Finite Element Analysis on Reinforced Concrete Beams Subject to Impact

The study of reinforced concrete beams under impact load has been conducted by many researchers previously with different methods. It is important to understand the behaviour of reinforced concrete beams during impact so that it can be used as a reference in designing the structures. Failure under this accidental load can be catastrophic if structures are under-designed due to lack of knowledge in the response of reinforced concrete under impact load. Finite element analysis is the common method used in solving explicit dynamic problems. LS-DYNA is utilised to conduct the numerical simulation using finite element analysis. This research aims to determine the failure mode of reinforced concrete beams as well as their responses after impact. Generally, two beams are being studied by varying the transverse reinforcement ratio. It was found that reinforced concrete beams subject to impact tend to fail in shear rather than flexure. The beam with stirrups is stiffer and becomes more ductile, exhibiting a more elastic behaviour and resists the shear force through larger displacement of beam. Dynamic increase factors are introduced to the material model as high strain rate causes strength enhancement in the concrete and steel reinforcement. High impact force from the impactor causes residual displacements of the beams and residual strains in the reinforcement because the materials have exceeded the yield point and enters plastic region where some elements have permanently deformed.