Comments to the paper "Reliability‐based evaluation of bond strength for tensed lapped joints and anchorages in new and existing reinforced concrete structures" by G. Mancini et al. in Structural Concrete, Vol. 19, No. 3, pp. 904–917.

The paper proposes different statistical parameters for model uncertainties depending if we are designing a new structure or evaluating an existing one. The reason is that for existing structures lower values of the concrete compressive strength as well as lower ratios of concrete cover to bar diameter can be found, in comparison to new structures. In my opinion, the correct approach to take into account the different level of uncertainty in new or existing structures would be to deal with the model uncertainty by splitting the range of possible parameters in different sets and to find the best fit between the experimental and model values for the different sets, independent of the type of structure (new or existing). [Extracted from the article]