A new general approach to derive normalised pressure impulse curves

A pressure impulse (PI) diagram is an important tool used for the preliminary design of structural members against blasts. Normalised PI diagrams can be derived using single degree of freedom (SDOF) theory to quickly determine the PI diagram of a given structural member. In order to use PI diagrams for blasts occurring in various confined environments, characterised by irregular shaped pulse loads, an investigation into the effects of pulse shape on a given point on the normalised PI curve is undertaken. Relying on the concept of the effective pulse load, three parameters which define the shape of the effective pulse load are determined. These parameters are then used to derive a method for determining a point on the normalised PI curve for elastic, rigid plastic and elastic plastic hardening structural members. The overall procedure can be iterated to determine many points, thus forming the entire normalised PI curve. Due to the generality of this new approach, it can be applied to structural members subjected to any arbitrary pulse load as long as its response and failure are controlled by its flexural behaviour.