Masonry enclosure walls: lessons learnt from the recent Abruzzo Earthquake

This paper approaches the issue of performance requirements and construction criteria for masonry enclosure and infill walls. Vertical building enclosures in European countries include, very often, non-loadbearing masonry walls, using horizontally hollowed clay bricks. These walls are generally supported and confined by a reinforced concrete frame structure of columns, beams or slabs. Since these walls are commonly considered to be non-structural elements, and their influence over the structural response is ignored, their consideration in the design of structures as well as its linkage to the surrounding structure is often negligent or insufficiently detailed. In consequence, non-structural elements, as for wall enclosures, are relatively sensitive to drift and acceleration demands when buildings are subjected to seismic actions. Many international standards and technical documents alert to the need of acceptability criteria for non-structural walls, however they do not specifically indicate how to prevent collapse and severe cracking and how to enhance the overall stability for severe seismic loading. In this paper, appropriate measures are proposed to improve both in-plane and out-of-plane integrity and the performance behaviour under seismic actions of external leaf of double leaf cavity walls as well as premature disintegration of the infill walls