Concrete pipe sleepers with low compressive strength

[amhaz75]

I'm looking into calculating the total load of a 10" fuel gas pipe and a 4" condensate pipe to be placed on a straight run of 10 concrete pipe sleepers spaced at 12m. The test result of the concrete compressive strength (28 days cube break) came out to be around 15 MPA (Spec calls for 27.6 MPA or 4000 psi). I'm trying to see if this concrete could be sufficient to hold to two pipes. How do I do this type of calculation?

 

[BigInch]

I believe it is, if the sleeper has continuous bearing on soil below. These pipes don't weigh much, even if filled with lead. I would pass it based on experience, without any calculation, if the concrete had at least minimum temperature reinforcement steel.

Loads
12m weight of pipes + contents as a vertical dead load,
then multiply each by 0.3 to simulate a thermal friction load from each pipe at point of contact at top of sleeper, directed parallel to axis of pipes.

 

[MickMc]

aalbuhse,

I have no comments on the sleepers themselves but would say that the 12m spacing looks excessive for both NPS 4 and NPS 10 and would expect spacing to be normally 6m - 8m to accommodate both sizes dependant on maximum allowable mid span deflection which varies with client.

Regards.

Mick.

 

[LittleInch]

How do you do it?. Calculate total weight on a sleeper. Work out bearing area. Find pressure.

You don't say how big your sleepers are, but so long as they are decent, i.e. not matchstick thickness then they should do. Of more importance is the span night. 12m is far too long for 4" and a bit of a push for 10".

The problem with low strength concrete is poor weather protection and frost can easily break up low strewgth concrete.

Are these sleepers just sitting on the ground or do they actually have other stresses?

I think though you don't have a real issue.

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