The objectives of this research were to develop (1) recommended specification provisions for highway structures foundation design, based on the load factor design philosophy, and (2) engineering manuals to assist in the design of foundation and substructure elements. The existing (14th edition) AASHTO Standard Specifications for Highway Bridges includes provisions for superstructure design based on allowable stress design methods or load factor design methods. However, only allowable stress design specification provisions are included in the Standard Specifications for the design of substructures, abutments, and retaining walls.
Research has been completed and the final report published as NCHRP Report 343: Manuals for the Design of Bridge Foundations. (Appendix A was not published but is available here.) The report contains 5 engineering manuals which provide a discussion on the methods and procedures recommended for the design of the various foundation and substructure elements, along with relevant code and commentary information and worked example problems. The 5 manuals cover driven piles, drilled piers, spread footings, abutments and retaining walls, and criteria for tolerable settlements. In addition, Report 343 includes complete recommended specification and commentary provisions for incorporation into Articles 4, 5 and 7 of the AASHTO Standard Specifications for Highway Bridges. AASHTO adopted the recommended specification provisions in 1992; they will be published by AASHTO as part of the 1993 Interim Specifications in mid-1993.