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Previous calibrations of resistance factors for load and resistance factored design (LRFD) of mechanically stabilized earth (MSE) retaining walls with galvanized metallic reinforcements have not considered cross-sectional area as a variable in the reliability analysis. The remaining cross section at the end of a 75-or 100-year design life is considered, however the metal loss from corrosion is estimated using recommended rates of metal loss that render conservative estimates of remaining cross section. This paper describes reliability-based calibration of resistance factors for the rupture limit state considering the variability of observed corrosion rates. Results are compared with resistance factors cited in the current American Association of State Highway and Transportation Officials (AASHTO) design specifications. The comparison identifies conditions for which the current AASHTO resistance factors achieve the targeted probability of failure inherent to the LRFD strategy.

The state of the practice of MSE wall design has become more complex as more and more systems, engineers and researchers have become involved in the practice. There are correct ways to design MSE walls, to apply traffic surcharge, to select design parameters and backfill, to assess service life, to address special design conditions such as bridge abutments, traffic barriers and earthquakes, and to select the wall design method itself. Yet the complexity persists, arising from policy changes and a multitude of design choices. This paper will discuss these and other areas of confusion and provide clarification regarding accepted, reliable methods of MSE design that have been proven in the field for more than forty years.

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