Police Barracks 4

[KCRatnayake]

Dear all,
I am a structural engineer practicing in Sri Lanka. I got to design some police barracks for areas recently liberated from terrorists. All of them are single storeyed structures and client specifically says that the roof should be flat concrete slab, in case of future attacks. I also know that these buildings should be concrete framed structures.
Can somebody give me some ideas what to consider in designing these kinds of structures? I.e. sizes of structural elements, spacing of columns, slab thickness etc.

KC

 

[concretemasonry]

Why do you think they should be framed concrete?

For security, you would reinforce the walls, so reinforced masonry on a one storey structure would be more effective since it combines the reinforcement/security and the ability to support the roof loads.

Being somwhat familiar with your construction, I would not expect many long spans or open areas in a barracks-type structure, so there would also be interior walls.

The traditional RCC columns with unreinforced masonry infill would probably not provide the desired security. You would not beable to use the traditional partially fired solid clay brick without complex bonding, but block are available in some areas of Sri Lanka.

 

[KCRatnayake]

Concretemasonry,
Reinforced masonry is not much popular in Sri Lanka. Anyway, at least, for this purpose I can think of using them.

KC

 

[concretemasonry]

I recognize that it not be too common since much of the construction is similar to India. Even if you do RCC columns, you still have to address the wall security.

If you have block available locally, you should be able to do it since your spans are probably quite short. You do not have a strength problem, but you need some grout to hold the rebar and bond it to the concrete block.

In the U.S. for maximum security over a long period (years), 8" spacing is common, but it is much less for other security levels. 24" on center may even be adeqaut.

I understand the security situation, since I had to sit on the runway waiting to take off for over an hour because the rebels shooting in the area. - I understand it is getting calmer and more secure now. Its a beautiful place!!

Dick

 

[msquared48]

I would consider a structural slab, covered with a minimum of 12" too 24" of soil as an energy absorbing element, then a 8" reinforced slab-on-grade over that. If you are interested in security, this should help with resisting mortar attacks. Hope the soil bearing is adequate.

I would also consider typical wall construction of two brick/CMU/concrete walls infilled interstitially with soil and tied together.

Mike McCann
McCann Engineering

 

[Rjeffery]

msquared48 are you suggesting a 2 wythe thick wall with rubble infill? (good suggestion, that!)

 

[msquared48]

That's another way to go.

The purpose is to absorb energy, and it is taken from ancient construction techniques to resist the battering from siege machines. It works. Look to Masada and the Hittites, to name a couple of examples.

If you are trying to resist the effects of a a bunker buster, forget it, but it will work against mortars, RPG's, and small arms, the transportable things terrorists use.

Mike McCann
McCann Engineering