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Nonlinear finite element analysis of punching shear strength of reinforced concrete slabs supported on L-shaped columns

Zhang Qing, Milligan Graeme J., Polak Maria Anna

Budownictwo i Architektura

2020

Vol. 19, no 4

125--138

Most current concrete design codes include provisions for punching shear of reinforced concrete slabs supported on columns with L, T, and cruciform shapes. Reference studies verifying the accuracy of these code provisions are typically not provided. Empirical data of punching failures of slabs supported on columns with L, T, and cruciform shapes are limited due to the cost and time required to test specimens with slab thicknesses and column sizes commonly used in practice. In this paper, the punching shear behaviour of five interior L-shaped slab-column connections, one without a slab opening and four with slab openings, subjected to static concentric loading are analyzed using a plasticity-based nonlinear finite element model (FEM) in ABAQUS. The FEM is similar to models previously calibrated at the University of Waterloo and are calibrated considering nine slabs that are tested to study the impact of column rectangularity on the punching shear behaviour of reinforced concrete slabs. The finite element analysis results indicate that shear stresses primarily concentrate around the ends of the L, and that current code predictions from ACI 318-19 and Eurocode 2 may be unconservative due to the assumed critical perimeters around L-shaped columns.

Role of dilatancy angle in plasticity-based models of concrete

Wosatko Adam, Winnicki Andrzej, Polak Maria Anna, Pamin Jerzy

Archives of Civil and Mechanical Engineering

2019

Vol. 19, no. 4

1268--1283

The so-called concrete damaged plasticity (CDP) model is frequently employed by ABAQUS users to simulate the behaviour of concrete. One important aspect of the model, namely the representation of material dilatancy, is evaluated in the paper. The role of the dilatancy angle in pressure-dependent plasticity models is reviewed. The plastic potential adopted in the CDP model is discussed. It is shown that the definitions of the angle in the CDP model and in the Burzynski–Drucker–Prager (BDP) plasticity model for a continuum can lead to different angle magnitudes. Two tests on concrete configurations are simulated to illustrate how strongly the angle influences the results: the Kupfer benchmark of a panel under uniaxial or biaxial compression and the punching shear response in a slab-column connection. The importance of viscosity in cracking simulation is thereby mentioned, the results are compared with experimental ones and mesh sensitivity is verified. Recommendations for analysis of concrete mechanics problems are formulated.