Sometimes it seems that the world of blast design is a little bit like the wild, wild, west right now. As more organizations, 
institutions, and owners have become aware of the need for protecting people and places from explosions, there has been an outpouring of new – and often conflicting – criteria and guideline documents. While this will be a very good thing in the long run, in the short run it can be confusing to the people who are trying to create buildings that mitigate the effects of blasts.
One of the areas of confusion is how to designate required glass responses. In this arena, three of the most commoncategorization systems come from the General Services Administration, ASTM F1642-04, and ASCE 59-11. To date the GSA has been the default system used in most design criteria, however the ASTM F1642 is becoming more common and we expect that this will become the default in the not-too-distant future. For instance the UFC 4-010-01 DoD Minimum Antiterrorism Standards For Buildings already references the classification system in the ASTM F1642-04 (note that the 2012 version of the UFC does this directly, while the 2013 version of the UFC references the ASTM F2912, which in turn references the ASTM F1642). This is all to the good, because not only does the industry seem to be converging to an accepted consensus based standard, but the ASTM F1642-04 provides a nicely detailed description of how to evaluate the post-test condition of the window system (i.e. provides dimensions, etc).
In order to help you navigate the different classifications we have created a table showing how the systems correspond to each other – this will be provided to attendees of our Protective Knowledge – Blast Resistance By Design course in May, 2015. Click here for more information on the class
Did you know… even if your building meets the required standoff distance, hardening measures are still most likely required to provide protection to occupants.
Required (or recommended) standoff distances (the distance between your structure and your protected perimeter) are developed by governments and agencies based on their analysis of the most likely threats that might be used against their facilities, the level of risk that is acceptable to their organization, and their ability to cost effectively harden their structures to the blast loads from an explosion at the prescribed standoff distance.
If you are involved in security planning and implementation for your facility, I recommend that you gather as much information as possible about the background of the prescribed standoff distances. Some of the information may not be available due to security concerns, but even a little information can help you better protect the people under your care.
• What vehicle or package size is the standoff distance based on?
This information can help you make decisions regarding physical protection, screening and surveillance in and around your building.
• Has your facility been designed or retrofitted to mitigate the effects of an explosion at the required standoff distance?
Standoff distance alone is rarely sufficient to offer adequate protection. Regularly designed buildings, while adequate for their original design intent, are not capable of providing protection against explosive forces.
• What level of protection is your building expected to provide based on the assumed charge size at the required standoff distance?
Even when buildings are designed to mitigate blast effects, they are not designed as bunkers, rather they are designed to provide a specific level of protection to the occupants. It can be important to know what level of protection was included in the design and what that means for sheltering in place, evacuation and other operational considerations.
• What building hardening measures, if any, were assumed to be implemented when the required standoff distance was decided upon?
Standoff distances are not developed in a vacuum and they often assume that certain blast mitigating measures are implemented (such as the installation of blast resistant windows or anti-shatter film). In order to get the intended benefit of the required standoff distance, it will be important to make sure that all the assumed mitigation measures are in place.
Want to learn more: Attend our latest class, Protective Knowledge – Blast Resistance By Design, May 4 – 8, 2015. Click here for more information.
Our own Khaled El-Domiaty, Vice President and Associate Principal of Stone Security Engineering, will be the lead speaker at an upcoming technical dinner seminar on February 9, 2015 in Al-Khobar Saudi Arabia. The seminar has been jointly organized by Support Lines General Contracting Est. and ASIS International Middle East Dhahran Chapter 72. Mr. El-Domiaty will be presenting “Blast Effects and Innovative Mitigating Techniques and Materials”. The presentation will cover:
