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This paper presents a refined Finite Element (FE) modeling strategy for analyzing the failure behavior of regular masonry structures reinforced with timber-based retrofit solutions. The proposed model schematizes the masonry as brick units, modeled using two-dimensional linear elastic plane stress elements, mutually joined through zero-thickness cohesive interface elements. These interface elements serve to reproduce the nonlinear behavior of masonry because of the occurrence of failure mechanisms of the mortar joints. Reinforced timber frame elements are modeled using truss elements that exhibit elastic brittle fracture behavior. The interaction between the masonry sub-structure and the reinforced timber frame system is accounted for using special constraint conditions that simulate the mechanical behavior of anchorage connections. The reliability of the proposed model in reproducing the failure behavior of masonry is assessed through comparisons with experimental and numerical data available in the literature. Additionally, the efficacy of the retrofit technique based on timber frame structures is investigated in detail through pushover analyses on a two-story masonry wall representative of real-life masonry buildings. The results indicate that the proposed retrofitting strategy is an effective and eco-friendly retrofit solution to enhance the in-plane bearing capacity of masonry structures subjected to horizontal forces.

The dynamics of a soft particle suspended in a viscous fluid can be changed by the presence of an elastic boundary. Understanding the mechanisms and dynamics of soft–soft surface interactions can provide valuable insights into many important research fields, including biomedical engineering, soft robotics development, and materials science. This work investigates the anomalous transport properties of a soft nanoparticle near a visco-elastic interface, where the particle consists of a polymer assembly in the form of a micelle and the interface is represented by a lipid bilayer membrane. Mesoscopic simulations using a dissipative particle dynamics model are performed to examine the impact of micelle's proximity to the membrane on its Brownian motion. Two different sizes are considered, which correspond to ≈ 10 − 20 n m in physical units. The wavelengths typically seen by the largest micelle fall within the range of wavenumbers where the Helfrich model captures fairly well the bilayer mechanical properties. Several independent simulations allowed us to compute the micelle trajectories during an observation time smaller than the diffusive time scale (whose order of magnitude is similar to the membrane relaxation time of the largest wavelengths), this time scale being hardly accessible by experiments. From the probability density function of the micelle normal position with respect to the membrane, it is observed that the position remains close to the starting position during ≈ 0.05 τ d (where τd corresponds to the diffusion time), which allowed us to compare the negative excess of mean-square displacement (MSD) to existing theories. In that time range, the MSD exhibits different behaviors along parallel and perpendicular directions. When the micelle is sufficiently close to the bilayer (its initial distance from the bilayer equals approximately twice its gyration radius), the micelle motion becomes quickly subdiffusive in the normal direction. Moreover, the temporal evolution of the micelle MSD excess in the perpendicular direction follows that of a nanoparticle near an elastic membrane. However, in the parallel direction, the MSD excess is rather similar to that of a nanoparticle near a liquid interface. [ABSTRACT FROM AUTHOR]

The evaluation of the seismic vulnerability of existing buildings is becoming very significant nowadays, especially for ancient masonry structures, that represent the cultural and historical heritage of our countries. In this research, the Cathedral of Santa Maria Assunta in Catanzaro (Italy) is analyzed to evaluate its structural response. The main physical properties of the constituent materials were deduced from an extensive diagnostic campaign, while the structural geometry and the construction details were derived from an accurate 3D laser scanner survey. A global dynamic analysis, based on the design response spectrum, is performed on a finite element model for studying the seismic response of the structure. Moreover, a local analysis is conducted to evaluate the safety factors corresponding to potential failure mechanisms along preassigned failure surfaces. Furthermore, pushover analyses are performed on macro-elements, properly extracted from the whole structure and with an independent behavior with regard to seismic actions. A novel model based on inter-element fracture approach is used for the material nonlinearity and its results are compared with a well-known classical damage model in order to point out the capability of the method. Finally, the results obtained with the three different models are compared in terms of seismic vulnerability indicators.

This article presents a detailed analysis of a numerical model for studying the failure of masonry structures that have been retrofitted with timber solutions. The model accurately reproduces the failure mechanisms of masonry and evaluates the effectiveness of timber-based retrofitting. The study validates the model through comparisons with experimental and numerical results and assesses its efficacy through nonlinear static analysis. The article also discusses the use of a timber frame system as a retrofitting strategy for masonry walls, highlighting its significant enhancement of the wall's load-bearing capacity against lateral forces. However, the post-peak behavior of the retrofitted cases reveals potential weaknesses in the timber frame system, which can lead to sudden drops in resistance. The article concludes by emphasizing the importance of preventing simultaneous failure of multiple bracing elements in the retrofitting system and the need for further research to improve its design and mitigate brittle behavior. [Extracted from the article]