Structural permanence in pre and post earthquake Lisbon: half-timbered walls in overhanging dwellings and in Pombalino buildings

Abstract

Timber frame walls represent a structural permanence in Portugal before and after the 1755 earthquake. Despite improvements made in the Pombalino buildings (late eighteenth century) for seismic design purposes, comparisons can be drawn with the use of mixed timber-masonry structure in overhanging medieval houses. The structural efficiency of medieval overhanging dwellings is due to the reduction in the weight from the lower to the upper floors, the ductile behaviour and the connections between the infill frame and the floor structure. A survey of examples still standing in Lisbon is carried out by the authors through archival dataset and on-site analysis. Special attention is paid to the degree of authenticity and state of conservation. Dissonances and continuities in the original construction and subsequent refurbishment are analysed in three cases that are selected for their localisation and remarkable architectural or typological features.