Numerical Modeling of Concrete Under Blast Loading

Abstract

The blast phenomenon is a complex phenomenon. For analysing and designing of the structures which involves the blast loading conditions requires a detailed understanding of blast waves and also the structural dynamic responses pertaining to these blast conditions. Brittle materials generally involves a non linear behaviour under blast or impact loading, resulting on a complex analysis. In the present scenario the risk of terrorist attacks has increased thus require the protection strategies against the Blast. Thus structural engineers are considering it as an important factor for designing and analysis purpose. With the advancement in the technology it becomes possible to perform the numerical simulations of concrete under dynamic loadings such as blast, impact, earthquake loadings etc. The reliability and accuracy of the results of numerical simulations is influenced by many factors such as velocity of impact, material properties, initial boundary conditions etc. The important factor to be considered among these factors is the material model as it should be universally true to give accurate results under different conditions (i.e. loading conditions, boundary conditions, initial predefined conditions etc.). These models are already included in the software like ABAQUS, LS-DYNA, ANSYS etc. In the present study ABAQUS FEA software has been used. The main aim is to model the concrete under blast loading and numerically simulate the dynamic response using ABAQUS to improve these responses by altering the properties of concrete. The effects of dynamic loads on the materials can be studied with the help of the Split Hopkinson Pressure Bar. It is generally used for testing the material under high strain rates generally between 102 to 104 s-1. The stress v/s time graph has been plotted to know the effect of stress on the samples relative to the time. Two samples have been taken for modeling, cube sample and disc sample. Results showed that the deformation in the disc starts along the diameter of the disc. For this sample firstly the elements from the edges starts to deform then proceeds to the middle portion along the diameter in which the waves propagate. The lower edge elements deform first then the effect propagates to upper portions. The results of the numerical simulations of the SFRC (Steel Fibre Reinforced Concrete) samples can be used to compare the results of the conventional concrete under blast impacts.