Reliability analysis of geogrid material with random nonlinear viscoelastic characteristics

Introduction. The behavior in the course of a time of geogrid material with random nonlinear viscoelastic characteristics under tension is analysed. Parameters of viscoelasticity are represented in form of Gaussian random vector. The components of this vector are taken from experimental data. Aim of the research. The objective of this research is the analysis of influence of different factors (value of applied load and the application of load in the form of random value instead of dead one, number of realizations, change of given level of strain) on providing of needed service life of geogrid material with given reliability level. Here reliability is interpreted as function of probability of non-failure. The first crossing of some given level by random strain is considered as a failure. The strain value corresponding to yield limit of geogrid material is accepted as the given level of longitudinal strain. Methods. The realizations of Gaussian random vector of viscoelastic parameters of material with given correlation matrix were imitated by means of linear transformation method. Results. It is demonstrated that longitudinal strain is Gaussian nonstationary random process which stochastic analysis can be made on base of 10 000 realizations. The dependencies on time of mathematical expectation and standard deviation of random longitudinal strain as well as function of probability of non-failure are found. Conclusion. It is shown that durability estimation found on base of the deterministic problem solution is overestimated in comparison with stochastic problem solution if the condition of given service life providing with some reliability level is set up.