Prediction of impact induced failure modes in reinforced concrete slabs through nonlinear transient dynamic finite element simulation

Abstract

A systematic numerical and analytical approach, to predict the various global failure modes such as flexural, punching shear and mixed flexure-shear failures along with the local failure modes such as crushing, cracking, spalling and scabbing, under impact load is investigated in this study. Numerical simulation on reinforced concrete (RC) slab impacted with cylindrical drop hammer has been carried out using ABAQUS finite element code to obtain the failure modes. Also a comparison has been made to validate the results of numerical simulation with the Zineddin and Krauthammer experimental results. The simulation results are in excellent agreement with the experimental failure modes reported by Zineddin and Krauthammer.The behavior of RC slab under impact load is simulated with the conventional limiting strain criteria as well as fracture energy softening models within the framework of damage plasticity model. It is found that the limiting strain criterion suffers from the limitation of mesh sensitivity and results from the fracture energy approach are close to the actual experimental results. Therefore the fracture energy softening models have been recommended as robust method for these types of studies.Besides the complexities due to concrete heterogeneity, the inelastic concrete and rebar behavior, strain rate effect and mesh sensitivity issues are addressed in the present paper to evolve a robust nonlinear transient dynamic finite element simulation. It is illustrated that the global and local failure modes can be numerically predicted through identifiable and measurable parameters such as the point of inflection, bi-axial failure criteria, strain based failure criteria, shear failure criteria, rebar strain and tensile damage profiles.