بررسی عددی و ارائه یک مدل ساختاری ترکیبی برای بتن تحت تاثیر بارگذاری با نرخ کرنش نسبتا بالا

  Abstract   Many concrete structures may be exposed to high rate dynamic loadings like impacts, explosions, etc. Thus, it is necessary to know the behavior of this material in order to predict the response of the structure. Understanding the response of concrete at high strain rates is a main factor both for a successful design of protective structures and reducing the damage of constructions. As the concrete is exposed to dynamic loading, its behavior depends on the strain rate. Therefore, an appropriate model is needed to present the theoretical characteristic of concrete correctly. The purpose of this paper is to present an approach used to couple the viscoplastic model with the damage theory. The proposed model is able to predict the dynamic strength and damage of concrete. The model was implemented as a material subroutine (UMAT) in ABAQUS FE software for simulation of the concrete specimen behavior in Split Hopkinson Pressure Bar (SHPB). The SHPB is an apparatus which is able to apply different strain rates on a cylindrical specimen and sketch the stress curve related to a specified strain rate. Finally, the result of the proposed model was compared to the experimental results and a good degree of agreement was observed.