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Airbus currently offers a wide range of cabin configurations, fuel tanks and cargo compartments for each of its aircraft models. All these configuration differences must be subjected to an amount of studies to ensure the operability and safety of the aircraft. One of the most critical and rigorous studies that each aircraft must overcome is the level of fuselage shear. The study consists of ensuring that the amount of shear suffered by the fuselage is lower than or equal to the safety values stipulated by Airbus. This verification process takes a long time and by that increases the computational and monetary costs for the company. This thesis deals with the development, implementation and verification of a new tool in order to offer solutions when the shear of an aircraft exceeds the reference and safety values. The aim is to reduce the amount of time and expenses for the certification of the aircrafts. First of all, the software that Airbus currently uses to calculate all the shear levels of the fuselage has been analyzed in detail. In a second step all requirements for the new tool development are discussed and reviewed with the Airbus stakeholders. After that the requested software is generated including the corresponding User Interface. Then the new tool has to be checked by a series of tests and certifications in order to ensure its operability in the industrial context by helping in the certification process of an aircraft.

Cosmological weak lensing probes can inform us of the contents and evolution of the universe, including the properties of dark matter and dark energy, which collectively make up $\sim 95\%$ of the universe. We live in an exciting period in scientific history; large scale astronomical surveys such as the Legacy Survey of Space and Time (LSST) will soon provide imaging for over a billion celestial objects, which timely coincides with recent advancements in probabilistic image-based machine learning. It is incumbent on scientists to leverage recent advancements to extract as much information as possible from large scale astronomical surveys to probe our universe. This thesis contains my contribution toward this objective.Precision cosmological measurements require accurate data analysis with precise uncertainties. The two critical data analysis tasks for weak lensing cosmological probes are 1) photometric redshift (photo-z) estimation and 2) galaxy shear estimation. These quantities allow us to map the distribution of galaxies in the sky and quantify the distribution of dark matter. Here we present results for photo-z estimation and galaxy shape estimation using probabilistic neural networks, using a novel dataset derived from the Hyper Suprime-Cam (HSC) Survey. In Chapter 1, we provide an introduction to weak lensing cosmological probes, photo-z estimation, and shear estimation. In Chapter 2, we introduce the machine-learning-ready dataset derived from HSC consisting of galaxy photometry, galaxy images, and spectroscopic redshifts. We make this dataset publicly available and utilize it for all photo-z estimation analyses in this work. In Chapter 3, we present a probabilistic photo-z estimation model using a Bayesian neural network (BNN) and compare its performance to alternative methods. In Chapter 4, we present an image-based probabilistic photo-z estimation model using a Bayesian convolutional neural network (BCNN) and compare its performance to alternative methods.

Le processus de pompage du béton revêt une importance capitale dans le secteur de construction, facilitant le transport du béton frais vers le site de coulée, voire des zones difficiles d’accès. Cette technique offre la possibilité d'atteindre des hauteurs et des distances considérables. Toutefois, ce processus n'est pas sans défis. Il est donc primordial de pouvoir bien prédire la pompabilité du béton. En effet, la pompabilité du béton dépend étroitement de ses propriétés rhéologiques et de sa capacité à former une couche de lubrification (CL) lors de son écoulement dans les conduites de pompage. Par conséquent, une bonne compréhension de la rhéologie du béton et des caractéristiques de la CL est essentielle, d’autant plus que les mécanismes de formation de cette dernière demeurent encore méconnus. Cette thèse se concentre sur l'étude de la dilatance de Reynolds (DR) en tant que mécanisme potentiel intervenant dans la formation de la CL, et elle vise à mettre en évidence les principaux paramètres qui les régissent. La première partie de l'étude présente le développement d'une nouvelle méthode pour évaluer les variations de volume induites par le cisaillement, nommée la dilatance de Reynolds du béton en écoulement à surface libre. Cette méthode, bien que plus fiable pour les bétons conventionnels, ne permet cependant pas d'explorer pleinement ce mécanisme. En conséquence, un nouveau dispositif empirique, le CRD-Test, a été conçu pour évaluer la dilatance de Reynolds des bétons autoplaçants soumis à différents scénarios de cisaillement à surface libre et sous pression, simulant ainsi les processus réels de coulage et de pompage. Dans cette seconde partie de l'étude, le béton autoplaçant (BAP) est considéré comme un mélange biphasique, composé de gros granulats (> 1,25 mm) immergés dans une matrice fluide de mortier fin (< 1,25 mm). En outre, le CRD-Test offre une couverture large des niveaux de cisaillement et de pression. Il repose sur un tribomètre à cylindre coaxi, Concrete pumping process is important in the construction sector, facilitating the transport of fresh concrete to the casting site, even in difficult-to-access areas. This technique enables the achievement of considerable heights and distances. However, this process presents challenges. Therefore, accurately predicting the pumpability of concrete appears to be essential. Indeed, concrete pumpability relies on its rheological properties and its ability to form a lubrication layer (LL) during its flow through pipes. Accordingly, it is worthy to mention that mastering the rheology of concrete and understanding the characteristics of the LL is important, especially considering that the mechanisms of LL formation remain not well understood. This project focuses on investigating Reynolds dilatancy (RD), a potential mechanism involved in LL formation, and aims to highlight the key parameters governing it. The first part of the study introduces the development of a new method to assess shear-induced variations (RD) at free-surface flow. This method, although more reliable for conventional vibrated concrete (CVC), it does not fully explore this mechanism. Consequently, a new empirical device, the CRD-Test, was designed to evaluate the RD of self-compacting concrete (SCC) subjected to various scenarios under free-surface and pressurized conditions, simulating real casting and pumping processes. In this second part of the study, SCC is considered as a biphasic mixture of coarser particles (> 1.25 mm) in a fluid matrix of fine mortar (< 1.25 mm). Moreover, the new experimental device, named CRD-Test, offers wide range of shear and pressure levels. It is based on a modified coaxial cylinder tribometer, with a rotational speed ranging from 0 to 3 rps, and an air pressure regulator from 0 to 300 kPa. The RD phenomenon is manifested by fluctuations in lateral pressure measured at the outer cylinder of this apparatus and it was investigated through new indices. Experimenta

Milk protein concentrates (MPCs) possess significant potential for diverse applications in the food industry. However, their heat stability may be a limitation to achieving optimal functional performance. Shearing, an inherent process in food manufacturing, can also influence the functionality of proteins. The aim of this research was to examine the heat stability of reconstituted MPCs prepared at two protein concentrations (4% and 8% w/w protein) when subjected to varying levels of shearing (100, 1000, or 1500 s−1) during heating at 90 °C for 5 min or 121 °C for 2.6 min. While the impact of shear was relatively minor at 4% protein, it was more pronounced in 8% protein MPC suspensions, leading to a considerable decline in heat stability. An increase in protein concentration to 8% amplified protein interactions, intensified by shearing. This, in turn, resulted in comparatively higher aggregation at elevated temperatures and subsequently reduced the heat stability of the reconstituted MPCs.

In the last decades, experimental and numerical studies on steel fiber-reinforced concrete have shown that providing suitable fiber content and distribu-tion in the matrix can improve the post-cracking strength of concrete. Although there is a large database of experimental and finite element model shear tests of steel fiber-reinforced concrete beams, there are not profuse test data and finite element models available for steel fiber-reinforced concrete beams with traditional transverse shear reinforcement (stirrups). In this work, the shear behavior of ultra-high-performance fiber-reinforced concrete beams with three different types of reinforcement is analyzed. For this purpose, a comparative study has been previously carried outo validate the finite element model with conventional rebars. From the results, it was observed that the maximum shear load increased by 39% to 48% depending on the type of steel fibers used, with respect to concrete without fiber reinforcement. The length and number of fibers had a direct effect on crack initiation and propagation., En las últimas décadas, los estudios experimentales y numéricos, sobre el hormigón reforzado con fibras de acero, han demostrado que un contenido y una distribución adecuados de las fibras en la matriz pueden mejorar la resistencia del hormigón tras la fisuración. Aunque existe una amplia base de datos de ensayos experimentales y numéricos a cortante de vigas de hormigón reforzado con fibras de acero, no se dispone de profusos datos de ensayos y modelos de elementos finitos para vigas de hormigón reforzado con fibras de acero con armadura transversal tradicional a cortante (estribos). En este trabajo se analiza el comportamiento a cortante de vigas de hormigón de ultra altas prestaciones reforzado con fibras con tres tipos diferentes de refuerzo. Para ello, previamente se ha realizado un estudio comparativo para validar el modelo de elementos finitos con armaduras convencionales. A partir de los resultados, se observó que la carga máxima de cortante aumentaba entre un 39% y un 48%, en función del tipo de fibras de acero utilizadas, respecto al hormigón sin refuerzo de fibras. La longitud y el número de fibras tenían un efecto directo sobre el inicio y la propagación de las fisuras.

In the last decades, experimental and numerical studies on steel fiber-reinforced concrete have shown that providing suitable fiber content and distribu-tion in the matrix can improve the post-cracking strength of concrete. Although there is a large database of experimental and finite element model shear tests of steel fiber-reinforced concrete beams, there are not profuse test data and finite element models available for steel fiber-reinforced concrete beams with traditional transverse shear reinforcement (stirrups). In this work, the shear behavior of ultra-high-performance fiber-reinforced concrete beams with three different types of reinforcement is analyzed. For this purpose, a comparative study has been previously carried outo validate the finite element model with conventional rebars. From the results, it was observed that the maximum shear load increased by 39% to 48% depending on the type of steel fibers used, with respect to concrete without fiber reinforcement. The length and number of fibers had a direct effect on crack initiation and propagation., En las últimas décadas, los estudios experimentales y numéricos, sobre el hormigón reforzado con fibras de acero, han demostrado que un contenido y una distribución adecuados de las fibras en la matriz pueden mejorar la resistencia del hormigón tras la fisuración. Aunque existe una amplia base de datos de ensayos experimentales y numéricos a cortante de vigas de hormigón reforzado con fibras de acero, no se dispone de profusos datos de ensayos y modelos de elementos finitos para vigas de hormigón reforzado con fibras de acero con armadura transversal tradicional a cortante (estribos). En este trabajo se analiza el comportamiento a cortante de vigas de hormigón de ultra altas prestaciones reforzado con fibras con tres tipos diferentes de refuerzo. Para ello, previamente se ha realizado un estudio comparativo para validar el modelo de elementos finitos con armaduras convencionales. A partir de los resultados, se observó que la carga máxima de cortante aumentaba entre un 39% y un 48%, en función del tipo de fibras de acero utilizadas, respecto al hormigón sin refuerzo de fibras. La longitud y el número de fibras tenían un efecto directo sobre el inicio y la propagación de las fisuras.

Chloride-induced deterioration of reinforced concrete (RC) structures is an increasingly vital topic among asset management and structural maintenance fields, as many RC bridges and other structures are reaching the end of their initial design lives. Deterioration of the transverse reinforcement in RC piers leads to the direct loss of shear and confinement-related mechanical properties as degradation advances with time. This research investigates the seismic response of fourteen short RC circular piers subjected to artificial chloride-induced corrosion. Each pier is designed to trigger a shear-dominated failure and artificially corroded at two current densities. A maximum average mass loss of 10.5% and 43.0% was measured in the longitudinal and spiral reinforcement, respectively. The influence of confinement effectiveness, spiral diameter, and aspect ratio on the rate of shear capacity degradation are included as test parameters in this study. Results indicate that shear deformation begins to govern performance at moderate to severe deterioration, which precedes the onset of brittle shear-dominated failure modes. Ultimate deflection is more adversely affected by increasing corrosion than all other measured properties, with a maximum observed reduction of 70.9% compared to a maximum 37.5% reduction observed in peak shear capacity. Several existing theoretical models are introduced and evaluated on their ability to predict the shear capacity of the experimental tests. Based on the results, those models directly evaluating the circular section without needing an equivalent section transformation offer the most accurate and reliable predictions.

The contribution deals with the shear resistance of prestressed beams and aims to compare experimental results with different design approaches. The experiment included two experimental tests on a sample prestressed beam. The course of the experiment is briefly described in the discussion. The prestressed beam, with an I cross-section, had bonded tendons and a total length of 7.0 m. A detailed description of the beam reinforcement, material characteristic and test setup are included. The reliability of individual design approaches is compared based on the analysis developed in this contribution.

Transition metal diborides crystallize in the a, y, or w type structure, in which pure transition metal layers alternate with pure boron layers stacked along the hexagonal [0001] axis. Here we view the prototypes as different stackings of the transition metal planes and suppose they can transform from one into another by a displacive transformation. Employing first-principles calculations, we simulate sliding of individual planes in the group IV-VII transition metal diborides along a transformation pathway connecting the a, y, and w structure. Chemistry-related trends are predicted in terms of energetic and structural changes along a transformation pathway, together with the mechanical and dynamical stability of the different stackings. Our results suggest that MnB2 and MoB2 possess the overall lowest sliding barriers among the investigated TMB2s. Furthermore, we discuss trends in strength and ductility indicators, including Young's modulus or Cauchy pressure, derived from elastic constants.

Biopolymer networks are assemblies of biopolymer chains that form into a coherent self-supporting structure and on the macro-scale appear as gels. These biopolymers often assemble in a very specific manner exhibiting various structures at different length scales. Thus, a structural hierarchy exists. This work investigates whey protein isolate as a model biopolymer system to establish the relationship between the 3D microstructure and the mechanics of the network. The molecular, aggregate, and micro through to macroscopic assemblies of these materials leads to their complex physical and rheological properties. The structure at multiple length scales has been examined using a range of techniques including but not limited to x-ray scattering, circular dichroism, and microscopy. The rheological properties of the gels and aggregate suspensions resulting from preparation methods incorporating heating, pH adjustment and shear is reported. Particular attention focuses on the application of shear forces during gelation and the effects on the microstructure, aggregation behaviour, particle sizes, and rheological properties of the resulting protein suspensions and gels produced during heating has been investigated. Models have been proposed to explain the results. A key finding from this work relates to the role of effective concentration, resulting from an interplay between nominal concentration and pH, in determining the outcome during biopolymer microparticulation. The use of small-scale perturbations to augment gel rheology was also examined with effects such as strain hardening being introduced into otherwise non-strain hardening gels. This research brings new insights to structural design principles and opens avenues to control the mechanics of gelled systems and the sizes of aggregates resulting from microparticulation.

Transition metal diborides crystallize in the a, y, or w type structure, in which pure transition metal layers alternate with pure boron layers stacked along the hexagonal [0001] axis. Here we view the prototypes as different stackings of the transition metal planes and suppose they can transform from one into another by a displacive transformation. Employing first-principles calculations, we simulate sliding of individual planes in the group IV-VII transition metal diborides along a transformation pathway connecting the a, y, and w structure. Chemistry-related trends are predicted in terms of energetic and structural changes along a transformation pathway, together with the mechanical and dynamical stability of the different stackings. Our results suggest that MnB2 and MoB2 possess the overall lowest sliding barriers among the investigated TMB2s. Furthermore, we discuss trends in strength and ductility indicators, including Young's modulus or Cauchy pressure, derived from elastic constants.

Within the frame of the revision of the Eurocode 2 for concrete structures, the section devoted to strut-and-tie design has been updated to enhance its applicability, its consistency with other sections and its ease-of-use. As a result, a number of changes have been introduced. Namely, the use of stress fields and their combination with classical strut-and-tie models has been incorporated. The changes in this section can be seen as an effort to provide a more comprehensive and general tool for designers, that can be transparently applied to any structural member with sufficient reinforcement for crack control. In this paper, the consistency between the strut-and-tie and the stress field methods is clarified as well as the fundamentals of the revision performed in Eurocode 2. The paper also elaborates how the code can be used for advanced analyses, considering in an explicit manner the compatibility of deformations to obtain refined estimates of the structural resistance..

Dowel action of the longitudinal reinforcement in RC beams without and with small amounts of shear reinforcement is typically considered a constant shear contribution determined from the splitting strength of the concrete cover. However, in a recent experimental investigation by the authors, it was shown that the shear force transferred by dowel action for beams without shear reinforcement should be determined from the dowel displacement and a linear elastic model and a rigid plastic dowel model. This article is aimed at extending this model to also cover members with small amounts of shear reinforcement. To that aim, a novel approach to calculate the shear force carried by dowel action of the longitudinal reinforcement in both beams with and without shear reinforcement is presented. The model is derived by establishing an equilibrium of work between the internal stored elastic or dissipated plastic energy and the external work performed by the shear force in the dowel. Additionally, a method to determine the displacement of the dowel from DIC measurements is presented. For the remaining shear-transfer actions, reasonable constitutive models from the literature are adapted. On the basis of DIC measurements, the shear force carried by each of the shear-transfer actions is calculated for 16 shear tests of beams without and with small amounts of shear reinforcement. The sum of shear force carried by each of the shear-transfer actions is shown to predict the applied shear force fairly well, from the development of the critical shear crack until failure. Additionally, it is shown that for beams with shear reinforcement below the minimum requirements according to the current design standards, the shear capacity is governed by aggregate interlock, residual tensile stresses, and the inclination of the compression chord. While for beams with shear reinforcement above the minimum requirements, the shear capacity is governed by the shear reinforcement and dowel action.

Recycling construction waste material offers a sustainable solution to the problem of disposing of concrete construction and demolition waste. The use of basalt fibers (BF) and basalt fiber-reinforced polymer (BFRP) reinforcing bars in concrete structures made of recycled concrete aggregate (RCA) would prolong their service life and reduce the maintenance cost. This research aims to investigate the potential use of BF, RCA, and BFRP reinforcing bars to produce sustainable and steel-free structural concrete. The study consisted of material characterization testing, numerical simulation, and large-scale beam testing. Material characterization tests were performed on normal-strength concrete (NSC) and high-strength concrete (HSC). The RCA replacement in characterization tests varied as 30, 60, and 100%. Three different sizes of BF i.e., 20, 43, and 50-mm in length were used in the characterization tests. The volume fraction (vf) of BF varied in the range of 0.5-1.5%. Fresh and hardened properties of concrete mixtures with different RCA replacement ratios and various combinations and volume fractions of BF were examined. Plain concrete mixtures made with RCA exhibited inferior properties relative to those made with natural aggregates (NA). The negative effect of RCA was more pronounced for HSC than NSC. The incorporation of BF improved the tensile properties of NA- and RCAbased concrete mixtures. The effectiveness of BF in improving the properties of concrete tended to be more pronounced for NSC than HSC. New tensile softening constitutive laws characterizing the post-cracking behavior of NA- and RCA-based concrete mixtures were established using an inverse analysis of characterization test data. The new tensile softening laws were used as input data in numerical simulation models of large-scale concrete beams made with RCA, BF, and BFRP reinforcing bars. The accuracy and validity of the numerical models developed in the present study were examine

Cracks that develop in concrete due to tensile stresses can lead to the corrosion of embedded reinforcing steel, which is a primary cause of concrete deterioration. It's common practice to introduce additional reinforcement to limit crack width in concrete. Another potential solution involves partially substituting concrete with alternative materials. Strain-hardening cementitious composites (SHCC) display ductile behavior, forming multiple fine cracks under tension, making them a potential candidate for use in conjunction with traditional concrete. This study aims to explore the flexural behavior of SHCC-RC hybrid beams and the shear behavior of SHCC-RC hybrid beams without transverse reinforcement. This investigation encompasses load-bearing capacity, crack patterns, crack width control, and post-cracking shear ductility. The SHCC-RC hybrid beams consist of a SHCC U-shaped formwork with lower-quality concrete cast inside. The feasibility of 3D printing the stay-in-place formwork is also under examination. Two types of experiments were conducted to examine the structural response of the SHCC-RC hybrid members: a four-point bending test to assess flexural behavior and a three-point bending test to study shear behavior. Digital image correlation (DIC) was used to evaluate cracking patterns and crack widths, and these measurements were corroborated with linear variable differential transformers (LVDTs). Four specimens underwent bending tests: a control beam, a hybrid beam with a transverse profiled interface, a hybrid beam with both transverse and longitudinal profiled interfaces, and a hybrid beam with a 3D printed SHCC formwork. The experimental results of the bending tests reveal that SHCC-RC hybrid beams exhibit significantly higher bending capacities compared to the control beam. Specifically, the control beam reached a capacity of 98.3 kN, while the hybrid beams with transverse, transverse and longitudinal interfaces, and a printed SHCC formwor, Civil Engineering

The CNSC, the Canadian regulator for the nuclear industry, participated in DECOVALEX-2023 Task G that focuses on the thermo (T) - hydro (H)- mechanical (M) behaviour of rock joints. Joints are omnipresent in rock masses and are planes of weakness in the host rock. When deep geological repositories (DGRs) for radioactive waste are being considered in areas where rock joints are present, the joints could be preferential pathways for radionuclide migration. Therefore, their THM behaviour must be better understood to assess the safety of the DGR. Under different possible internal and external perturbations, a joint can move by shear and dilation. If the joint crosses the emplacement area of a waste container, the heat generated from the waste can itself induce shearing of the joint. Excessive shear movement can in turn lead to failure of the container, resulting in earlier release of radionuclides. Furthermore, dilation that might accompany shear, results in an increase in the joint aperture creating a faster flow path for radionuclide transport. Mathematical models are important tools that need to be developed and employed, in order to assess joint shear and dilation under different loading conditions, such as the heat generated from the emplaced waste. The authors have developed such a mathematical model based on a macroscopic formulation within the framework of elasto-plasticity. It is verified against analytical solutions and validated against shear under constant normal load tests and thermal shearing tests of joints in granite.

Tunnels are one of the types of infrastructure extensively developed in recent decades to improve the mobility of people and goods, as well as for utility purposes. Substituting the conventional in situ lining technique with precast concrete tunnel lining (PCTL) segments in infrastructure projects maintains time and emphasizes workers’ safety with superior quality. The main durability issue facing PCTL segments is the corrosion of the steel reinforcement due to harsh environmental conditions. Corrosion of embedded reinforcing bars and the related deterioration of PCTL segments are the primary modes that accelerate failure and can jeopardize structural integrity. This premature degradation requires costly repairs and rehabilitation for tunnels. The use of glass fiber-reinforced polymer (GFRP) bars in PCTLs as an alternative to corrodible steel bars has emerged as a realistic, cost-effective solution, particularly when high resistance to environmental attack is required. In recent years, few studies have been conducted on bending and thrust tests to simulate the provisional and permanent loads that affect the life cycle of GFRP-reinforced PCTLs. Additionally, current design provisions do not address the design of PCTL segments reinforced internally with FRP bars. To date, the punching and shear behavior of GFRP-reinforced PCTL segments with different parameters have not been investigated. In this research study, the experimental program consisted of two phases. The first phase was conducted on an investigation of the punching behavior of PCTL segments reinforced with GFRP bars and ties. A total of eight full-scale rhomboidal PCTL segments measuring 1500 mm in width and 250 mm in thickness, and with an arc length of 3100 mm and 2100 mm were designed, cast, and tested under concentrated load until failure. The second phase included testing of nine (five convex and four concave) full-scale PCTL segments to investigate the shear behavior of tunnel segments under, Les tunnels sont l'un des types d'infrastructures largement développés au cours des dernières décennies pour améliorer la mobilité des personnes et des marchandises, ainsi qu'à des fins utilitaires. Le remplacement de la technique conventionnelle de revêtement in situ par des voussoirs de revêtement de tunnels en béton préfabriqué (RTBP) permet de gagner du temps et de mettre l'accent sur la sécurité des travailleurs avec une qualité supérieure. Le principal problème auquel sont confrontés les voussoirs de RTBP est la corrosion de l'armature d’acier due aux conditions environnementales. La corrosion des barres d'armature d’acier et la détérioration des voussoirs de RTBP constitue la principale cause de défaillance qui pourrait mettre en péril l'intégrité structurelle du tunnel. Cette dégradation due à la corrosion d’armature d’acier nécessite des réparations et des réhabilitations coûteuses pour les tunnels. L'utilisation de barres d’armature en polymère renforcé de fibres de verre (PRFV) dans les voussoirs de RTBP comme alternative aux barres d'acier constitue une bonne solution, en particulier lorsqu'une résistance élevée aux agressions environnementales est requise. Très peu d'études et de travaux de recherche ont été menés sur le comportement en flexion et de poussée de voussoirs de revêtement de tunnels en béton préfabriqué (RTBP) armé d’armature en polymère renforcé de fibres de verre (PRFV). Ces charges de flexion et de poussée représentent les charges provisoires et permanentes dans les structures de revêtement de tunnels. En outre, les dispositions de conception actuelles dans les normes ne sont pas applicables à la conception de voussoirs de revêtement de tunnels en béton préfabriqué (RTBP) armé d’armature en polymère renforcé de fibres de verre (PRFV). La résistance et le comportement des voussoirs de revêtements de tunnels en béton préfabriqué (RTBP) armé d’armature en PRFV sous des charges de poinçonnement de l’effort tranchant (cisaillement) est un dom

The paper focuses on the finite element modelling of a floor slab made of prefabricated hollow core floor units. The subject of the numerical analysis is a floor that has been investigated experimentally in VTT, Finland. The DIANA finite element analysis software has been used. Internal forces and displacements, as well as a failure load obtained from the finite element model, are compared with selected provisions given in the literature. The numerical analysis confirmed the inconsistencies and unreliability of existing models mentioned in the authors’ previous papers. The modelling technique presented in the paper, which takes into account the possibility of cracking of longitudinal joints between prefabricated units, provided reliable results consistent with experimental results.

Small amounts of shear reinforcement are often assumed to increase the shear capacity of RC beams, compared to an identical beam without shear reinforcement. However, in a recent experimental campaign, the shear capacity of beams with a shear reinforcement ratio below the minimum requirements according to the design standards turned out to be similar to identical beams without shear reinforcement. This paper presents a detailed analysis of why the shear capacity may be similar for beams without- and beams with small amounts of shear reinforcement. This includes the influence of small amounts of shear reinforcement on the shear behaviour and shear-transferring mechanisms. The analysis shows that the crack development is more severe at the ultimate load for beams with a small amount of shear reinforcement compared to beams without shear reinforcement. This more severe crack development is shown to cause an overestimation of the shear contribution from aggregate interlock when applying a well-known constitutive model often used for beams without shear reinforcement. Therefore, a new expression for the aggregate interlock stresses is proposed. A comparison of the proposed expression with Mixed-Mode crack opening tests shows a good agreement with the test for both small and large crack openings. By applying the proposed expression on the measured crack kinematics it is shown that for a large shear contribution from aggregate interlock the shear contribution from the shear reinforcement is very limited and as the aggregate interlock stresses decrease the shear contribution from the shear reinforcement increases. This shift in the governing shear-transferring mechanism can help to improve the requirements for the minimum shear reinforcement often found in the design standards.

Thin-walled textile-reinforced concrete beams have recently emerged as a promising approach for material-efficient design. However, the increased complexity of the formwork is a major challenge in implementing such elements for broader use in the construction industry. This study presents a novel type of stay-in-place flexible formworks with integrated textile reinforcement. The use of weft-knitted textiles allows the integration of continuous high-strength rovings as shear reinforcement and the introduction of spatial features within the fabric to guide bending-active rods to shape the complex cross-section geometry. The manufacturing procedure and the structural performance were investigated in an experimental campaign consisting of four concrete beams with I-profile cross sections tested in three-point bending, where aramid rovings were used for the shear and conventional deformed steel bars for the flexural reinforcement. The transverse reinforcement ratio proved to be essential in increasing the shear strength. Thereby, the use of digital image correlation measurements of the surface deformations allowed the direct assessment of the strains and, thus, the mechanical activation of the textile reinforcement. The full tensile capacity of all the aramid rovings crossing the governing crack could not be exploited due to the brittle material behavior, resulting in a progressive failure once the first roving reached its tensile strength. Compatibility-based stress fields were used to predict the load-deformation and failure behavior of the tested beams, which resulted in an excellent agreement of the ultimate loads and failure modes obtained from the model with the observations and results from the experiments., Applied Mechanics

Identification of the mechanical performance of pharmaceuticals in the drug discovery process can determine the tabletability of a target molecule. Determination of the active slip systems and their ranking in molecular crystals is challenging because molecules offer a set of configurational variables absent from metallic or simple ionic materials, such as bond rotations, molecular rotations, and the relative orientation of molecules. This paper uses two computational methods, the rigid-block and tensor-based shearing methods, to calculate the slip barriers and gain insights regarding the slip deformation of simple molecular crystalline materials, using diatomic solid oxygen and anthracene as examples. Both methods use constrained quasi-static energy minimisation to simulate the materials' displacement and homogeneous shearing. These shearing methods rank the slip systems in oxygen and anthracene in agreement with experiment, including those reported herein where two previously unknown active slip systems in the basal plane of anthracene were identified independently from the computations. Internal degrees of freedom, in the form of shear-induced molecular rotations, critically influence the slip barriers and deformation mechanism. Our results uncover rotational twinning, which is linked to crystallographic symmetry rather than partial dislocations, while homogeneous shear of anthracene leads to a series of polymorphic transitions. The results also provide alternative interpretations of slip-observed morphologies.

One of the barriers to implementation of steel fiber reinforced concrete (SFRC) into structural applications is the lack of understanding of the shear behaviour of SFRC members. This paper proposes a theoretical model for the shear capacity of SFRC members with mild steel reinforcement based on the shear-carrying mechanisms and sectional analysis. The model is derived completely theoretically, based on concepts from the literature, and does not include new empirical aspects. The approach is then compared to 323 experiments from the literature of beams with slender, rectangular cross-sections failing in shear. It is found that the model is slightly conservative, and experimental research necessary to further develop the model is described. The presented theory aims to be a framework for a fully theoretical description of the shear capacity of SFRC members with longitudinal reinforcement and without shear reinforcement., Concrete Structures

Load testing and in some cases failure (or collapse) testing of bridges is a method to learn more about the behaviour of full-scale bridges in site conditions. Since such experiments, especially failure tests, are expensive, an extensive preparation of these tests is important. This paper addresses the question of when a bridge is a good candidate for a load test or a failure test. To answer this question, a multi-level assessment methodology is developed. The proposed method includes a decision tree that helps users decide which method should be used to reach the desired level of accuracy. These procedures are followed to carry out an assessment based on the load and resistance models and factors from the code, as well as to estimate the maximum required load in a collapse test based on average values and a single tandem. The procedures are illustrated with the case of the Nieuwklap Bridge in the province Groningen, the Netherlands. The multi-level analysis showed that testing the Nieuwklap bridge would most likely not result in a shear failure, and thus the test would not meet the goals of a collapse test in shear, which would provide valuable research insights. On a more abstract level, the result of this research is the development of a multi-level decision-making procedure that can be used to evaluate if a field test should be planned and can meet the identified goals., Concrete Structures

Corrosion on bridges is a common issue since it can be caused by multiple agents such as marine environments or deicing chemicals. The damages caused by these agents, if left unmitigated, may lead to failure of the superstructures. If corrosion is present in the end regions of the beams, failure of the girders will likely be in shear, which is a sudden failure mode and not the preferred limit state. Therefore, it is beneficial to study repair practices and their advantages, as repairs are often more cost-effective than building entirely new structures. Repairing prestressed girders for shear is not common practice, but with the number of superstructures considered structurally deficient in the United States, additional consideration should be given to repair methods. In this study, two beams were extracted from two decommissioned bridges and were repaired using Carbon Fiber Reinforced Polymer (CFRP) to investigate how well proposed repairs functioned. One of the beams is an American Association of State Highway and Transportation Officials (AASHTO) Type II beam, while the second one is an adjacent box beam. Before repairs were done, the beams had their ends further damaged with accelerated corrosion induced via electrolysis to ensure that the beams would have enough deterioration in their shear span to simulate the worst-case scenario found in the field. Afterwards, the girders had their damage and residual strength estimated, and repairs were designed using guidelines from the American Concrete Institute (ACI) and AASHTO for CFRP repairs. Since the adjacent box beam could only be repaired in flexure, it failed in shear with a load similar to previous studies done in beams from the same bridge, which indicates that repairs for box beams need further investigation. The repairs on the AASHTO Type II beam worked well for shear, and both ends failed in flexure, which is an improved failure mode since failing in flexure is more ductile and predictable than shear failures

Canvas paintings are prone to environmental ageing. Hence, the structural conservation of canvas paintings may require lining, a process in which a secondary canvas is adhered to the reverse of the damaged original canvas to provide additional support. Choosing the optimum adhesive in combination with a lining method is crucial and yet challenging, as they should preferably be mechanically and chemically stable and reversible for at least 100 years. Comprehensive data on thermal and long term mechanical behaviour of prevalently used adhesives and their bonded assemblies to canvas is scarce and yet necessary to enable conservators for a proper choice of the materials in terms of durability. In this study, four prevalently used adhesives in the conservation of canvas paintings are investigated and their creep performance is evaluated and benchmarked at three different temperatures and environmental relative humidities (RHs). These adhesives are either bio-based (animal glue-starch paste and beeswax-dammar resin mixtures), or synthetic (BEVA® 371 and an aqueous Plextol™ D540/K360 dispersion mixture). Differential Scanning Calorimetry (DSC) technique is used to study the thermal transitions at different RHs. T-peel and lap shear tests are performed to determine the fracture behaviour and shear strength respectively. An in-house built creep set-up equipped with environmental control is developed which allows investigation of the mechanical creep for different canvas bonded assemblies. The results demonstrate the effects of temperature and relative humidity on the creep behaviour of lined canvases, which are related to their physical response. Moreover, the animal glue-starch paste shows the best creep mechanical performance for this application, while the PlextolTM acrylic dispersion mixture in combination with Mist-Lining is a better alternative when both environment and reversibility are considered., Adhesion Institute, Bio-based Structures & Materials

Edge shear layer collapse causes edge cooling and aggravates radiative effects. This paper details on the microscopic dynamics of the emergence of power (Q) scaling of density limit (DL) from the shear layer collapse transport bifurcation scenario. The analysis is based on a novel 4-field model, which evolves turbulence energy, zonal flow energy, temperature gradient and density, including the neoclassical screening of zonal flow response. Bifurcation analysis yields power scaling of critical density for shear layer collapse as n c r i t ∼ Q 1 / 3 . The favorable Q scaling of the DL emerges from the fact that the shear layer strength increases with Q, thus preventing shear layer collapse. This in turn reduces particle transport and improves particle confinement. RMP induced ambient stochastic fields degrade the shear layer by inducing decoherence in the Reynolds stress. As a result the particle transport increases and particle confinement degrades. This leads to the emergence of unfavorable stochastic field intensity ( b s t 2 ) scaling of the critical density as n c r i t ∼ ( 1 + b s t 2 ) − 5 / 3 . All fields, including zonal flow shear, exhibit hysteresis when the power (Q) is ramped cyclically across the bifurcation point. The hysteresis is due to dynamical delay in bifurcation on account of critical slowing down. Thus, the dynamical hysteresis here is fundamentally different from the hysteresis associated with the existence of bi-stable states.

Edge shear layer collapse causes edge cooling and aggravates radiative effects. This paper details on the microscopic dynamics of the emergence of power (Q) scaling of density limit (DL) from the shear layer collapse transport bifurcation scenario. The analysis is based on a novel 4-field model, which evolves turbulence energy, zonal flow energy, temperature gradient and density, including the neoclassical screening of zonal flow response. Bifurcation analysis yields power scaling of critical density for shear layer collapse as n c r i t ∼ Q 1 / 3 . The favorable Q scaling of the DL emerges from the fact that the shear layer strength increases with Q, thus preventing shear layer collapse. This in turn reduces particle transport and improves particle confinement. RMP induced ambient stochastic fields degrade the shear layer by inducing decoherence in the Reynolds stress. As a result the particle transport increases and particle confinement degrades. This leads to the emergence of unfavorable stochastic field intensity ( b s t 2 ) scaling of the critical density as n c r i t ∼ ( 1 + b s t 2 ) − 5 / 3 . All fields, including zonal flow shear, exhibit hysteresis when the power (Q) is ramped cyclically across the bifurcation point. The hysteresis is due to dynamical delay in bifurcation on account of critical slowing down. Thus, the dynamical hysteresis here is fundamentally different from the hysteresis associated with the existence of bi-stable states.

The aim of this study was to evaluate the effect of heat treatment on surface roughness, shear strength and hardness of two tropical wood species, namely batai (Paraserainthes falcataria) and sesendok (Endospermum malaccensis). Samples were exposed to temperature levels of 120 ºC and 180 ºC for 3 h and 6 h. The surface quality of the control and heat-treated samples were determined using a stylus technique. Hardness and shear strength of the samples were evaluated using Janka hardness and block-shear test, respectively. The results reveal that the surface roughness of batai improved 3 % for 80-grit and 5 % for 180-grit samples while surface roughness of sesendok improved 7 % and 10 % for 80-grit and 180-grit, respectively by the increase of the heat temperature and prolonged durations. Analysis of variance (ANOVA) also revealed that most of the tested properties on the treated wood were significantly affected by the species, girt number and also temperature. In contrast to the untreated wood species, the heat-treated wood species exhibited lower values of shear strength and hardness. Overall, the hardness and shear of both species were adversely influenced by heat exposure

Corrosion on bridges is a common issue since it can be caused by multiple agents such as marine environments or deicing chemicals. The damages caused by these agents, if left unmitigated, may lead to failure of the superstructures. If corrosion is present in the end regions of the beams, failure of the girders will likely be in shear, which is a sudden failure mode and not the preferred limit state. Therefore, it is beneficial to study repair practices and their advantages, as repairs are often more cost-effective than building entirely new structures. Repairing prestressed girders for shear is not common practice, but with the number of superstructures considered structurally deficient in the United States, additional consideration should be given to repair methods. In this study, two beams were extracted from two decommissioned bridges and were repaired using Carbon Fiber Reinforced Polymer (CFRP) to investigate how well proposed repairs functioned. One of the beams is an American Association of State Highway and Transportation Officials (AASHTO) Type II beam, while the second one is an adjacent box beam. Before repairs were done, the beams had their ends further damaged with accelerated corrosion induced via electrolysis to ensure that the beams would have enough deterioration in their shear span to simulate the worst-case scenario found in the field. Afterwards, the girders had their damage and residual strength estimated, and repairs were designed using guidelines from the American Concrete Institute (ACI) and AASHTO for CFRP repairs. Since the adjacent box beam could only be repaired in flexure, it failed in shear with a load similar to previous studies done in beams from the same bridge, which indicates that repairs for box beams need further investigation. The repairs on the AASHTO Type II beam worked well for shear, and both ends failed in flexure, which is an improved failure mode since failing in flexure is more ductile and predictable than shear failures

The available numerical methods for performing finite element unit cell calculations under stress states evolving in a predefined manner restrict the most general stress state to a single shear stress component superimposed on three normal stress components. The present study builds on and extends state of the art such that the behavior of a unit cell under the most complex stress states, comprising three shear and three normal stress components, can be explored. The proposed method is implemented in the commercial finite element software Abaqus. Three-dimensional cubic unit cells containing either a void or a particle at the center and subjected to various stress states showed that the developed method is accurate and computationally efficient. Furthermore, simulations using voided unit cells demonstrate that ductile failure is an anisotropic process, with anisotropy intensifying in the presence of shear loads. That is, void growth and strain localization leading to ductile fracture are influenced by the relative ratios of all shear stress components as well as the stress triaxiality and the Lode parameter.

The available numerical methods for performing finite element unit cell calculations under stress states evolving in a predefined manner restrict the most general stress state to a single shear stress component superimposed on three normal stress components. The present study builds on and extends state of the art such that the behavior of a unit cell under the most complex stress states, comprising three shear and three normal stress components, can be explored. The proposed method is implemented in the commercial finite element software Abaqus. Three-dimensional cubic unit cells containing either a void or a particle at the center and subjected to various stress states showed that the developed method is accurate and computationally efficient. Furthermore, simulations using voided unit cells demonstrate that ductile failure is an anisotropic process, with anisotropy intensifying in the presence of shear loads. That is, void growth and strain localization leading to ductile fracture are influenced by the relative ratios of all shear stress components as well as the stress triaxiality and the Lode parameter.

In this paper, we present an analysis of the conservation of currents in a full-F electromagnetic gyro-kinetic model in the long-wavelength limit. This equation corresponds to what is usually called the 'vorticity equation', which is not strictly correct as it cannot be formulated as the curl of a velocity equation. In the paper, we will therefore use the term 'current conservation equation' instead. Our results are relevant to reduced plasma descriptions like gyro-kinetic, drift-kinetic, gyro-fluid and drift-fluid models for tokamaks and stellarators. The equation describes the change of the polarization charge density (often called 'vorticity') in terms of the polarization stress due to the E x B flow, external sources and three currents: the parallel current, the curvature current and a current related to the magnetic field fluctuations. We compare this equation with previous drift- and gyro-fluid equations and find general agreement, except in the vorticity source terms where previous drift-fluid models fail to capture the heating and density sources. We discuss the role of currents in the dynamics of diamagnetic and E x B flow shear. The possible connection between these currents with phenomena observed in experiments that influence the radial electric field in the edge of tokamak plasmas, like resonant magnetic perturbations, and different magnetic field configurations and shapes, is presented.