Target reliabilities for heritage structures derived from cost optimization

In the last decade, structural reliability and safety efforts have been oriented toward the assessment of existing structures and the development of related target reliability levels. However, up‐to‐date there is no consensus on the reliability philosophy that should be followed when considering the assessment of heritage structures, and the level of reliability which is appropriate to them. In this study, a framework is proposed which derives new values for the economically optimal target reliability for the upgrade of a structure, , and the reliability threshold for upgrade, , considering the cultural heritage value of the structure. The total expected life cycle cost is minimized, assuming that the structure is given up after collapse, as heritage value is typically lost after failure. The target reliability values are based on three main parameters: the relative annual benefit of using the structure (affected by its heritage value), the relative cost of failure and the relative cost of increasing the reliability. Target reliability values are proposed specifically for heritage structures, considering a range of the main input parameters.