Non-linear soil modelling by correction of the hysteretic damping using a modified Iwan model together with Masing rules

摘要

Even at this time, there is no universal mathematical model that can adequately describe the actual behaviour of cyclically loaded soils but rather thoughtful attempts were made to describe the appropriate behaviour for a well-defined soil type. The overestimation of damping ratio at large strain can result when the hysteretic damping is calculated using the unloading-reloading stress-strain hysteresis loop obtained by the second Masing rules. In this paper, a method is proposed to overcome the encountered problem of overestimation of hysteretic damping by including a factor modulus λ_1 to correct the hysteretic damping in order to have a good agreement between numerical and experimental results. By this method, the initial hyperbolic backbone curve is segmented by a series of linear elements and the Masing rules are associated with the Iwan model. For low shear strains (λ ≤ 3.10~(-2)), a corrector factor λ_1, (rather than the reduction factor) will be in the interval (1 ≤ λ_1 ≤ 7) and in the interval (0.4 ≤ λ_1 ≤ 1.0) for the other cases (γ > 3.10~(-2)), in such way that the obtained results will be in good agreement with experimental ones.