Existing Structures—A Regulatory Antagonism?

Dealing with existing structures, either for assessing and/or judging the structural qualities or for revamping, mending, or strengthening, inevitably provokes a dilemma: the dilemma of existing, decade-long successfully used structures which exhibit no signs of damage, overstraining, or fatigue, not complying with the rules to be followed when taking the actual standards and regulations as a base for the deliberations. This disaccord is in many cases resolvable by addressing the fundamental hierarchy of standards and by using structure-specific, that is, individualised assessments methods based on the principles laid out, for example, in EN 1990:2021 “Basis of Structural Design.” Instead of using lump-sum safety factors, the standard procedure to be found in the structural engineer’s toolbox, this strategy leads, via the determination of structure-related failure probabilities and the comparison of these values with the generally accepted reference value, 10⁻⁶ per year for typical building constructions, to a bespoken and more generalised formulation of the structure’s quality.