Conservation Principles and Performance Based Strengthening of Heritage Buildings in Post-event Reconstruction

Abstract

Recommendations for repairing and strengthening historic buildings after an earthquake and before the next in modern times go back to the contribution to the ICOMOS General Assembly of 1987 by Sir Bernard Fielden "Between two Earthquakes" (Fielden 1987). In that circumstance two important points were made: the first is that failure and damage should be used to understand performance and behaviour, so as to avoid measures that do not work. The second is that the engineer work should be integrated into the architecture historical methodology. Almost 30 years later this contribution investigate to which extent these two recommendations have been fulfilled, whether there is a common understanding between the conservation and the seismic engineering community and whether lessons from past failures are informing new strengthening strategies. IntroductionThe global seismic response of historic masonry buildings is highly influenced by the integrity of the connections among vertical and horizontal structural elements, to ensure the so-called box behaviour. Such behaviour, providing the transfer of inertial and dynamic actions from elements working in flexure out-of-plane to elements working in in-plane shear, leads to a global response best suited to the strength capacity of the constitutive materials, and hence enhanced performance and lower damage levels. While, many properly designed buildings of the past demonstrated such behavior when exposed to seismic action and successfully survived ground shaking (D'Ayala 2011;Tavares et al. 2014), too often, due to

A multi-hazard risk prioritisation framework for cultural heritage assets

“…In fact, the lack of any hazard-resistant design (in most of the cases) and the presence of material degradation due to ageing, together with the possible presence of structural modifications and local repair and/or partial or total reconstructions over time, result in high levels of vulnerability characterising those assets (e.g. Despotaki et al, 2018;D'Ayala, 2014). In addition, assessing expected losses for a given set of hazard scenarios is a complex task because of the tangible and intangible values of CH assets (e.g.…”

Effectiveness of seismic strengthening to repeated earthquakes in historic urban contexts

“…While they were not explicitly concerned with issues of authenticity and preservation of historic character, the use of technologies and materials substantially homogeneous to the original ones delivered good seismic response and contributed to the urban character to the extent that these features today represent the characteristic heritage value of the town. Conversely, the approach to strengthening developed during the twentieth century as highlighted in D’Ayala (2014) and discussed in Section 2 was possibly more preoccupied with issues of preservation; however, the strengthening interventions were substantially driven by concrete technology and structural engineering concepts relating to frame behaviour rather than masonry wall response. Ring beams and concrete slabs replaced traditional wooden floors and ties.…”

“…Recurring observations of damage in earthquake-prone countries worldwide has shown the lack of systematic critical approach towards assessing the effectiveness of strengthening to prevent damage and casualties, while also preserving the architectural value of heritage buildings (D’Ayala, 2014). Norcia represents a unique case to evaluate the effectiveness of historic and recent strengthening interventions implemented following the destructive seismic events that characterised its history.…”

A New Method for Assessing Compatibility of Consolidation Procedures with Conservation Principles: Intervention Quality Index (IQI)

“…From recent studies of the seismic fragility assessment at macro-scale and singlebuilding-scale of Built heritage [1], [2], [3], [4], [5], and [6], it emerged that several URM monuments, in particular churches, even those consolidated and repaired after a seismic event, demonstrated inadequate performance during sequent ones. For this reason, several investigations were carried out to develop guidelines and standards for repairing, consolidating and strengthening URM built heritage while respecting ICOMOS conservation philosophy.…”