Eurocodes: using reliability analysis to combine action effects

The head structural Eurocode for the design of buildings and other civil engineering works, EN 1990 Basis of Structural Design, establishes for all the Eurocodes the principles and requirements for safety, serviceability and durability. It provides alternative design procedures, for which national choice is allowed, in particular for the three fundamental combinations of action effects for the persistent and transient design situations in the verification of ultimate limit states. An example of a generic structural element shows that the alternative combinations may lead to considerably different reliability levels depending upon the ratio of variable actions to the total load. Probabilistic methods of structural reliability theory are used to identify characteristic features of each combination and to formulate general recommendations for the BSI National Annex for EN 1990.