A model for the out-of-plane dynamic analysis of unreinforced masonry walls in buildings with flexible diaphragms

•An analytical model is proposed for out-of-plane dynamic analysis of URM walls.•The model has 2-DOF and considers the wall attached to a flexible diaphragm.•Two rigid bodies are connected by intermediate hinge and restrained by a top spring.•The equations of motion of the 2-DOF model are derived.•Time-history analyses are performed on walls with variable spring stiffness.

This paper proposes a model for simulating the dynamic behaviour of slender external walls of unreinforced masonry buildings with flexible diaphragms subjected to out-of-plane bending. The proposed model is characterized by two degrees of freedom (2DOF) and allows to perform time-history analyses in order to study the influence of diaphragm flexibility on the displacement capacity and demand of walls in out-of-plane bending. The wall has been modelled as an assemblage of two rigid bodies connected by an intermediate hinge and restrained at the top by a spring: the damping has been modelled through the introduction of the coefficient of restitution. The equations of motion of the 2DOF system have been derived and integrated in the time domain. Dynamic analyses of a set of walls subjected to Gaussian impulses and recorded ground motions have been performed in order to compare the response of the simply supported wall with that of the wall with an elastic spring at the top.