Seismic upgrading of existing masonry structures: A state-of-the-art review

This paper presents a state-of-the-art review on the available seismic upgrading techniques of existing masonry structures, which comprise a very common structural material including most of the surviving historic structures worldwide. Due to their increased age and vulnerability, masonry buildings and structures are generally in greater need of structural retrofitting than newer ones constructed with more modern materials. The discussed techniques are divided into three major categories, according to the way they affect the building's load-bearing mechanism. The first one includes those which target individual structural elements aiming to enhance their cyclic behavior. The second one includes those techniques which aim to improve the overall structural integrity of a given structure. Finally, methods which aim at reducing the internal seismically induced forces using special devices comprise the final category. Both conventional and novel upgrading techniques are covered, but the emphasis is clearly on the latter, while the integration of seismic upgrading techniques with measures for energy upgrading is briefly discussed for masonry building envelopes. •Seismic upgrading the existing URM structures is gaining more and more attention.•Techniques to upgrade individual elements and the overall integrity of URM structures.•Conventional and novel techniques are reviewed in terms of strengths and weaknesses.•Combining seismic & energy retrofitting is feasible for masonry building envelopes.