This paper investigates the accuracy of pushover-based methods in predicting the seismic response of slender masonry towers, through comparison with the results from a large number of nonlinear time-history dynamic analyses. In... more
This paper investigates the accuracy of pushover-based methods in predicting the seismic response of slender masonry towers, through comparison with the results from a large number of nonlinear time-history dynamic analyses. In particular, conventional pushover analyses, in both their force-and displacement-based variants, are considered, and seismic assessment through the well-established N2 method is also addressed. The study is conducted by applying a simple non-linear elastic model recently developed and implemented in the computational code MADY to represent slender masonry structures. The model enables both pushover analyses and non-linear dynamic analyses to be performed with a minimum of effort. A multi-record incremental dynamic analysis carried out for a quite large number of structural cases, each of which is subjected to a comprehensive set of dynamic nonlinear analyses, is used to evaluate the accuracy of pushover methods in predicting the global structural response, as represented by the usual capacity curve together with a damage curve, both of which are compared with dynamic envelopes. Local responses, in terms of lateral displacements and the distribution of damage along the tower height are also compared. The results reveal that the key issue in the accuracy of pushover methods is the nature of the lateral load applied, that is, whether it is a force or a displacement. Different ranges of expected deformation are suggested for adopting each type of lateral load to better represent the actual behaviour of masonry towers and their damage under seismic events through pushover methods. Keywords Masonry towers · Pushover analysis · Nonlinear static procedures · No tension material · Incremental dynamic analysis · Force-based and displacement-based pushover
A refined one-storey model has been developed which is able to evidence effects of interaction phenomena between axial and lateral forces in vertical resisting elements on torsional response of plan asymmetric building structures.... more
A refined one-storey model has been developed which is able to evidence effects of interaction phenomena between axial and lateral forces in vertical resisting elements on torsional response of plan asymmetric building structures. Previous research has shown that influence of inelastic interaction is significant, leading to larger peak ductility demands and, mainly, to larger plan-disuniformity of demands in resisting elements. In this paper, the new model is used to re-evaluate, in the light of interaction phenomena, the performances of plan asymmetric system designed according to torsional provisions of the European code Eurocode8, in order to asses its suitability regarding torsional specification.
A refined numerical model of one-storey asymmetric building structure is presented which is able to overcome limitations of simplified models used so far. Namely, effects of inelastic interaction between axial force and bi-directional... more
A refined numerical model of one-storey asymmetric building structure is presented which is able to overcome limitations of simplified models used so far. Namely, effects of inelastic interaction between axial force and bi-directional horizontal forces in resisting elements as well as effects of vertical input ground motions can be taken into account with this new idealization, contrary to previous models which have been developed under the assumption that resisting elements are capable to sustain uni-directional horizontal forces only. The new model is used in this paper to evaluate the effects of inelastic interaction for torsionally-stiff asymmetric systems, considering two-component earthquake excitations.
In this paper, a numerical method is presented to perform non-linear dynamic analysis of coupled transverse and longitudinal oscillations of masonry beams with different constrains when subjected to any dynamic loading type, including... more
In this paper, a numerical method is presented to perform non-linear dynamic analysis of coupled transverse and longitudinal oscillations of masonry beams with different constrains when subjected to any dynamic loading type, including vertical and transverse motion imposed at their support. In developing the model, a non-linear constitutive equation giving stress characteristics as a function of strain ones, for materials with no tensile strength and limited compressive strength, has been used. The model allows to analyse dynamic behaviour of masonry slender structures with primarily flexural behaviour -such as towers -under multi-component earthquake excitations: it seems a useful model since it requires short computational time, while accounting for the material non-linear behaviour. Results from a case study evidence the difference in dynamic response with respect to responses obtained both from a linear elastic analysis and from a simpler non-linear model, where no allowance for...
Background: Some typologies of masonry constructions (e.g. towers or walls with openings) can be reasonably studied through simple beam or frame-like models. For these structures, shear mechanisms often play an important role inducing... more
Background: Some typologies of masonry constructions (e.g. towers or walls with openings) can be reasonably studied through simple beam or frame-like models. For these structures, shear mechanisms often play an important role inducing failure and collapse. Objective: The paper presents an enriched beam model for studying the in-plane response of masonry walls. Initially formulated for masonry columns, towers and masonry slender structures in general, the model is now modified in order to also capture the shear failure mechanisms, in addition to the flexural ones. Methods: Starting with a one-dimensional no-tension model, a strength domain in the plane of the axial and tangential stress of the beam has been added, which has been defined by limiting both the stress shear component with respect to any possible direction and the main compressive stress. Results: The model, implemented in the FEM computational code MADY, allows for short computational times in studying the response of si...
A refined one-storey model has been developed which is able to evidence effects of interaction phenomena between axial and lateral forces in vertical resisting elements on torsional response of plan asymmetric building structures.... more
A refined one-storey model has been developed which is able to evidence effects of interaction phenomena between axial and lateral forces in vertical resisting elements on torsional response of plan asymmetric building structures. Previous research has shown that influence of inelastic interaction is significant, leading to larger peak ductility demands and, mainly, to larger plan-disuniformity of demands in resisting elements. In this paper, the new model is used to re-evaluate, in the light of interaction phenomena, the performances of plan asymmetric system designed according to torsional provisions of the European code Eurocode8, in order to asses its suitability regarding torsional specification.
A numerical method is described for the semi-explicit solution of the constitutive equation of an orthotropic non-linear elastic material with various constraints on the stress. Each constraint forces the stress to belong to a closed and... more
A numerical method is described for the semi-explicit solution of the constitutive equation of an orthotropic non-linear elastic material with various constraints on the stress. Each constraint forces the stress to belong to a closed and convex cone in the space of second order symmetric tensors, and via the choice of appropriate values cones vertex is possible to assign different strength characteristic in different directions. The constitutive equation thus formulated allows to model masonry with very general textures. However application to problems of equilibrium and evolution requires some numerical expedients which are described in detail in this paper. The equation, implemented in the MADY finite element code, has been used to examine how the masonry panel strength changes as a function of traction directions. The results have been compared with the analougous obtained modelling the masonry at the micro scale.
A numerical method is described for the semi-explicit solution of the constitutive equation of an orthotropic non-linear elastic material with various constraints on the stress. Each constraint forces the stress to belong to a closed and... more
A numerical method is described for the semi-explicit solution of the constitutive equation of an orthotropic non-linear elastic material with various constraints on the stress. Each constraint forces the stress to belong to a closed and convex cone in the space of second order symmetric tensors, and via the choice of appropriate values cones vertex is possible to assign different strength characteristic in different directions. The constitutive equation thus formulated allows to model masonry with very general textures. However application to problems of equilibrium and evolution requires some numerical expedients which are described in detail in this paper. The equation, implemented in the MADY finite element code, has been used to examine how the masonry panel strength changes as a function of traction directions. The results have been compared with the analougous obtained modelling the masonry at the micro scale.
The paper presents a method for determining the evolution of the cumulative distribution function of random processes which are encountered in the study of dynamic systems with some uncertainties in the characterizing parameters. It is... more
The paper presents a method for determining the evolution of the cumulative distribution function of random processes which are encountered in the study of dynamic systems with some uncertainties in the characterizing parameters. It is proved that these distribution functions are the solution of a partial differential equation, whose coefficients can be determined once the dynamic system has been solved, and whose numerical solution can be obtained with the finite difference method. Two simple problems are solved here both explicitly and numerically, then the obtained results are compared with each other.
