For the geosynthetics community, the conversation around the Simplified Method vs. the Stiffness Method for internal stability design in mechanically stabilized earth (MSE) walls has been a vocal one. Research has shown that the traditional Simplified Method of design was not as effective as it could be for predicting reinforcement loads compared to measured loads. This was felt to be particularly true when extensible reinforcements (like geogrids) were used in the design.
The major 2020 update to the AASHTO LRFD Bridge Design Specifications in the United States adopted the Stiffness Method for geosynthetic-reinforced MSE walls; meaning: we now have both the Stiffness Method (United States) and Simplified Method (Canada) being used in North America.
The International Geosynthetics Society – North American Chapter (IGS-NA) is helping sort out how to interpret these methodologies with a new webinar, “AASHTO Migration from the Simplified Method to the Stiffness Method for Internal Stability Design of MSE Walls.” They’ve tapped Dr. Richard Bathurst (GeoEngineering Centre at Queen’s-RMC) to lead the discussion. Dr. Bathurst is one of the world’s leading voices in the conversation surrounding internal stability design, the value of the Stiffness method, and MSE walls.
When: September 23, 12:00 – 1:00 pm
INTERNAL STABILITY DESIGN
In a promotion for the event, IGS-NA writes:
The Stiffness Method approach represents a paradigm shift on how reinforcement loads are calculated for internal stability design of MSE walls under operational conditions. The Stiffness Method, as the name implies, includes the tensile stiffness of the reinforcement as a key factor determining the loads developed in reinforcement layers under operational conditions. The Simplified Method is a strength-based approach which cannot distinguish between reinforcement materials falling within the same classification. The Stiffness Method has the additional benefit of being seamless across relatively extensible (geosynthetic reinforcement materials) and relatively inextensible materials (steel grids and steel strips). Practical impacts on design outcomes using the two approaches are identified.
This is an incredible opportunity to learn from one of the leading geotechnical minds in the world.
ABOUT THE PRESENTER
Dr. Richard J. Bathurst (P. Eng., Ph.D., FRSC, FEIC, FCAE) is Professor Emeritus of Civil Engineering at the Royal Military College of Canada where he has taught since 1980. He has authored or co-authored more than 400 papers in referred journals, conference proceedings and research monographs. He has made contributions in the areas of micromechanics of granular soils, railway ballast and track dynamics, pavements, unsaturated soil-geotextile behaviour, constitutive modelling of geosynthetic soil reinforcement materials, new test methods and the development of transparent granular soil surrogates for geotechnical laboratory-scale testing. Dr. Bathurst’s primary research activities are focused on the use of geosynthetic and metallic reinforcement in earth retaining wall systems, numerical modelling, seismic performance and design of these systems, probabilistic design of reinforced and unreinforced soil structures, reliability-based design, load and resistance factor design (LRFD) calibration of soil-structures, and LRFD code development. Dr. Bathurst is Editor-in-Chief of the peer-reviewed technical journal Geosynthetics International, published by the Institute of Civil Engineers in the UK, and Associate Editor of the International Journal of Geomechanics published by the ASCE.