Click here to go to iStandoff-Web, or read below for important user information.
Background
The US Department of Defense has released an updated version of their Unified Facilities Criteria UFC 4-010-01 DoD Minimum Antiterrorism Standards for Buildings. The newest version includes Change 1 October 1, 2013. Some of the biggest changes are to the Conventional Construction standoff distances. Overall, the document provides baseline requirements for the design of buildings occupied by DoD personnel. The intent of the standards is to “minimize mass casualties in buildings or portions of buildings owned, leased, privatized, or otherwise occupied, managed, or controlled by or for DoD in the event of a terrorist attack.”
Standoff Distances
One of the techniques to achieve this goal is through the use of Standoff which is “a distance maintained between a building or portion thereof and the potential location for an explosive detonation.” From a criteria perspective, the document has two types of standoff distances:
• “Minimum standoff distance. The smallest permissible standoff distance for new construction, regardless of any analysis results or hardening of the building. For existing buildings, standoff should never be less than this distance, but may with appropriate hardening or analysis where this distance is unachievable.”
• “Conventional construction standoff distance. The standoff distances at which conventional construction may be used for building components other than doors and windows without a specific analysis of blast effects, except as otherwise required in these standards.” The Conventional Construction standoff distances are based on the specific material and construction type of a building. Change 1, October 1, 2013 modifies the standoff distances from those included in the previous version of the document.
In order to determine the project specific Conventional Construction two tables (Table B-1 and Table B-2) need to be cross-consulted. (The table shown in the application is a reproduction of Table B-1: Standoff Distances for New and Existing Buildings from the UFC document).
How to Use iStandoff-Web
This Application automates the process of determining Conventional Construction standoff distances and provides the applicable distances with one click.
Select the appropriate wall material from the either the ‘Non-Lead Bearing’ or ‘Load Bearing Wall’ drop down menus (center two columns on the table). The table will update itself to show the Conventional Construction standoff distances for the selected wall material.
There are table footnotes for each of the different wall types that contain important information regarding the applicability of the standoff distances.
Caution
Caution to all! Even when the building walls meet Conventional Construction standoff distances, the doors and windows still need to be designed to the actual pressures and impulses at the faces of the building. For the shorter standoff distances this can be complicated and cost-prohibitive, so make sure you think through all the requirements before making site layout decisions.
Additional Support
For wall types not included in the tables, or buildings that do not meet the Conventional Construction standoff distances for their specific wall type (both of these cases require explicit blast design), window and door designs, or other blast and ATFP related issues, call Stone Security Engineering at (646) 649-3169 or email Michael Hahn at Mike@StoneSecurityEngineering.com.