Pin Piles

[zigmark]

Condition;

State Park welcome center building located in coastal V zone and is required to be elevated on a deep foundation system. Proposed deep foundation system is to place an elevated slab on 4" diameter hollow steel "pin piles". We are 2012 IBC, Seismic Zone D.

My questions are regarding the "pin piles" which is not a code term. Sorting through Chapter 18 requirements for deep foundations I find a minimum diameter of 8" for the steel piles per 1810.3.5.3.2. The exceptions allow micro piles which at first glance seems to be where the designer is headed. Further research leads me to the fact that micro piles (Section 1810.3.10) are a bored and grouted system seemingly with reinforcement and are considered an alternate means in my seismic zone Section 1810.3.10.4? Does anyone out there have experience with this type of a proposal. I typically see reinforced concrete columns not steel pipe. Any and all help is welcomed. ZIG

 

[cda]

http://www.nicholsonconstruction.com/techresources/techPapers/PDF/Pin%20Piles%20for%20Building%20Foundations.pdf

http://www.nicholsonconstruction.com/techresources/techPapers/PDF/PinPilesUnderpinning.pdf

Pin piles mini piles same thing??

http://www.haywardbaker.com/WhatWeDo/Techniques/StructuralSupport/Micropiles/default.aspx

 

[jdfruit]

Key issue will be pile shaft constraint and how that relates to the pile/slab connections for lateral moments. You will need a very knowlegable geotech engineer working in collaboration with a structural engineer that knows the pile system well.

 

[zigmark]

cda- Thank you for the links I have seen both of those reports. This particular application is not proposing to drill or grout these are being proposed as driven hollow steel tubes with caps after the fact.

jd- I do not disagree that a well detailed and coordinated effort for the design will be necessary and why I need to be sure their design is based on something applicable.

Just to throw it out there... Being steel pipe deep foundation elements and since all deep foundation elements are required to be designed does the minimum of 8" diameter apply IBC 1810.3.5.3.2? Can a design usurp this minimum? If so why provide a minimum?

ZIG

 

[jdfruit]

ZIG

I may have found what you are looking for:

1810.1.4 Special types of deep foundations. The use of

types of deep foundation elements not specifically mentioned

herein is permitted, subject to the approval of the

building official, upon the submission of acceptable test

data, calculations and other information relating to the

structural properties and load capacity of such elements.

The allowable stresses for materials shall not in any case

exceed the limitations specified herein.

 

[zigmark]

jd-

See this is the reason I subscribe here... another set of eyes. I swear I have been through these code sections during the discussions about this topic in office a hundred times and looked over that section.

ZIG

 

[JBI]

The 'devil' is in the details... which must be provided as jdfruit notes above.