Bonded Particle Model for Numerical Analysis of Concrete Fracture under Impact Loading

Linear elastic fracture mechanics and homogenization techniques have shown limitations in concrete fracture analysis due to the existence of localized damage zone and instabilities near the crack region. Concrete structures which are primarily quasi-brittle material present rate dependent failure modes, and fracture properties under impact or blast loading. Experiments show that concrete may exhibit viscoplasticity, strain rate and hydrostatic pressure dependent damage and crack propagation. This paper describes an explicit approach of discrete particles bonded with Euler-Bernoulli beams to simulate dynamic fracture in concrete. The fracture is initiated in the beam network and propagated and energy is dissipated according to the prescribed fracture energy. The bonded particle model has shown advanced capability to predict processes including microcracking, crack deflection, bridging and branching occurring in the fracture process zone under impact loading.
It can also predict to some extent the crack propagation velocity. A quasi-brittle fracture model with rate
dependent strength is elaborated to capture rate dependent behavior at high and moderate strain rates where the concrete exhibit increased load carrying capacity. In order to ensure stability of this program, numerical localnon viscous damping is used. The effect of particle size and bonds in overall response was also investigated.