Design of Sliding Door for TNT Explosion 1

[Angre]

Hi All,

We have a request from client to design a sliding door system to resist explosion from 50kg of TNT at distance of 0.50 m.

Now, I'm familiar with designing for blast resistant doors in petrochemical facilities, but this is something entirely different.

Are there any design guidelines for designing to such explosive related blasts?

Rgds

Angre

 

[IRstuff]

There are publications from various agencies, FEMA USACE, etc., that I think cover this sort of thing. 0.5 m sounds like an intentional blast, particularly since it's 50 kg of TNT. Does the door need to work afterwards, or simply prevent entry?

TTFN
I can do absolutely anything. I'm an expert!
faq731-376 forum1529

 

[Angre]

Hi IRStuff,

I've done some Web Search and come across Sadvosky's equation.It is a three term eqation with dominating term of 7.0*TNT weight in kg/(distance in metres)^3 = 7*50/.5^3 = 2800 atm

This is almost impossible to design to. I'm pondering over the matter, as to should I inform the client that this is almost impossible to design for and ask for more reasonable parameters.

Rgds
Angre

 

[TehMightyEngineer]

Perhaps you can come up with a design that has replaceable components after damage. Such as a concrete filled door with steel plates reinforced. The steel plates could be designed to buckle and deform, dissipating energy, and the concrete acts as a restraining mass but otherwise remains undamaged. The steel plates can then be replaced as desired.

But, yes, I'd say they should revise their loading to be less conservative. Unless of course the consequence of failure means that such conservativeness is warranted.

Professional and Structural Engineer (ME, NH)
American Concrete Industries

http://www.americanconcrete.com

 

[1gibson]

I'll apologize in advance (maybe I watched too much coyote and roadrunner as a kid) but I have to say it:

Have you considered quickly painting a big black circle on the floor where the 50kg of TNT is sitting, so that it will fall through and the threat will be eliminated?

 

[BUGGAR]

Tell your client to watch Mythbusters.

 

[Teguci]

http://www.clarkpacific.com/content/documents/Blast_Design_Considerations_-_Ascent_2011.pdf

Article with references at the end. I imagine the references all require authentication though. The article seems to indicate that the impulse load should not be looked at statically as that would be way too conservative.

 

[Angre]

I've come across designs of doors with filled with concrete, but they were designed for about 5 atm (~50 t /sqm).
This case though is far more than 5 atm.
1gibsons suggestion though meant in jest, does indicate some way forward. May be a damage absorbing replaceable cladding is the way forward.
Teguci's reference also indicates that the demand on the door is not linearly proportional to the amount of TNT.

 

[mike20793]

This needs to be left up to a specialty contractors. There is software available to do the design but it requires a DoD clearance. There are also some public documents relating to the design but specific values will require the same DoD clearance. I've done plenty of military buildings and blast effects are always a specialty designer.

 

[Lomarandil]

Not all software for blast resistance requires DOD clearance. As I recall, LS-Dyna was particularly well suited for it.

Granted, by the time you look at learning a new FEA package, you may wish you'd gone with a specialty contractor.

 

[mike20793]

That's good know. I guess I am misinformed to the availability of blast software. You would think they'd be careful what they let people get their hands on.

 

[IRstuff]

Will the walls attached to this sliding door survive the blast?

Some things to look at;

http://www.fema.gov/media-library-data/20130726-1455-20490-4910/fema426_ch3.pdf

http://www.fema.gov/pdf/plan/prevent/rms/453/fema453.pdf

https://www.fema.gov/media-library-data/20130726-1833-25045-0079/fema_p_439b.pdf

http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_645.pdf

this one is specifically labeled: "BLAST RESISTANT DOORS"

https://www.wbdg.org/ccb/DOD/UFGS/UFGS 08 39 54.pdf

http://pdc.usace.army.mil/library

has a couple of spreadsheets and documents related to blast resistance

TTFN
I can do absolutely anything. I'm an expert!
faq731-376 forum1529

 

[Lomarandil]

Mike, if someone intelligent enough to get ahold of LS-Dyna and apply it in a nefarious manner is on your watch list, you've got bigger problems. It's not, shall we say, cutting edge UI.

 

[BrianPetersen]

1gibson's fix only works when there is a cartoon wolf holding the TNT.

 

[jayrod12]

He's a coyote.

 

[Angre]

Found a way out.
ABAQUS Examples Manual has a similar problem solved along with the model files.

 

[thaidavid40]

From experience, please note that all of the blast doors I have seen that are required to resist anything like the explosive charge you listed above have all been swinging (hinged) doors (storage bunkers, rocket silo caps, etc.). I don't think that I have ever seen a single sliding-type door for this level of application. I would be interested in the details of how you make a sliding door work out - if it does.
Dave

Thaidavid

 

[haynewp]

I would be interested in how the rest of the door assembly is shown to work and not just the thick steel plate making up the leaf itself.

 

[3DDave]

There are sliding doors on missile silos; They are expecting a bit more than TNT, though I think they are expected to meet their design requirement only once.

Interesting problem.

 

[Angre]

thaidavid40, You are right, the client has expressed preference for swing doors over sliding doors.
I feel that with sliding doors, the design of iron mongery would be simpler.

Haynewp, along with leaf, we have to design for door frame, hinges and bolts.
We get the forces acting on these items through FEM analysis and design using conventional methods.
There is also the option of going to specialised vendors(for hinges and sliding bolts and they come up components to resist the given forces.

Rgds