The following article was originally published in March 2013. It was written by our company's founder, Jeff Lange. We've updated it to reflect current industry facts and trends.
Although there are no regulations in place for the design and construction of blast-resistant buildings, many of us are working toward that goal. In the meantime, here is a list of questions everyone should ask before buying a blast-resistant building.
1. Was the Module designed and tested by a blast expert?
The science of blast-resistant building design is no longer a new science, but it is still true that only a small group of experts have tested their designs.
Make sure your blast-resistant building design has been taken off the drawing board and successfully blast-tested under the supervision of a well credentialed engineer.
There's no shame in asking about your vendor's "experts." Even if they are civil or structural engineers, it's worth knowing about their training and background. Do they have years of experience in the science of blast-resistant design, or did they take a three day course to qualify them?
2. Are blast test reports specific and conclusive?
There are many interpretations of the term blast-tested (see question five), but a successfully blast-tested building has the proven ability to actually save lives. Pay special attention to duration and psi ratings when you review blast test reports because different applications call for different specifications. A laboratory blast-resistant building placed next to a blowdown stack should carry a higher rating, such as 8 psi, while a guard shack placed at the perimeter of your facility may only need a 3- to 5-psi rating.
3. Was it blast-tested for nonstructural/ structural components?
If a structure survives a blast but its interior walls, lights or other fixtures create shrapnel, the risk of casualties is still high. Always ask blast-resistant building vendors to provide data and rationale for nonstructural items including wall and ceiling finishes, light fixtures, plumbing fixtures, cabinets, placement of open shelving (should be no higher than 40 inches above the floor) and placement of any intake points (which can vary in height, but need to be properly sealed for the environment or hazard).
4. Can the following information be provided?
- Was the blast-resistant module tested dynamically rather than statically?
- Was it tested in a free field environment?
- Was a P-I (pressure-impulse) curve generated to show the blast-resistant building's response over a wide range of blast loading?
These items are too technical to cover in the context of this article but should be on your list of discussions to initiate with any blast-resistant building vendor. Our engineering department can even address these issues with you too.
5. Does the Building's response level demonstrate its capability to save lives?
As mentioned in question two, interpretation of ratings is everything. A blast-resistant building vendor can claim its product has been blast-tested (and maybe it has) but if closer examination of test data demonstrates a high-response result, this is not the structure you want protecting your personnel. Response level ratings have been established by the American Society of Civil Engineers to predict the extent of repair resources needed after an explosion. Here's the key: high response equals high damage, so it's crucial to study the response level table, then take a very close look at any blast-resistant module's response rating for a given duration and psi (as proven through actual blast testing).
With continued research and product development, previously hazy areas of blast-resistant building engineering are quickly coming into focus. When you go shopping for blast-resistant buildings, it's important to ask solid questions and expect solid answers. What it really boils down to is finding a vendor committed to doing the right thing, and this commitment will be visible in the vendor's documentation.