Risk Assessment and Planning for Blast Design of Facilities with No Known Explosives

Protective design methods for blast, shock, and impact loading, such as from a blast event, are not addressed in typical design codes, but may be requested by project owners or end users. A risk assessment provides a basis of understanding from which users and stakeholders can make informed decisions to direct protective design for a project. Risk assessments include identifying asset values and threats, determining vulnerabilities, quantifying the impact of a loss event, and suggesting risk mitigation measures. For Department of Defense (DoD) facilities, this process is required and follows the procedures set forth in the UFC 4-020-01 DoD Security Engineering Facilities Planning Manual resulting in a level of protection (LOP) and a design basis threat (DBT) for the project facility. When explosive threats are identified for a project, the LOP dictates the performance-based criteria based on allowable damage in the event of the DBT incident. This paper highlights two case studies where the building designs deviated from the risk assessment results. In one case the users and stakeholders employed the risk reduction method to reduce potential damages and asset loss by decreasing the allowable damage for a modified DBT. In the other case, the users and stakeholders chose to accept the risks associated with designing the facility to a lower level of protection than determined from the risk assessment. Though government agencies have their own methods for producing risk assessments, the private sector may rely on protective design specialists to assist in determining risks and the appropriate protective design criteria for a project. This paper aims to generalize the procedure set in UFC 4-020-01 to be adaptable to a variety of projects based on understanding user goals and risk tolerances.