Nonlinear Quasi-Static Finite Element Analysis of Flat Plate Using Damage Plasticity Model

Flat slabs have become very popular in Bangladesh mainly due to their aesthetic view and satisfactory behavior under vertical loading. But since they are quite vulnerable in earthquakes, repair and retrofit are the only options they have of withstanding the stresses due to major earthquakes. Nonlinear Quasi-Static Analysis of flat slabs is performed in this work to check the performance against punching, comparing numerical results with experimental observations from reversible load tests. Since punching shear is the most damaging of the possible seismic distresses, this study focuses on simulating punching shear failure due to earthquake. Numerical simulations are illustrated using computational modeling by the well-known software ABAQUS to obtain outputs for understanding seismic performance of flat plate structural system. Finite element method (FEM) incorporating Concrete Damage Plasticity (CDP) model accomplishes the numerical simulation. The CDP model is used to perform the iterations at nonlinear stages and visualize real-time crack pattern and failure type of structural system. Evaluating models are simulated as Reinforced Concrete (RC) flat plate structure, comparing with flat plate strengthened by using Wing Walls. Three-dimensional quasi-static nonlinear finite element analysis exhibits numerical solutions that predict the experimental outputs with visualization of localized failure patterns as well. The results are promising and numerical simulations reasonably satisfy the experiments. Before retrofit, the maximum load from numerical simulation was 5.98 kN compared to experimental result of 6.08 kN. The corresponding values came out to be 15.93 kN and 16.60 kN respectively after strengthening. The adaptability of CDP model in nonlinear seismic evaluation by FEM can have broad acceptance since the procedure is able to bypass analytical complexity, assure accuracy of numerical simulation and visualize failure pattern, validating the performance of such sophisticated and complex physical systems