Seismic assessment of an existing masonry building: Collège de Cojonnex

The seismic assessment of existing unreinforced masonry buildings to determine their vulnerability is a critical issue for all earthquake-prone locations, and Switzerland is no exception. As a result, a thorough examination of the behaviour of masonry structures subjected to earthquakes is required. To do so, a model of the building in question should be made, but choosing which type of model to use can be challenging as many are offered in the literature. For unreinforced masonry buildings, the "Equivalent Frame Model" (EFM) is becoming increasingly popular. This model strikes a decent balance between accuracy and computational requirements. The walls are separated into two zones in this model: rigid zones and deformable zones, which are themselves further divided into two regions: piers and spandrels. In this report, the seismic behaviour of the school building of Cojonnex, located in Blonay, Switzerland, is studied in more detail. The building in question was constructed in 1924 and is made of unreinforced stone masonry walls with reinforced concrete slabs. First of all, the modelling assumptions and the discretisation are assessed. Then, in order to better understand the modelling sensitivities associated with the EFM of this particular building, a sensitivity analysis is conducted on the different parameters of the masonry. After that, the building is tested in conditions as close to reality as possible, with an earthquake that matches the local acceleration design spectrum and with the values of parameters taken from the literature and the Swiss codes. The results obtained with the EFM model are then compared to simple hand calculations. I