Simulation of punching and post-punching shear behaviours of RC slab–column connections

Abstract

The punching and post-punching shear behaviours of reinforced concrete (RC) flat plate structures are often studied by using a representative slab–column connection isolated from the parent structure. In this study, a set of numerical modelling techniques is established to create a competent three-dimensional non-linear model to simulate punching and post-punching shear behaviours of RC slab–column connections without shear reinforcement, through the use of which the punching shear failure featuring a critical punching shear surface and an abrupt drop of the applied force in the load–displacement response is able to be accurately reproduced. The post-punching shear behaviour, taking the form of an increased load-carrying capacity which is ceased by rebar fracture in the suspension stage, is also well captured. Using the proposed numerical model, typical punching and post-punching shear failure mechanisms are studied in some detail.

A preliminary analysis and discussion of the condominium building collapse in surfside, Florida, US, June 24, 2021

“…The reinforcement layout of the column strip is shown in 9. Previous studies [9][10][11][12][13][14][15] reveal that the mechanical performance of the slab-column joint after punching shear failure is mainly dominated by the through-column integrity rebars. The following two typical characteristics can be summarized from the reinforcement layout of the collapsed structure: 1) the flexural reinforcement at the slab top is trimmed at a certain distance away from the column faces; 2) half amount of the integrity reinforcement at the slab bottom is cut off at the slabcolumn joint region, and the remaining half is overlapped within the column region, in which the overlap length of the rebars is only 149 mm.…”

“…Note that different design codes set distinctively different requirements for the reinforcement detailing of the joints [7,8]. The performance difference of various kinds of detailing can only be compared through experiments or refined FE analyses [9][10][11][12][13][14][15][16]. Experimentally, the punching shear and post-punching failure behaviors of a series of interior slab-column joints subjected to either concentric loading or eccentric loading were investigated, considering the effects of different punching shear directions, slab thicknesses, reinforcement ratios, and strengthening methods [10,14,15].…”

“…The performance difference of various kinds of detailing can only be compared through experiments or refined FE analyses [9][10][11][12][13][14][15][16]. Experimentally, the punching shear and post-punching failure behaviors of a series of interior slab-column joints subjected to either concentric loading or eccentric loading were investigated, considering the effects of different punching shear directions, slab thicknesses, reinforcement ratios, and strengthening methods [10,14,15]. It was found that the post-punching bearing and deformation capacities of the slab-column joints were predominantly determined by the through-column integrity reinforcement, and the addition of the embedded beams facilitated greater deformation and load capacities in the large-deformation suspension stage.…”

“…The load redistribution patterns of these substructures were examined and accurately quantified under different column removal scenarios. Numerically, a set of 3D nonlinear finite element modeling techniques, using LS-DYNA software, was proposed to investigate the progressive collapse behavior of flat plate structures [10,14,15]. For computational efficiency, an FE analysis of a representative slab-column joint of the collapsed building is performed and detailed in Section 3 of this paper.…”

Comparative and Parametric Studies on Behavior of RC-Flat Plates Subjected to Interior-Column Loss

“…A damage formulation to enable material softening was also implemented in this model in which the fracture energies in three states of stress (i.e. pure shear, uniaxial compression and uniaxial tension) were calculated based on a mesh size calibration (Xue et al 2020). As a brittle shear-type failure was expected in the simulation, the keyword *MAT_ADD_EROSION was used to allow element deletion in which the maximum effective strain c,max  , representing the distortional deformation of elements, was selected.…”