Retrofitting masonry heritage in seismic areas by preserving its structural historical identity

Some structural issues concerning the preservation of built historic heritage are presented and discussed in this paper. In spite of the great amount of theoretical, numerical, and experimental studies made in the last decades, the designers involved in structural rehabilitation have been so far mostly spectators in the drawing of the guidelines and provisions that are nowadays the basis for any judgment by the heritage authority in approving rehabilitation proposals. Structural safety, however, is becoming a top priority, mostly because of some recent seismic events. As a consequence, to improve structural safety under seismic loading, a number of research projects has been recently focused on the mechanical properties of traditional materials, having in mind the following tenet, that the original structural behavior, the original texture and even past modifications (if any) of the construction should be respected, as much as possible. Hence, the need and urgency to save the architectural heritage (by increasing significantly the safety factors) is emphasized in this paper, to avoid wasting past investments and to optimize future investments. As an example, at least the following two steps should be taken: (a) revised policies for non-destructive testing (NDT) and semi-destructive testing (SMT), to properly evaluate the mechanical properties of the constructions to be repaired; and (b) improved mathematical models to predict realistically and in a designer-friendly way the structural behavior of heritage constructions. Unfortunately, these two steps are hardly taken today in most retrofitting processes.