Unsymmetric-plan masonry buildings: pushover vs nonlinear dynamic analysis

This paper deals with the inelastic torsional behavior of unreinforced low-rise masonry buildings. First, the nonlinear dynamic response of unsymmetric-plan buildings under different seismic inputs is compared with the one of the counterpart symmetric variant in order to assess the torsional coupling arising from unsymmetry. The buildings are studied through the finite element method, adopting suitable constitutive models which implement well known concepts of damaged elasticity in combination with tensile and compressive plasticity. The accuracy of 3D pushover analysis, performed with two invariant distributions of lateral forces, is then assessed comparing the results in terms of horizontal displacement and damage at walls with the ones provided by the nonlinear timehistory analysis. It is shown that pushover can adequately evaluate floor displacements but significantly underestimates damage at walls, even if combined with results of linear dynamic spectral analysis.