Shake-table investigation of a timber retrofit solution for unreinforced masonry cavity-wall buildings

Two unreinforced masonry full-scale building prototypes with identical geometrical features were tested dynamically on the shake-table at the EUCENTRE laboratories in Pavia, one in its bare conditions and one in retrofitted configuration, within a comprehensive research campaign on the vulnerability of existing Dutch structures. The tested buildings represented the end-unit of a two-storey terraced house typical of the Groningen region of The Netherlands, which has been recently affected by induced seismicity due to gas extraction. The original structural system consists of cavity walls without any particular seismic design or detailing. The prototypes included two storeys, with a reinforced concrete slab at the first floor, a flexible timber diaphragm at the second one and a pitched timber roof supported by two gable walls. The retrofit system consisted of timber frames mechanically connected to the building piers and floors, on which oriented-strand boards were nailed. The incremental dynamic tests were performed up to the near-collapse conditions of the two specimens, using the same input motion representative of Groningen induced seismicity. This paper describes the characteristics of the tested buildings and compares the observed damage patterns.