Representative values for use in the verification of limit states in the frame of the future Eurocode 7

Abstract

The aim of this paper is to explain the concepts behind the different terms involved in the determination of ground properties in the frame of the Eurocodes. The process begins with all the different terms that appear in the ground investigation and monitoring phases: historical, assessed, test, monitored and derived values. It continues with the determination of the “representative value” that is the value that affects the occurrence of the limit state. This value is factored by the material factor to obtain the “design value” that will be used in the verification of the different ultimate and serviceability limit states of the geotechnical structures using the “Partial Factor Method”. The future Eurocode 7 establishes two possible ways to determine such “representative value” of a ground property: selecting the value by engineering judgment and comparable experience in similar cases, being in this case termed as “nominal value”; or evaluating the value by statistical methods, being in this case termed as “characteristic value”. Additionally, the paper gives a brief outline of the statistical method to determine the characteristic value of a ground property and an example to show how it can be used.