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La tradition orale des Lacandons comprend des incantations thérapeutiques supposées combattre certains maux d’origine magique. Le sujet de la présente étude est un enchantement qui est prononcé pour guérir une personne souffrant d’une douleur aiguë et subite dans une partie de son corps – bras, jambe ou poitrine. Cette douleur est causée par une flèche invisible décochée par Kan Huuneh, une manifestation de Kisin, le dieu malveillant du monde souterrain. L’âme de chaque être humain possède un double qui vit dans la forêt du monde souterrain sous la forme d’un singe-araignée. Kisin chasse le singe (tout comme les Lacandons jadis) et lorsque sa flèche atteint sa proie, elle atteint simultanément et au même endroit la personne dont ce singe-araignée est le double de l’âme. L’incantation décrit la technique de fabrication de l’arc et des flèches, et les matériaux qu’utilise Kan Huuneh/Kisin (en particulier les plumes d’oiseaux pour empenner ses flèches), qui ne correspondent pas aux normes techniques des Lacandons ; elle mentionne aussi les endroits où Kan Huuneh se place à l’affût de sa victime et comment sa flèche est neutralisée par l’homme qui prononce les formules incantatoires. La tradición oral de los lacandones incluye encantamientos para curar ciertos dolores de tipo mágico. El tema del presente ensayo es un conjuro que se pronuncia para aliviar a una persona que sufre un dolor agudo y repentino en un brazo, una pierna, o en su pecho. La causa del dolor es una flecha invisible que arroja Kan Huuneh, una manifestación de Kisin, el dios malévolo del bajo mundo. Cada ser humano posee un alma, la cual a su vez tiene un doble que vive en la selva del inframundo bajo la forma de un mono-araña. Kisin caza monos en la selva (así como los lacandones en otro tiempo), y cuando su flecha alcanza a un mono hiere al mismo tiempo, en la misma parte del cuerpo, a la persona cuya alma tiene como doble a este mono-araña. El encantamiento describe la técnica para hacer las flechas y el arco, y los materiales que Kan Huuneh/Kisin utiliza (particularmente las plumas de aves para emplumar sus flechas), los cuales no son los apropiados según las normas técnicas lacandonas. El conjuro menciona los lugares donde Kan Huuneh se pone al asecho, y como finalmente su flecha es neutralizada por el hombre que pronuncia las fórmulas mágicas. Lacandon oral tradition includes curing incantations which were believed to stop pains of a magical nature. The subject of the present study is a spell that is uttered to alleviate an acute and sudden pain that a person feels in a specific part of his/her body— arm, leg or chest. Such a pain is caused by an invisible arrow that has been shot by Kan Huuneh, a manifestation of Kisin, the evil god of the underworld. According to Lacandon beliefs, each person’s soul has a double which lives in the forest of the underworld in the shape of a spider-monkey. As Lacandon did in the past, Kisin hunts monkeys; and when his arrow pierces the arm, leg or chest of a monkey, the person whose soul’s double is that particular monkey feels the pain in the same part of her/his body. The incantation describes the technique of bow and arrow making, as well as the material used by Kan Huuneh/Kisin (for instance, the birds’ feathers he utilizes to feather his arrows), which does not fit at all Lacandon technical norms. The spell also mentions the places where Kan Huuneh might hide to shoot people, and finally it tells how Kisin’s arrow can be broken by the man who utters the magical words.

This general review is addressed to a large audience made up of specialists and connoisseurs in the aim to offer a prismatic and dynamic point of view on Notre-Dame de Paris. With a « modern» approach, authors wanted to see and revisit differently Notre-Dame de Paris under three prisms which are subject to the constraints of socio-cultural vectors, of economic and socio-professional vectors and of human vectors in relation with power and history of France. In this way, levers emerge. They have helped this emblematic cathedral, World Heritage, to endure through centuries. Morever, different elements emerge also to understand the national caracter of this unique cathedral in the french landscanp monuments. Morever, they have transformed its complexity into richness and a wonderfull heritage left to the future generations. Note: This review isn’t exhaustive at all ; authors had to made choses to create a particular light on Notre-Dame de Paris. Click on * in the text to obtain books and articles on line. On the map, click on (1) to access to the museum’s collections., Cette revue générale a été construite pour offrir, à un public composé de spécialistes ou encore de simples curieux ou passionnés, un regard prismatique et dynamique de Notre-Dame de Paris. Par cette approche « moderne », les auteurs ont voulu revisiter Notre-Dame sous trois prismes distincts relevant à la fois des vecteurs socio-culturels, des vecteurs économiques et socio-professionnels, mais également des vecteurs humains étroitement liés au pouvoir et à l’histoire de France. Se sont ainsi dégagé les leviers qui ont permis à une cathédrale emblématique au destin national, patrimoine mondial de l’Humanité, de se construire dans la durée pour faire de sa complexité une richesse, un fabuleux héritage offert aux générations futures auxquelles elle se trouve confiée. Remarque : Cette revue n’est en rien exhaustive et les auteurs ont dû faire des choix dans l’éclairage qu’ils ont voulu donner à Notre-Dame de Paris. Cliquez sur * en note pour accéder à la bibliographie en ligne. Sur les cartes, cliquez (1) sur pour accéder aux musées.

Culminant à 80 m de hauteur, la flèche de la cathédrale de Senlis a depuis longtemps suscité l’admiration, sans pour autant bénéficier d’une étude architecturale précise en raison de sa position abrupte. La numérisation de la tour au moyen d’un scanner laser 3D en 2015 a permis d’ouvrir la voie à une analyse détaillée de la structure. Pour s’accorder avec les préceptes de l’archéologie du bâti, l’utilisation des outils numériques et l’interprétation des résultats doivent se faire dans la prudence et être constamment croisés avec les observations in situ. Le recours à l’archéologie spatiale, à savoir l’évaluation des déformations subies par les édifices grâce aux numérisations 3D, développée par Andrew Tallon dans la dernière décennie, apporte un nouvel éclairage sur les conditions d’édification ainsi que sur l’évolution de la flèche dans le temps. En outre, l’étude du comportement mécanique, réalisée grâce à un modèle 3D de la flèche soumis à des phénomènes informatiquement reproduits, comme le vent ou le poids propre, étaie des questionnements auparavant limités, notamment sur le rôle des pinacles. Ces perspectives d’études offertes par les techniques de numérisation et de calcul encouragent ainsi fortement l’interdisciplinarité en histoire de l’architecture médiévale. With a height of 80 meters, the spire of Senlis Cathedral long inspired admiration, but has not yet benefitted from a precise architectural study due to its imposing height. The digitization of the tower by means of a 3D laser scanner in 2015 provided an opportunity to precisely understand the structure. The archaeology of the building demands the prudent use of digital techniques as well as the prudent interpretation of the results, carried out in parallel with in situ observation. The use of spatial archaeology, in other words the evaluation of the deformations through 3D digitization, developed by Andrew Tallon in the last decade, sheds new light on the context and condition of the building as well as on the evolution of the spire over time. In addition, the study of the mechanical behaviour, carried out thanks to the 3D model of the spire, which reproduces natural phenomena such as wind or dead weight, opens up previously limited questions, especially on the role of pinnacles. These research perspectives offered with digitization and mechanical analysis strongly encourage interdisciplinarity in the history of medieval architecture.

International audience; In order to improve the efficiency of aircraft engines, the reduction of clearances between blade tips and their surrounding casing is one avenue manufacturers consider to lower aerodynamic losses. This reduction increases the risk of blade tip/casing contact interactions under nominal operating conditions. Designers need tools to accurately predict subsequent nonlinear vibrations. Engineers and researchers have developed a variety of sophisticated numerical models to predict blades' responses. These models are related to distinct frameworks (time/frequency domain) and various solution algorithms (explicit/implicit time integration schemes, penalty/Lagrange multiplier contact treatment...) which calls for comparative analyses. However, published results are often limited for the sake of confidentiality thus preventing any detailed confrontation. While qualitative understanding can be gained from simplified academic models, full scale models are needed to predict complex interactions in a realistic manner. In this context, this paper proposes a benchmark featuring detailed simulations and analyses of a full 3D finite element model based on the open NASA rotor 37 compressor blade to facilitate reproducibility and collaboration across the research community. NASA rotor 37, a compressor stage widely used as a test case in aerodynamic simulations and validations, has the advantage of presenting a realistic blade geometry. The geometry of the blade is built from publicly available reports. The paper provides details on the geometry, the numerical model and the results to allow an easy use of this model across the fields of structural dynamics. Two contact scenarios are investigated: one with direct contact against the casing, and one with abradable material deposited on the casing to mitigate contact severity through wear. The nonlinear vibration response of the blade is simulated in the time domain. It is evidenced that the addition of the abradable material decreases the amplitude of vibration for most of the angular speeds investigated. However, new interactions appear for some angular speeds. The obtained results are consistent with previous simulations on industrial geometries. Based on works showing improved aerodynamic performances when the blade is tilted, a total of seven geometries are investigated: the reference blade, with a straight vertical stacking line similar to the original rotor 37, two forward-leaned blades, two backward-swept blades and two full forward chordwise swept blades. The sweep and lean variations are shown to have a dramatic impact on the vibration response: the backward sweep results in an increased blade's robustness to contact events and the full forward chordwise sweep in a reduced robustness, while the forward lean leads to a robustness similar to the reference blade.; La réduction des jeux aubes/carter est un des principaux axes de recherche considérés par les ingénieurs pour améliorer le rendement des dernières générations de moteurs d'avion. Un frein évident à cette réduction des jeux est lié au fait qu'elle favorise inévitablement l'apparition de contacts entre les différents composants tournants (tels que les aubes) et fixes (les carters environnants). Plusieurs défis doivent alors être relevés par les concepteurs, notamment la possibilité de prédire numériquement le comportement vibratoire des aubes à la suite de tels contacts. En l'absence d'un cadre théorique unifié pour l'analyse de systèmes mécaniques subissant des contacts structuraux, les différents motoristes ont---dans le cadre de collaborations avec différents centres de recherche---développé des outils numériques en s'appuyant sur des stratégies de résolution variées: paradigmes fréquentiel ou temporel, schémas d'intégration temporelle explicite ou implicite, traitement du contact par multiplicateurs de Lagrange ou méthode de la pénalité\dots Bien que de nombreux résultats associés à ces différents modèles aient été publiés dans la littérature, les contraintes en termes de confidentialité nuisent fortement à la reproductibilité des analyses effectuées. Dans ce contexte, cet article présente un cas test pour l'analyse de la réponse au contact d'un modèle éléments finis 3D s'appuyant sur une géométrie ouverte: l'aube rotor37 de la NASA. L'objectif est de permettre d'établir un point de comparaison pour différentes méthodes et favoriser ainsi la confrontation des méthodes existantes.L'aube rotor37 de la NASA, qui a été largement utilisée pour le développement et la validation de méthodes de résolutions de problèmes aérodynamiques, a l'avantage de disposer d'un profil réaliste, représentatif d'une aube de moteur d'avion. Pour cet article, la géométrie de l'aube est construite sur base de rapports publics disponibles en ligne. L'outil utilisé pour la construction du modèle est librement téléchargeable sur le site HAL https://hal.archives-ouvertes.fr/hal-02127993.Deux scénarios de contact sont considérés, avec et sans revêtement abradable sur le carter (supposé parfaitement rigide). Le comportement vibratoire de l'aube est simulé dans le domaine temporel à l'aide d'un schéma d'intégration temporel explicite. Sur base de travaux relatifs aux performances aérodynamiques de l'aube rotor37, plusieurs variantes du profil sont considérées dans le but de fournir la première étude comparative des performances combinées aérodynamiques et dynamiques en réponse au contact.

Introduction. The aim of this study was to characterise the whole body dynamics and upper and lower joint kinematics during two common fencing steps: the lunge and the fleche. Material and methods. Two male competitive epee fencers were studied. Kinematics data were collected at 120 Hz (BTS Smart system) and ground reaction forces were measured at 120 Hz (Kistler platform). The resultant centre of gravity and end segment velocities were calculated. Temporal events were referenced to the horizontal ground reaction force. Time domain linear joint velocities were extracted. Results. At the whole-body level, the resultant centre of gravity velocity was higher during the fleche (2.64 and 2.89 m/s) than during the lunge (1.94 and 2.21 m/s). At the joint level, the wrist and elbow attained their peak velocities earlier than the proximal joint for both the lunge and the fleche for both athletes. Conclusions. The sequence of peak segmental velocities followed a distal to proximal sequence for both fencing steps.

Les représentations des migrations, Séminaire du laboratoire Migrations internationales, espaces et sociétés (Migrinter), Poitiers, FRANCE, 04-/04/2019 - 04/04/2019; Les images cartographiques produites au cours du temps sur des mouvements et déplacements apparaissent diverses dans leur forme, dans leur fond et dans leur mise en oeuvre. Dans la mesure où elles peuvent être (perçues comme) complexes, il devient intéressant de les examiner de plus près. Pour cela, il convient d'adopter une posture critique dé-constructive de ces images pour essayer d'identifier les éléments qui les composent, leur structure élémentaire et plus loin leur fondement théorique. Quel est le processus mis en oeuvre pour réaliser cette carte de migrations ? Dans quel cadre théorique (approche réseau, approche gravitaire, approche visuelle) s'inscrit-elle ? Quel phénomène y est symbolisé ? A l'aide de quels procédés ? Cette seconde partie du séminaire met en oeuvre une approche compréhensive à visée pédagogique, pour présenter les enjeux théoriques et méthodologiques d'une cartographie de migrations. Le rappel des notions mobilisées concernant la mesure de l'information est mis en perspective avec la symbolisation cartographique qui peut être réalisée en lien avec une difficulté spécifique qui se pose d'emblée pour les migrations. L'usage de la flèche génère une erreur qui conduit généralement à interpréter son dessin sur une carte comme une généralisation de comportements individuels, alors qu'elle symbolise plutôt le comportement d'un agrégat - et non celui d'un groupe ou d'un individu. Son examen conduit à arbitrer sur le choix du niveau de chacune des composantes (sociale, spatiale, temporelle ...) mobilisée dans l'analyse cartographique des déplacements, en général. La prise en compte de ces choix théoriques dans la symbolisation graphique des migrations n'est donc pas sans conséquences sur le type d'images réalisée, sur leur signification. On montre enfin qu'il existe en réalité trois modalités cartographiques de ces déplacements qui diffèrent fondamentalement sur les plan graphique et théorique.

Based on several conventional geography works and/or artistic works – some of them made by the authors of this paper –, this article focuses on how the mapping of international migrations has evolved since the beginning of the 1990s. The representation of migratory movements, which oscillates between arrows, measurements of stocks and different forms of design, implies both scientific and political stakes for the cartography and geography of migrations. After making a brief recalling of the changes that the mapping of migratory flows has experienced from its origins in the 19th century until today, the authors refer to the main technical and epistemological challenges that cartography of migratory movements and the presentations of itineraries raise nowadays. Finally the article analyses the new cartographic forms that have emerged since the beginning of the 2000s within the interconnected domains of sciences, arts, and militancy. À partir de diverses réalisations conventionnelles en géographie et/ou artistiques, parmi lesquels des travaux réalisés par les auteurs, cet article s’intéresse à la manière dont la cartographie des migrations internationales a évolué depuis le début des années 1990. La représentation des mouvements migratoires, qui oscille entre des flèches, des mesures de stocks et diverses formes de dessin, soulève autant d’enjeux scientifiques et politiques posés à la cartographie et géographie des migrations. Après un bref rappel des changements qu’a connus la cartographie des flux migratoires, depuis ses origines, au XIXe siècle, jusqu’à aujourd’hui, les auteurs évoquent les principaux défis techniques et épistémologiques que les cartes de flux ou représentant des itinéraires ne cessent de poser. Puis pour terminer, sont présentées de nouvelles formes cartographiques, ayant émergé depuis le début des années 2000, dans les domaines croisés de la science, de l’art et du militantisme. Partiendo de diversos trabajos convencionales de geografía y/o artísticos – algunos de ellos realizados por los propios autores –, este artículo pretende mostrar cómo la cartografía de las migraciones internacionales ha ido evolucionando desde principios de los años 1990. La representación de los movimientos migratorios, que abarca desde flechas, hasta medidas de reserva y diferentes formas de diseño, supone para la cartografía y la geografía de las migraciones toda una serie de retos, tanto científicos como políticos. Tras hacer un repaso de los cambios que ha ido experimentando la cartografía de los flujos migratorios desde sus orígenes en el siglo XIX hasta la actualidad, los autores presentan los principales retos técnicos y epistemológicos que los mapas de flujos y las representaciones de itinerarios continúan planteando en el momento actual. Por último, se presentan nuevas formas cartográficas surgidas a partir del 2000 que se inscriben en ámbitos interconectados como la ciencia, el arte y el activismo.

International audience; Based on several conventional geography works and/or artistic works – some of them made by the authors of this paper –, this article focuses on how the mapping of international migrations has evolved since the beginning of the 1990s. The representation of migratory movements, which oscillates between arrows, measurements of stocks and different forms of design, implies both scientific and political stakes for the cartography and geography of migrations. After making a brief recalling of the changes that the mapping of migratory flows has experienced from its origins in the 19th century until today, the authors refer to the main technical and epistemological challenges that cartography of migratory movements and the presentations of itineraries raise nowadays. Finally the article analyses the new cartographic forms that have emerged since the beginning of the 2000s within the interconnected domains of sciences, arts, and militancy.; Partiendo de diversos trabajos convencionales de geografía y/o artísticos – algunos de ellos realizados por los propios autores –, este artículo pretende mostrar cómo la cartografía de las migraciones internacionales ha ido evolucionando desde principios de los años 1990. La representación de los movimientos migratorios, que abarca desde flechas, hasta medidas de reserva y diferentes formas de diseño, supone para la cartografía y la geografía de las migraciones toda una serie de retos, tanto científicos como políticos. Tras hacer un repaso de los cambios que ha ido experimentando la cartografía de los flujos migratorios desde sus orígenes en el siglo XIX hasta la actualidad, los autores presentan los principales retos técnicos y epistemológicos que los mapas de flujos y las representaciones de itinerarios continúan planteando en el momento actual. Por último, se presentan nuevas formas cartográficas surgidas a partir del 2000 que se inscriben en ámbitos interconectados como la ciencia, el arte y el activismo.; À partir de diverses réalisations conventionnelles en géographie et/ou artistiques, parmi lesquels des travaux réalisés par les auteurs, cet article s’intéresse à la manière dont la cartographie des migrations internationales a évolué depuis le début des années 1990. La représentation des mouvements migratoires, qui oscille entre des flèches, des mesures de stocks et diverses formes de dessin, soulève autant d’enjeux scientifiques et politiques posés à la cartographie et géographie des migrations. Après un bref rappel des changements qu’a connus la cartographie des flux migratoires, depuis ses origines, au XIXe siècle, jusqu’à aujourd’hui, les auteurs évoquent les principaux défis techniques et épistémologiques que les cartes de flux ou représentant des itinéraires ne cessent de poser. Puis pour terminer, sont présentées de nouvelles formes cartographiques, ayant émergé depuis le début des années 2000, dans les domaines croisés de la science, de l’art et du militantisme.

The nonlinear behavior of cable-supported bridges is governed by the geometric nonlinearity of cables, which is attributable to sag and sliding effects at the saddle. In a cable-stayed bridge with a midspan saddle, and in all suspension bridges, cable sliding can occur at the saddle under extreme forces, such as those caused by an earthquake or typhoon. However, the conventional method of analysis of cable-supported bridges does not consider the effect of cable sliding at the saddle; instead it regards those cables as fixed. This assumption might lead to a misunderstanding of the global structure system. The goal of this study is to develop a three-dimensional (3D) elastic cable finite element that considers the sliding effect and uses a geometric nonlinear cable finite element based on elastic catenary theory. In this study, two types of sliding were considered: the roller sliding condition without friction and the frictional sliding condition. These were formulated to derive the nodal force vectors and tangential stiffness matrices. To validate the proposed 3D cable sliding element, experiments were conducted for both sliding conditions, and results were compared with calculations of the amount of sliding and displacement at the loading point. In addition, a cable-supported structural system was analyzed to investigate the characteristics of a realistic structure with cable sliding. Overall calculations using the 3D cable sliding model were in very good agreement with the measured values.

Precast concrete girder camber can vary significantly between the time of prestress release and the time of erection. This occurs even in cases in which two identically prestressed concrete girders are stored in the same manner and erected at the same time. The variations in camber become more significant as the use of high-strength concrete, longer spans, and more heavily prestressed concrete girders continues to increase. Camber as large as 8 in. (200 mm) with 3 in. (80 mm) variability is not uncommon. This problem may not be a safety issue, but it creates challenges for designers, owners, and contractors. This paper addresses several issues related to prediction, design, and construction to accommodate variability in prestressed concrete girder camber: • In design, it is impossible to precisely predict camber. However, if modern methods for calculating modulus of elasticity, creep, and prestress loss are used, the error in estimating the mean camber should be reduced and the most probable range of camber can be predicted. • Recommendations for determining final girder seat elevations and detailing of the composite action reinforcement can be made to accommodate the predicted camber and its variability. • A frequent point of contention between the owner and the contractor is the cost incurred for concrete shims over girder flanges that are thicker than designed in order to accommodate camber that is larger than predicted. This paper includes detailed design examples. The discussion is limited to conditions up to and including application of the deck slab weight.

Stiffness variations and wave propagation in railway catenaries are the main sources of contact loss between the pantograph and the railway catenary. The pre-sag of a contact wire is sometimes introduced to compensate for the stiffness variation. To include the pre-sag’s influence on the dynamic interaction of the pantograph–catenary, we present a modified single-degree-of-freedom (SDOF) dynamic system with a time-varying stiffness that is based on a simplified model from a previous study. The pantograph–catenary parameters that are related to the optimal pre-sag to minimise variations in the contact force are obtained by solving the equations of the SDOF dynamic system. The amount of optimal pre-sag is determined from parameters such as speed, span length, uplift, and the stiffness variation coefficient. Because wave propagation is not allowed in the SDOF model, we investigate the influence of pre-sag on the dynamic interaction between the pantograph and the catenary by using both SDOF and finite element method (FEM) models. These models show that, by using the optimal pre-sag, we can significantly reduce the variation in the contact force in the medium-speed range, which is near the 1/2 sub-resonance speed. The influence of pre-sag is confirmed by a field test that was performed on a Korean conventional catenary. However, the FEM model shows that in the high-speed range near 300 km h −1 , the introduction of the pre-sag can reduce the variation in the contact force slightly only if uplift force subject to the pantograph is large enough to cause slackening in the droppers next to the supports. Otherwise, it does not reduce the variation in the contact force. The FEM also shows that the optimal pre-sag (less than 1/2000 of span length) in the high-speed range is much smaller than that (about 1/1000 of span length) in the medium-speed range.

An energy-based method is developed in the present paper to evaluate the damping property of a stay cable when transversely attached to a viscous damper. The overall increase of the cable damping offered by the external damper is determined by examining the time history of the kinetic energy in the damped cable. The concept of kinetic energy decay ratio is introduced as a key index to evaluate the effectiveness of a damper design in suppressing cable vibration. Compared to earlier studies, the proposed energy-based approach has no restrictions on the damper location. In addition, the flexural rigidity and sag extensibility of the cable are included in the formulation. Numerical simulation of free vibration of a damped stay cable is conducted using ABAQUS. To assist the design process, a set of damping estimation curves, which directly relate a damper design with the corresponding equivalent structural damping in a damped cable are developed for the practical parameter ranges of bridge stay cables. A number of numerical examples are presented. The validity and accuracy of the proposed method and damping estimation curves are verified by comparing with other studies. Results show that the energy-based approach developed in the present study is effective and efficient in determining the overall damping property of a cable-damper system, particularly in the preliminary stage of a damper design. In addition, the flexible applications of the developed damping estimation curves to damper design are demonstrated through these examples.

This paper addresses the Jacobian analysis of a long-span cable-driven manipulator. The Jacobian matrix that maps the infinitesimal change of the cable length coordinate to that of the end-effector coordinate is deduced and then employed to numerically achieve the forward solution of cable-driven manipulators in the static state or moving slowly enough to neglect their dynamics. The catenary curve is utilized to account for the cable sag effects. Therefore, determining the Jacobian matrix involves not only the geometrical constraints but also the equilibrium equations of the manipulator. The incremental relationship between the displacement of the end-effector and the cable length variation is derived according to the static equilibrium equations. Numerical examples of the feed supporting system of a large radio telescope show that the method proposed can successfully find the forward solution with a very high precision.

The initiation, growth, and stability of buckling driven debonding in structural assemblies of stiff blocks, compliant joints, and adhesively bonded composite layers are analytically investigated. The model is developed with focus on masonry walls externally strengthened with composite materials where static and, mainly, dynamic loads may induce compression in the strengthening layers triggering a buckling driven debonding near the joints. The model introduces the interfacial nonlinearity (debonding) through a cohesive interface approach. The geometrical nonlinearity is introduced through the kinematics of intermediate class of deformation (large deflections, moderate rotations, small strains), and the material nonlinearity of the masonry construction is introduced through the constitutive law for the mortar joints. A numerical study of the debonding process in strengthened masonry walls is presented. The study uses the periodicity of the wall for sub-structuring and examines configurations that include composite strips or sheets, strengthening on one face of the wall or on both faces, and compliant mortar materials. Emphasis is placed on the localized debonding near the joint, its stability characteristics, and the possibility to detect the debonding process before it reaches the point of instability.

The plastic response of clamped mild steel, copper, and aluminum circular plates, subjected to blast loads is investigated by experimental and analytical methods. Extensive experimental results concerning, variations of central deflection are presented. The effects of plate thickness, standoff distance, and material properties on the midpoint deflection and deformation profile are considered. This paper also presents analytical method for determining deflection of fully clamped thin circular plates. The plates are made from a rigid perfectly plastic material and subjected to transverse localized and uniform impulsive loading. The essence of the model is to describe deformation profile with the aid of appropriate function based on the type of distribution of load and to performing upper bound analysis. It provides a way of studying and understanding the plastic deformation of impulsively loaded circular plate. The solutions obtained are in very good agreement with different set of experimental results.

This paper presents results of a study on the stability capacity and lateral bracing force of wood beam-columns subjected to biaxial eccentric compression loading. A numerical analysis model based on the column deflection curve method was developed. The model considers nonlinear parallel-to-wood-grain stress-strain relationship, size and stress distribution effects of wood strength, shear deformation, and the P-Delta effect of compression load. Material property tests and biaxial eccentric compression tests of wood beam-columns were conducted to provide input parameters and verification for the model. Good agreement was achieved. The adequacy of the 2% rule of thumb was also studied.

This article presents a novel model of an ionomeric polymer metal composite (IPMC) material. An IPMC is modeled as a lossy RC distributed line. Unlike other electro-mechanical models of an IPMC, the distributed nature of our model permits modeling the non-uniform bending of the material. Instead of modeling the tip deflection or uniform deformation of the material, we model the changing curvature. The transient behavior of the electrical signal as well as the transient bending of the IPMC are described by partial differential equations. By implementing the proper initial and boundary conditions we develop the analytical description of the possibly non-uniform transient behavior of an IPMC consistent with the experimental results.

The limit state of serviceability of deflection and cracking is verified for recron3s fiber-reinforced ferrocement hollow slabs with mesh and skeletal reinforcements. About nine slabs are considered for the investigation. The slabs were subjected to one-way cyclic loading by applying two line loads at one-third span. A theoretical model is developed for the deflection of recron3s fiber-reinforced ferrocement hollow slabs and it is validated by the experimental data. The experimental results are very close to the analytical values, especially at the service load, and it is established that such slabs satisfy the serviceability requirements of deflection and crack width as specified by the Ferrocement Model Code.

The thesis is composed of an experimental and Finite Element Modeling (FEM) study, investigating the effectiveness of the (Near Surface Mounted CFRP rods technique (NSM)) on the corroded RC beams. In the NSM technique, the CFRP rods are placed inside pre-cut grooves and are bonded to the concrete with epoxy adhesive. The thesis studies the failure modes and the mechanical performance of the corroded RC beams due to steel corrosion and finally, the prediction of the mechanical behaviour of the repaired corroded RC beams using nonlinear models based on FE numerical modelling. The corroded RC beams studied here in this study were exposed to natural corrosion for more than 28 years. The first part includes experimental results which were obtained on two beams: (one corroded and one control beams, both are 3 metres long) repaired or strengthened in bending with one 6-mm-diameter NSM CFRP rod. The beams were tested in a three-point bending test up to failure. Overall stiffness was studied. Ultimate capacity, ductility and failure modes were also reviewed. Finally some comparisons were made between repaired and non-repaired beams in order to assess the effectiveness of the NSM technique... The second part discusses the experimental results of two short corroded beams, which were tested under three-point bending until failure, along with two short control beams of the same characteristics (age, length and cross-section). One RC corroded deep beam was repaired in bending and the other one was repaired in both bending and shear with NSM CFRP rods. After the beams had been tested up to failure, the main steel bars and the stirrups were extracted from the beams and the loss of mass was measured and plotted for both the longitudinal and transverse reinforcement. The slip of tensile reinforcement at the end of the beams was also measured during the tests. The effect of corrosion and the effect of repairing with CFRP NSM rods in bending and shear on the behaviour of deep beams are discussed. Experimental results showed that both corroded and control deep beams repaired only in bending failed due to shear failure mode(diagonal tension failure), while corroded and control beams repaired in both bending and shear failed due to concrete crushing. The test results also showed that the corrosion of both longitudinal and transversal reinforcement hardly modified the mechanical response of deep beams... The third part shows experimental results and numerical modelling results of 2D finite element model using the FEMIX computer code were obtained on five, 3-metre-long beams: three corroded RC beams and two control beams. Two beams, one corroded and one control were repaired or strengthened in bending with NSM CFRP rod and were then tested in three-point bending up to failure. The FE numerical modelling results from FEMIX were compatible with the experimental ones except for the repaired corroded beam, for which a three-dimensional model using the commercial software ABAQUS was required... Finally, the last part presents 3D numerical modelling results in terms of load-deflection curves, and failure modes for 4 short corroded beams: two corroded beams and two control beams, half of the beams were let repaired or strengthened in bending only with NSM CFRP rods while the others were repaired or strengthened in both bending and shear with NSM technique. Results showed that the FE model was able to capture the main aspects of the experimental load-deflection curves of the RC beams, moreover it has presented the experimental failure modes and FE numerical modelling crack patterns and both gave similar results for both shear-repaired and non-shear repaired beams, three dimensional crack patterns were produced for shear-repaired beams in order to investigate the splitting cracks occurred at the middle of the beams and near the support.; Cette thèse s’intéresse à l’efficacité des renforcements par matériaux composites à base de fibres carbone (CFRP : Carbon Fiber Reinforced Polymer) par la technique NSM (Near Surface Mounted ; réalisation d’engravures sur la surface du béton) pour requalifier les structures corrodées. Elle est composée d’une partie expérimentale et d’une partie modélisation par la méthode des Eléments Finis (EF). La technique NSM consiste à réaliser des engravures sur la surface du béton où sont insérés les joncs de carbone rendus adhérents par remplissage d’une résine époxy. Les éléments étudiés dans cette thèse sont des poutres en béton armé naturellement corrodées pendant 28 années d’exposition à un environnement salin. Dans cette thèse, nous nous intéressons aux modes de rupture et à la capacité portante à la fois : en flexion et à l’effort tranchant. Le degré de corrosion a été mesuré par la méthode de perte de masses locales après la fin des essais mécaniques sur les barres longitudinales ainsi que sur les cadres d’effort tranchant. La première partie présente les résultats expérimentaux obtenus sur une poutre corrodée et une poutre témoin réparée ou renforcée en flexion par un jonc de carbone de 6 mm de diamètre inséré dans la surface tendue par la technique NSM. Les essais ont pour objectif d’étudier la capacité portante, la flèche à la ruine, la rigidité en flexion et le mode de ruine des deux poutres afin de vérifier l’efficacité du renforcement ou de la réparation... La seconde partie présente les résultats expérimentaux obtenus sur des poutres courtes permettant de mettre en avant la résistance vis à vis de l’effort tranchant. A partir des poutres longues testées dans la première partie, deux poutres courtes corrodées et deux poutres courtes témoins sont extraites. Une poutre courte corrodée et une poutre témoin sont réparées ou renforcées en flexion et une poutre corrodée et une poutre témoin sont en plus réparées ou renforcées vis-à-vis à l’effort tranchant par des joncs de carbone de 6 mm de diamètre par la technique NSM. L’éventuel glissement des armatures longitudinales sur les appuis a été mesuré durant les essais de flexion 3 points. Les résultats expérimentaux montrent que la corrosion des armatures longitudinales et la corrosion des cadres d’effort tranchant n’affectent pas le mode de ruine et modifient très peu les capacités portantes. La réparation vis-à-vis de l’effort tranchant avec la technique NSM change le mode de ruine de la formation d’une fissure diagonale due au glissement des barres d’acier tendues, à la formation d’une large fissure de flexion à mi-travée suivie de l’écrasement du béton comprimé... La troisième partie s’intéresse à la modélisation par la méthode de modélisation par EF du comportement global en flexion. Une première approche 2D est élaborée avec le code FEMIX développé à l’Université de Minho par le professeur Barros. Cinq poutres sont modélisées : 3 corrodées dont une réparée par la technique NSM et 2 témoins dont une renforcée par la technique NSM. La modélisation par EF donne de bons résultats sauf dans le cas de la poutre corrodée réparée dont le mode de ruine est non conventionnel (séparation du béton d’enrobage)... La quatrième et dernière partie est consacrée à l’étude numérique des poutres courtes. Quatre poutres sont modélisées : 2 corrodées réparées dont une réparée vis-à-vis de l’effort tranchant et 2 témoins renforcées dont une renforcée vis-à-vis de l’effort tranchant. La modélisation par EF est faite en 3D en utilisant le code FEMIX. Les résultats numériques reproduisent correctement les aspects importants du comportement force-flèche ainsi que les modes de fissuration à la ruine pour les poutres réparées vis-à-vis de l’effort tranchant ou non.

The corrosion of steel elements embedded in concrete was identified as the main cause of structural deteriorations and deficiencies in buildings. Repair and rehabilitation costs in the USA, Canada and most European countries represent a substantial percentage of expenses related to infrastructures. Alternative FRP reinforcements in glass, carbon or basalt have been studied for the past twenty years owing to their resistance to corrosion, their light weight and their considerable tensile strength. The mechanical properties of fiber-reinforced polymers with an elastic behavior differ to the mechanical properties of steel, with an elastic-plastic behavior. This induces a change of the dimension calculations of the structure. In particular, in the case of a standard reinforced concrete beam, the flexural ultimate strength would usually be located in the reinforcements in traction for steel reinforcements, while a crushing failure of the concrete would be preferable in FRP beams. The objective of this thesis is to better understand the system {concrete + fiber-reinforced polymer reinforcements} in view of dimensioning building structures with these alternative reinforcements. These FRP reinforcements have already been used for bridge decks and magnetic suspension train tracks but no applications have been found for buildings except a few rare cases of hospital buildings or rooms adjoined to others containing magnetic apparatus, for example Magnetic Resonance Imagery (MRI), which are reinforced with FRP reinforcements to avoid resonance problems. Even if FRP reinforcements would appear to be a promising solution in terms of corrosion problems, designers and engineers have been confronted with many questions relative to the use of these materials in a building application, both in terms of the mechanics involved for the structures and economic and environmental issues. This thesis is therefore focused on the design aspect of concrete structures comprising innovating and more durable reinforced concrete, La corrosion de l'acier dans le béton a été identifiée comme la principale cause des détériorations et déficiences structurelles. Les coûts de réparations et réhabilitations aux Etats-Unis, au Canada et dans la majorité des pays européens représentent un pourcentage important des dépenses liées aux infrastructures. En raison de leur résistance à la corrosion, de leur légèreté et d'une grande résistance à la traction, les armatures alternatives en PRF de verre, carbone ou basalte sont étudiées depuis une vingtaine d’années. Les propriétés mécaniques des armatures en polymères renforcés de fibres au comportement élastique diffèrent de celle de l'acier au comportement élasto-plastique. La substitution des armatures métalliques par des PRF va modifier les comportements structuraux généralement observés dans des structures béton armé traditionnelles. Cela va également induire un changement au niveau des calculs de dimensionnement de la structure. En particulier, dans le cas d'une poutre en béton armé standard, la rupture en flexion de la poutre sera habituellement par rupture des armatures en traction dans le cas de l'acier, alors que la rupture par compression du béton sera préférable pour les poutres renforcées par des PRF. L'objectif de cette thèse est une meilleure compréhension du système {béton + armatures en polymères renforcés de fibres} en vue de dimensionner des structures de bâtiment avec ces armatures alternatives. Ces armatures PRF ont déjà été utilisées pour des tabliers de ponts ou des voies de train à sustentation magnétique, mais aucune application pour des bâtiments à part quelques rares cas de construction d'hôpitaux où les pièces attenantes aux salles contenant des appareils magnétiques, tels que l'IRM afin d’éviter les phénomènes de résonance. Même si les renforcements PRF semblent une solution prometteuse vis-à-vis des problèmes de corrosion, les designers et ingénieurs sont confrontés à de nombreuses questions quant à l'utilisation de ces matériaux pour une application bâtiment, que ce soit pour la mécanique des structures ou des aspects économico-environnemental. Cette thèse s'inscrit donc dans la problématique de conception de structures en béton armé innovantes et plus durables

Ce travail porte sur l'étude de poutres en béton renforcées par des armatures Polymères Renforcées de Fibres (PRF) en verre ou en carbone à la place des armatures en acier. L'analyse de poutres sur appuis simples et de portiques testés expérimentalement montre que l'Etat Limite de Service nécessite de mettre plus d'armatures que pour le respect de l'Etat Limite Ultime. Les codes réglementaires en vigueur pour l'utilisation de ces nouvelles armatures sont vérifiés pour les poutres en appuis simples, ce qui met en évidence une sous-estimation fréquente de la flèche. Une approche scientifique rigoureuse prenant en compte les effets systèmes est alors développée se basant sur l'équilibre des forces de la section au centre de la poutre. Dans le cas des portiques, la redistribution des moments au cours du chargement est étudiée et un comportement typique est mis en évidence par l'étude des résultats expérimentaux. La flèche est alors estimée par l'intégration de la courbure le long de la poutre. Enfin, des diagrammes de tendances de dimensionnement sont tracés en faisant varier les sections de poutres, leur longueur ou encore la résistance du béton en compression pour voir leur influence.

The process of model set-up for the full system (the catenary system, the pantograph system and the overlap span) is described in detail. Especially, the nonlinear element of the dropper (may be slacken) is drawn out and is considered independently. Its dynamic force is exerted on the catenary wire and the contact wire separately. By the interface of the software ANSYS and Visual C++, the initial tension of each dropper is carried out for any appointed sag. On the basis of this, the static curve of the catenary wire and the contact wire is figured out and the final length of the dropper is obtained accordingly to offer effective guidance for the workers on the spot. Adjusting the original model of the pantograph system, the problem of the overlap span is solved. At last, by using a hybrid method, FEM and mode superposition technique, the degrees of the full system is reduced greatly and the computational speed increases. The result of the simulation is fit for the actual phenomenon. Thus, the method of this paper is valid.

Stiffeners which are used to strengthen a plate can be constructed of piezoceramic materials and subsequently used as piezo actuators to improve the load carrying capacity of the plate. In the present study, a fibre composite plate with initial imperfections and under in-plane compressive loads is studied with a view towards minimizing its deflection using the piezo actuators and the fibre orientations. Piezoceramic stiffeners are bonded symmetrically on the top and bottom of the plate and deployed as actuators. Two cases of electric fields, namely, the in-phase and out-of-phase voltages are applied to the actuators. The presence of initial deflections leads to deformation under the in-plane compressive loads which should be less than the critical buckling load. Two cases of initial imperfections are considered, and the first one is the deterministic initial deflections which are known a priori and as such they are given as input parameters for the problem. In the second case the initial deflections are uncertain and they have to be obtained according to a given criterion. In the present study they are determined to produce the least favourable initial deflection (largest deflection) at a given point and the solution is obtained by convex modelling. The effect of the actuators, the ply angles and the voltage are studied and their effects on the transverse deflection are investigated. A performance index involving the L2 norm of the deflections is minimized using the piezo effect and as well as the ply angles the optimal values of which are determined for various problem parameters.

This paper investigates the effects of the shear span:depth a/d ratio and effective depth d on the behaviour and shear strength of large reinforced concrete deep and shallow beams. A total of seven large- and medium-sized specimens were tested to failure under two-point symmetric top loading to determine their diagonal cracking and ultimate shear strengths. It was found that the beams' ultimate shear strength reduced sharply when the overall height increased from 500 to 1000 mm. The diagonal cracking strength was, however, not size dependent. The shear strength reduction is related to the a/d ratio: that is, at a critical a/d value, the size effect becomes very pronounced; beyond it, the size effect is not as apparent. After diagonal cracking has occurred, deep beams behave like a tied arch, with uncracked concrete as compression struts and main longitudinal reinforcement as tension ties. A finite element program ‘WCOMD’ was used to supplement the experimental investigation on size effect. Based on test results, finite element modelling (FEM) and a tied arch analogy, the myth of size effect is unravelled.

The seed moduli chosen for backcalculation analysis of multilayer flexible pavements can have significant impacts on the performance of backcalculation software and, sometimes, the final solutions of the backcalculated moduli. Practically all backcalculation programs provide internally generated seed moduli for backcalculation analysis. However, as the internally generated seed moduli do not always produce satisfactory results, the use of user-input seed moduli is generally encouraged. With the aim of providing useful guidance in the choice of seed moduli, a seed modulus generation algorithm, 2L-BACK, for multilayer flexible pavements based on a closed-form modulus backcalculation solution for two-layer flexible pavement structures was developed. The proposed algorithm does not require any subjective judgment by the user. An evaluation analysis of the effectiveness of the proposed procedure is presented by the use of two types of backcalculation software, MICHBACK and EVERCALC, and is based on measured an...

In the analysis and design of steel–concrete composite girders of a bridge, deflections, stresses, and strengths are typically obtained from elementary beam bending theory by utilizing the effective flange width concept. Shear lag effects are accounted for indirectly, by replacing the actual slab width by an appropriate reduced “effective” width. Besides the exact numerical values that can be given by numerical analysis of a bridge, it is necessary that code provisions should provide simplified practical method of evaluation of effective flange width without significant loss of accuracy. So each code implements different ideas and approaches for specifying effective flange width. Comparing them highlights distinct philosophies underlying the various effective width code formulations, which is the main objective of this paper. In this paper, the effective flange width provisions in the US, Britain, Canada, Japan, and European Committee are presented and compared. Characteristics of each provision are briefly described and summarized. Numerical comparisons for simply-supported spans and negative moment regions of continuous spans follow. The paper concludes with a summary outlining the commonalities and main differences among all these provisions.

In this paper, an experimental investigation is carried out to determine the important factors in causing cracks and the rupture of steel members and their elements under large imposed and repeated deformations, and the quantitative relationships between the important physical factors leading to failure. Nine thin-plates and 28 angles served as specimens, and were subjected to repeated axial loading after undergoing inelastic buckling. Particular attention was paid to the effects of loading patterns, failure modes, and the cross-sectional shape of the very-low-cycle fatigue behavior under repetitious loading in the order of a few to 20 cycles. The experimental results show that energy dissipation capacity depends on the entire history of loading, the failure mode, the slenderness ratio, and the width-to-thickness ratio. No simple quantitative relations were observed between the initiation of the visible cracks or rupture and the energy dissipation capacity. The maximum values of residual “net” strains are found to range from 25% to 40%, independent of the test parameters.

The objective of this study was to determine the effect of intermediate diaphragms on the stiffness of precast prestressed AASHTO type bridge girders, combined with the actual bearing stiffness and thermal changes. Some of the parameters studied include the presence of intermediate diaphragms, bridge skewness, temperature change, and an increase in bearing stiffness due to cold temperature or aging. A finite element model of a bridge superstructure containing Florida Bulb Tee 78 girders was created. This model was subjected to an HL93 truck load as suggested by the AASHTO LRFD. Results indicate that intermediate diaphragms have a modest positive effect of reducing the maximum deflections for the chosen girder, with the effect varying with skewness and thermal change.

A study was conducted to define an equivalency criterion for five materials used for working platforms during pavement construction on a poor subgrade: conventional crushed rock (referred to as breaker run) and four alternatives (Grade 2 gravel, foundry slag, bottom ash, and foundry sand). A layer of alternative material was considered equivalent if the total deflection of the alternative material was equal to that of breaker run under the same construction loading. Total deflection data for the equivalency assessment were obtained from a large-scale model experiment (LSME) simulating a prototype-scale pavement structure. Total deflections obtained from the LSME were checked against deflections measured in the field with a rolling wheel deflectometer and with an analytical method developed for unpaved roads. Design charts were developed for selecting the equivalent thickness of alternative working platform materials so that the alternative and a layer of breaker run provided equal deflection.

A series of elastoplastic large deflection FEM analyses has been performed on hatch covers of bulk carriers subjected to lateral load. Two types of hatch covers are considered which are the folding type and the side-sliding type. For the folding-type cover, one size is considered which is for Handy size bulk carrier, whilst for the side-sliding-type cover, two sizes are considered which are for Panamax and Cape size bulk carriers. For each type, two hatch covers are selected which are designed in accordance with the old ICLL rule and new IACS rule, respectively. Calculated collapse strengths are compared with individual design loads, and a strength assessment is performed. On the basis of collapse behaviour observed in FEM analyses, a simple method is proposed to evaluate the collapse strength of a hatch cover subjected to lateral load. It is confirmed that the collapse strength is accurately predicted by the proposed method.

This paper proposes engineering estimation equations for the maximum deflection of a cylinder subject to bending under elastic–plastic and elastic–creep conditions. Being based on the reference stress approach, the proposed equations are simple to use and can accommodate general tensile and creep behaviors. Validation against detailed 3D finite element (FE) results using actual stress–strain data and realistic creep-deformation data shows excellent agreement, which provides confidence in the use of the proposed equation. Based on the proposed equations, together with information on in-service inspection data, discussion is given how to estimate future time-dependent and time-independent deflection of the CANDU pressure tube. Thus, the present result would be valuable information for integrity assessment of the CANDU pressure tube.

The paper deals with the non-linear dynamic analysis of cables with a pair of viscous dampers close to one support. Such cables are characterized by a sag-to-chord-length ratio below 0.02, for which natural frequencies for the vertical and the horizontal vibrations are pair-wise close. Under resonance the non-linear coupling of pairs of modes may cause whirling harmonic motions around the chord line. Whirling motion may occur after bifurcation from single-mode response for harmonic loads in either vertical or horizontal direction. The non-linear features are included in the two coupled modes, while all other modes are treated as linear. The motion is discretized by expansion in terms of the damped complex eigenfunctions. The applied base functions fulfil the transition condition at the damper, leading to fast convergence of the expansion. It is demonstrated that the behaviour of the whirling motion is controlled primarily by the damper acting in the direction of the unloaded mode, whereas the magnitude of the damper in the loaded mode is less important. If the dampers in the vertical and horizontal direction are close to the optimal value of the corresponding taut cable case, substantial reduction of the vibration level of the whirling mode as well as the frequency interval of its occurrence is attained.

For the purpose of developing a vibration-based tension force evaluation procedure for bridge cables using measured multimode frequencies, an investigation on accurate finite element modelling of large-diameter sagged cables taking into account flexural rigidity and sag extensibility is carried out in this paper. A three-node curved isoparametric finite element is formulated for dynamic analysis of bridge stay cables by regarding the cable as a combination of an “ideal cable element” and a fictitious curved beam element in the variational sense. With the developed finite element formulation, parametric studies are conducted to evaluate the relationship between the modal properties and cable parameters lying in a wide range covering most of the cables in existing cable-supported bridges, and the effect of cable bending stiffness and sag on the natural frequencies. A case study is eventually provided to compare the measured natural frequencies of main cables of the Tsing Ma Bridge and the computed frequencies with and without considering cable bending stiffness. The results show that ignoring bending stiffness gives rise to unacceptable errors in predicting higher order natural frequencies of the cables, and the proposed finite element formulation provides an accurate baseline model for cable tension identification from measured multimode frequencies.

In this paper a realistic estimation of the effective breadth of a stiffened plate is presented. For the estimation of the effective breadth the adopted model contrary to the models used previously takes into account the resulting inplane forces and deformations of the plate as well as the axial forces and deformations of the beam, due to combined response of the system. The analysis consists in isolating the beams from the plate by sections parallel to the lower outer surface of the plate. The forces at the interface, which produce lateral deflection and inplane deformation to the plate and lateral deflection and axial deformation to the beam, are established using continuity conditions at the interface. The solution of the arising plate and beam problems, which are nonlinearly coupled, is achieved using the analog equation method. After the solution of the plate––beams system is achieved, the distribution of the axial stresses across the plate, resulting from both the bending and the inplane action of the plate, is obtained. Integrating this distribution across the plate the values of the effective breadth are obtained. The influence of these values from the beam stiffness and their variation along the longitudinal direction of the plate are shown as compared with those obtained from various codes through numerical examples with great practical interest.

This paper focuses on the flexural behaviour of RC beams strengthened using carbon fibre pultruded plates. Several parameters (number of layers, effect of a pre-cracking) are investigated in a first experimental part on full-scale beams. Then a non linear finite element (FE) analysis is proposed in order to complete the analysis of the behaviour of the strengthened beams. An elastoplastic behaviour with hardening is assumed for reinforced concrete and interface elements are used to model the steel-concrete bond and the adhesive. They enable to study the normal and shear stress distribution in the adhesive. This numerical analysis also includes simulations on pre-cracked beams.

WOS: 000172089100008 Two deflection functions due to both flexure and shear of an orthotropic cantilever beam subjected to both point and distributed loads have been obtained by the use of anisotropic elasticity theory. The deflections at the free end of the beam are calculated in order to see the effect of shear by using the obtained functions for different materials and fiber directions. In particular, when the cross-sectional height to beam-length ratio is equal to or greater than 0.25 or when the fiber directions are 0 and 90 degrees, the results show that ignoring shear effects causes significant error level in the deflections. (C) 2001 Elsevier Science Ltd. All rights reserved.

As an alternative to strain measurement, a sensor of structural deflection curvature has been reported by the present authors. The operation of this `curvature gauge' is now explained and computer simulated in order to improve its performance and visualize the effects within its optical fibre, that curves together with the supporting structure under bending loading. The simulation results have been verified against known test cases. They allowed fabrication of `modal curvature gauges' that, through distributed measurements, can resolve deflection mode-shapes of vibrating structures such that each one is only sensitive to a designated vibration mode while virtually insensitive to other dominant modes.

The large deflection analysis of a pre-stressed annular plate with a central rigid boss subjected to axisymmetric loading is presented. The factors affecting the transition from plate behaviour to membrane behaviour (e.g. thickness, in-plane tension and material properties) are studied. The effect of boss size and pre-tension on the effective stiffness of the plate are investigated. The extent of the bending boundary layers at the edges of the plate are quantified. All results are presented in non-dimensional form. The design implications for microelectromechanical system components are assessed.

In this paper a solution to the problem of prestressed concrete slab-and-beam structures including creep and shrinkage effect is presented. The adopted model takes into account the resulting inplane forces and deformations of the plate as well as the axial forces and deformations of the beam, due to combined response of the system. The analysis consists in isolating the beams from the plate by sections parallel to the lower outer surface of the plate. The forces at the interface, which produce lateral deflection and inplane deformation to the plate and lateral deflection and axial deformation to the beam, are established using continuity conditions at the interface. The influence of creep and shrinkage effect relative with the time of the casting and the time of the loading of the plate and the beams is taken into account. The estimation of the prestressing axial force of the beams is accomplished iteratively. Both instant (e.g. friction, slip of anchorage) and time dependent losses are encountered. The solution of the arising plate and beam problems, which are nonlinearly coupled, is achieved using the analog equation method (AEM). The adopted model, compared with those ignoring the inplane forces and deformations, describes better the actual response of the plate–beams system and permits the evaluation of the shear forces at the interfaces, the knowledge of which is very important in the design of prefabricated ribbed plates.

Lobsters use their antennae to navigate among obstacles along the ocean floor. Effective ambulation requires that the lobster, or a biomimetic lobster robot whose behavior is patterned after a real lobster, must distinguish between antenna bending due to contact and bending due to flow. The analysis presented here shows that the key feature appears to be the taper of the antennae. The curvature of a tapered antenna due to an end-load is nearly constant whereas the curvature distribution due to flow is nearly a quadratic function of the arc-length measured from the tip of the antenna.

Stretch bending is a process of considerable importance for plastic forming purposes. Effective operations in the industry demand sufficient knowledge of how different parameters influence the process as well as the final shape of the product. Numerical simulations are an effective way of investigating these issues. However, the numerical model must be validated in order to obtain reliable results. This paper presents an analysis model in the code LS-DYNA which is shown to represent the behaviour in laboratory tests well. The model is subsequently used to check the influence of certain parameters on the response in a stretch bending process. Simple, analytical methods are also presented. It is shown that the local deformations of the cross-section during bending are primarily controlled by the geometry and tensile force level. The main parameters influencing the springback during unloading are the strain hardening properties of the material, and the tensile force.

This investigation deals with deformations of individual cross-sectional members as flanges and webs in bending of rectangular hollow sections. Part I describes the experimental work, while analytical models developed to predict pre- and post-buckling deformations are presented in a paper to follow (Part II). The experimental program involved rectangular single- and double-chamber aluminium alloy AA6060 extrusions with three different wall thicknesses. The profiles were given two distinct heat treatments to obtain different hardening characteristics. Multiaxial tests were performed to determine the mechanical properties of the materials. The profiles were then bent into a number of different bend radii. Measurements of strains, curvatures, deflections and bending forces were taken. The results show that cross-sectional distortions take place from the very beginning of bending; at first in the form of a uniform sagging-like deformation along the entire length of both sides of the bend until the inner (compressive) flange buckles into several half-waves, superimposing the pre-deformation modes. The instant at which buckling occurs is found to be mainly associated with the width-to-thickness ratio of the flange and the strain hardening characteristic of the material. The magnitude of pre- and post-deformations, however, appears to be more directly related to the actual width of the flange than to its slenderness. The material stress–strain curve is shown to have an increasingly effect on the distortions of members directly sustained to buckling as bending proceeds beyond the onset of buckling, leading to severely concentrated deformations for sections made of low hardening materials. The material has less impact on sagging of the outer (tensile) flange.

This paper proposes a simplified, but effective, algorithm to obtain critical design moments for clamped and/or elastically supported parking garage girders, beams and slabs. Maintaining the uniformly distributed load concept, the equivalent vehicle load factors which can simulate vehicle load effects without conducting additional sophisticated numerical analyses for the concentrated loads are introduced. After determining a standard design vehicle of 2.4 tons through an investigation of small to medium-sized vehicles made in Korea, finite element analyses for concentrated wheel loads were carried out by referring to the influence lines for the girders and beams and influence surfaces for the slabs. Based on the obtained member forces, we determined the equivalent vehicle load factors for the girders, beams and slabs which represent the ratios of member forces under vehicle loads to those under uniformly distributed loads. In addition, the relationships between the equivalent vehicle load factors and sectional dimensions were established by regression and used to obtain the design moments by vehicle loads. The member forces calculated by the proposed method are compared with the results of different approaches mentioned in current design codes with the objective of establishing the relative efficiencies of the proposed method.

An experimental stretch bending study is presented in this paper. A total of 29 tests on 2 m long rectangular hollow section aluminum specimens were performed in a purpose-built stretch bending rig. The tests were carried out under different tensile force combinations, or tensile sequences, in order to investigate the influence of the force on certain response parameters. Stretch bending is an important industrial forming process, and die force, sagging, and springback are thus considered the most relevant response parameters. The tests show that the sagging is very sensitive to the applied tensile sequence. Furthermore, a close correlation between sagging development and strain evolution is observed. The springback is controlled by the tensile force level immediately before unloading. Finally, the difference in response between two tests performed with different constant, tensile force levels is insignificant.

The structure and mechanical properties (bending strength and bending deflection) of three alloys with high content of eutectic constituents were investigated. The formation of the structure is considered according to the Ti-Ga-Si phase diagram presented by the sections through the points of compositions of the alloys investigated. The mechanical properties have been determined by means of bending test of the samples by a scheme of the three-point bend in the air in the temperature interval of 20–800°C. The correlation between the structure and mechanical properties is considered.

The results of a test on a full-scale 5 m continuous slab are used to study the methods of analysis and calculation of deflection of reinforced concrete flat slabs. The most commonly used methods for the analysis of flat slabs, namely the equivalent frame method, the prismatic member method, the direct design method, and the finite element method, are critically compared using the results of the slab tested. Based on the comparison with the unbalanced column moments in the test, improvements for the prismatic member method are suggested. For the deflection calculations of cracked reinforced concrete flexural members, three methods are investigated: the effective moment of inertia approach, the mean curvature approach, and the bilinear method given in the CEB manual for deflections. To calculate the deflections of flat slabs as column and field strip deflections, new coefficients for distributing the bending moments between the column and middle strips are proposed.Key words: analysis, deflection, flat concrete slab, test.

An explicit solution is presented for three-layer beams with non-identical and semi-rigidly connected layers. Exact designer-usable equations for calculating mid-span deflection due to bending deformation and interlayer slip of a simply supported layered beam subjected to a uniformly distributed load and a point load applied at mid-span are also given. Calculated results agree well with the results from finite element analyses and from tests.Key words: layered beam, semi-rigid connection, explicit solution.

The ruling span method is used by line engineers to calculate the approximate tension in a multi-span dead-ended line section. Providing satisfactory results for level spans, it may, however, result in an error of over 30% if it is used to calculate tensions in significantly long and steep spans e.g., in mountainous terrain. Following the ruling span concept in general, this paper presents equations to calculate tensions for inclined single spans or multi-span line sections based on calculation of conductor length in three-dimensional space. These equations include the equivalent parameters such as equivalent inclined span, equivalent slope, equivalent load, equivalent effective tension-all needed to take into account the effect on tension of the changing geometry and length of conductors in significantly inclined spans. The numerical examples show the effect of span inclination on conductor tension calculated using these equations. A simple and accurate equation (without hyperbolic functions) is derived to calculate conductor length in an inclined span. This paper also addresses calculation of sags in nonlevel spans. The presented method integrates the practicality of the ruling span concept with the accuracy of the three-dimensional vector method for analysis of inclined spans. This method is most efficient for overhead lines in mountainous terrain.

A mathematical model of the flight of the arrow during its discharge from a bow was proposed by Pekalski (1990). His description of the model was incomplete. In this paper, I give a full description of the model. Furthermore, I propose some improvements that make his model more consistent with reality. One achievement is the modelling of contact of the arrow and grip; the pressure button is modelled as a unilateral elastic support. The acceleration force acting upon the arrow during the launch is predicted by an advanced mathematical model of bow dynamics. There is a satisfactory conformity of the simulation and experimental results. The new model predicts that the arrow leaves the pressure button before it leaves the string, as reported previously. The ability to model arrow dynamics can be used to improve the adjustment of the bow-arrow system for optimal performance.