Timber framed with masonry infill: a historical anti-seismic device. The Portuguese Pombaline gaiola.

Post-seismic reconstruction and seismic prevention have always been a major concern worldwide.This work analyses the Pombaline gaiola (meaning cage), a structural system of masonryreinforcement used in the reconstruction of Lisbon following the earthquake of 1755. A gaiola consistsin the insertion of a three-dimensional timber frame embedded in stone masonry in order to bindtogether the various structural parts, and contribute to the overall seismic resistance. Timber framedreinforcement is an old anti-seismic device that may be globally observed in the history of theconstructive technology. From the Roman times, this system spread in the Mediterranean area duringthe XVIII century but a large quantity of examples can be observed almost worldwide. The Pombalinegaiola is analysed from an architectural, constructive, and structural point of view to show how thattraditional system made a robust (re)construction possible. Beyond the suboptimal rules of the art andtacit historical instances, and by means of philological criterion and detailed analysis of seismicimprovement, contemporary preservation works should ensure the structural safety of the historicalconstruction. In such a perspective, this study examines aspects of diffused timber frameworks withmasonry infill that go beyond the anti-seismic technology and develops guidelines for preservation.