Reduction of Housner’s Coefficient of Restitution for Masonry Walls Under One-Sided Rocking

Abstract

The out-of-plane dynamics of masonry walls is strongly influenced by seismic input, mass, wall geometry and boundary conditions. Nevertheless, the parameter that mostly affects the dynamic response of a rocking wall is the coefficient of restitution, defined by Housner as ratio of angular velocity after and before an impact on the ground. Such a parameter defines the amount of energy dissipated over motion and is of paramount importance in assessing the seismic vulnerability of a rocking wall, due to the sensitivity of the dynamic response to small changes of it. This paper critically illustrates the preliminary results of an experimental campaign performed on a masonry wall subjected to one-sided rocking. These results are presented in terms of experimental ratios of coefficients of restitution. Two methods for calculating the experimental ratios of coefficients of restitution are described according to whether rocking is one-sided or two-sided. In addition, the paper compares these ratios with those of other experimental tests on two sided rocking and horizontally restrained masonry walls available in the literature. A numerical example is provided by showing that the assumption of a correct coefficient of restitution is crucial for a realistic and correct seismic vulnerability assessment.

Parametric HBIM Procedure for the Structural Evaluation of Heritage Masonry Buildings

“…The definition of the simplified structural model and the choice of the most appropriate analysis technique are still critical steps in the evaluation procedure of existing masonry buildings [6,7]. As reported in the Italian guidelines for the assessment and reduction of seismic risk of cultural heritage [16], masonry buildings are characterized by considerable uncertainties about the mechanical properties of the materials used and the efficiency of the connections between structural elements, often associated with complex structural schemes [17][18][19]. For this reason, in structural codes, reference mechanical models are commonly provided and specialized methods for preventive risk assessment are suggested considering the most common structural types and configurations, including models for "Churches, places of worship and other structures with large spaces, without intermediate structural horizontal elements" and for "Palaces, villas and other structures with spine walls and intermediate structural horizontal elements" [16].…”