LRFD Calibration of Internal Limit States for Polymer Strap MSE Walls

The paper demonstrates load and resistance factor design (LRFD) calibration for tensile strength, connection strength, pullout, and soil failure internal stability limit states for polyester strap mechanically stabilized earth (MSE) walls using a reliability theory-based approach. The calibrations are carried out using the simplified and stiffness methods to compute tensile loads and the pullout and connection models found in current LRFD specifications for MSE walls. LRFD calibration is also carried out for the soil failure limit, which is unique to the stiffness method. Computed resistance factors in combination with code-specified load factors are compiled in tables based on US and Canadian LRFD practice. Recommended resistance factors are provided for both jurisdictions. Actual margins of safety expressed as a reliability index are calculated using current and proposed new resistance factors for the case when each limit state is just satisfied. Example designs are provided to show the impact on reinforcement demand when using different load models in combination with current and proposed new resistance factors.