Unreinforced Masonry Structures‘ Seismic Improvement with F.R.C.M. : the Experience of the Vanvitellian Palazzo Murena of Perugia

The aim of the contribution is to illustrate strengthening design in regard to the conservation of Palazzo Murena in Perugia, designed in the eighteenth century by the prominent Architect Luigi Vanvitelli. Starting from an accurate historical analysis and taking into account experimental campaign and results of numerical analysis, the vulnerable elements of the construction have been highlighted. A local reinforcement intervention is proposed with the aim of retain the historical value of the architectural characteristics; this consists of the application of plaster with Fiber Reinforced Cementitious Matrix, F.R.C.M., to achieve an adequate strength, without adding supplemental weight to the masonry structure and therefore avoiding an increase of the seismic vulnerability. The benefits of the application of F.R.C.M. materials, also with respect to different reinforcement techniques are broaden

Limit analysis of non-periodic masonry by means of discontinuity layout optimization

Masonry structures forming part of our historical heritage were often constructed using nonperiodic textures. In this case, unlike the situation for masonry with periodic textures, few methods are available to estimate wall strength and, moreover, available methods are often difficult to apply. In this work, Discontinuity Layout Optimization (DLO) is proposed as a method of estimating the failure load and associated mechanism of masonry walls constructed with non-periodic textures. In the first part three different textures are considered (periodic, quasi-periodic and chaotic) with a simplified scheme and a parametric analysis is undertaken, considering the variation of the height of the panel. A further classification for quasi-periodic textures is then provided and a DLO rigid block analysis is carried for square panels to show the influence of such textures. The results highlight the importance of the parameters considered in the analysis, and that DLO is a suitable method to investigate their influence

Evaluation of a Statistically Equivalent Periodic Unit Cell for a quasi-periodic masonry

AbstractThe paper presents a method to estimate the Statistically Equivalent Periodic Unit Cell (SEPUC) corresponding to a masonry with quasi-periodic texture. The identification of the texture and the constituent phases (unit blocks and mortar joints) is achieved by means of digital image processing techniques applied to color image of the masonry wall. A statistical analysis of geometrical parameters (width and height of blocks, thickness and length of mortar joints) allows to estimate their probability distribution and to identify the typology of the texture. Subsequently a Monte Carlo analysis is performed using several tentative SEPUCs generated with different dimensions of blocks and joints according to the estimated distributions. A criterion was eventually proposed to identify, among the numerically generated ones, the SEPUC which is more suitable to model the behavior of masonry wall. The SEPUC is analyzed with techniques available for periodic texture, applying periodic boundary conditions, in order to estimate the equivalent elastic stiffness. The proposed method is validated comparing the results in the elastic range obtained with SEPUC and those obtained imposing essential and natural boundary conditions on the original texture

Longitudinal waves in a nonlocal rod by fractional Laplacian

The article deals with the longitudinal waves in a nonlocal elastic rod. Regarding the nonlocal elasticity the Eringeen model has been assumed; the novelty is that this model is described in terms of the fractional Laplace operator. The standing waves are obtained by numerical solutions of the fractional differential equation in one-dimensional continuum. The obtained results are in accordance with the ones reported in the literature and highlight the dispersion phenomenon. The effects of the nonlocal contribution and of the fractional Laplacian order are also analyzed

Simple Homogenized Numerical Model for the Analysis of Multi-leaf Masonry Walls

A simple numerical model for the analysis of multi-leaf walls is discussed. These are featured rather frequently in masonry buildings across Europe, and are characterized by a low resistance to out-of-plane actions, which often causes the partial or total collapse of the structure. A 2D FE mesh is created directly from the sketch of each wythe, which is later exploited for deriving the 2D homogenized failure surface of the single layers. A weighted average is operated among the homogenized stresses to obtain the failure surface of the multi-leaf wall. Then, the out-of-plane bending moment for each layer is evaluated by assuming a constant distribution of the homogenized stress over the thickness. The overall out-of-plane failure surface in terms of bending moments is then obtained for the whole wall, assuming each layer to behave separately in bending. The model is applied on two walls displaying distinct layouts of units: one presents a running bond masonry consisting of tuff blocks, the other is constituted by randomly-assembled stones. The results show an overall higher resistance of the randomly-assembled wall with respect to the running bond one, both for the in- and out-of-plane behaviors