Investigation of the Performance of Simplified Constitutive Models in Nonlinear 1D Effective Stress Ground Response Analysis

ABSTRACT Several building codes, such as the National Building Code of Canada, recommend that an effective stress ground response analysis be performed if a liquefiable stratum is identified within a soil profile. Although, constitutive models for total stress ground response analysis have been well verified against earthquake recordings, existing models for effective stress ground response analysis have yet to be thoroughly validated. This article investigates the predictions of five pore pressure models derived for effective stress ground response analysis. First, a dataset of five downhole arrays and two centrifuge experiments in which a potential of liquefaction was identified is presented. The profiles and ground-motion recordings are selected to represent a broad range of soil properties, ground-motion intensities, and excess-pore pressure generation levels. The differences between predictions of the effective stress models against commonly used 1D ground response total stress equivalent-linear and nonlinear analyses are evaluated. The predicted and measured motions are compared in terms of spectral response and amplification factor. The pore pressure response of all models is evaluated as a function of shear strain and found to agree well with published correlations representing the expected behavior of liquefiable soils. Although, the models show the ability to capture liquefaction triggering, the results indicate that for the selected dataset, total stress simulations were found to be, at least, as precise and accurate as the effective stress simulations. Therefore, simplified models for effective stress ground analysis should be used with caution by practicing engineers to predict surface spectra but can be used confidently to assess the potential for liquefaction triggering.