ACI 318-05, CSA A23.3-04, Eurocode 2 (2003), DIN 1045-1 (2001), BS 8110-97 and CEB-FIP MC 90 Provisions for Punching Shear of Reinforced Concrete Flat Slabs

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Title: ACI 318-05, CSA A23.3-04, Eurocode 2 (2003), DIN 1045-1 (2001), BS 8110-97 and CEB-FIP MC 90 Provisions for Punching Shear of Reinforced Concrete Flat Slabs

Author(s): N.J. Gardner

Publication: Special Publication

Volume: 232

Issue:

Appears on pages(s): 1-22

Keywords: code provisions; flat slabs; punching shear; structural design

Date: 10/1/2005

Abstract:
This paper describes and evaluates the punching shear provisions of ACI318-05, CSA A23.3-04, Eurocode 2 (2003), DIN 1045-1 (2001), BS 8110-97 and CEB-FIPMC 90 for interior columns without moment transfer and interior, edge and cornerconnections with moment transfer. All code column slab punching shear predictionswith moment transfer are extensions of the no-moment transfer provisions - any lack ofconservatism in the no-moment transfer provisions are reflected in the moment transfercomparisons.The validity of the interior connection, no moment transfer, punching shear provisionswere evaluated using the information from the data bank developed by the PunchingShear Working Group of fib Commission 4. The code provisions for interior columns withmoment transfer and edge columns connections under gravity loads were comparedwith data taken from the University of Alberta Research Report No.223 (Afhami,Alexander and Simmonds 1998). The code provisions for corner column slabconnections were compared with data from Zaghool (1971) and Walker and Regan(1987).BS 8110, DIN 1045-1 and CEB-FIP MC 90, which have size effect and reinforcement ratioterms and use control perimeters 1.5d, 1.5d, and 2.0d from the column, have smallercoefficients of variation than ACI 318 and CSA A23.3 for interior column slabconnections. However, these codes do not have general provisions for punching undercombined shear and moment transfer for edge and corner connections. Their simpleshear stress multipliers are limited to gravity load moments. Calculated statisticalindicators show that only ACI 318 satisfies the requirement of a 5% fractile valuegreater than one for concentric punching shear. The shear resistance coefficients of BS8110, CEB-FIP MC 90, CSA A23.3-04, and DIN 1045-1 should be reduced to meet a 5%fractile value of unity.ACI 318 and CSA A23.3 should be modified to include size effect terms and use the cuberoot of the concrete strength. A minimum flexural reinforcement ratio of 0.75% shouldbe specified in regions susceptible to punching shear. The consequences of permittinguse of a rectangular control perimeter have to be acknowledged.