ABSTRACT
ABSTRACT: In October of 2007 the AASHTO LRFD Bridge Design Specification became the mandatory design code for highway structures in the United States. This has introduced a number of changes in the design and analysis procedures that engineers have to follow. This paper takes an in-depth look at the differences between the Standard Specifications and the LRFD specification and how they apply to earth retaining structures. Calculations for several examples were carried out to examine the effect of the new design standards on structural proportioning and cost. For structures 15’ and taller, the difference between the LRFD and the Standard Specifications was minimal. However, designing shorter walls using the LRFD code can result in an increase in footing length of about 30% and an increase in cost of about 10%. While these cost impacts to a structure can be significant, the new code provides a safe and reliable method of design which is of paramount importance to engineers and the public.
