87,331 research outputs found
The effectiveness of the DIC as a measurement system in SRG shear strengthened reinforced concrete beams
No full textSteel Reinforced Grout (SRG) materials are generating considerable interest as strengthening system of reinforced concrete (RC) structures. They are finding increasing use in several civil engineering applications mainly due to the advantages they offer over traditional material such as high strength to weight ratio, ease of application, durability and low price. This paper describes the results of an experimental investigation carried out on SRG shear strengthened RC beams and gives evidence of the Digital Image Correlation (DIC) effectiveness as a measurement system. The tests performed had two main objectives: (i) assess the effectiveness of continuous and discontinuous U-wrapped jackets comprising a different number of layers and strips; (ii) assess the shear crack distribution during the tests by means of the DIC measurements. The results confirmed that reinforcing RC beams with SRG jackets can increase the load-bearing capacity; when the beam was reinforced with a continuous two-layered SRG strip, an increase of 84% was observed (compared to the unreinforced beam). The Linear Variable Differential Transformers (LVDT) measurements validated the results obtained by means of the DIC
Structural Assessment of a Heritage Building in the UNESCO Site of Alberobello
No full textThe cultural building Heritage is widespread all around the world and mainly consists of masonry structures. The UNESCO Map indicates about the 50% of this Heritage is placed in Italy, where seismic risk is recognized in the whole national territory. One of the most notorious sites is the city of Alberobello due to the presence of the well-known Trulli: the old city. With their cone-shaped roof made by stones, the Trulli are a unique example of architectural heritage. Moreover, the relatively new area is full of historical buildings that are an additional Heritage for the city. This study reports on the structural assessment of a large masonry structure faced in front of the Trulli zone, which is considered to be one of the first building of the old city. The building is the results of an aggregation of different units in which several masonry typologies met, at different ages. The historical and geometrical surveys were both performed in order to plan in-situ investigations aimed to reach an adequate level of confidence with respect to the mechanical properties of the masonry, according to the technical codes. A global analysis was performed by finite element method (FEM). Thus, the vulnerability assessment is herein reported and discussed for this complex buildin
Experimental Investigation and Numerical Analysis of Bond Behavior in SRG-Strengthened Masonry Prisms Using UHTSS and Stainless-Steel Fibers
No full textThis paper deals with the experimental and numerical study of the bond behavior of two steel reinforced grout (SRG)-strengthened masonry systems. Ten shear bond tests were carried out on prismatic masonry specimens. The data of experimental tests are recorded and results are given in terms of load/stress-global slip curves, failure modes, tables, graphs and photographic reports, comparing the results of the two strengthening systems. Two kinds of steel fibers available in marketplace were used: ultra-high tensile strength steel galvanized micro-cords and stainless-steel strands. The main target is to obtain information on the behavior of the bond between masonry surface and the two types of SRG composites, which are characterized by two substantial differences: tensile strength with a ratio of 2.4 and the corresponding surface mass density with a ratio of 0.30. Finally, the influence of the matrices coupled with the two systems is critically analyzed. The characterization of the bond behavior is necessary in order to confirm the performance of the SRG systems that have become increasingly used and attractive. It also aims to make a contribution to the existing knowledge especially in relation to the use of low resistance steel fibers (stainless steel) which are still few studied today. Furthermore, using a suitable interface law proposed in the literature, a numerical model is defined and employed to simulate the behavior of the specimens tested in the laboratory. The comparisons show a good agreement between numerical and experimental results in terms of the maximum load, load versus global-slip curves, and crack patterns
Three-dimensional numerical modeling of rc beam strengthened in shear with steel reinforced grout (Srg)
No full textA numerical model implemented in a finite element code is proposed; it was adopted to analyze the mechanical performances of the strengthened reinforced concrete beams in shear by SRG system until their collapse. The SRG-to-concrete interface was reproduced by a cohesive model, in particular this model is characterized by three failure modes, the first (mode I) associated to the normal stresses, while the other two (mode II and III) associated to shear stresses. Moreover, as damage contact, in this preliminary work a bi-linear local bond-slip law was adopted. The implemented numerical procedure is verified by a comparison between its predictions and test results in terms of ultimate loads, load-deflection diagrams and crack pattern with respect to the result present in literature
Freeze/Thaw Effect on the Mechanical Properties of FRCM System
No full textNowadays the use of FRPs (fibre reinforced polymers) and FRCMs (fabric reinforced cementitious mortar) is largely adopted in the field of the structural retrofitting. Nonetheless, the durability issue is a lightly investigated phenomenon, but it is important for the long-term effects on the effectiveness of external reinforcement. This paper presents the results about the main aspects related to the effects of the freeze/thaw cycles on the mechanical characteristics and on the stress-transfer mechanism between both the fabric and the matrix and the composite strip with respect to the concrete substrate. The investigated parameters were the number of layers and the FRCM-reinforcement type. In particular, the direct tensile, the single-lap and direct-shear test were all performed and compared
Solid-gas hydrogenation of hex-3-yne and 1,4-cyclohexadiene in the presence of Ru3(CO)9(H)(PPh2), Ru3(CO)10(H)(PPh2), Ru3(CO)7(PPh”)(C6H4) and Ru4(CO)11(PPh)(C6H4) deposited on pyrex glass, silica and alumina
No full textExperimental Analysis of the Mechanical Response of Masonry Columns Partially Confined with PBO FRCM (Fabric Reinforced Cementitious Mortar) Composites
No full textAn experimental investigation on partially PBO (short of Polyparaphenylenebenzobisthiazole) FRCM (Fiber Reinforced Cementitious Mortar) confined clay brick masonry columns has been conducted. Ten small-scale specimens measuring 445 mm high with a square cross-section of the 250 mm side have been tested under monotonic axial loading until collapse. Two columns were unconfined, while the remaining ones were confined with single-layer PBO FRCM jackets varying the geometric configuration along their height. The vertical spacing ratio sf’/sf, being sf’ and sf the center-to-center and the net spacings between two consecutive jackets, respectively, was considered as the key parameter of the confinement configuration. The failure modes, stress–strain curves and peak axial stress and strain values are reported. The experimental results have been compared to the predictions of models found in the Italian guidelines CNR DT 215/2018 and the American ACI 549-R20 standards. The main aspects analyzed involved (i) the evaluation of the effectiveness of partial confinement on the mechanical response of columns, (ii) the definition of the mechanical and geometrical parameters that influence the structural response of partially confined columns, and (iii) the development of appropriate analytical models for the prediction of the resisting capacity of masonry columns partially confined with PBO FRCM
Impiego dei raggi X per la diagnosi delle alterazioni interne del legno in diverse specie arboree
No full textPoudre de verre dans le béton
No full text56 f. : ill. ; 30 cm. (+ CD-Rom)Le problème environnemental que posent les déchets non biodégradables, tels que les bouteilles non réutilisables (verre), devient une préoccupation majeure au regard des quantités énormes produites dans les grandes villes. L’une des rares voies de recyclage de ces déchets est de les réutiliser dans les procédés de construction (béton). Ainsi, le verre est un matériau riche en silice et en sodium. Son utilisation dans une matrice cimentaire entraine deux réactions à effet contraire : la réaction alcali silice néfaste pour les bétons par les gonflements qu’elle génère et la réaction pouzzolanique qui est bénéfique. Pour cela, la poudre de verre peut devenir un débouché commercial très important
Un verre ça va
No full textUn verre ça va, trois verres. Bonjour des dégâts! (1984, F) by French committee of education in health
Commercial: The small episodic films aim to prevent harm from heavy alcohol consumption.
Scene: alcohol mixed adults strong nontransgressive in company
A young man offers a young woman another drink, but she refuses to have more than the one before.
Clip: 67A (Addictions 2
- …
