FINITE ELEMENT ANALYSIS OF FAILURE MODES OF BLAST-LOADED R/C BEAMS

The flexural failure mode of R/C frames or beams is usually observed in case of blast loads with long duration. However, shear failure mode may occur before the flexural failure takes place in case of blast loads with short duration such as impulsive loadings induced by chemical explosion. This phenomenon is observed in both laboratory and in-situ tests. The reason is that the impulsive loading excites the shear force in the component of the structures and causes the structures fail in the manner of shear failure. Based on Timoshenko beam theory, a non-linear layered beam element is proposed in this paper to investigate the response and failure modes of blast-loaded R/C beams. Non-linear material properties, strain-rate effects of concrete and steel are taken into account in the material models. The dynamic responses and various failure modes, including flexure, flexure-shear and shear of the blast-loaded R/C beams are predicted. A good agreement between the numerical results and experimental results is reached.