Design shear reinforcement for slab which to resist punching stress around. In aci 31814, the twoway shear provisions are all expressed in terms of stress v n, v c, v s, used in aci 318 11 for slabcolumn connections subject to axial load and moment, never force v n, v c, v s, used in aci 318 11 for slabcolumn connections subject to concentric axial load only. Concrete circular column punching shear pdf book manual. Pile supported foundation pile cap analysis and design. To examine the validity of the ecp203, aci 318, and bs8110 codes provisions on punching shear, the results of 55 reinforced concrete flat slabs were analyzed and compared with the ultimate. Structure magazine significant changes between aci 31811. Pdf effects of openings on the punching shear strength. Aci 31819 updates aci 31819 minnesota concrete council. Pdf prediction of punching shear capacity of rc flat slabs using. Aci 318 11 was adopted as a standard of the american concrete institute may 24, 2011, to supersede aci 31808 in accordance with the institutes standardization procedure and was published august 2011. Pdf design of acitype punching shear reinforcement to. The only capacity considered for punching shear is the concrete itself.
Eight twoway slab specimens using two different types of aggregate natural and recycled and two aggregate nominal sizes 12. Where the control perimeter u is defined at a distance of 0. The punch area is calculated at an average distance of d2 from column face on all sides fig. Punching shear behavior of recycled aggregate reinforced.
Oneway shear at corner pile the oneway shear is checked at a distance d, but no more than in. Fir this purpose, the ability of aci 318 11, ts500 and eurocode2 to estimate punching shear strength was examined in light of experimental results compiled from previous research. The openings one or two were adjacent to the shorter sides of rectangular supports and had widths equal to those of the supports. New methods to resisting punching shear stress in reinforced. Interior and exterior connections were examined in the course of the study. Punching shear crack is not intercepted by reinforcement, substantially reducing punching shear strength possible punching shear problem in podium slabs. This is called beam shear or oneway shear as it resembles the shear check in a concrete beam. This limit can be raised to this was originally suggested in aci 421. As a result, users will obtain a better background and understanding of the code. The punching resistance of flat slabs without transverse reinforcement and for square columns with side lengths less than 4d is given by aci 318 11 21 using eq. 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. For the aci 31808, aci 318 11, and aci 31814 standards, lightweight concrete is considered. The critical section adopted by the british standard, bs8110 15, lies at 1. An opening that is contained completely within the punching check is not considered a discontinuous edge, regardless of its size.
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 of reinforced concrete flat plates with openings. Overview punching shear calculation applies to columnsupported slabs, classified as twoway structural. In aci 318 11 aci committee 318 2011, it is assumed that slabcolumn frames that are not part of the seismic forceresisting system have adequate drift capacity if one of the following conditions is met. This writing i defines the different conditions for punching shear calculation, ii presents the. The reorganized aci 31814 code iowa state university. Footings example 1design of a square spread footing of a seven. Aci design handbook in accordance with aci 31805 circular critical section properties for twoway shear stress calculations for circular column are shown below. One check recognizes that the footing may fail in shear as a wide beam along a critical section at a distance d from the column face in each direction. Footings example 1 design of a square spread footing of a. Really a story about cheese cheese a metaphor for what we want to have in life, whether it is a job, a. What are the footing shear checks required by aci 318 per aci 318, two separate shear checks are required.
Check the adequacy of slab thickness for punching shear twoway. It is possible that punching shear failures can occur around walls especially walls with a short length. Pdf this paper describes a series of tests that were carried out at imperial college london to determine the efficiency of stirrups when used. Pdf design of acitype punching shear reinforcement to eurocode 2. Overview punching shear calculation applies to columnsupported slabs, classified as twoway structural systems. Aci318m08 material and material factors concrete2 cylinder strength at 28 days, as specified by the. The aci design handbook from sp17 97 thru sp17 11 utilizes exact circular critical shear perimeter located d2 away from circular column perimeter as per the provisions for slabs and footings within chapter 11 of aci 318 aci 31895, 11. Punching shear of flat slabs is a local, brittle failure that may occur before the more favourable ductile flexural failure. Design of aci type punching shear reinforcement to eurocode 2 article pdf available in magazine of concrete research 621. The reinforced shear stresses v u on the column sections are limited to a maximum of. Punching of high strength concrete flat slabs without shear.
It was later decided to place the contents of aci 318 11 chapter 22 in aci 31814 chapter 14. 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. This study focused on punching shear behavior of the footingtocolumn connection. The strength design combinations required for shear design of beams and punching shear require the full pt forces primary and secondary. Punching shear resistance of steelconcretesteel sandwich. The basic requirements for punching shear in concrete slabs are the same in the aci 318 14 code and the guides aci 421. Interactive design aids in accordance to us codes aci 31811, aisc 14th. Another key consideration for reliably predicting the shear capacity of twoway slabs is the socalled size effect. The punching shear behavior of interior slabcolumn connection in flat plates is tested in the reinforced concrete laboratory of the faculty of engineering, alexandria university.
Twoway punching shear calculations for concrete slab supported by circular. This is because it was initially planned that aci 318 11 chapter 22 on plain concrete would become a separate standard. Behavior of biaxially loaded slabcolumn connectionswith shear. Precast spandrel beam for combined shear and torsion aci 318 page. The ratio of flexural reinforcement, is also one of.
Punching shear resistance of reinforced concrete footings scielo. Significant changes from the 2011 to the 2014 edition of aci 318. Although footing present different geometric characteristics, their punching shear design is based on the empirical methods used for flat slabs. This study develops an artificial neural network ann modelling for the prediction of punching shear strength of flat slabs using 281 test data available in the literature. However, the equations and the details of the shear reinforcement to satisfy the basic requirements are different in aci 352. According to the aci 318 11 14, the critical perimeter is assumed at 0. Punching shear twoway shear beam shear oneway shear minimum reinforcement in the following, the values in square brackets are defaults of the program. Building code requirements for structural concrete aci 31811 and.
If any of the above conditions are not met, equations 22. Aci mn updates to aci 31819, april 2nd, 2019 aci 31819 updates catherine french cse distinguished professor. The higher limit is also applied to all sections in. Effects of slab flexural reinforcement on the punching shear strength and deformation capacity of corner slabcolumn connections without shear reinforcement.
Design the pile cap shown in the following figure with 12 in. Pdf effects of openings on the punching shear strength of. Punching strength of flat slabs with and without shear. The calculations above may be simplified using the approximation of equivalent sections as shown in aci 8. Punching strength of flat slabs with and without shear reinforcement. As a result, the punching shear design of footing is mainly based on the research results of the slabtocolumn connection, and most design codes, such as cebfip and aci, do not distinguish between the slab and footing in the design specification. Table 1 shows a sidebyside comparison of the organization of aci 318 11 and aci 31814. In aci 318 11, the punching shear resistance of the concrete slab can be determined by b3 v vu a h c where v punching shear resistance of the slab. It is suggested that the shear stress used for the concrete in aci 31811 could be increased for the assessment of strengths at the edges of zones. Punching shear behaviour of shear reinforced concrete slabs. Figure 3 shows the effect of increasing the slab effective depth on the normalized punching capacity 4v test v aci for selected test results extracted from the aci 445 punching shear test databank ospina et al.
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