Performance of reinforced concrete slabs under punching loads
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ORIGINAL ARTICLE
Performance of reinforced concrete slabs under punching loads Mohamed Said
. Ahmed A. Mahmoud . Ahmed Salah
Received: 28 September 2019 / Accepted: 16 June 2020 Ó RILEM 2020
Abstract The experimental program of this study consisted of 12 slab specimens. The parameters investigated include ratio of reinforcement in compression and tension, amount of shear reinforcement and arrangement of shear reinforcement. Flexural reinforcement ratio especially in tension had a noticeable effect on the mode of failure and ultimate punching capacity of slabs. The enhancement in the ultimate loads due to increasing tensile reinforcement ratio was ranging between 26.0 and 42.0%. Slightly enhancement (up to 12%) in ultimate loads was observed as a result of increasing compressive steel ratio. Provision of shear reinforcement was shown to be increased the perimeter of the failure. The ultimate loads were increased with the addition of single leg stirrups as shear reinforcement particularly in case of radial arrangement of shear reinforcement. The ECCS shows the most conservative prediction for punching shear capacity specially in case of using shear reinforcement and the mean predicted-to-experimental ultimate load is shown to be 0.7. The predictions following the ACI and CSA are closet to the experimental results. The mean predicted-to-experimental ultimate load is shown to be 0.8 for ACI and 0.96 for CSA. The BS provisions for punching shear analysis were shown to be overestimated in some cases, where M. Said (&) A. A. Mahmoud A. Salah Civil Engineering Department, Faculty of Engineering, Benha University, Shoubra, Cairo, Egypt e-mail: [email protected]
the mean predicted-to-experimental ultimate load is shown to be 1.19. Keywords Punching Flexural reinforcement Shear reinforcement Energy absorption Ductility
1 Introduction Punching shear resistance is a major item in flat slabs design. The punching shear failure follows a mechanism that leads to the development of a failure surface in the vicinity of the supported column. The design procedures of flat slabs are governed mostly by a mode of shear failure. The shear failure occurs in the vicinity of the supporting columns is due to 2-way action of the slab. In case of the beam action, the slab behaves as a wide beam and the failure extends along the entire width of the slab near the supports [1–3]. The punching shear capacities of the tested slabs [4–6] were compared to the values predicted by the provisions of ACI 318 [7]. Predictions calculated by ACI 318 are very conservative due to the control perimeter located at 0.5d from the column face. Yang et al. [8] conducted experimental work consisted of testing six slab specimens. The objective of this investigation was discussing the influence of using high-strength steel on punching shear response of flat slabs. Replacement of conventional steel bars with
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high-strength steel bars, having the same area, resulted in a
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