Seismic performance of existing low-rise URM buildingsconsidering the addition of new stories

Abstract

In low-rise unreinforced masonry (URM) buildings, structural design is generally performed considering the load effects induced by seismic forces as well as the vertical loads. However, there might be cases where the additional or unforeseen loads may be encountered during the lifespan of these buildings. The loads that are induced from the addition of a new storey during the service life is a good example for these additional loads. Since the reconstruction licenses and building height limits specified by the local authorities may vary in life cycle of the structures, it is important to decide the addition of a storey to an existing building considering the structural safety concerns. In this study, an existing low-rise URM building is modelled with added stories (subsequently planned after its construction), and numerical analyses are carried out considering the extra loads of this additional stories. The aim of this study is to assess the earthquake performance of the structures considering this unforeseen situation which was not considered in the original structural design. The suitability of the initial structural design project to the existing building was examined by the site investigations. The results of the analytical analysis were compared with the seismic code requirements, and the seismic performance level of the building is estimated. The study is intended to be useful in determining the path to be followed for the determination of the seismic capacity if existing buildings are exposed to such additional loads. The findings of this study could be used to design local and global retrofitting works. Especially, for the typologies underwent such interventions, solutions that reduce earthquake demands by providing high lateral strength and rigidity could be considered. It is believed that the outcomes obtained with respect to the evaluation of this case study could be generalized to a wide variety of such template buildings and extrapolated for a wide masonry building type.