Deep Foundations: Schema Discussion

[nickmachairas]

Requesting your comments and feedback on deep foundation elements. Thank you.

[nickmachairas]

In "PileDrivingRecord Measurement Properties" I notice that there are no blows per foot or blows per inch. How is this handled?

[dponti]

This is handled by a combination of of the properties blow_count and pen_increment. Measurements of blows/ft would have the blow count be the value of blow_count and a value of pen_increment assigned to 12 (assuming that the uom for pen_increment is set to inches. When shifting to blows/in, the pen_increment value would change to 1. This approach allows for any combination of blows/penetration increment that might be encountered during a pile driving run.

[samullaney]

Regarding the "Pile Driving Forms" listed on the Deep Foundations Schema Development page, PennDOT also uses another from, CS-5, Pile Hammer Data (https://www.dot.state.pa.us/public/pubsforms/Forms/CS-5.pdf).

[dponti]

The form you present includes data contained in DIGGS objects that capture 1) pile hammer, 2) pile cap, 3) pile cushion, and 3) the pile itself (DIGGS AbstractPile). I have made modifications to these objects to capture some properties not included originally. These changes are not copied in the åWIki, but can be view in the development schema documentation here:

https://diggsml.org/docs/latest/Piling_xsd_Element_diggs_PileDriveHammer.html#PileDriveHammer
https://diggsml.org/docs/latest/Piling_xsd_Element_diggs_PileCap.html#PileCap
https://diggsml.org/docs/latest/Piling_xsd_Element_diggs_Cushion.html#Cushion
https://diggsml.org/docs/latest/Piling_xsd_Element_diggs_AbstractPile.html#AbstractPile

A couple of questions:

1. Please confirm that the Cap Block is equivalent to a Pile Cap (eg. a foundation element that sits on multiple piles and used to distribute structure weight to the piles).
2. Is factored resistance equivalent to nominal pile capacity.
3. Please explain As Ordered ASTM Specification - what is Fy and (ks) referring to? Is this a design specification for the pile or an "as built" property.
4. It appears that Pile lengths to be driven is a design specification and not an as-built property. Is this correct? Can the "as-built" property of pile lengths be derived from the total length of the driven pile and the location of splices?

[samullaney]

The CS-5 is a form submitted to supplement the WEAP analysis. The WEAP analysis is run to “approve” the proposed hammer, i.e., all the information on the CS-5 are estimations and manufacturer data (not as-built information).

Please see my responses to your questions:

1. On the CS-5 form, the Cap Block is another term for Hammer Cushion. The Hammer Cushion acts to cushion the hammer on impact and is located between the striker plate and the helmet. For concrete piles, there can be an additional cushion (between the helmet and top of the pile), termed a pile cushion (see screenshot below from NHI and my red markups).

2. No, the “Factored Resistance” is equal to the “Nominal Resistance” * Resistance Factor. For steel piles driven to refusal on rock (structural resistance controls), the RF is based on the applicable driving condition – severe (0.5), good (0.6), soluble (0.273) per PennDOT Publication 15M, DM-4 Section 6.15.2. For piles, where geotechnical resistance controls, the RF is applied to the nominal geotechnical resistance (to determine the factored resistance) and is based on the recommended field testing, i.e., RF = 0.65 (PDA), RF = 0.8 (Static Load testing and PDA) – see AASHTO Table 10.5.5.2.3-1. The actual design load is to be less than the “factored resistance”.

Beyond the CS-5 form (placed on project plans) there is also the “Required Driving Resistance”, which is a value different from both the “Nominal Resistance” and “Factored Resistance”. For an HP12x74 (50ksi) steel pile, the required driving resistance is 554 kips (RF.severe0.66FyAs)/(RF when PDA is used) = (0.50.665021.8)/0.65 = 554 kips. The “Required Driving Resistance” is the resistance that the pile should be driven to (i.e., the PDA/CAPWAP result). The PDA/CAPWAP results are multiplied by 0.65 and that value must meet or exceed the “Factored Resistance”. I’m not sure that they is necessary to include in the schema, but wanted to share for your use.

3. The Fy is the yield strength of the steel pile, 50 ksi is typical. You spec the strength of material you want during design.
4. The “Pile Lengths to be driven (ft.)” is the estimated pile length, based on design. If the pile length differs in the field, that would be the “as-built” pile length.

[samullaney]

I participate in the DIGGS codelist calls and I was tasked with working up a draft equipment codelist. The draft codelist includes pile hammer types and pile hammer components. I am not sure if it would be of use for this effort. Link to draft codelist: https://github.com/DIGGSml/def/blob/master/Draft%20Excel%20Codelists/draft_equipment_codelist_R01_20240510.xlsx

[dponti]

Thanks for this - please look at the Driven PIle objects that we've specialized so far and comment on the properties for these objects Perhaps other specializations for pile driving equipment is in order.

Note DIGGS currently considers the pile cushion (Cushion) to be a component object dependent on the pile driving activity, because it is a consumable product that can deform during pile driving nd not reusable as other equipment is. Please corrct if this should be an equipment object (thus cpotentially arries make model, serial number , calibration audit trail, etc.

[samullaney]

There are different types of hammer cushions (e.g., Aluminum/micarta, Conbest, etc.) and that factors into the WEAP Analysis/pile hammer approval. I agree that hammer cushion is a consumable product that does deform and “wear out”. I am in agreement to leave it as a component object.

[dponti]

Added a new required property to AbstractPile (thus all piles will inherit) named pileSizeDesignation, as a codeType, defined as "A code or name identifying the pile size (typically diameter and weight/unit length) along with other shape parameters as applicable. Intended to come from a controlled list of terms, Example: HP 200 x 64, You may view in documentation here: https://diggsml.org/docs/latest/Piling_xsd_Element_diggs_AbstractPile.html#AbstractPile