SEISMIC RETROFITTING OF POST-WWII MID-RISE UNREINFORCED MASONRY RESIDENTIAL BUILDINGS IN THE BALKANS

Abstract

There is a significant building stock of the existing low- and mid-rise unreinforced masonry (URM) buildings constructed after World War II in Serbia and neighbouring countries. Numerous buildings of this typology collapsed in the devastating 1963 Skopje, North Macedonia earthquake, causing fatalities, injuries, and property losses, and experienced damage in a few recent earthquakes in the region, including the 2010 Kraljevo, Serbia earthquake and the 2020 Petrinja, Croatia earthquake. These buildings are 3- to 5-storey high, have URM walls and rigid reinforced concrete (RC) or semi-prefabricated concrete and masonry floor slabs, usually with a RC ring beam at each floor level. The paper will provide an overview of seismic retrofitting approaches for these buildings, starting from provisions of design codes which were previously followed in Serbia and former Yugoslavia as well as Eurocode 8 (Part 3). Conventional seismic retrofitting technologies based on RC wall overlays which were applied in past earthquakes, including the 2010 Kraljevo earthquake, will be presented and their advantages and disadvantages will be discussed. Finally, a case study of a building in Kraljevo which was damaged in the 2010 earthquake and subsequently retrofitted, will be presented, including the results of seismic analysis and design solution. The paper should be of interest to engineers and academics interested in seismic retrofitting of masonry buildings.