1,721,012 research outputs found
Resistance of corroded RC beams: Extending fib Model Code 2010 models
Full text linkThe residual resistance of corroded reinforced concrete members depends on steel and concrete cross section loss and deterioration of material properties for steel, concrete, and bond. The paper considers these phenomena in models for resistance calculations, starting from the cross section and stress field models in Model Code 2010. The aim of this study is to develop models proposed by Coronelli et al., using a recently proposed approach by Blomfors et al. to model bond of corroded reinforcement based on the Model Code 2010 bond stress–slip relation. Flexure, shear, and anchorage resistance of corroded reinforced concrete beams are studied. The verification is carried out by comparison with tests on corroded beams with different shear span-to-depth ratios. The bond deterioration leads to changes in the inclination of the stress fields in B regions and anchorage failures. The reduced resistance and the changes of the failure modes caused by the deterioration phenomena are captured by the modeling approach
The structural life of a Cathedral and the worksites of the Duomo di Milano
Full text linkThe life of Milan Cathedral is described with the evolution of the structural system and the restorations carried out throughout the centuries. The organization of the Veneranda Fabbrica del Duomo di Milano is outlined, with the latest restoration interventions. The case study of the construction and restorations of the Tiburio with its supporting pillars is analyzed, from the initial design to the dramatic damage in the 20th century. The rebirth of the Cathedral was the fruit of restorations preserving the structural identity of the monument up to the present. The conclusions address the study of damage and maintenance and repair operations of mon-umental heritage buildings within a life cycle perspective, in relation to the underlying socie-tal values
Numerical Analysis of Mechanical Damage in Ribbed Masonry Vaults under Differential Settlements
No full textThe present study takes advantage of a parametric model, which allows one to create automatically complex structural models of ribbed masonry vaults. Two numerical modelling strategies are discussed: a 3D continuum and a 3D contact-based model. The effects of settlements are studied by imposing vertical displacement at the vault supports up to collapse. Predictions of each modelling strategy are compared with actual damage observation. A representative square vault of Milan Cathedral is studied here, aiming to understand the causes of the damage documented through the years. The structure is noted to have suffered structural damage in the vaulting system due to a long history of soil settlements. The geometry is based on a photogrammetric scanning, and the three-dimensional solid models are created through parametric reconstruction procedures, including details such as springing, arch, ribs, web, and rubble-fill. Both modelling strategies allow to highlight the vulnerability of masonry vaults due to settlements. Significant differences in prediction capabilities are noted when large displacements and separation of elements are involved. The simulations show the possibility of predicting and interpreting different complex damage phenomena as arch block damage or sliding, and web–arch detachment, which is frequently observed in historical structures
Structural assessment of iron tie rods based on numerical modelling and experimental observations in Milan Cathedral
No full textIron ties contribute to the stability of structural systems having vaults and arches. The axial force in the iron ties is not easily to be measured but this knowledge is important for assessing the safety of these members. In the case of breakage of iron tie rods, the assessment study needs to understand the causes of the failures. Experimental data are collected, and models are used for their interpretation. The aim of this paper is to propose a new integrated experimental and numerical approach for the structural analysis of tie rod tensions in historical buildings. The study considers an application at Milan Cathedral, where recently some iron tie failures were observed. The collected data taken into account are: (a) Point cloud measurement of the geometry (b) Understanding of construction phases, (c) Soil-settlement measurement in the last 50 years, (d) Experimental measurement of the iron ties axial force, and (e) Documentation of damage and iron tie failures in the last century. It is here proposed to use an advanced numerical model for simulating, interpreting and predicting the measured response of the iron ties. The finite element numerical model includes detailed geometry of elements, material properties of masonry based on texture observations and iron ties modelling. The paper shows how the actual structural configuration, the choices on material properties, the consideration of construction stages or load history and soil settlements affect the tension state in the iron ties. In particular, it is demonstrated through the carried-out analysis the possibility to correlate the tension force in the ties with soil settlements. Finally, the developed numerical model can be used also during practical maintenance operations of iron tie replacement, by predicting the stressed state, the possible lateral displacements of the pier and the associated structural safety
DIGITAL MODELLING AND ANALYSIS OF MASONRY VAULTS
Full text linkThe focus of this paper is to discuss the peculiarities of the digital modelling of masonry cross vaults. The proposed methodological approach for a multidisciplinary study of masonry vaults will be focused on: geometrical survey, crack pattern, geometrical modelling, and safety assessment based on structural analysis.Automatic reconstruction procedures recently proposed in the literature for ribbed masonry vaults, are used to overcome time-consuming modelling tasks. The created digital models take into consideration the different aspects of the three-dimensional geometry, the internal divisions with variations of material properties in different parts, and a suitable discretization for finite element analysis. Moreover, the same model can be used in BIM (Building Information Modelling), judged as a suitable environment in which to combine different aspects of the restoration works such as: documentation, intervention design, and the data system in an unique model. The same model is then used to perform finite element analysis. Each of these aspects is clarified with examples of different vaults typology coming from case studies as that of the church of St. Bassiano in Pizzighettone (Cremona) or the notable Milan Cathedral.</p
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