Updating the safety level of concrete elements after conformity control

As a result of the conformity assessment of concrete production, certain cocnrete lots are rejected. Due to this filtering effect of conformity control, the strength distribution of the accepted concrete lots will have a higher mean and a lower standard deviation in comparison to the strength distribution of the entire production. The influence of this effect is investigated on prior strength distributions of different concrete classes available in literature. Based on Bayesian statistics, these prior distributions are updated through numerical integration, taking into account the calculated operating characteristic of the investigated conformity criteria. Using standard structural reliability methods, the filter effect can be translated into an effect on the safety level of structural concrete elements. As an example, the influence of the current EN206-1 conformity criteria on the prior distributions is investigated and the effect on the safety level is calculated, taking into account autocorrelation between consecutive test results