Seismic upgrading of old masonry buildings by seismic isolation and CFRP laminates: a shaking-table study of reduced scale models

The efficiency of improving the seismic resistance of old masonry buildings by means of seismic isolation and confining the structure with CFRP laminate strips has been investigated. Five models of a simple two-story brick masonry building with wooden floors without wall ties have been tested on the shaking table. The control model has been built directly on the foundation slab. The second model has been separated from it by a damp-proof course in the form of a PVC sheet placed in the bed-joint between the second and the third course, whereas the third model has been isolated by rubber isolators placed between the foundation slab and structural walls. Models four and five have been confined with CFRP laminate strips, simulating the wall ties placed horizontally and vertically at floor levels and corners of the building, respectively. One of the CFRP strengthened models has been placed on seismic isolators. Tests have shown that a simple PVC sheet damp-proof course cannot be considered as seismic isolator unless adequately designed. Tests have also shown that the isolators alone did not prevent the separation of the walls. However, both models confined with CFRP strips exhibited significantly improved seismic behavior. The models did not collapse even when subjected to significantly stronger shaking table motion than that resisted by the control model without wall ties.