Newmark deformation analysis with degrading yield acceleration

This paper presents a Newmark seismic deformation analysis in which a degrading yield acceleration has been implemented. The degradation of yield acceleration is modeled with a simple linear degradation model. Using a typical solid waste landfill composite cover configuration and actual interface shear strength testing results, the conservatism associated with seismic deformation analysis performed using the classical Newmark approach and a constant yield acceleration based upon residual and/or large deformation interface shear strength is investigated. The influence on permanent seismic deformation of the normal stress acting on the interface is also examined. Results indicate that Newmark seismic deformation analysis based solely on residual or large strain shear strength parameters is conservative.