Influence of boundary conditions on the out‐of‐plane response of brick masonry walls in buildings with RC slabs

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SummaryAn analytical model describing the flexural response of vertically spanning out-of-plane loaded unreinforced masonry walls is presented in this paper. The model is based on the second-order Euler-Bernoulli beam theory and captures important characteristics of the out-of-plane response of masonry walls that have been observed in experimental tests and from numerical studies but for which an analytical solution was still lacking: the onset and the evolution of cracking, the peak strength of the out-of-plane loaded walls, and the softening of the response due to P−Δ effects. The model is validated against experimental results, and the comparison shows that the model captures both the prepeak and postpeak response of the walls. From the analytical model of the force-displacement curve, a formula for the maximum out-of-plane strength of the walls is derived, which can be directly applied in engineering practice. KEYWORDSanalytical model, out-of-plane behaviour, pushover analysis, unreinforced masonry

Section: Modelling Of the Boundary Conditionsmentioning

confidence: 99%

Analytical model for the out‐of‐plane response of vertically spanning unreinforced masonry walls

Godio

Beyer

2017

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“…The numerical model consisted in a discrete element model in which the wall was idealised as a single rigid block; the analytical model used for the force-based and displacement-based assessment was a single degree of freedom system with a trilinear force-displacement relationship. 6 Moreover, with respect to Tondelli et al, 26 a refined contact discretisation is herein adopted, which allows covering configurations in which the wall deformability is relatively high. In that parametric study, the force-based and the displacement-based assessment methods were found to be conservative in 99% and 90% of the cases, respectively.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of force‐based and displacement‐based out‐of‐plane seismic assessment methods for unreinforced masonry walls through refined model simulations

Godio

Beyer

2018

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Summary The performance of force‐based and displacement‐based seismic assessment methods for the life‐safety limit state check of out‐of‐plane loaded unreinforced masonry walls is evaluated on the basis of refined numerical simulations. For this purpose, a discrete element model of a vertically spanning wall is built and validated against experimental results from static and dynamic test conditions. The model is then analysed for a large range of wall configurations. For each configuration, a static pushover analysis and a series of incremental dynamic analyses are run, the latter permitting to determine the capacity of the wall under dynamic loading. The accuracy of the assessment methods in predicting the acceleration at which the walls collapse is evaluated. It is found that the displacement‐based method is more accurate, robust, and safe than the force‐based method. The comparison also shows that for walls characterised by a relatively high ratio of axial load to Euler's critical load, both assessment methods lead to an overestimation of the wall capacity. As a remedy, a modification to the methods based on a recently developed mechanical model is put forward and tested. For the force‐based method, it is additionally suggested to set for walls with relatively high overburden ratios the behaviour factor equal to 1. To ensure reproducibility of this study, all input and output files of the numerical simulations are made publicly available.

“…It is evident that the planar analysis is unconservative, even when the results along 2 directions are combined, and that 3D analysis is necessary. 2D analysis can only be used for the study of structures that are either constrained to rock in‐plane (like bridges with shear keys in one direction) or rock in‐plane because of their geometrical shape (eg, masonry among others).…”

Section: Wobbling Isolation Of Bridges: Proof Of Concept and Limitatimentioning

confidence: 99%

Seismic response of a wobbling 3D frame

Vassiliou

2017

Summary This paper investigates the 3D response of a slab supported by wobbling columns. The columns are not allowed neither to slide nor to roll out of their initial position. An analytical model is proposed, the equations of motion are derived, and they are solved numerically. The paper concludes that the addition of the slab makes the columns more stable. In fact, the system is almost equivalent to the response of a solitary column with the same aspect ratio yet larger size. However, it is also shown that the system is less stable than its planar counterpart and that planar analysis can only qualitatively describe the behavior of 3D structures. A case study shows that the concept could be used as a seismic isolation technique for bridges. However, more research need to be performed on defining proper intensity measures for uplifting structures, as it is shown that there is large record‐to‐record variability, even when intensity measures developed for rocking structures are used.