Impact of seismic rehabilitation and presence of unreinforced masonry (URM) infill walls on the dynamic characteristics of a hospital building in Montreal

Unreinforced masonry (URM) infill walls are extensively used in buildings; they are normally considered as nonstructural components and their structural effects are often neglected in seismic analysis. However they interact with their bounding frame under seismic actions resulting in significant changes in the dynamic properties of the building, which can lead to structural damage and increased floor accelerations. To evaluate the structural contribution of infill walls, two eleven-storey wings of a paediatric research hospital located in Montreal, Canada, have been selected as a case study. A detailed elastic finite element model was generated which included the infill walls. Ambient vibration measurements were also done in both buildings to extract their dominant dynamic properties and calibrate the numerical models. Subjecting the calibrated models to a set of ground accelerograms, interstorey-drift curves and floor response spectra were developed. The effects of seismic retrofit and infill walls on the dynamic properties and seismic response of the buildings were addressed by comparing the results of different numerical models.