Seismic Vulnerability Indicators for Timber Roof Structures

Among the factors that most likely affect the seismic response of timber roof structures are: the conceptual design of the structure, in terms of typology and of specific factors as the presence of unrestrained thrusts; the condition of the supports connecting the roof to the underlying structure; the type and condition of carpentry joints; the dimensions of timber elements; and the general state of conservation. A methodology proposed for assessing the seismic vulnerability comprises two steps. The first consists in a visual inspection of the structure, to be performed according to a standardized procedure. In the second, the information that was collected is used as the basis for evaluating a series of specific vulnerability indicators. These indicators quantify and grade the influencing factors listed above. Among them, the original conceptual design has a primary role in the capability of responding to seismic excitation. The factors associated to the structural typology that contribute positively to the seismic response, or to vulnerability when lacking, amount to: (a) a correct association of span, structural typology, and element sections according to values that comply with a sound constructional tradition, and (b) effective links between trusse