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Title: Effect of Support Geometry on the Punching Shear Behaviour of Reinforced Concrete Flat Slabs

Author(s): Graeme J. Milligan, Qing Zhang and Maria Anna Polak

Publication: Symposium Paper

Volume: 353


Appears on pages(s): 29-49

Keywords: punching shear, reinforced concrete slabs, finite element analysis, concrete damaged plasticity model, rectangular columns, L columns, T columns, Cruciform columns, irregular columns

DOI: 10.14359/51737110

Date: 7/1/2022

Reinforced concrete slabs are commonly supported on non-circular or non-square columns. ACI 318-19 contains punching provisions for irregular column geometries which are based on limited experimental databases. In this paper, nonlinear finite element models are used to analyze the impact of support geometry (size and shape) on the shear behaviour of reinforced concrete slabs subjected to vertical loads. The impact on the slab shear stress distribution along the support perimeter and ACI 318-19 critical perimeter for connections is also analyzed. The numerical analysis predicts shear stresses to concentrate at the corners and along the short sides of the supports. The ACI 318-19 punching shear provisions are unconservative compared to the numerical predictions for L, T, and cruciform-shaped columns, and for rectangular columns where the ratio of the minimum column dimension to the effective slab depth exceeds approximately 1.3.