Allowable Pile Lateral Deflection

[irawanfirmansyah]

Hello,
I need a reference on any international building code which specify the allowable pile lateral deflection against base shear, for highrise buildings.
Any input, suggestion will be appreciated

 

[pelelo]

As a rule of thumb, engineers use 1% of the diameter of the pile as the allowable lateral deflection.

 

[SoilRocks]

I don't usually see a structural engineer use a percentage of the pile diameter. Almost 100% of the time, I see them pick an allowable deflection, and apply a factor of safety to the ultimate lateral load that will produce that deflection. The deflections I see structural engineers use most range from 1/4 to 3/4 inch of deflection. I provide the lateral load at the top of pile that will produce that deflection, and they apply a factor of safety to that load - usually 1.5 for transient loads is my understanding.

 

[irawanfirmansyah]

Thanks to pelelo and SoilRocks for the input. I agree with SoilRock that allowable lateral deflection is not related to pile diameter. What I normally do is to calculate the lateral force corresponding to lateral deflection of 1/4 to 1/2 inch. This lateral force is the allowable force, and I do not use any SF, as I already use limited lateral deflection.
Iam reviewing a foundation design for a 40 storey building in one site with 19m soft, underconsolidated soil at the upper part, in such that lateral capacity of pile dictates the required number of piles. This condition make me curious whether it is common to adopt larger lateral deflection than I normally use. Should there any body know about this, please share with me. Thank you.

 

[msucog]

i use lateral force corresponging to 1/4 inch deflection but i'd have to look back to see if ibc actually calls out 1/4 inch...i do know the references i've traditionally use refer to 1/4 inch. you could always defer to the building code lateral capacities but they are crazy conservative assuming a psuedo-worst case scenario (which is actually reasonable for such a nice/neat table). of course, it ultimately depends on how much of the top of the pile you consider is providing the passive resistence in addition to whether it is acting over 1D or 3D or more.

as far as the 'percentage of pile diameter' approach, i'd say it also depends on the pile type too.