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Several regularized formulations exist in the literature, such as nonlocal constitutive models, for the objective simulation of localized deformations in quasibrittle materials that prevent the well-known pathological dependence on the employed mesh. Although they usually require a significant discretization to represent the localization zone of a given material, characterized by some length scale linked to its microstructure, scaling techniques exist to derive representative parameters for full-scale simulation of geotechnical problems. However, the softening response observed in conventional triaxial or uniaxial compression tests is not solely a constitutive feature but also the result of a complex boundary value problem (BVP), where the specific localization pattern formed affects the global response of the experiment. Therefore, constitutive softening parameters should be backcalculated through the simulation of a given laboratory test as a BVP. However, as demonstrated in this paper, the cylindrical geometry of the samples in conventional tests hinders the onset of localization, resulting in a stiffer response that underestimates the resulting nominal softening rate. Within this context, the paper aimed to demonstrate the complexity and difficulty in the determination of a softening rate for nonlocal constitutive models from data of conventional triaxial tests performed on cylindrical specimens and to provide relevant insights toward a practical procedure for the determination of parameters in regularized simulations of quasibrittle geomaterials for practical applications. [ABSTRACT FROM AUTHOR]

Due to the extensive use of one-dimensional equivalent linear analyses to determine the free-field response of nonlinear soil deposits, dynamic numerical simulations able to reproduce an analogous response to equivalent linear codes are of great value for practical engineering, particularly for dynamic soil-structure interaction problems. An appealing alternative, for problems not close to a failure condition, is to assume a linear elastic behaviour of the soil but with stiffness parameters derived from one-dimensional equivalent linear analyses, i.e. consistent with the level of deformation induced by the input motion. In this approach, energy dissipation has to be artificially incorporated through material damping formulations. In this work, local, Rayleigh, and hysteretic damping formulations in FLAC were assessed to emulate results from one-dimensional equivalent linear analysis. A main feature of the analyses is that they consider a site having a considerably stratified soil deposit, in which the shear wave velocity profile displays significant variations and where the selection of some parameters in the damping formulations is not a trivial task. Results provide relevant insights into the performance of the adopted damping formulations and the selection of material damping parameters to reproduce results of equivalent linear analyses. [ABSTRACT FROM AUTHOR]