Recursive partitioning and Gaussian Process Regression for the detection and localization of damages in pultruded Glass Fiber Reinforced Polymer material

In this paper, a methodology for the detection and localization of damages in composite pultruded members is proposed. This is particularly relevant to thin-walled pultruded members, which are typically characterized by orthotropic behavior, anisotropic along the fibers and isotropic in the cross section. Hence, a method to detect and localize damage, and the influence these might have on the performance of thin-walled Glass Fiber Reinforced Polymer (GFRP) members, is proposed and applied to both numerical and experimental data. Specifically, the numerical and experimental modal shapes of a narrow flange pultruded profile are analyzed. The reliability of the proposed semiparametric statistical method, which is based on Gaussian Processes Regression and Bayesian-based Recursive Partitioning, is analyzed on a narrow flange profile, artificially affected by sawed notches with incremental depth. The numerical investigation is carried out via finite element models (FEMs) of the cracked beam, where the dynamic parameters and the modal shapes are computed. In total, three different crack sizes are investigated, to compare the results with the experimental ones. Finally, the proposed approach is further extended and validated on numerically simulated frame structures

Sensitivity to damage imperfection for multileaf masonry walls based on vibrational analyses

Damage-imperfection indicators based on variation of dynamic parameters allow to identify the intrinsic discontinuity and the damage of structures. Here, the structural health monitoring through the vibration-based approach has been carried out by two steps on three different multileaf masonry specimens (full infill, damaged infill, and strengthened infill) subjected to uniaxial compressive load. In the first step, the characterization of initial conditions based on the investigation of the intrinsic discontinuity and the manufacturing imperfections has been done. In this phase, the detection, localization, assessment, and prediction of damage have been given by the comparison between the experimental and numerical modal data calculated by the commercial finite element code. Subsequently, in the second step, starting from the identification of undamaged condition, the damage effects on changes of the dynamic parameters have been recorded. As well known, the incoherent response between the leaves is related to frequency values, damping ratios, and modal shapes

Structural and Thermal Behaviour of a Timber-concrete Prefabricated Composite Wall System

Abstract Wood is the oldest building materials and still now it plays an important role in the construction sector. There are many general advantages in using timber for building purposes. First of all, it is an environmentally friendly, easily recyclable material; it has a low weight in relation to strength, which is advantageous for transport, handling and production; moreover wood has aesthetic qualities, which give great possibilities in architectural design. Lastly wooden structures have an excellent performance in case of earthquake if compared to traditional structures. In Europe the development of the timber-concrete composite structures (TCC) began during a shortage of steel for reinforcement in concrete in the beginning of XX century. TCC application was primarily a refurbishment technique for old historical buildings, during the last 50 years interest in TCC systems has increased, resulting in the construction also of new buildings. This paper presents the analysis of the structural and thermal behaviour of an timber-concrete prefabricated composite wall system, the Concrete Glulam Framed Panel (CGFP) which is a panel made of a concrete slab and a structural glulam frame. The research analyses the structural performance with quasi-static in-plane tests, focused on the in-plane strength and stiffness of individual panels, and the thermal behaviour of the system with steady state tests using an hot box apparatus. The results validate the efficacy of proposed system ensuring the resistance and the dissipative structural behaviour through the hierarchy response characterized by the wood frame, the braced reinforced concrete panel of the singular module and by the rocking effects of global system. On the other side hot-box measures demonstrated a high level of thermal resistance of the system reaching U-values around 0,20 W m -2 K -1 . Moreover experimental data permitted to calibrate a FEM model with which will be possible to study and analyse the panels in different conditions and configuration in both mechanical and thermal field

Sensitivity analysis of damaged monumental structures: the example of S. Maria del Suffragio in L'Aquila

In Italy, which accounts for an impressive number of architectural heritage sites, a large part of the territory is subject to seismic risk. Nonetheless, also the two recent examples of the 2009 L'Aquila earthquake and 2012 Emilia earthquake confirmed and highlighted the vulnerability of cultural heritage structures to these types of events. In this paper the church of Santa Maria del Suffragio (Anime Sante) in L'Aquila is used as a benchmark for the experimental validation of a finite element model on the basis of the data gathered by the permanent structural health monitoring system installed on the building by IUAV in 2009. Structural health monitoring techniques have been largely applied to cultural Heritage buildings in recent times, mostly because of their non-destructive nature, and they have proven to be a valid tool in assessing the damage evolution and in characterising the global dynamic behaviour of the structure. In particular, a global sensitivity analysis technique has been applied to a finite element model. The model underwent a model updating procedure on the parameters chosen in the sensitivity analysis. The calibrated model is an invaluable tool in assessing the dynamic behaviour of the structure and may serve for several purpose

" Sensitivity analysis of damaged monumental structures: the example of S. Maria del Suffragio in L'Aquila "

In Italy, which accounts for an impressive number of architectural heritage sites, a large part of the territory is subject to seismic risk. Nonetheless, also the two recent examples of the 2009 L'Aquila earthquake and 2012 Emilia earthquake confirmed and highlighted the vulnerability of cultural heritage structures to these types of events. In this paper the church of Santa Maria del Suffragio (Anime Sante) in L'Aquila is used as a benchmark for the experimental validation of a finite element model on the basis of the data gathered by the permanent structural health monitoring system installed on the building by IUAV in 2009. Structural health monitoring techniques have been largely applied to cultural Heritage buildings in recent times, mostly because of their non-destructive nature, and they have proven to be a valid tool in assessing the damage evolution and in characterising the global dynamic behaviour of the structure. In particular, a global sensitivity analysis technique has been applied to a finite element model. The model underwent a model updating procedure on the parameters chosen in the sensitivity analysis. The calibrated model is an invaluable tool in assessing the dynamic behaviour of the structure and may serve for several purposes

A Computer Vision-Based Approach for Non-contact Modal Analysis and Finite Element Model Updating

Computer vision-based techniques for modal analysis and system identification are rapidly becoming of great interest for both academic research and engineering practice in structural engineering. For instance, this is particularly relevant in fields such as bridge or tall building monitoring, where the large size of the structure would require an expensive sensor network, and for the characterisation of very slender, highly-flexible structural components, where physically-attached sensors cannot be deployed without altering the mass and stiffness of the system under investigation. This study concerns the latter case. Here, an algorithm for the full-field, non-contact extraction and processing of useful information from vibrational data is applied. Firstly, video acquisition is used to capture rapidly very spatially- and temporally-dense information regarding the vibrational behaviour of a high-aspect-ratio (HAR) prototype wing, with high image quality and high frame rate. Video processing is then applied to extract displacement time histories from the collected data; in turn, these are used to perform Modal Analysis (MA) and Finite Element Model Updating (FEMU). Results are benchmarked against the ones obtained from a single-point laser Doppler vibrometer (LDV). The study is performed on the beam-like spar of the wing prototype with and without the sensors attached to appreciate the disruptive effects of sensor loading. Promising results were achieved

Middle Palaeolithic technical behaviour: Material import-export and Levallois production at the SU 13 of Oscurusciuto rock shelter, Southern Italy

The Oscurusciuto rock shelter, located in southern Italy (Puglia), has yielded a long Middle Palaeolithic stratigraphy rich in lithic assemblages, fireplaces and faunal remains, attesting Neanderthal occupation during the MIS 3. This paper is focused on the stratigraphic unit 13, consisting of a sandy compact deposit mixed with pyroclastic sediment above a thick level of tephra-US 14, identified as Mt. Epomeo green tuff (dated Ar/Ar ~ 55 ka).Level 13 represents the first stable human occupation after the deposition of tephra. Our goal was to examine the lithic assemblage of this stratigraphic unit by means of an interdisciplinary approach (technology, RMU, refitting program) in order to identify the economic behaviour and technical strategies of Neanderthals occupying the stratigraphic unit 13 of Oscurusciuto.The technical strategies applied indicate fragmentation of the reduction processes, as well as probable events of importation and exportation of objects. The lithic material were introduced at different stages of manufacturing. Pieces were introduced in the form of rough objects (pebbles), as well as semi-finished items, and as finished tools. This fragmentation of the chaîne opératoire also demonstrate the palimpsest nature of the level which is made up of different events happening one after another.The main concept of debitage was Levallois, generally realized on local jasper and siliceous limestone pebbles or cortical flakes. Jasper and siliceous limestone flakes, backed flakes and convergent flakes were the technological objectives of the debitage. A marginal volumetric debitage aimed at producing bladelets was also attested

Grotta del Cavallo (Apulia-Southern Italy). The Uluzzian in the mirror

The Uluzzian techno-complex is commonly considered to be a \u201ctransitional industry\u201d mostly on the basis of some inferred characteristics such as a chiefly flake-based production, a small amount of Upper Palaeolithic-like tools and a combination of Middle and Upper Palaeolithic elements both in the toolkit and in the technical systems. Following its discovery, the Uluzzian was identified as the Italian counterpart of the French Ch\ue2telperronian and attributed to Neandertals. However, a study issued in 2011 has established the modern character of the two deciduous teeth found in 1964 in the Uluzzian deposit of Grotta del Cavallo, fostering renewed interests to the Uluzzian culture, which real nature is almost unknown to the international scientific community. Here we provide preliminary results of the study on the lithic assemblage from the earliest Uluzzian layer and on backed pieces from the whole Uluzzian sequence of Grotta del Cavallo (Apulia, Italy), the type site of the Uluzzian. Moreover, besides a thorough review on the stratigraphy of Grotta del Cavallo (Supplementary Materials), we provide updated information on the human remains by presenting two unpublished teeth from the reworked deposit of the same cave. We conclude that the early Uluzzians demonstrate original technological behavior and innovations devoid of any features deriving or directly linked with the late Mousterian of Southern Italy. Therefore, the novelty nature of the Uluzzian techno-complex (with respect to the preceding Mousterian) complies with the recent reassessment of the two deciduous teeth from Grotta del Cavallo in suggesting an earliest migration of modern humans in southern Europe around 45,000 years ago

Earliest evidence of dental caries manipulation in the Late Upper Palaeolithic

Prehistoric dental treatments were extremely rare, and the few documented cases are known from the Neolithic, when the adoption of early farming culture caused an increase of carious lesions. Here we report the earliest evidence of dental caries intervention on a Late Upper Palaeolithic modern human specimen (Villabruna) from a burial in Northern Italy. Using Scanning Electron Microscopy we show the presence of striations deriving from the manipulation of a large occlusal carious cavity of the lower right third molar. The striations have a “V”-shaped transverse section and several parallel micro-scratches at their base, as typically displayed by cutmarks on teeth. Based on in vitro experimental replication and a complete functional reconstruction of the Villabruna dental arches, we confirm that the identified striations and the associated extensive enamel chipping on the mesial wall of the cavity were produced ante-mortem by pointed flint tools during scratching and levering activities. The Villabruna specimen is therefore the oldest known evidence of dental caries intervention, suggesting at least some knowledge of disease treatment well before the Neolithic. This study suggests that primitive forms of carious treatment in human evolution entail an adaptation of the well-known toothpicking for levering and scratching rather than drilling practices

Distribuição vertical da composição química e da uniformidade no tamanho de grãos em plantas de soja de tipo de crescimento determinado e indeterminado.

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