As part of our On-Call Geotechnical Services contract with the Arizona Department of Transportation, NCS was tasked with reviewing and implementing the AASHTO Load and Resistance Factor Design (LRFD) Bridge Design Specifications as it pertains to geotechnical engineering.  NCS’ scope of work included the comparison of new methods prescribed in the LRFD specifications with the current state of the practice, and the preparation of policy memoranda that would form the baseline of the new standard of practice for geotechnical engineering in Arizona. Three (3) of these memoranda were issued in February of 2008 and are discussed in more detail on our ADOT LRFD Policy Memoranda page.

Over the course of this project, detailed parametric analyses were performed, as well as a thorough review of various editions and interims of the LRFD specifications.  In particular, NCS critically evaluated the LRFD specifications with respect to local practices and identified several modifications for consideration by the agencies.  Detailed reliability based calibrations based on Monte-Carlo numerical simulations were performed to evaluate resistance factors.  Some of these calibration efforts were also presented to AASHTO T-15 committee meeting in Delaware in June 2007. 
As the new LRFD specifications are officially brought into practice by agencies in Arizona and other parts of the country, NCS, with our intimate familiarity with the specifications as well as instructional background is at the forefront of the geotechnical community in terms of our implementation of the new design procedures on live projects as well as the training of other agencies and consultants.

Some Practical Considerations for LRFD Implementation for Geotechnical Features. Presented by Naresh Samtani at the 56th Annual Minnesota Geotechnical Engineering Conference in Minneapolis, MN on February 29, 2008.

Practical Suggestions for Implementation of LRFD Specifications for Geotechnical Features. Presented by Naresh Samtani at the 2008 TRB (Transportation Research Board) Conference in Washington D.C. on January 16, 2008.

LRFD Article 2: LRFD for Substructures - Concept of Failure and Reliability Index - by Naresh Samtani. Revised May 8, 2007 (R0). NCS Article #: 01-0607-R0. HTML version also published at GeoPrac.net.

LRFD For Bridge Substructures Presentation Notes (AzSCE May 8, 2007) - Presented by Naresh Samtani to the Bridge Technical Comittee of the AzSCE. (Revised May 18, 2007)

LRFD Article 1: LRFD for Substructures - Limit States and Interaction between Structural and Geotechnical Specialists - by Naresh Samtani. Revised May 8, 2007 (R0). NCS Article #: 01-0507-R0. HTML version also published at GeoPrac.net.

A Primer on LRFD (January 10, 2006) - Presentation notes from a Naresh Samtani presentation to the AzSCE Bridge Technical Committee.