Mitigating Seismic Risks in Historical Masonry: An Example Project

Abstract

Protection of cultural heritage buildings against strong seismic events is one of the most challenging tasks modern engineers are called to tackle. Masonry structures are complex with regional and historical diversities rendering extremely difficult defining generalized rules. A holistic approach that involves interdisciplinary collaboration and a full package of engineering from monitoring to testing is a necessity. The sources for assessment, strengthening, and preservation are not enough for the entire inventory of heritage buildings, thus there always exists need for conducting risk studies to estimate the seismic risk these structures are exposed to. The main ingredient of seismic risk studies is the definition of the structural limit states, which is one of the most challenging topics since the historical structures rarely possess similarities among them while their response is characterized by complex interaction of structural components. This paper presents a scientific project funded to contribute to the mitigation of seismic risk in the historical peninsula of Istanbul where Eastern Rome, Byzantine, and Ottoman structures populate almost every street. A complete approach has been followed in the project, the main activities of which consist of creating a wide strong ground motion and ambient vibration network, building and testing large-scale specimens to define limit states of the masonry heritage structures and combining the monitoring an testing findings with analytical modelling tools. The project resulted in a Master Plan in which steps to be taken to protect the existing heritage buildings in the historical peninsula of Istanbul is proposed and discussed. NEED FOR A HOLISTIC APPROACH In parts of the world with a rich inventory of heritage structures, management, including intervention, of these structures has always been a challenge, especially for high levels of seismic hazard. Istanbul has experienced large magnitude earthquakes that caused tragic damages to the heritage building stock in the past (Bal et al., 2015). Unfortunately, decision for prioritizing the assessment and restoration of certain historical structures over others is commonly not based on a sound rationalized set of criteria, associated with technical and historical importance aspects, but is completely political, resulting in neglecting a number of historical structures that stay in obscurity despite their undeniable value. Funds are directed accordingly, without any optimization considerations though sources are limited, needs are immediate and ATC & SEI 2015 185