Buildings with unreinforced masonry (URM) infills is a common construction practice worldwide. To... more Buildings with unreinforced masonry (URM) infills is a common construction practice worldwide. To correctly assess the seismic performance of such structures, the analysis of the masonry infills under in-plane (IP) and out-of-plane (OOP) loading, as well as their interaction, is essential. The aim of this paper is to present a new macro-element modelling technique able to simulate the IP and OOP response of URM infilled frames subjected to earthquakes. The model consists of a horizontal, a vertical and two diagonal struts represented by fiber section beam-column elements. The compressive behavior of the struts are defined by empirical strength and strain parameters. The paper also discusses on derivation of the empirical parameters based on the actual properties of infill wall. The proposed macro-element model has been validated with experimental results available in the literature. From the numerical analysis, a good agreement between the experimental and numerical results was obtained.
During earthquakes, infills are subjected to In-Plane (IP) and Out-Of-Plane (OOP) actions. In the... more During earthquakes, infills are subjected to In-Plane (IP) and Out-Of-Plane (OOP) actions. In the case of strong earthquakes, infills may progressively change their mechanical behavior resulting in a reduction of IP and OOP stiffness and strength. Recent earthquakes have proved that the OOP collapse of infills is a diffused mechanism also for buildings designed to resist seismic events in agreement to the most modern codes. This is potentially a very dangerous event with risk for human health. The strong interaction between IP and OOP behavior of infills traduces in a progressive reduction of the OOP strength. The IP damaging loads may cause a loss of the OOP capacity not predicted during the design process or during the safety assessment. Unfortunately, a very low number of experimental tests is available in the literature that does not allow definitively reliable prediction laws for the degrading of the OOP mechanical properties. Further, only in few cases codes suggest adequate strategies to face this question. For what above, in this paper the reduction of OOP stiffness and strength because of the IP damage is studied by an extended numerical experimental campaign based on FE models to be considered as complementary of the few laboratory experimental tests available in the literature. On the base of the numerical results, a proposal for the prediction of the variation of the mechanical characteristics of infills with respect to OOP actions is presented after an extended discussion on the existing strategies. The nonlinear behavior of infills and the arch effect between infill and the surrounding frame, where effective, have been replicated by the FE models here discussed, trying to simulate the real case of unreinforced masonry (URM) infills.
Proceedings of the 7th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COMPDYN 2015), 2019
Earthquakes produce on infills In-Plane (IP) and Out-Of-Plane (OOP) actions. The recent earthquak... more Earthquakes produce on infills In-Plane (IP) and Out-Of-Plane (OOP) actions. The recent earthquakes have proved that the OOP collapse of infills is a diffused mechanism also in buildings designed to resist to seismic events in agreement to the most modern strategies. This fact makes the question arises about the safety of infills with respect OOP actions. The strong interaction between IP and OOP behaviour of infills traduces in a progressively reduction of the OOP strength. Further, only in few cases codes suggest adequate strategies to face this issue. For what above, in the paper the reduction of OOP strength because of the IP damage is studied by an extended numerical experimental campaign based on FE models to be considered as complementary to the very few laboratory experimental tests available in the literature.
Buildings with unreinforced masonry (URM) infills is a common construction practice worldwide. To... more Buildings with unreinforced masonry (URM) infills is a common construction practice worldwide. To correctly assess the seismic performance of such structures, the analysis of the masonry infills under in-plane (IP) and out-of-plane (OOP) loading, as well as their interaction, is essential. The aim of this paper is to present a new macro-element modelling technique able to simulate the IP and OOP response of URM infilled frames subjected to earthquakes. The model consists of a horizontal, a vertical and two diagonal struts represented by fiber section beam-column elements. The compressive behavior of the struts are defined by empirical strength and strain parameters. The paper also discusses on derivation of the empirical parameters based on the actual properties of infill wall. The proposed macro-element model has been validated with experimental results available in the literature. From the numerical analysis, a good agreement between the experimental and numerical results was obtained.
During earthquakes, infills are subjected to In-Plane (IP) and Out-Of-Plane (OOP) actions. In the... more During earthquakes, infills are subjected to In-Plane (IP) and Out-Of-Plane (OOP) actions. In the case of strong earthquakes, infills may progressively change their mechanical behavior resulting in a reduction of IP and OOP stiffness and strength. Recent earthquakes have proved that the OOP collapse of infills is a diffused mechanism also for buildings designed to resist seismic events in agreement to the most modern codes. This is potentially a very dangerous event with risk for human health. The strong interaction between IP and OOP behavior of infills traduces in a progressive reduction of the OOP strength. The IP damaging loads may cause a loss of the OOP capacity not predicted during the design process or during the safety assessment. Unfortunately, a very low number of experimental tests is available in the literature that does not allow definitively reliable prediction laws for the degrading of the OOP mechanical properties. Further, only in few cases codes suggest adequate strategies to face this question. For what above, in this paper the reduction of OOP stiffness and strength because of the IP damage is studied by an extended numerical experimental campaign based on FE models to be considered as complementary of the few laboratory experimental tests available in the literature. On the base of the numerical results, a proposal for the prediction of the variation of the mechanical characteristics of infills with respect to OOP actions is presented after an extended discussion on the existing strategies. The nonlinear behavior of infills and the arch effect between infill and the surrounding frame, where effective, have been replicated by the FE models here discussed, trying to simulate the real case of unreinforced masonry (URM) infills.
Proceedings of the 7th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COMPDYN 2015), 2019
Earthquakes produce on infills In-Plane (IP) and Out-Of-Plane (OOP) actions. The recent earthquak... more Earthquakes produce on infills In-Plane (IP) and Out-Of-Plane (OOP) actions. The recent earthquakes have proved that the OOP collapse of infills is a diffused mechanism also in buildings designed to resist to seismic events in agreement to the most modern strategies. This fact makes the question arises about the safety of infills with respect OOP actions. The strong interaction between IP and OOP behaviour of infills traduces in a progressively reduction of the OOP strength. Further, only in few cases codes suggest adequate strategies to face this issue. For what above, in the paper the reduction of OOP strength because of the IP damage is studied by an extended numerical experimental campaign based on FE models to be considered as complementary to the very few laboratory experimental tests available in the literature.
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