Toward Practical Modelling of Reinforced Concrete Flat Slab Systems

There is increasing demand for practical modelling procedures that can be used to assess the performance of reinforced concrete (RC) structures. The numerical assessment of RC slabs at the system level typically involves one of two modelling procedures: i) models constructed with the use of three-dimensional solid finite elements, or ii) models constructed using some form of layered element, usually developed on the basis of the plane sections assumption. The use of solids has been shown to provide good structural performance estimates for RC flat plates; however, the investigation of even a single slab-column connection can be extremely costly as fine meshes consisting of many degrees of freedom are usually required. Conversely, while layered elements are computationally more efficient, they typically provide extremely coarse estimates of the out-of- plane (through-thickness) shear response and generally cannot capture the influence of disturbances developed in slab-column connection regions.

This paper presents the application of an alternative RC slab system modelling procedure. Low-cost layered thick-shell finite elements that can adequately model through-thickness shearing effects were used to capture global slab system behaviour and a simple sectional analysis modification procedure was used to accommodate strength enhancements attributed to slab disturbances. Employing the formulations of the Disturbed Stress Field Model (DSFM), the thick-shell finite element analysis procedure was used to model the response of RC slab-column connections under concentric shear loading conditions. Shell element-based numerical responses were compared with those obtained using more conventional modelling procedures (e.g., solid continuum), and were contrasted with experimental data. Further, the validated RC slab modelling procedure was used to analyze the response of a slab subsystem test available in the current database of experimental literature, and was shown to provide good agreement with test results.