Design of Vaults 2

[KCRatnayake]

Dear all,
Can one of you help me to solve the following problem?

I'm designing a 3 storeyed bank building. There is a vault on the 1st floor level. I thought of having 9" thick concrete walls around the vault. Is there any other considerations when you design these type of structures? If you could provide me with a web-link (if available), that would be ideal.

Regards,
Clefcon

 

[UcfSE]

You should coordinate that with the architect. On the banks I have worked on, there is a pre-manufactured vault that is used with no need for engineering. The manufacturer or architect will also suggest a foundation thickness and reinforcing for the area under the vault.

 

[MiketheEngineer]

If you do end up designing the concrete walls - will you please leave an area about 2' x 2' without rebar.....

Then share that information with the forum.. Don't forget the address..

Thanks

 

[SperlingPE]

Concur with UcSFE
The recent bank structures that I have worked on utilized a pre-manufactured vault wall and ceiling. The floor was recommended by the vault wall supplier and constructed by the general contractor (concrete sub). The latest recommendation that I used was (3) mats of steel with reinforcing in each direction and 12" minimum concrete thickness. This wault was elevated above the basement. There is some coordination to be done between the vault wall supplier and vault floor dealing with connections/support.

 

[JEmH]

A little off topic, but I thought I'd share. We just demolished a vault from a 1900 era bank building as part of a big rehab project. This vault was in the basement and had a single mat of 7/8" round bars at 6" both ways, centered in 12" walls and ceiling, sitting on the plain concrete floor. It yielded easily to modern equipment, but I had to wonder if at the time it was thought to be "indestructable."

 

[Madikins]

Equally off the direct topic, but some owners are especially interested in the robustness of the vault to sustain some pretty high levels of attack. For instances, one agressive way to break into a vault is the use of a 'burn bar,' which is a thermal tube burning oxygen and solid fuels at an ultra high temperature sufficient to cut through both concrete and steel.

One low tech, but effective way to prolong break through from this means of attack is to insert staggered layers of expanded polystyrene boards within the thick concrete walls. The EPS boards serves to foul and gum-up the tips of these burn bars to such an extent that it greatly delays burn through, hopefully allowing the authorities to arrive in time to save the day!

 

[Lutfi]

My experience is exactly that of UcfSE

Regards,
Lutfi

 

[dik]

Banks often have different levels of protection for vaults and different specifications for each type.... for MiketheEng... with atomic hydrogen torches (burning bars) reinforcing matters little... I remember the first news article about burning bars and about two weeks later it was used for a bank heist in Montreal...

Dik

 

[MiketheEngineer]

Wish I had known that on the last heist - took us forever to get through that bank vault wall....

 

[KCRatnayake]

Thanks to you all. Your posts are very helpful.

Clefcon

 

[Loui1]

I think the main consideration is that a structural engineer shouldnt be designing the security aspects of a bank vault.

Either get a premanufactured vault or a consultant that is specialized in this area.

FYI: All bank vaults can be broken into, they're just something gives law enforcement time to get to the scene. Better vaults take longer to get into, etc.

 

[RARWOOD]

If you search around a little on the web, you should be able to find some guidlines.

I,ve only worked on one bank valult. The requirements were for 3 layers of staggered #8 bars. I don't remember the exact spacing but I think it was 3" oc or less. The requirement was based on the maximum drill size. Above that size the bar spacing was such that you could not drill through the wall with out hitting a rebar.

 

[PSlem]

I supervised some underpinning on an old courthouse in south GA. Someone years ago had broke in and chipped away around the large steel door all night, but failed to get it loose. I went in the vault to discover it had an outside window!

 

[dik]

Loui1... I've designed a lot of attack resistant entrances and I'm not an architect... or a specialist... came upon it by glancing at a set of drawings showing Lexguard being supported in a flimsy frame and wall... for 30-06 level of attack... Architect was really proud of is 'bulletproof' sample until I drilled a hole through it with my .338...

As far as bars go... did some work on a jail once and the main entrance had a floor to ceiling wall of bars... 1" dia through 3/8" straps with four lines of weld dribbled on the bars to keep from sliding the straps down the bar... the whole wall was secured at the ceiling with three 3/8" lag bolts... Ho Hum...

Dik

 

[KCRatnayake]

Dik,
I did some surfing on "Atomic Hydrogen Torch". It generates a temperature in excess of 3,500 degree Centrigrade. (Diamond Evaporates, Titanium melts) .......

Hope not many people have access to these kinds of products!

Clefcon

 

[dik]

First encountered this about 30 years back... Gets warm enough to really warm concrete with or without rebar... If you look up the manner in which it works... it's easy to build one...

Dik