Nonlinear seismic behaviour of concrete arch bridges

Arch bridge structural solution has been known for centuries, in fact the simple nature of arch that require low tension and shear strength was an advantage as the simple materials like stone and brick were the only option back in ancient centuries. By the pass of time especially after industrial revolution, the new materials were adopted in construction of arch bridges to reach longer spans. Nowadays one long span arch bridge is made of steel, concrete or combination of these two as "CFST", as the result of using these high strength materials, very long spans can be achieved. The current record for longest arch belongs to Chaotianmen bridge over Yangtze river in China with 552 meters span made of steel and the longest reinforced concrete type is Wanxian bridge which also cross the Yangtze river through a 420 meters span. Today the designer is no longer limited by span length as long as arch bridge is the most applicable solution among other approaches, i.e. cable stayed and suspended bridges are more reasonable if very long span is desired. Like any super structure, the economical and architectural aspects in construction of a bridge is extremely important, in other words, as a narrower bridge has better appearance, it also require smaller volume of material which make the design more economical. Design of such bridge, beside the high strength materials, requires precise structural analysis approaches capable of integrating the combination of material behaviour and complex geometry of structure and various types of loads which may be applied to bridge during its service life. Depend on the design strategy, analysis may only evaluates the linear elastic behaviour of structure or consider the nonlinear properties as well. Although most of structures in the past were designed to act in their elastic range, the rapid increase in computational capacity allow us to consider different sources of nonlinearities in order to achieve a more realistic evaluations where the dynamic behaviour of bridge is important especially in seismic zones where large movements may occur or structure experience P - _ effect during the earthquake. The above mentioned type of analysis is computationally expensive and very time consuming. In recent years, several methods were proposed in order to resolve this problem. Discussion of recent developments on these methods and their application on long span concrete arch bridges is the main goal of this research. Accordingly available long span concrete arch bridges have been studied to gather the critical information about their geometrical aspects and properties of their materials. Based on concluded information, several concrete arch bridges were designed for further studies. The main span of these bridges range from 100 to 400 meters. The Structural analysis methods implemented in in this study are as following: Elastic Analysis: Direct Response History Analysis (DRHA): This method solves the direct equation of motion over time history of applied acceleration or imposed load in linear elastic range. Modal Response History Analysis (MRHA): Similar to DRHA, this method is also based on time history, but the equation of motion is simplified to single degree of freedom system and calculates the response of each mode independently. Performing this analysis require less time than DRHA. Modal Response Spectrum Analysis (MRSA): As it is obvious from its name, this method calculates the peak response of structure for each mode and combine them using modal combination rules based on the introduced spectra of ground motion. This method is expected to be fastest among Elastic analysis. Inelastic Analysis: Nonlinear Response History Analysis (NL-RHA): The most accurate strategy to address significant nonlinearities in structural dynamics is undoubtedly the nonlinear response history analysis which is similar to DRHA but extended to inelastic range by updating the stiffness matrix for every iteration. This onerous task, clearly increase the computational cost especially for unsymmetrical buildings that requires to be analyzed in a full 3D model for taking the torsional effects in to consideration. Modal Pushover Analysis (MPA): The Modal Pushover Analysis is basically the MRHA but extended to inelastic stage. After all, the MRHA cannot solve the system of dynamics because the resisting force fs(u; u_ ) is unknown for inelastic stage. The solution of MPA for this obstacle is using the previously recorded fs to evaluate system of dynamics. Extended Modal Pushover Analysis (EMPA): Expanded Modal pushover is a one of very recent proposed methods which evaluates response of structure under multi-directional excitation using the modal pushover analysis strategy. In one specific mode,the original pushover neglect the contribution of the directions different than characteristic one, this is reasonable in regular symmetric building but a structure with complex shape like long span arch bridges may go through strong modal coupling. This method intend to consider modal coupling while it take same time of computation as MPA. Coupled Nonlinear Static Pushover Analysis (CNSP): The EMPA includes the contribution of non-characteristic direction to the formal MPA procedure. However the static pushovers in EMPA are performed individually for every mode, accordingly the resulted values from different modes can be combined but this is only valid in elastic phase; as soon as any element in structure starts yielding the neutral axis of that section is no longer fixed for both response during the earthquake, meaning the longitudinal deflection unavoidably affect the transverse one or vice versa. To overcome this drawback, the CNSP suggests executing pushover analysis for governing modes of each direction at the same time. This strategy is estimated to be more accurate than MPA and EMPA, moreover the calculation time is reduced because only one pushover analysis is required. Regardless of the strategy, the accuracy of structural analysis is highly dependent on modelling and numerical integration approaches used in evaluation of each method. Therefore the widely used Finite Element Method is implemented in process of all analysis performed in this research. In order to address the study, chapter 2, starts with gathered information about constructed long span arch bridges, this chapter continuous with geometrical and material definition of new models. Chapter 3 provides the detailed information about structural analysis strategies; furthermore the step by step description of procedure of all methods is available in Appendix A. The document ends with the description of results and conclusion of chapter 4.

A multidisciplinary reference framework to support innovative design, implementation and assessment of chronic care models

Hoy en día, por primera vez en la historia, la mayor parte de la población podrá vivir hasta los sesenta años y más (United Nations, 2015). Sin embargo, todavía existe poca evidencia que demuestre que las personas mayores, estén viviendo con mejor salud que sus padres, a la misma edad, ya que la mayoría de los problemas de salud en edades avanzadas están asociados a las enfermedades crónicas (WHO, 2015). Los sistemas sanitarios de los países desarrollados funcionan adecuadamente cuando se trata del cuidado de enfermedades agudas, pero no son lo suficientemente eficaces en la gestión de las enfermedades crónicas. Durante la última década, se han realizado esfuerzos para mejorar esta gestión, por medio de la utilización de estrategias de prevención y de reenfoque de la provisión de los servicios de atención para la salud (Kane et al. 2005). Según una revisión sistemática de modelos de cuidado de salud, comisionada por el sistema nacional de salud Británico, pocos modelos han conceptualizado cuáles son los componentes que hay que utilizar para proporcionar un cuidado crónico efectivo, y estos componentes no han sido suficientemente estructurados y articulados. Por lo tanto, no hay suficiente evidencia sobre el impacto real de cualquier modelo existente en la actualidad (Ham, 2006). Las innovaciones podrían ayudar a conseguir mejores diagnósticos, tratamientos y gestión de pacientes crónicos, así como a dar soporte a los profesionales y a los pacientes en el cuidado. Sin embargo, la forma en las que estas innovaciones se proporcionan no es lo suficientemente eficiente, efectiva y amigable para el usuario. Para mejorar esto, hace falta crear equipos de trabajo y estrategias multidisciplinares. En conclusión, hacen falta actividades que permitan conseguir que las innovaciones sean utilizadas en los sistemas de salud que quieren mejorar la gestión del cuidado crónico, para que sea posible: 1) traducir la “atención sanitaria basada en la evidencia” en “conocimiento factible”; 2) hacer frente a la complejidad de la atención sanitaria a través de una investigación multidisciplinaria; 3) identificar una aproximación sistemática para que se establezcan intervenciones innovadoras en el cuidado de salud. El marco de referencia desarrollado en este trabajo de investigación es un intento de aportar estas mejoras. Las siguientes hipótesis han sido propuestas: Hipótesis 1: es posible definir un proceso de traducción que convierta un modelo de cuidado crónico en una descripción estructurada de objetivos, requisitos e indicadores clave de rendimiento. Hipótesis 2: el proceso de traducción, si se ejecuta a través de elementos basados en la evidencia, multidisciplinares y de orientación económica, puede convertir un modelo de cuidado crónico en un marco descriptivo, que define el ciclo de vida de soluciones innovadoras para el cuidado de enfermedades crónicas. Hipótesis 3: es posible definir un método para evaluar procesos, resultados y capacidad de desarrollar habilidades, y asistir equipos multidisciplinares en la creación de soluciones innovadoras para el cuidado crónico. Hipótesis 4: es posible dar soporte al desarrollo de soluciones innovadoras para el cuidado crónico a través de un marco de referencia y conseguir efectos positivos, medidos en indicadores clave de rendimiento. Para verificar las hipótesis, se ha definido una aproximación metodológica compuesta de cuatro Fases, cada una asociada a una hipótesis. Antes de esto, se ha llevado a cabo una “Fase 0”, donde se han analizado los antecedentes sobre el problema (i.e. adopción sistemática de la innovación en el cuidado crónico) desde una perspectiva multi-dominio y multi-disciplinar. Durante la fase 1, se ha desarrollado un Proceso de Traducción del Conocimiento, elaborado a partir del JBI Joanna Briggs Institute (JBI) model of evidence-based healthcare (Pearson, 2005), y sobre el cual se han definido cuatro Bloques de Innovación. Estos bloques consisten en una descripción de elementos innovadores, definidos en la fase 0, que han sido añadidos a los cuatros elementos que componen el modelo JBI. El trabajo llevado a cabo en esta fase ha servido también para definir los materiales que el proceso de traducción tiene que ejecutar. La traducción que se ha llevado a cabo en la fase 2, y que traduce la mejor evidencia disponible de cuidado crónico en acción: resultado de este proceso de traducción es la parte descriptiva del marco de referencia, que consiste en una descripción de un modelo de cuidado crónico (se ha elegido el Chronic Care Model, Wagner, 1996) en términos de objetivos, especificaciones e indicadores clave de rendimiento y organizada en tres ciclos de innovación (diseño, implementación y evaluación). Este resultado ha permitido verificar la segunda hipótesis. Durante la fase 3, para demostrar la tercera hipótesis, se ha desarrollado un método-mixto de evaluación de equipos multidisciplinares que trabajan en innovaciones para el cuidado crónico. Este método se ha creado a partir del método mixto usado para la evaluación de equipo multidisciplinares translacionales (Wooden, 2013). El método creado añade una dimensión procedural al marco. El resultado de esta fase consiste, por lo tanto, en una primera versión del marco de referencia, lista para ser experimentada. En la fase 4, se ha validado el marco a través de un caso de estudio multinivel y con técnicas de observación-participante como método de recolección de datos. Como caso de estudio se han elegido las actividades de investigación que el grupo de investigación LifeStech ha desarrollado desde el 2008 para mejorar la gestión de la diabetes, actividades realizadas en un contexto internacional. Los resultados demuestran que el marco ha permitido mejorar las actividades de trabajo en distintos niveles: 1) la calidad y cantidad de las publicaciones; 2) se han conseguido dos contratos de investigación sobre diabetes: el primero es un proyecto de investigación aplicada, el segundo es un proyecto financiado para acelerar las innovaciones en el mercado; 3) a través de los indicadores claves de rendimiento propuestos en el marco, una prueba de concepto de un prototipo desarrollado en un proyecto de investigación ha sido transformada en una evaluación temprana de una intervención eHealth para el manejo de la diabetes, que ha sido recientemente incluida en Repositorio de prácticas innovadoras del Partenariado de Innovación Europeo en Envejecimiento saludable y activo. La verificación de las 4 hipótesis ha permitido demonstrar la hipótesis principal de este trabajo de investigación: es posible contribuir a crear un puente entre la atención sanitaria y la innovación y, por lo tanto, mejorar la manera en que el cuidado crónico sea procurado en los sistemas sanitarios. ABSTRACT Nowadays, for the first time in history, most people can expect to live into their sixties and beyond (United Nations, 2015). However, little evidence suggests that older people are experiencing better health than their parents, and most of the health problems of older age are linked to Chronic Diseases (WHO, 2015). The established health care systems in developed countries are well suited to the treatment of acute diseases but are mostly inadequate for dealing with CDs. Healthcare systems are challenging the burden of chronic diseases by putting more emphasis on the prevention of disease and by looking for new ways to reorient the provision of care (Kane et al., 2005). According to an evidence-based review commissioned by the British NHS Institute, few models have conceptualized effective components of care for CDs and these components have been not structured and articulated. “Consequently, there is limited evidence about the real impact of any of the existing models” (Ham, 2006). Innovations could support to achieve better diagnosis, treatment and management for patients across the continuum of care, by supporting health professionals and empowering patients to take responsibility. However, the way they are delivered is not sufficiently efficient, effective and consumer friendly. The improvement of innovation delivery, involves the creation of multidisciplinary research teams and taskforces, rather than just working teams. There are several actions to improve the adoption of innovations from healthcare systems that are tackling the epidemics of CDs: 1) Translate Evidence-Based Healthcare (EBH) into actionable knowledge; 2) Face the complexity of healthcare through multidisciplinary research; 3) Identify a systematic approach to support effective implementation of healthcare interventions through innovation. The framework proposed in this research work is an attempt to provide these improvements. The following hypotheses have been drafted: Hypothesis 1: it is possible to define a translation process to convert a model of chronic care into a structured description of goals, requirements and key performance indicators. Hypothesis 2: a translation process, if executed through evidence-based, multidisciplinary, holistic and business-oriented elements, can convert a model of chronic care in a descriptive framework, which defines the whole development cycle of innovative solutions for chronic disease management. Hypothesis 3: it is possible to design a method to evaluate processes, outcomes and skill acquisition capacities, and assist multidisciplinary research teams in the creation of innovative solutions for chronic disease management. Hypothesis 4: it is possible to assist the development of innovative solutions for chronic disease management through a reference framework and produce positive effects, measured through key performance indicators. In order to verify the hypotheses, a methodological approach, composed of four Phases that correspond to each one of the stated hypothesis, was defined. Prior to this, a “Phase 0”, consisting in a multi-domain and multi-disciplinary background analysis of the problem (i.e.: systematic adoption of innovation to chronic care), was carried out. During phase 1, in order to verify the first hypothesis, a Knowledge Translation Process (KTP) was developed, starting from the JBI Joanna Briggs Institute (JBI) model of evidence-based healthcare was used (Pearson, 2005) and adding Four Innovation Blocks. These blocks represent an enriched description, added to the JBI model, to accelerate the transformation of evidence-healthcare through innovation; the innovation blocks are built on top of the conclusions drawn after Phase 0. The background analysis gave also indication on the materials and methods to be used for the execution of the KTP, carried out during phase 2, that translates the actual best available evidence for chronic care into action: this resulted in a descriptive Framework, which is a description of a model of chronic care (the Chronic Care Model was chosen, Wagner, 1996) in terms of goals, specified requirements and Key Performance Indicators, and articulated in the three development cycles of innovation (i.e. design, implementation and evaluation). Thanks to this result the second hypothesis was verified. During phase 3, in order to verify the third hypothesis, a mixed-method to evaluate multidisciplinary teams working on innovations for chronic care, was created, based on a mixed-method used for the evaluation of Multidisciplinary Translational Teams (Wooden, 2013). This method adds a procedural dimension to the descriptive component of the Framework, The result of this phase consisted in a draft version of the framework, ready to be tested in a real scenario. During phase 4, a single and multilevel case study, with participant-observation data collection, was carried out, in order to have a complete but at the same time multi-sectorial evaluation of the framework. The activities that the LifeStech research group carried out since 2008 to improve the management of diabetes have been selected as case study. The results achieved showed that the framework allowed to improve the research activities in different directions: the quality and quantity of the research publications that LifeStech has issued, have increased substantially; 2 project grants to improve the management of diabetes, have been assigned: the first is a grant funding applied research while the second is about accelerating innovations into the market; by using the assessment KPIs of the framework, the proof of concept validation of a prototype developed in a research project was transformed into an early stage assessment of innovative eHealth intervention for Diabetes Management, which has been recently included in the repository of innovative practice of the European Innovation Partnership on Active and Health Ageing initiative. The verification of the 4 hypotheses lead to verify the main hypothesis of this research work: it is possible to contribute to bridge the gap between healthcare and innovation and, in turn, improve the way chronic care is delivered by healthcare systems.

Analysis of single and binary phases in cerium doped sodium bismuth titanate -Na0.5Bi0.5TiO3 materials

The pure and cerium doped sodium bismuth titanate inorganic powders were synthesized by solid state reaction method. The presence of rhombohedral phase was observed in cerium doped NBT compounds. At 1200 ºC, the 5% of cerium doped NBT compound forms single perovskite phase. The samples of x = 0.10 and 0.15 were heat treated to 1350 ºC, the binary phases with cerium and bismuth oxides were observed. The X-ray diffraction, fourier transform infrared spectroscopy, reflectance spectra, differential thermal analysis and thermo gravimetric analysis were used to analyze the various properties of samples. Moreover, the effects of cerium doping and calcining temperature on NBT samples were investigated. In this work we present our recent results on the synthesis and characterization of Ce doped sodium bismuth titanate materials.

A Wireless Charging System Applying Phase-Shift and Amplitude Control to Maximize Efficiency and Extractable Power

Wireless power transfer (WPT) is an emerging technology with an increasing number of potential applications to transfer power from a transmitter to a mobile receiver over a relatively large air gap. However, its widespread application is hampered due to the relatively low efficiency of current Wireless power transfer (WPT) systems. This study presents a concept to maximize the efficiency as well as to increase the amount of extractable power of a WPT system operating in nonresonant operation. The proposed method is based on actively modifying the equivalent secondary-side load impedance by controlling the phase-shift of the active rectifier and its output voltage level. The presented hardware prototype represents a complete wireless charging system, including a dc-dc converter which is used to charge a battery at the output of the system. Experimental results are shown for the proposed concept in comparison to a conventional synchronous rectification approach. The presented optimization method clearly outperforms state-of-the-art solutions in terms of efficiency and extractable power.