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Foundation capacity increase

Foundation capacity increase

Foundation capacity increase

(OP)
Hi, have you ever use or gotten a recommendation for increasing the lateral capacity of piles for short term loads? I think that this (1/3 increment in capacity) is more applicable for axial capacities (although ASCE 7-10 does not indicate this explicitly). Any feedback will be appreciated.

RE: Foundation capacity increase

The old allowable increase of 1/3 for transient loads (like wind or seismic) is no longer applicable with "modern" load combinations (e.g. at least ASCE 7-05, possibly earlier).

Now, if you're talking about some sort of geotechnical response in the short-term due to an undrained cohesive material or something like that... that's a different animal (that you should take up with the geotechnical engineer who prescribed it). But I suspect that's not what you mean.

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The name is a long story -- just call me Lo.

RE: Foundation capacity increase

I'm going off memory here so I apologize If I'm mistaken, but it's in the 2012 IBC and you can use the stress increase if you use the alternative load combinations.

RE: Foundation capacity increase

(OP)
Thanks for the responses. I am involved with the geotechnical portion so I wanted to hear the input from the structural side. We normally still keep recommending the 1/3 increase for vertical capacities, but I was not sure if this also has been considered for lateral capacities. I would say that since the modulus of the soil gets reduced as the strain increases and considering that the modulus is one of the main parameters for lateral capacities (although is not sensitive to large changes of the modulus), I think that this increament does not need to be considered for lateral capacities.

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