Influence of site effects on the seismic vulnerability of masonry and reinforced concrete buildings in Tuzla (Bosnia and Herzegovina)

Tuzla is the third most populated city in Bosnia and Herzegovina. In the last 50 years, Tuzla has experienced several minor and moderate earthquakes. On August 30th, 2019, an earthquake of magnitude m b = 4.7 and the intensity from V to VI according to the MCS scale hit an area located 6 km from Mramor a village located 10 km from Tuzla. The city of Tuzla is known for salt and coal exploitation, which has caused the settlement of the city of Tuzla. Assessment of the seismic risk depends on various features, from the availability of data, knowledge regarding the buildings to the selection of vulnerability method that is going to be applied. The outcome risk assessment due to ground motion represents the first step to support the decisions and actions to mitigate potential losses. From the available database, all the structures located in Tuzla were elaborated, leading to a sample of 203 buildings, including reinforced concrete buildings, unreinforced masonry with flexible and rigid floors, and confined masonry buildings. The RISK-UE Building Category Matrix was used for structural and typological characterization of the elaborated buildings. The range of the construction period for the selected sample is from 1961 to 2014. The elaborated structures were residential buildings either for individual or collective housing. This paper aims to provide preliminary information regarding seismic risk in the Tuzla region taking into account the specific site effects on the vulnerability by applying the macroseismic model. The vulnerability index is calculated by applying the macroseismic method being a function of the type of building, behavior modifier factors, and regional vulnerability factors. The seismic risk in the town of Tuzla is in the range from medium to high. Site characteristics have been incorporated in the calculation, leading to amplification of damage and higher vulnerability of structures.