Effect of Contact Explosions on Cratering, Spalling, and Breaching Damage of Concrete Components: Critical Review, Recent Advancements, and Future Perspectives

With the rise in intentional and accidental explosions worldwide, several research efforts are focused on the behavior of reinforced concrete (RC) members subjected to contact explosion. The event of a contact explosion is different from a far-field explosion because it causes local damage (cratering, spalling, breaching) to the member, thus affecting its residual capacity. The present study comprehensively reviews the existing experimental, numerical, and analytical methods to quantify the blast load and behavior of RC members subjected to a contact explosion. The widely used ConWep model is unsuitable for contact explosions because it neglects the occurrence of wave superposition, reflection, member properties, etc. On studying the experiments, it has been observed that the presence of reinforcement, fibers, and meshes, along with the use of high-strength concrete and ultrahigh-performance concrete, exhibits a positive influence on the blast resistance of slabs under a contact explosion. Further, the behavior of beams (length of damage zone) is influenced by the presence of stirrups, strain development, and loading condition. The location of explosives, presence of transverse reinforcement, axial load, and aspect ratio are factors that influence the behavior of RC columns. On studying the guidelines stated in codes and standards, it was observed that the event of a contact explosion, to our best knowledge, has not yet been investigated thoroughly. This study also highlights the pressing need to develop numerical and analytical studies to predict the behavior of RC beams and columns subjected to a contact detonation.