Study on behavior of concrete fins against blast pressure

Abstract

Designing structures against blast loading is becoming more and more important as the number of terrorists attacks are increasing day by day. It is necessary to protect the structures against a credible blast load to ensure the safety of the occupants. In this context, blast resisting facades are incorporated in buildings to avoid the blast pressure waves entering into the building as the highest damage is done by the pressure waves when compared with the fragments moved by an explosion. Pressure waves could damage the axially loaded elements and it may lead to progressive collapse of the structure. This study investigated the behaviour of concrete fins and they were categorized depending on the failure mode which is based on the occupancy levels such as immediate occupancy, life safety and collapse prevention. Concrete fins were analysed using Sap2000 software by taking into account the material nonlinearity and loading nonlinearity. Weight of blasting materials, standoff distance, fin spacing, fin size and reinforcement ratios were varied to create different analysis cases. When the standoff distance was 50m, all the analysis cases were in immediate occupancy level, and it was found that standoff distance of 25m is as the manageable distance in blast. However, standoff distance of 10m resulted many analysis cases exceeded the collapse prevention limit. It was identified that standoff distance of 25m as the manageable limit with respect to the safety and the cost.