Determination of Required No. of Piles in Eurocode

[neukcm]

Good day Everyone!

In Eurocode to determine the required no.of piles you are given two sets of combinations both for actions and for pile geotechnical capacity as given below: (for precast concrete piles)

SET A : Loads : 1.35Gk + 1.50Qk divided by
Pile Total Resistance: (Qb/1.0 + Qs/1.0)/1.40

SET B : Loads : 1.0Gk + 1.30Qk divided by
Pile Total Resistance: (Qb/1.70 + Qs/1.50)/1.40

where Gk = permanent loads; Qk = variable loads; Qb and Qs pile bearing and shaft resistance respectively. Whichever combination that gives max. no. of piles will be adopted.

Now in my recent project my total pile resistance (Qs & Qb) exceeded the allowable pile structural capacity of 0.25*FC*Ap. My question is, what set of load combination do i need to use if i'm going to adopt allowable pile structural capacity? Is it SET B?

Thanks in advance and please share the link or reference if you have. Thanks again


Neukcm

 

[BigH]

I will admit that I am not familiar with the Eurocode - but in looking at things - the first is the geotechnical issues to determine the pile capacity; the second is the structural capacity of the pile. If the geotechnical capacity is smaller than the structural you would use the geotechnical; if the structural capacity of the pile is less than the geotechnical, it seems obvious, at least to me, that you would use the structural capacity. It is a "this" or "this" whichever is less . . . scenario. For steel piles you could always increase the structural capacity by increasing the thickness of the round pile wall or thickness of the web in an H-pile.

 

[neukcm]

Great to see your reply BigH, Thanks.

I'm stucked on this situation right at the moment, gone thru with the codes as well and has been looking for the correct approach.
The thing is, my total geotechnical pile capacity (Pile bearing + Pile Shaft resistance) exceeded my pile structural capacity, Qb + Qs > 0.25*Fc*Ap, definitely it is the minimum of the two criterias that must be adopted as what the codes says and what you seconded also.

To simplify my query:

SET A : Loads : 1.35Gk + 1.50Qk divided by
Pile Total Resistance: (Qb/1.0 + Qs/1.0)/1.40

SET B : Loads : 1.0Gk + 1.30Qk divided by
Pile Total Resistance: (Qb/1.70 + Qs/1.50)/1.40

In my Case : Loads : ___________ divided by
Pile Structural Capacity: 0.25*Fc*Ap?

Thanks and let me know if there's something wrong with my details above.

neukcm