Design of Geosynthetic MSE Walls Supporting Bridge Abutment Footings Using the Stiffness Method

Current AASHTO load and resistance factor design (LRFD) specifications in the US have adopted the stiffness method for the internal stability design of geosynthetic mechanically stabilized earth (MSE) walls. The same method will appear in a future edition of the corresponding CSA LRFD code in Canada. During the development of the stiffness method, the problem of a bridge abutment footing seated on the top of a MSE wall structure was not investigated. This paper presents an initial attempt for a method to include the additional footing loads in the calculation of reinforcement loads and strains using the AASHTO stiffness method and correction factors applied to the 1H:2V footing load dispersion method. The example uses the soil properties from the well-documented SR-18 walls in the US and considers walls of three different heights, four different reinforcement stiffness values, and three different reinforcement spacings.