Recent communications with the WSDOT Geotechnical Services Branch have resulted in establishing the following procedure for pile foundation design and modification to LRFD General Notes:
The pile ultimate bearing resistance included in the General Notes shall be taken as the maximum factored pile loading from the applicable service, strength, and extreme-event limit states divided by the applicable resistance factor for pile bearing as specified in the geotechnical report.
A table of all pile loadings and tip elevations, and a pile layout shall be submitted to the geotechnical engineer for the project for review as soon as the foundation design is completed. The submittal to the project geotechnical engineer shall also include the factored service load per pier to check group settlement. The project geotechnical engineer needs to submit to bridge designer an overdrive estimate to be includes in the Bridge Special Provision for overdriving.
To be consistent with the requirements of the WSDOT Geotechnical Design Manual article 188.8.131.52.3, the Geotechnical Services Branch recommends that only pile ultimate bearing resistance shall be shown in the General Notes. The ultimate pile bearing resistance shall be taken as the maximum pile loading from the applicable service, strength and extreme-event limit states.
The designer shall submit a separate table showing all pile loadings and tip elevations, and pile layout plan view to the geotechnical engineer for the project prior to the completion of the project.
If you have any questions regarding these issues, please contact Chyuan-Shen Lee at 705-7441 or Bijan Khaleghi at 705-7181.
cc: Mohammad Sheikhizadeh, Bridge Construction - 47354
Example for GENERAL NOTES
Piles shall be driven to an Ultimate Bearing Resistance as follows:
Example for Pile Design Data Sheet
The following tables including pile foundation layout and loading shall be submitted to the geotechnical engineer for the project at the early stage of design for their review.
* Values in this table are per pile and are the maximum values at the pier. If no piles go into uplift, enter 0.0 for uplift loading.
** Include loading due to downdrag but does not include the effect of loss of friction.
***Ultimate bearing resistance is the maximum factored compression load divided by the resistance factor.