Seismic vulnerability of unreinforced masonry walls: Linear and nonlinear, static and dynamic properties compared

The seismic behavior of masonry panels and masonry walls loaded in their plane is studied by finite element models using different seismic procedures. Linear static and dynamic analyses are considered according to the Italian building code. Monotonous and cyclic nonlinear static analyses as well as nonlinear dynamic analysis in the time-domain are performed on a finite element models. The applicability of the various seismic analysis procedures and the approximations in the reduction of a problem – to its nature – dynamic and non-linear to a static or linear one are widely discussed in the literature in the case of steel-framed or reinforced concrete structures; however, no systematic study is present for masonry structures. In particular, the inelastic displacement demand for masonry walls could be different from that of a steel or reinforced concrete frame, even if they have similar nonlinear static responses. In fact, masonry cyclic behavior can be quite different from the hysteretic one characterizing steel and reinforced concrete elements. In addition, the force reduction factors for masonry proposed by the building codes do not appear to have been subject to an as thorough evaluation as other building technologies. Both problems are addressed in the paper.