Seismic vulnerability assessment of timber roof structures: criteria and procedures

Timber roof structures have shown strong influence on the behavior of masonry buildings during earthquakes. In a seismic event, they may link walls and favour the development of a positive global response, or suffer damage that may extend to masonry elements. In a perspective of risk mitigation, basic criteria and procedures for assessing the seismic vulnerability of timber roof structures are needed. As a result of an extended research, the main factors that determine seismic vulnerability in such structures have been identified. The steps of an assessment procedure developed within the research program are discussed. The procedure comprises initial visual inspection for collecting data and information on the main parameters that are significant in seismic conditions, and their subsequent classification according to a grading system. Critical aspects of the structure are pointed out and may be possibly reduced. In applications and case studies performed so far the procedure has proven useful to focus attention on the seismic qualification of these timber structures that were originally conceived with regard to vertical loads.