Application of Normalized Pressure Impulse Diagrams for Vented and Unvented Confined Blasts

A pressure impulse (PI) diagram is a tool typically used for the preliminary design of structural members against external blasts. Using single-degree-of-freedom (SDOF) theory, numerous studies have been conducted on PI curves for structural members subjected to idealized pulse loads typically associated with free field blasts. However, owing to the complex nature of confined blasts, characterized by multiple peaks and long-lasting gas pressures, PI curves derived for such pulse loads cannot be applied to confined blasts. As the confinement magnifies the effects of a blast, resulting in more serious damage to surrounding structural members, such effects should be taken into consideration when using analysis and design tools. Therefore, a new approach for deriving PI curves was applied to confined blasts. First, the approach was used to derive PI curves for pulse loads associated with vented confined blasts. The PI curves derived using the new approach were compared to those using traditional techniques. Then, to determine the response of structural members to unvented confined blasts, in which regular PI curves cannot be used, a new technique was provided. The technique utilizes the concept of the effective pulse load to determine effective PI curves.