1 of 5

Upcoming NCHRP Synthesis Survey:��Agency-specific Resistance Factors for Geotechnical Design

Andy Boeckmann & Erik Loehr

2 of 5

Motivations for Agency-specific Models

  • AASHTO empirical methods (alpha, beta, modified Gates formula, etc.) have small resistance factors
  • Appropriately so! Foundation capacity inherently variable:
    1. Construction practices
    2. Effect of local geology
    3. Within-site variability
  • Effects of (1) and (2) are reduced by using agency-specific models�🡪 Better predictions & higher resistance factors

3 of 5

Objectives of NCHRP 53-06 are to Document:

  • Extent to which state DOTs have developed agency-specific methods and resistance factors
  • Which methods have been developed (i.e. what types of foundations, loading, limit states, etc.)
  • Details of development
  • Challenges of development
  • Benefits of development

4 of 5

Need your input!

  • Online survey link will come before the end of January
  • Invitation will come from myself or Erik with follow-up from NCHRP
  • Mailing list consists of state foundation and geotechnical engineers, but may need input from others:
    • Please forward to or share with a colleague
  • Please complete by mid-February (2 or 3 weeks)

5 of 5

Thank you

Andy Boeckmann

aboeckmann@dba.world

573-424-0017

​