Some statistical aspects of the semi-probablistic approach (partial factoring) of the EUROCODE 7

Abstract

The definition of the characteristic values of the soil parameters (according to EUROCODE 7) constitutes one of the most critical tasks in geotechnical calculations. The methods and the procedures related to the calculation of the characteristic values for the soil parameters with normal or lognormal distribution, related to four several cases (for statistical ``known´´ or ``unknown´´ parameter and for average value or extreme value), considering the cases when previous knowledges are or are not available are summarized in this paper. The confidence level concept is connected to the design value and the partial factor concepts. In addition, some interesting cases are analysed (i.e. the case of parameters that vary with depth, a case where the characteristic value of the lower estimate of the mean is greater than the upper estimate of the mean of the parameter value).