on the footing, either interior, edge or corner, per the expression. The provisions for punching shear design according to eurocode 2 cannot be applied efficiently without a software solution. 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. Pdf simplified punching shear design method for slabcolumn. Pile supported foundation pile cap analysis and design based on a geotechnical study, a pile supported foundation is required to support a heavily loaded building column. The bottom of the footing is ft below finished grade. Some special types of reinforcement are also available in the market for this purpose.
Introduction to punching shear reinforcement 4 advantages of the jordahl punching shear reinforcement jda 5 design according to eta6 6 9 summary of proofs 6 round cut guide 6 design load 7 punching shear resistance without punching shear reinforcement 7 punching shear resistance with doubleheaded anchors 8. Example calculation external corner condition a circular pattern square corner 36 36 17. Design example of punching shear in slabs eurocode 2. Pile supported foundation pile cap analysis and design. Pdf design of acitype punching shear reinforcement to. Punching shear strength as function of slab rotation the opening of the critical shear crack reduces the strength of the inclined concrete compression strut carrying shear and eventually leads to the punching shear failure. Punching shear at the basic control perimeter without reinforcement a basic control perimeter length. Pdf the aims of this study is to present a new simple accurate equation to determine the punching shear strength of normal and high strength.
Punching shear how to design against punching shear forces. Footings example 1 design of a square spread footing of a. 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. Comparison of punching shear design provisions for flat slabs. Punching shear calculation applies to columnsupported slabs, classified as twoway structural systems. Design of reinforced concrete slabs 103 calculated punching shear stress at perimeter ui shear force per unit width for bending about xaxis shear force per unit width for bending about yaxis maximum crack width mm depth of neutral axis from compression face distance from edge in ldirection to start of a yield line. Punching shear capacity of fibre reinforced concrete slabs. Calculation of shear reinforcement nominal shear strength provided by concrete according to eq. This verification example provides stepbystep calculations which serve as an overview of the punching shear process. Footings example 1design of a square spread footing of a seven. Example a mat foundation is to be design by the conventional method. Footings example 1design of a square spread footing of a sevenstory building. Design codes, however, are generally also applicable to thick slabs and footings 0. The design shear force v d is below the maximum punching strength v rd,max.
Example calculation internal corner condition a circular pattern square column 38 38 contents design manual to ec2 v. To check if shear reinforcement and which system can be used, one can calculate the minimal needed value of factor ksys. The concrete shear strength in oneway action is defined by the expression. Aci 318r emphasizes the importance of anchorage details and accurate placement of the shear reinforcement, especially in thin slabs.
Taking an internal column from the load takedown example refer to page. An example is the calculation of the load increment factor. Design the pile cap shown in the following figure with 12 in. Concentric punching shear strength of reinforced concrete. Punching shear safe 2016 tutorial example and practical. The punch area is calculated at an average distance of d2 from column face on all sides fig. Design of foundations universiti teknologi malaysia. Punching shear design according to eurocode 2 in rfem. Joint research centre, via enrico fermi 2749, tp 480, 21027 ispra va, italy. Punching shear reinforcement will be required but there will only be 1 or 2 perimeters. It was of interest to compare the proposal with the current punching shear design provisions.
The punching shear is a failure mechanism in structural members like slabs and foundation by shear under the action of concentrated loads. Punching strength with shear reinforcement firstly, one has to check if the design shear force v d is smaller than the maximum punching. Punching shear is a phenomenon where a concentrated force on a slab causes a. For pier caps, the magnitude of the torsional moments is typically small relative to the torsional cracking. Twoway punching shear calculations are performed to ensure that the concrete slab design shear strength, vn, shall be greater than or equal to the factored shear stress, vu.
Punching strength with shear reinforcement firstly, one has to check if the design shear force v d is smaller than the maximum punching strength v rd,max. If the concrete s shear capacity is smaller then the actual shear force. Shear reinforcement is also provided around the column to reduce the effect of the punching shear. Halfen hdb punching shear and shear reinforcement 4 7 hdb punching shear reinforcement 5 hdbs shear reinforcement 6 product overview 8 halfen hdb as punching shear and shear reinforcement 8 calculation. This writing i defines the different conditions for punching shear calculation, ii presents the relationships used for code check of each condition using aci318, iii presents a numerical example for each condition, and iv demonstrates that the program adaptbuilder. Punching strength of flat slabs with and without shear. Feb 06, 2019 in this video, we investigate how to analyze a slab for punching shear, how to design rebar and stud rails, and some theory, tips and tricks. Punching shear check at wall ends and wall corners trenno structural 19 jul 18 09.
Punching shear is a phenomenon where a concentrated force on a slab causes a shear failure cone that punches through. In this video, we investigate how to analyze a slab for punching shear, how to design rebar and stud rails, and some theory, tips and tricks. Punching shear is a type of failure of reinforced concrete slabs subjected to high. The home is located on little bay in harrison county, mississippi, approximately. The basic perimeter, u 1 is at 2d eff from the column. The analytical basis of previous work by other researchers was used to propose a formula to calculate the punching shear strength of flat plates with good accuracy for a wide. In most cases, this reaction is the one from the column acting against the slab. As discussed in chapter 4, the critical section for punching shear is located at distance d 2 from column faces and usually takes the shape of the column. A general procedure for evaluation of the punching shear strength of slab. Punching force kn perimeter mm plate thickness mm shear strength kn mm 2 converted into metric tons. Punching shear stress check and reinforcement design based.
Punching shear stress check and reinforcement design based on. Effectiveness of punching shear reinforcement to en 199211. Aug 14, 2017 the concrete shear strength in oneway action is defined by the expression. Punching shear arises when a concentrated load is applied to a small area of a slab or, most commonly, the reaction of a column against a slab. Jul 31, 2012 the formulation for punching shear is presented in context help, which is available within the safe interface through help documentation verification aci318. This writing i defines the different conditions for punching shear calculation, ii presents the relationships used for code check of each condition using aci318, iii presents a numerical example for each condition, and iv demonstrates that the program adaptpt correctly. The critical section of punching shear stress is at a distance, d2, from edge of pile, d is the effective depth of pile cap. The action of concentrated loads is on a smaller area in the structural members. Oct 12, 2017 shear reinforcement is also provided around the column to reduce the effect of the punching shear. Footing thickness is adequate for resisting punching shear once vu vc. Punching shear check at wall ends and wall corners.
The resulting stresses are verified along defined control perimeters around the loaded area. Aci design handbook in accordance with aci 31805 circular critical section properties for twoway shear stress calculations for circular column are shown below. European commission joint research centre institute for the protection and security of the citizen contact information address. Punching shear reinforcement punching shear worked example from worked examples to ec2. The punching shear strength of the concrete is not sufficient. Sep 03, 2011 design of reinforced concrete slabs 103 calculated punching shear stress at perimeter ui shear force per unit width for bending about xaxis shear force per unit width for bending about yaxis maximum crack width mm depth of neutral axis from compression face distance from edge in ldirection to start of a yield line. Footings example 1design of a square spread footing of a sevenstory building design and detail a typical square spread footing of a six bay by five bay sevenstory building, founded on stiff soil, supporting a 24 in. Punching shear strength of reinforced concrete slabs. The punching shear strength predicted by the fuzzybased model is compared with those predicted by current punching shear strength models widely used in the design practice, such as aci 31805.
Punching shear calculations are provided for columnspedestals that land on concrete slabs. Department of mechanics, materials and structures english. Punching strength without shear reinforcement the punching shear strength of the concrete is not sufficient. Punching shear resistance is, as the article states, a planar phenomenon rather than a point stress phenomenon. Design step 7 design of substructure prestressed concrete. The first punching model alternative is proposed in dafstb beton kalender 2011, and the second punching model alternative is established in swedish concrete association report no. The aim of this master thesis was to compare the punching shear resistance obtained in accordance with both design codes. Design of acitype punching shear reinforcement to eurocode 2 article pdf available in magazine of concrete research 621. The sample calculation is based on a twostory home with a 8foot by 4 foot footprint and a mean roof height of 6 feet above grade. Design step 7 design of substructure prestressed concrete bridge design example task order dtfh6102t63032 741 shear capacity or flexural capacity and, hence, can be neglected. According to muttoni and schwartz,12 the width of the critical crack can. Effective punching shear and moment capacity of flat plate.
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