Dynamic analysis of masonry chimneys by means of a simple Rigid Beam Model

In this contribution, a simple and effective Rigid Beam Model, recently introduced for simulating the dynamic behavior of slender freestanding masonry columns and walls, is adopted and improved for studying masonry chimneys. These structures represent a particular masonry building typology, characterized by a conical shape with a very large slenderness, they are prone to collapse in case of seismic actions due to poor material mechanical characteristics and poor state of conservation. The original model is improved by considering the chimney subdivided into several portions along its height, and each portion is modelled as a rigid beam element with an annular cross-section. Small displacements and no-sliding at the interfaces between the beam elements are the main adopted hypotheses, following the typical assumptions taken by Housner. Material nonlinearity is considered by means of a moment-rotation constitutive law at interface level, also accounting for masonry stiffness and tensile strength. Several numerical tests are performed by considering an existing case study and comparing the modal analysis results of the Rigid Beam Model with respect to those obtained with traditional FE models; then, harmonic tests with varying acceleration and frequency are performed.