Structural Floor for Hangars

[smcp4blo]

Hello,

I've been asked to design a structural floor for a Hangar inside an airport. I've been using the FAA program (FAARFIELD) which calculates using finite element methods the thickness of different layer such as base, subbase, etc depending on CBR values. However, this program and, ergo, the FAA designs pavements for taxi lanes depending on how many landings and takeoffs the airplanes do, in this case, the Hangar is for maintenance purposes, so the airplane will not move for at least 8 months making it a static load.

So, I studied ACI360-10 and I can see there are different design methodologys to calculate thickness of concrete over the grade, however, I haven't found the way to calculate thickness of concrete AND the layers below. In other words, ACI360 uses the K (reaction modulus of grade) and with that number you can get the thickness of concrete, and that's it; I need a way to design the layers from below the concrete in order to reduce concrete.

Any ideas, comments?

Thanks!

 

[hokie66]

Whatever method you use, I doubt that you will be able to "reduce concrete". A static load on a concrete pavement is worse than a moving load. Of course, your static load won't contain the loading of passengers, baggage, and freight which the FAA procedure would include. I wouldn't want a hangar designed with a pavement less than required for a taxiway for the same type aircraft.

 

[smcp4blo]

Well actually the weight for design if the maximum, which includes passengers, baggage, etc.

My first design is always as a taxi lane, on this design if you include 3 or 4 layers below the concrete and you vary the CBR values and thickness, concrete thickness can be decreased significantly; that's why I need a way to design this layers for a static load, in order to find the best solution...

Any comments? Thanks!

 

[Ron]

Design for the anticipated aircraft loading. If the stress in the concrete is less than 1/2 the modulus of rupture, then don't worry about the number of repetitions...irrelevant.

 

[smcp4blo]

Thanks for your comments, however my doubt remains, maybe I'm not being clear...

My question is using ACI360 or PCA, how do I design the layers below the concrete (base and subbase)?

Thank you!