Investigation into the Material Response of Concretes when Subject to Blast and Fragment Loading

Abstract

Vehicle Bourne Improvised Explosive Devices (VBIEDs) are utilised globally by terrorist organisations and radical individuals to inflict mass casualties. Many of these casualties are caused by the collapse of structures due to damage sustained by the blast and fragmentation loadings produced by the VBIED. As such it is important to understand how these loadings affect structures so as to improve design and increase structure survivability. Historically significant research effort has been invested in understanding the blast and fragmentation loadings produced by conventional weapons. The loadings produced by VBIEDs are often considerably different with much larger, slower fragments. Little work has been undertaken in documenting these loadings and how they damage structural materials such as concrete. As such, when designing for threats of this type the fragmentation loading produced by a VBIED is often ignored. This thesis aims to investigate; the loadings produced by bare explosive charges and VBIED surrogate charges, and how the blast and fragmentation loadings contribute to the deflection and damage of concrete panels. Panels with approximate dimensions of 1200 mm by 1200 mm and with thicknesses varying between 100 and 200 mm were tested. Panels were constructed from low-strength concrete, moderate-strength concrete, and Ultra-High Performance Concrete (UHPC). Testing found that the fragment loading produced by the VBIED surrogate was sufficient to produce a global response in the panels as well as localised damage. As such, fragmentation loadings should not be ignored when predicting the response of structures to VBIED threats. Synergistic effects, between the blast and fragmentation loadings were, were observed for panels with sufficiently low flexural stiffness.