A macro‐model with nonlinear springs for seismic analysis of URM buildings

Abstract

Seismic assessment of existing unreinforced masonry buildings represents a current challenge in structural engineering. Many historical masonry buildings in earthquake regions were not designed to withstand seismic loading, thus these structures often do not meet the basic safety requirements recommended by current seismic codes and need to be strengthened considering the results from realistic structural analysis. This paper presents an efficient modelling strategy for representing the nonlinear response of unreinforced masonry components under in-plane cyclic loading which can be used for practical and accurate seismic assessment of masonry buildings. According to the proposed strategy, a generic masonry perforated walls is modelled using an equivalent frame approach, where each masonry component is described utilising multi-spring nonlinear elements connected by rigid links. When modelling piers and spandrels, nonlinear springs are placed at the two ends of the masonry element for describing the flexural behaviour, and in the middle for representing the response in shear. Specific hysteretic rules allowing for degradation of stiffness and strength are then used for modelling the member response under cyclic loading. The accuracy and the significant potential of the proposed modelling approach are shown in several numerical examples, including comparisons against experimental results and the nonlinear dynamic analysis of a building structure

A hysteresis model for timber joints with dowel-type fasteners

“…1). In this study, these springs are simulated with User Element Subroutines (UELs) taken from Rinaldin et al [20,38]. A preliminary version of this model was presented by Rinaldin [39].…”

Vulnerabilidad sísmica del patrimonio edificado del Centro Histórico de la Ciudad de Cuenca: Lineamientos generales y avances del proyecto

“…El uso de elementos spring se explica por el hecho de que Ruaumoko captura mejor el comportamiento no lineal a corte de los miembros de MNR con este tipo de elemento antes que con sus elementos frame (Jiménez, 2016). El MPE desarrollado en Jiménez (2016) se basó en el de Amadio, Rinaldin, & Macorini (2011), del cual adopta su modelo cinemático y cuya validación numérica se enriqueció con más ejemplos y una discusión más profunda en Rinaldin, Amadio, & Macorini (2016). En la Figura 9, se muestra un esquema de dicho modelo, su discretización en macro-elementos verticales y horizontales: pilares y vigas-dintel, respectivamente.…”

Review of experimental cyclic tests on unreinforced and strengthened masonry spandrels and numerical modelling of their cyclic behaviour

“…These springs connects two coincident nodes and returns to the solver force and stiffness corresponding to a given displacement. This model was previously developed for masonry piers in [28]. The element can represent the cyclic behaviour of a masonry spandrel using the hysteretic law proposed by Tomazevic and Lutman [29], as can be seen in Fig.…”

“…The stiffness degradation parameter a can be assumed as 0.8, which means that the unloading stiffness immediately before failure is the 80% of the elastic one, while the strength degradation parameter b may be taken equal to 0.06, as suggested by Tomazevic and Lutman [29] after an experimental campaign on masonry piers, and as confirmed by Gattesco and Macorini [21]. The model, described completely in [28], is used also for masonry piers. The elastic stiffness of the spring is:…”