bluuebunny/crossref_metadata_2025 huggingface dataset:
Size Isn’t Everything - Compositional Variation in Hybrid Organic-Inorganic Lead Halide Perovskites: Kinetically- versus Thermodynamically-controlled Synthesis
Authors: Tian Jiyu , Zysman-Colman Eli , Morrison Finlay
Published: February 2021

The formation and study of a partial solid solution Az1-xFAxPbBr3, using ‘similar’ sized cations azetidinium (Az+) and formamidinium (FA+), was explored via mechanosynthesis and precipitation synthesis. The composition and lattice parameters of samples from both syntheses were analysed by 1H NMR and Rietveld refinement of the powder X-ray diffraction. A clear mismatch in the composition of the perovskite was found between the precipitated samples and the corresponding solutions. Such a mismatch was not observed for samples obtained via mechanosynthesis. The discrepancy suggests products are kinetically-controlled during precipitation, compared to thermodynamically-controlled mechanosynthesis. Furthermore, the cell volume as a function of composition in both 6H (Az-rich) and 3C (FA-rich) solid solutions suggests that FA+ is actually smaller than Az+, contradicting the literature. In the 3C (Az-poor) solid solutions, the extent of Az1-xFAxPbBr3 is unexpectedly smaller than Az1-xMAxPbBr3, again in contradiction to the expectation based on the reported cation sizes. These results indicate that other factors, as yet unidentified, must also contribute to the solid solution formation of organic-inorganic hybrid perovskites, not simply the relative sizes of the A-site cations.
On the Temperature Dependence of Vaporization Enthalpy and its Correlation with Surface Tension
Authors: Alibakhshi Amin , Hartke Bernd
Published: February 2021

Temperature dependence of vaporization enthalpy is one of the most important thermophysical properties of compounds. In the present study, we theoretically developed relationships applicable to evaluation of vaporization enthalpy of compounds from diverse chemical families for a wide temperature range from melting point to the critical temperature. One outcome of the proposed approach is a relationship describing the correlation between the surface tension and vaporization enthalpy which outperforms the extensively applied Kabo method proposed for the same purpose.
Determining Performance Limits for Non-Aqueous Redox Flow Batteries
Authors: Tang Zhijiang , Kaur Aman Preet , Pezeshki Alan , Modekrutti Subrahmanyam , Delnick Frank , Zawodzinski Thomas , Veith Gabriel , Odom Susan
Published: February 2021

In this work, we explore the limits of performance and energy density of a non-aqueous redox flow battery under ideal conditions. We compared the performance of an organic redox couple in a symmetric cell to that of a vanadium redox flow cell. Based on cycling performance, we expect that ­– when losses from separators and poor ionic conductivity are minimized – a non-aqueous flow cell operating at 3.5 V should have a 35% higher energy density than V4/5+ couple in aqueous system at 100 mA∙cm-2 current density for a system that could operate at 3.5 V.
CRITERIOS DE SELECCIÓN FINANCIEROS APLICADOS EN EL SECTOR BANCARIO PERUANO A PARTIR DE LAS TASAS DE INTERÉS
Authors: Huacchillo Pardo, Mg. Letty Angélica , Crisanto Velasco, Mg. Robert Soriano , Farfán León, Bach. Emily Victoria
Published: February 2021

En el presente artículo se muestra un análisis acerca de las tasas de interés activas en moneda nacional en el sector bancario peruano para las medianas y pequeñas empresas, porque este tipo de tasa es muy importante para que los empresarios al momento de adquirir un crédito bancario en las entidades financieras de Piura, sepan cuál de ellas les oferta un crédito con interés menos oneroso, teniendo en cuenta que la tasa de interés activa en el sistema bancario, es la lucro que el banco u otra entidad financiera obtiene por el crédito dinerario -u otros productos-que otorga a sus usuarios; para ello, se empleó la investigación cuantitativa, utilizando la entrevista a los empresarios de las pequeñas y medianas empresas – MYPES- que adquirieron crédito bancario. La población estuvo conformada por todas las entidades bancarias de la ciudad de Miguel Grau Seminario. (Tamayo, 1997, la población es estudiada porque todos sus elementos tienen por lo menos una característica común observable en un lugar y en un momento determinado, que se relaciona con el fenómeno objeto de estudios, lo que conlleva al origen de la obtención de los datos de la investigación); en tanto que la muestra estuvo constituida por las entidades bancarias del sector privado que operen sólo en la ciudad de Piura; que tienen como característica común el haber adquirido - alguna vez-, crédito bancario.
IMPLEMENTACIÓN DE UN SISTEMA DE SEGURIDAD Y SALUD EN EL TRABAJO Y LA ACCIDENTABILIDAD Y PRODUCTIVIDAD EN UNA INDUSTRIA ARROCERA
Authors: Franciosi Willis, Mg. Juan José , Vidarte Llaja, Mg. Annié Mariella
Published: February 2021

Hoy, las organizaciones para ser competitivas requieren demostrar resultados con enfoque de sostenibilidad. En el aspecto social de la sostenibilidad está la seguridad del trabajador en las organizaciones, lo cual fue el motivo de la presente investigación, a fin de mejorar la productividad reduciendo costos por accidentes, cumpliendo con la normativa relacionada. Para implementar el sistema de gestión de pérdidas laborales se asumió el modelo OHSAS 18001, por su correspondencia con la Ley Nº 29783. Se realizó la evaluación de riesgos, definiéndose los más relevantes y se generó los programas de prevención correspondientes. Se abordó todas las dimensiones del sistema, con instrumentos e indicadores, según requisitos de dicho modelo. El objetivo del artículo fue determinar la influencia de la Implementación del Sistema de Gestión de Seguridad y Salud en el Trabajo en la accidentabilidad y la productividad en una industria arrocera.  El diseño de la investigación es explicativo; se utilizó instrumentos para medir la implementación del sistema y su influencia en la accidentabilidad y la productividad. La población fue el conjunto de accidentes ocurridos en la empresa, en el período 2012 – 2014, como muestra se tomó el 100% de los datos. Los resultados mostraron que la Implementación del sistema preventivo logró disminuir la accidentabilidad e influyó en el incremento de la productividad en una industria arrocera, ello se corroboró con la prueba de contrastación de Pearson, por lo que se cumplió con el objetivo de la investigación.
Detecting Real Earthquakes Using Artificial Earthquakes: On the Use of Synthetic Waveforms in Matched-Filter Earthquake Detection
Authors: Chamberlain Calum , Townend John
Published: February 2021

©2018. American Geophysical Union. All Rights Reserved. Matched-filters are an increasingly popular tool for earthquake detection, but their reliance on a priori knowledge of the targets of interest limits their application to regions with previously documented seismicity. We explore an extension to the matched-filter method to detect earthquakes and low-frequency earthquakes on local to regional scales. We show that it is possible to increase the number of detections compared with standard energy-based methods, with low false-detection rates, using suites of synthetic waveforms as templates. We apply this to a microearthquake swarm and an aftershock sequence, and to detect low-frequency earthquakes. We also explore the sensitivity of detections to the synthetic source's location and focal mechanism. Source-receiver geometry has a first-order control on how sensitive matched-filter detectors are to variations in source location and focal mechanism, and this likely applies to detections made using both synthetic and real templates.
Enseñanza por competencia, desafío de la educación universitaria del siglo XXI
Authors: Bravo Bonoso Delia Georgina , Delgado Bernal Doris Susana , Sornoza Zavala Gioryi Augusto , Yaguana Martínez Yadira Vanesa
Published: February 2021

El vertiginoso desarrollo tecnológico ha impactado hacia modelos de producción más especializados por lo que, la competencia en el ámbito laboral exige de profesionales cada vez con mayores destrezas; la enseñanza por competencias en las universidades, constituye el desafío de nuestra época, convirtiéndose en la estrategia pedagógica que acierta la polémica de la formación vocacional y que responde a las necesidades del mundo cambiante del siglo XXI. Este modelo educativo desarrollado en el mundo entero, ha tenido principal auge en Europa, adoptado en virtud de la libre movilidad de los profesionales del territorio de la Unión Europea, por lo que los principales estudios refieren a la experiencia que aporta el viejo continente. En el marco de este modelo, gira la histórica polémica sobre la educación profezionalizante y la educación humanista. En torno a este debate, surge el presente estudio de investigación documental para identificar principales avenencias y desafíos de este modelo, proporcionando aportes teóricos que permita al profesional en materia, la profundización del estudio de la enseñanza por competencia, y aporte a la adecuación requerida en función de su efectiva aplicabilidad como respuesta a la educación que reclama el mundo de hoy.
Comentarios acerca del lavado de activos y el delito previo, especial referencia al COIP
Authors: Banchón Cabrera Jennifer Katiusca , Suqui Romero Gabriel Yovany
Published: February 2021

La complejidad del delito de lavado de activos se evidencia no sólo en la redacción del tipo penal escogida por el legislador ecuatoriano, sino que también en la figura del delito previo como un elemento constitutivo del delito de lavado de activos. Por lo antes expuesto, el objetivo de esta investigación es delimitar el alcance de la normativa internacional en el ordenamiento jurídico penal ecuatoriano respecto al delito de lavado de activos con énfasis en los lineamientos del delito previo, mediante el análisis sistemático y dogmático de la normativa penal, para comprender la naturaleza e influencia de este delito previo dentro de los procesos penales. Finalmente, se arriba a la conclusión que el tipo penal de lavado de activos, desde la óptica mundial destaca la importancia que se le dio en un primer momento al estar íntimamente arraigado a delitos graves, en especial al narcotráfico, para luego ser considerado un delito autónomo. Con base a lo analizado, el delito previo tiene una incidencia fundamental en el tipo penal del lavado de activos, aunque se visualiza de forma clara que la única referencia o ligadura que en el caso ecuatoriano realiza el legislador es con los bienes y su ilicitud, tal como emana de la redacción del tipo penal.
Causas y efectos de los pacientes diagnosticados con el mal de Parkinson
Authors: Muentes Solorzano Jeniffer Maricruz , Lucas Quijije Johanna Katherine , Menéndez Pin Tania del Rocío , Cornejo Vera Jonathan Vinicio
Published: February 2021

La enfermedad de Parkinson (EP) es un trastorno neurológico progresivo conocido por una gran cantidad de características motoras y no motoras que pueden afectar la función en un grado variable. Esta revisión describe las características clínicas de la EP con énfasis en aquellas que diferencian la enfermedad de otros trastornos parkinsonianos. Debido a que no existe una prueba definitiva para el diagnóstico de la EP, la enfermedad debe diagnosticarse con base en criterios clínicos. El temblor en reposo, la bradicinesia, la rigidez y la pérdida de los reflejos posturales se consideran generalmente los signos cardinales de la EP. La presencia y la presentación específica de estas características se utilizan para diferenciar la EP de los trastornos parkinsonianos relacionados. Otras características clínicas incluyen síntomas motores secundarios (por ejemplo: Hipomimia, disartria, disfagia, sialorrea, micrografía, marcha arrastrando los pies, festinación, congelación, distonía, reflejos glabelares), síntomas no motores (por ejemplo: Disfunción autonómica, anomalías cognitivas / neuroconductuales, trastornos del sueño y anomalías sensoriales como anosmia, parestesias y dolor). La ausencia de temblor en reposo, la aparición temprana de dificultad para caminar, la inestabilidad postural, la demencia, las alucinaciones y la presencia de disautonomía, oftalmoparesia, ataxia y otras características atípicas, junto con una respuesta deficiente o nula a la levodopa, sugieren diagnósticos distintos de la EP. Un conocimiento profundo del amplio espectro de manifestaciones clínicas de la EP es fundamental para el diagnóstico adecuado de la enfermedad. Las mutaciones o variantes genéticas, las anomalías en la neuroimagen y otras pruebas son biomarcadores potenciales que pueden mejorar el diagnóstico y permitir la identificación de personas en riesgo.
Relación del síndrome metabólico en el riesgo de enfermedades cardiovasculares
Authors: Araujo Egas Carla María , Castillo Aldás Karla Misshell , Londoño Mateus Juan Carlos , Revelo Benavides Karen Michel
Published: February 2021

El síndrome metabólico (MetS) se ha definido de diferentes formas, sin embargo, los componentes claves comunes a la mayoría de las definiciones son los diferentes factores de riesgo que incluyen adiposidad abdominal, alteración de la glucosa en ayunas, hipertensión y dislipidemia. Un mediador principal del MetS parece ser la resistencia a la insulina, que se relaciona con el desarrollo de disfunciones vasculares y metabólicas que preceden a la enfermedad cardiovascular manifiesta y la diabetes tipo 2. La evidencia sugiere que los mecanismos subyacentes al elevado riesgo cardiovascular asociado con el MetS comienzan con un daño orgánico subclínico. La terapia para MetS se dirige a componentes individuales del síndrome e incluye intervenciones en el estilo de vida, terapia modificadora de lípidos y agentes antihipertensivos, en particular aquellos que inhiben el sistema renina-angiotensina. Los resultados de los ensayos de inhibidores de la enzima convertidora de angiotensina y bloqueadores de los receptores de angiotensina han demostrado reducciones en la diabetes de nueva aparición y eventos cardiovasculares en una amplia gama de pacientes. Actualmente se están llevando a cabo ensayos clínicos para investigar más el papel de estos fármacos en la prevención primaria de la diabetes tipo 2 en pacientes con MetS. El propósito de este artículo es revisar el MetS desde la perspectiva cardiológica con la esperanza de que una mejor comprensión de los vínculos entre el MetS y la enfermedad cardiovascular pueda conducir a una mejor gestión de las personas en riesgo.
Vigilancia epidemiológica y actividades de atención primaria en salud (APS) del Ecuador
Authors: Delgado Bernal Doris Susana , Villacreses Veliz Elvira Geoconda , Solórzano Solórzano Sidar Edgardo , Delgado López Deysi
Published: February 2021

La Vigilancia Epidemiológica y la Atención Primaria en Salud (APS) son dos componentes fundamentales del sistema de salud de cualquier nación. En Ecuador, son dirigidos por el Ministerio de Salud Pública. Asimismo, colaboran activamente otros sectores públicos y privados; no gubernamentales; y la sociedad civil, como un nuevo modelo de sistema de atención sanitario integrado. El objetivo del presente estudio consiste en plasmar aspectos generales del sistema de vigilancia epidemiológica del Ecuador, así como de la APS, incluyendo algunas de sus principales actividades en la nación. Igualmente, se destaca la importancia del apoyo intersectorial para el desarrollo del sistema de salud integrado. El modelo de investigación es una revisión de tipo documental bibliográfico. En Ecuador la Vigilancia Epidemiológica es regida por la Subsecretaria Nacional de Vigilancia de la Salud Pública y trabaja conjuntamente con el apoyo de la OMS y la OPS con la finalidad de detectar las situaciones de salud de la nación, así como de planear las acciones a tomar para la solución de las mismas. En cuanto a la estrategia de APS Renovada incluye, entre otros, el Modelo de Atención Integral de Salud (MAIS) y el Modelo de Atención Integral de Salud con enfoque Familiar, Comunitario e Intercultural (MAIS-FC), los cuales trabajan para orientar a la construcción, cuidado y recuperación de la salud en todas sus dimensiones. El rol que juega el apoyo intersectorial resulta de vital importancia para el sistema de salud nacional, por cuanto permite incorporar al sector público y privado y no gubernamental en diferentes proyectos para alcanzar en beneficio de la salud integral de todos los ecuatorianos. Es en la articulación de todos estos elementos que el sistema de salud progresará a lo largo del tiempo en el alcance de los objetivos de salud que se plantee la nación.
Estudio del uso de técnicas de inteligencia artificial aplicadas para análisis de suelos para el sector agrícola
Authors: Bonilla Segovia Juan Sebastian , Dávila Rojas Francisco Andrés , Villa Quishpe Manuel William
Published: February 2021

La aplicación de la inteligencia artificial (IA) ha sido evidente en el sector agrícola. Hoy en día, la agricultura se enfrenta a numerosos desafíos para maximizar su rendimiento, incluidos tratamientos inadecuados del suelo, infestación de enfermedades, plagas, entre otros, por lo que la necesidad del manejo de big data se ha vuelto un requisito fundamental en este sector para incrementar el conocimiento entre los agricultores y la tecnología. El concepto principal de IA en la agricultura es su flexibilidad, alto rendimiento, precisión y rentabilidad. La automatización de la agricultura es la principal preocupación y el tema emergente de todos los países, ya que, los métodos tradicionales utilizados por los agricultores ya no son suficientes para satisfacer la creciente demanda de aumento de la población. En relación con esto, se introdujeron nuevos métodos automatizados que satisfacen las necesidades alimentarias y proporcionan grandes oportunidades de empleo, trayendo una revolución agrícola en este sector. El uso de inteligencia artificial y de las nuevas tecnologías ha protegido el cultivo a través del rendimiento de varios factores como los cambios climáticos, el crecimiento de la población, los problemas de empleo y la seguridad alimentaria, brindando beneficios en el uso adecuado del agua, pesticidas, herbicidas, así como también, ayudando en el uso eficiente de la mano de obra, elevando la productividad, mejorando la calidad y manteniendo la fertilidad del suelo. Este artículo presenta una revisión de las aplicaciones de la IA en el suelo, manejo de cultivos, manejo de malezas y enfermedades por administración. Se presta especial atención a la fuerza y limitaciones de la aplicación y la forma de utilizar expertos sistemas para una mayor productividad.
Aspectos fisiopatológicos en la hipertensión portal
Authors: Muñoz Andrade Luis Adrián , Mera Sabando Ana Julia , López Álvarez Eva Yulissa , Tóala Cedeño Johan Alexander
Published: February 2021

La hipertensión portal es una enfermedad que generalmente, se presenta en paciente con enfermedades hepáticas crónicas, como la cirrosis. Sin embargo, esta se puede presentar por otros motivos como la hipertensión portal no cirrótica, producida por la esquistosomiasis. Y que se puede clasificar como hipertensión portal prehepática, intrahepática o posthepática. La metodología de la investigación, es una revisión bibliográfica, que se apoyó en medios electrónicos como fuente primaria para la obtención de la información, gracias a medios electrónicos como revistas, páginas web, entre otros. Entre las conclusiones que se pueden derivar de la investigación están, que el estudio de la fisiopatología de la hipertensión portal, ha evolucionado los últimos años. La obstrucción del flujo venoso portal, por los cambios en la arquitectura del hígado y vasodilatación esplanica y sistémica. Hacia un estado hemodinámico, regulado por componentes neurales, celulares y humorales, que actúan de manera endocrina, paracrina y autocrina. En la actualidad hay diferentes tipos de mecanismos de diagnóstico de la hipertensión portal. Uno de los más utilizados y confiables es el gradiente de presión venosa hepática (GPHV), que aunque es un método invasivo, sigue siendo el más sensible y específico, para su diagnóstico. Por otro lado, la elastografía por resonancia magnética, el fibrotest y ARFI, son métodos no invasivos, pero requieren un valor (> 12 mm Hg), para su diagnóstico, lo que la limitan en su uso cotidiano en la evaluación de pacientes con hepatopatías crónicas.
Manejo de neumotórax espontaneo
Authors: Esquivel Ramírez Danilo Francisco , Hernández Negrete Elsa Lissette , Tupiza Luna Fanny Katherine , Barcia Velásquez Christian Andrés
Published: February 2021

Como lo define la bibliografía, el neumotórax es la acumulación de aire en el espacio pleural, que se puede producir espontáneamente, es decir, por otras afecciones y el no espontaneo que es producido generalmente por un evento traumático. El diagnostico se confirma con la realización generalmente de una radiografía de tórax, sin embargo, estudios más profundas pueden sugerir un TAC torácico o una Gasometría. La revisión médica inicial es determinante para poder identificar qué tipo de neumotórax está presente para de esta manera decidir el tratamiento más adecuado. La metodología de la investigación, es una revisión bibliográfica, apoyada en medios electrónicos como fuente primaria de la obtención de la información. El manejo del neumotórax conlleva dos tipos de tratamientos, el primero que es el terapéutico y el segundo es el quirúrgico que contempla la cirugía convencional o la cirugía videotoracoscópica.
Inmunoterapia en hematología: avances y novedad
Authors: Sacoto Carranza Henrry Willan , Intriago Cevallos Verónica Deniss , Suarez Loor Wilfrido Alejandro , Gallegos Saucedo Jessica Marlene
Published: February 2021

Las enfermedades hematológicas, como su nombre lo indica, son enfermedades de la sangre, que generalmente han sido combatidas con quimioterapia, terapias combinadas y trasplantes de medula ósea, en el caso de las leucemias mieloide aguda, entre otras. Sin embargo la evolución de la medicina en el estudio de nuevos tratamientos para el combate de las enfermedades hematológicas ha traído la introducción de la inmunoterapia como uno de los avances para el combate del miso. En este caso no es más que la modificación genética de elementos claves del organismo para la destrucción de las células cancerígenas. La metodología de la investigación, es una revisión bibliográfica, apoyada en medios electrónicos como fuente primaria de la obtención de la información. Los últimos avances efectivos y prometedores para algunas enfermedades hematológicas como la leucemia linfoblástica aguda de precursores B en niños y adultos jóvenes y del linfoma difuso de células grandes B del adulto, gracias a la aprobación de tisagenlecleucel y axicabtagene ciloleucel fármacos creados por medio de la manipulación de células T con receptor de antígeno quimérico (CAR-T). Sin embargo no hay que dejar de tomar en cuenta los puntos de control inmunitario y sus inhibidores (ICIS) como el Ipilimumab y el Pembrolizumab para el combate de neoplasias ginecológicas, aprobados desde hace algunos años y otros en estudios.
Load carrying behaviour of beams with bent-up bars as shear reinforcement
Authors: Huber Tobias , Huber Patrick , Kollegger Johann , Vill Markus
Published: February 2021

During the second half of the last century it was common in Europe to use bent-up bars of the longitudinal flexural reinforcement near the support of one-way slab bridges to strengthen their shear capacity. As current codes do not offer clear concepts for evaluating the capacity of those structures, many of them have to be strengthened with expensive measures to comply with the standards. Therefore, an experimental series was conducted at TU Wien which included seven slab strips with the dimensions of 6.50/0.55/0.40 meters. The investigated parameters were the position and number of bent-up bars and the point of load introduction. The results exhibited that the activation of these bars is strongly dependent on the reinforcement layout as well as on the loading point. This is confirmed by the crack patterns and the covered development of the cracks.
A New Improved Type of Friction Connection – An Experimental Study
Authors: Varedian Mattias , Collin Peter , Eriksson Kjell
Published: February 2021

Indenters in the slip planes of a bolted lap joint increase its load bearing capacity. In an experimental study, conducted at the Luleå University of Technology, Sweden, a part of the European R&D project PROLIFE, RFCS 2015-00025, indenters between two plates a) were loaded in compression and b) shear loaded in a lap joint. The load to press a 2.5 mm diameter stainless steel indenter 2.3 mm into the plates was 11 kN and the effective friction of the joint was improved. In a reference test with two shear planes and plain as rolled plates, no indenters and an M30 bolt pre-loaded to 320 kN, the joint slip resistance force was 54.5 kN and the effective friction coefficientμeff=0.09. For an identical arrangement but with 29 indenters per shear plane, the slip resistance was close to 250 kN andμeff was increased to 0.40, at the current Eurocode acceptable joint slip of 0.15 mm.
Structural Efficiency of Cold-Formed Steel Beams with Stiffeners in the Web
Authors: Rodrigues Luís
Published: February 2021

This paper reports a series of flexural tests at ambient and fire conditions on simply supported cold- formed steel (CFS) beams using two different configurations – with and without web stiffeners. The main objective of these tests at ambient temperatures was to assess the ultimate strength of the beams and to provide a reference for the fire tests. On the other hand, the major purposes of these tests under fire conditions were to assess their critical temperature and critical time as well as to observe the effect of the stiffeners on the beams under different restraining conditions, including no restraints, partial axial restraint to the thermal elongation of the beam and partial rotational restraint at the beam supports. In addition, a comparison of both experimental results at ambient and fire conditions with predictions from currently available design rules is shown. Finally, it is worth mentioning that the use of CFS beams with web stiffeners might not be always a good solution, depending on their slenderness and boundary conditions.
Performance Analysis of Recycled and Natural Aggregate Concrete Column with Varying Design Parameters
Authors: Hossain Mosharef , Alam Shahria
Published: February 2021

An analytical approach is made to show the performance of recycled aggregate concrete (RAC) columns with varying design parameters and to compare these with natural aggregate concrete (NAC) columns. The design parameters taken into consideration include concrete compressive strength, steel yield strength, longitudinal reinforcement ratio, and applied axial load. These factors were considered for two different aspect ratios which ensure flexural failure behaviour of column. A two-level factorial analysis was performed, and the columns were modelled and analysed using SeismoStruct, a finite element analysis software. The observed responses include: base shear capacity and displacement at first cracking; first yielding of steel; first crushing of concrete; and the ductility of the column. The pushover analysis was used to determine the performance of each column and statistical software R was used for the analysis of variance (ANOVA), which determines the percent contribution of each design parameter and their interactions on various performance criteria. The analysis shows that, RAC columns perform with improved ductility compared to NAC column.
Modular steel lamella roofs by Hugo Junkers A lightweight structure from the 1920s
Authors: Tutsch Joram , Barthel Rainer
Published: February 2021

In the mid-1920s, the German engineer Hugo Junkers (1859-1935) designed an innovative roof construction that is regarded a milestone in the development of lightweight structures. A rhomboid framework of slender steel elements forms a barrel vault that covers a span of up to 50 meters. More than 200 of these roofs – and associated patents – have been commercialized and built all over the world. Unfortunately, most of them do not exist anymore or are in bad condition.

Figure 1. Inner view of hangar with Junkers roof in northern Munich (Tutsch, 2013)

This paper describes the historical steps of the technical development of the construction (in Chapter 1). The framework is designed along strict geometric rules, which in turn have a large influence on the load-bearing behaviour. Both geometry and structure are systematically analysed (in Chapter 2 and 3).

Finally, an example of the investigations and the analysis of a hangar from 1934 (Fig. 1) in northern Munich is presented (in Chapter 4).
Parametric simulation of non-symmetric cable-stayed bridges
Authors: Jorquera-Lucerga Juan José , Lozano-Galant Jose Antonio , Turmo José
Published: February 2021

The rapid bloom of cable-stayed bridges has been propitiated by the development of erection techniques and improvements of construction materials. Nevertheless, the economic boom of the last decade has deflected attention from economic cost to iconic aesthetical appearance increasing significantly designer’s freedom. This structural freedom has enabled the proliferation of a number of non-symmetric cable-stayed bridges. Despite of the number of built examples, the analysis of non-symmetrical cable-stayed bridges has not received considerable attention from the researchers. In fact, the effects of the main design parameters in the structural behavior of these bridges are not addressed in detail in the literature. To fill this gap, this paper studies the structural response of a number of non-symmetrical cable-stayed bridges. With this aim, a parametric analysis is performed to evaluate the effect of each of the main design parameters (the ratio between the main and the back span length, the pylon, the deck and backstay stiffnesses, the pylon inclination, and the stay configuration) of this kind of bridges. Furthermore, the role of the geometrical nonlinearity and the steel consumption in stays are evaluated.
Remaining Strength Evaluations and Reinforcement Methods of Plate Girders with Corrosion near Supports
Authors: Asao Naoyuki , Fujii Katashi , Ogami Hiroshi
Published: February 2021

In Japan, a lot of steel railway bridges were constructed during the period of rapid economic growth in the 1960s. Now, since over 50 years have passed, the aging of these structures has become conspicuous and a major social problem. In particular, for steel plate girders with open deck system, deterioration and damage due to corrosion are becoming pronounced. Nevertheless, the remaining strength evaluation and its reinforcement methods of corroded structures are not always sufficient. Therefore the purpose of this study is to propose an analytically-based evaluation method and a reliable measure to reinforce in the maintenance field of steel railway bridges. The following are noted: 1) Regarding the shear capacity of plate girders with corrosion near supports, the remaining strength depends on the corroded surface condition of each component such as a web or a vertical stiffener. And, according to the form and degree of corrosion, the fracture mode also changes from the buckling of web to the buckling of cross-shape column consisting of the web and vertical stiffener. The result shows that the corroded web has more effect on the shear capacity than the vertical stiffener. 2) Regarding the separation between the web and bottom flange due to corrosion near supports, the remaining strength is deteriorated more rapidly than above case 1, when the separation range lengthens more than the sole plate area. 3) For the reduction of the remaining shear capacity in the above cases 1 and 2, the load bearing capacity can be improved dramatically by unsophisticated attachments as reinforced members.
Effect of corrosion on bond performance of corroded pretensioned prestressed concrete beams
Authors: Zhang Jianren , Yi Ju , Ma Yafei , Wang Lei , Peng Hui
Published: February 2021

The bond behaviour between corroded strand and concrete in pre-tensioned prestressed concrete beam is investigated experimentally in the present paper. A total of nine pre-tensioned beams are fabricated and eight of them are accelerated to concrete cracking, with one uncorroded beam as control. Data on the distribution of corrosion-induced crack, force-slip responses, and failure modes are obtained. Effects of strand corrosion on the load-slip curves are studied. At last, the final failure modes and the ultimate strength of the beams are analysed. Experimental results show that the bond stiffness and strength do not decrease until the corrosion loss and crack width exceeds 5.1% and 0.27 mm, respectively. The failure mode of beams change with the increasing of strand corrosion. When the corrosion loss is less than 5.1%，beams PS0-PS4 fail in concrete crushing, accompanying with strand yielding. When the corrosion loss exceeds 6.91%, the beams fail in strand rupturing without detecting yielding plateau. The degradation of strand tensile strength plays a more important role than degradation of bond strength when strand reaches certain corrosion loss.
Bridge deck deflection: importance of early shrinkage
Authors: Menétrey Philippe , Broquet Claude , Pires Francisco
Published: February 2021

The construction of the viaduct over the A9 highway, a semi-integral prestressed concrete bridge with a total span of 351.60 m, was accompanied by uncertainties about the importance of long- term effects on the deck deformations. To clarify these, deformation measurements have been carried out using optical fibers, which turned out to be a powerful measurement tool enabling the recording of the whole construction process.

The measurements of the deck allowed identifying the various causes of deformation: an expansion period caused by the hydration heat release, a contraction due to early shrinkage; some deformations due to construction stages such as prestressing of the deck and lowering the formwork, and deformation due to creep.

Analysing the early stages of deformations allowed the development of a structural model for concrete which distinguishes the point of zero deformation and the one of zero stress. The point of zero deformation occurs after the dormant phase, some hours after concreting, when concrete is transforming from liquid to solid state. The point of zero stress occurs few days after concreting when the deformations reach a clear peak value defined as the “birth of the concrete structure”. Up to this point of birth, the deformations occurring in the structure induce stress. Distinguishing these two points allows matching the experimental measurements and explaining the early cracking observed in concrete structures.

It is shown that prediction of the deformations with numerical models is possible as long as the construction stages, the long-term effects and early shrinkage are considered. However, early shrinkage occurring after the birth of the concrete structure, which reaches values around 0.3 ‰ during the first weeks, has to be added to the currently used strain values of shrinkage. Generally speaking, early shrinkage has to be considered in the design to explain and avoid early age cracking in concrete structures.
Spreading suspension cable at the Rhinebridge Emmerich, Germany
Authors: Boué Andreas
Published: February 2021

The Rhinebridge Emmerich of 1962 is a suspension bridge, with two 77 m high steel pylons, and 500 m long. The suspending cables consist of 61 parallel locked coil strands. The hangers are fixed to the suspension package by an iron cast saddle-clamp each. Corrosion products had spilled from the inside of the suspension cable at the lowest point. In order to investigate the corrosion of the cable in the interior, the suspension cable was opened under terms of running traffic using a special device with grippers. As a result, the strands of the cable could have been inspected all around. It was found, that the more than 50 years old strands are in very good condition. After documentation the strands have been cleaned, coated and lead back into the suspension package. The old saddle-clamp was fixed again and suspension cables were replaced.
Analysis of Confederation Bridge Pier Behaviour Following Blizzard Using Pier Tiltmeter Monitoring System
Authors: McCallum-Mantha Brittany , Newhook John , McGinn Donald
Published: February 2021

The pier tiltmeter monitoring system for the Confederation Bridge was developed for continuous positional monitoring of all 44 main bridge piers to aid in operational management decisions. All piers were instrumented with digital, biaxial tiltmeters in early 2014, permitting the ability to measure certain response characteristics over 11 kilometers of bridge and 21 portal frame substructures. This was one of the first structures to have an extensive real-time, accessible tiltmeter system as part of a long-term monitoring project. The first major event occurring once the tiltmeters were functional was a blizzard in February of 2015. This event was used for analysis to demonstrate the monitoring system was able to confirm that all main bridge piers returned to their initial position following the event and also, that the behaviour of the piers had not changed or suffered any damage. The maximum increase in traverse tilt during the blizzard was found to be 680 microradians. This pier rotation was found to vary across the structure (i.e. from pier to pier), although a correlation with pier height was found. The peak mean wind speed logged by the weather station during the event was 127 km/h (15 minute average). The transverse behaviour of all piers during the blizzard with respect to wind was examined; results found were in agreement with those from other major storms logged, especially when only winds nearly normal to the structure were considered. Within one week of the blizzard event, the transverse position of all bridge piers was confirmed to be within 2-3 mm of the position recorded before the storm.
Seismic Performance of Concrete-Filled Double-Layer Steel Tubular Column under High Axial Load
Authors: Li Wencong
Published: February 2021

Concrete-filled steel tubular (CFT) columns have been widely used in building structures because of excellent earthquake-resistant properties such as high stiffness, high strength, good ductility and large energy absorption capacity. In past years, a special cross-section of column with the concrete-filled double-skin steel tubes (CFDSTs), was proposed by several researchers due to some advantages in respect of CFT column, which include reducing total dead load of structure, lowering concrete consumption, increase in section modulus and improving cyclic performance. However, the hollow part of cross-section can lead to significant axial compressive strain under high axial load. In this study, a different cross-section of column with concrete-filled double-layer steel tubes (CFDLTs), transforming from the CFDST column by filling the hollow part of cross-section with concrete, is proposed to decrease the axial compressive strain. Quasi-static cyclic tests of the CFDST and CFDLT column specimens were carried out under constant axial force ratio of 0.5 to investigate the effect of hollow section of column and solid section of column on the seismic performance. The experimental results showed that the CFDLT column specimen exhibits higher lateral load capacity and ductility. It is clarified that progress of axial compressive strain can be remarkably prevented for the CFDLT column specimen.
Plus-Energy façades with smart materials for future building envelopes
Authors: Horn Sebastian , Weller Bernhard , Seeger Julia
Published: February 2021

Façade constructions and their opaque areas show great potential for generating energy by using photovoltaics (PV). The performance of PV modules decreases with increasing cell temperature. To reach lower module temperatures even in insulated façade constructions without rear ventilation, a composite construction using smart materials was examined. By mounting phase change materials (PCM) on the backside of the PV module, the PCM can absorb thermal energy from the PV module by melting from solid to liquid during the day. Rising module temperatures can thus be buffered. At night, the thermal energy in the PCM is released back into the ambient air.

For future applications, the article outlines an approach of integrating hybrid panels in façade constructions. These elements combine PV modules and thermal collectors in order to generate thermal and electrical energy with a high efficiency due to the low temperatures of the PV cells.
Design of instrumented bearings for direct measure of bridge live loads
Authors: Dubbs Nathaniel C.
Published: February 2021

A long span steel through truss was scheduled for expansion bearing replacement as part of an overall rehabilitation project. At the time, a Structural Health Monitoring (SHM) system was being designed to investigate how overloaded trucks were affecting the performance of the bridge. Due to the opportunity presented by the bearing replacement project, the concept of instrumenting the new bearings with load cells was accepted by the bridge owner and a formal design was commissioned. A prototype bearing was constructed and evaluated through rigorous testing in a laboratory setting to ensure that the addition of sensors in the load path of the bearings would not compromise the integrity or safety of the bridge. Upon completion of the acceptance testing of the prototype bearing, the full construction of the bearing assemblies and their subsequent installation was started. The paper discusses the various challenges associated with the design, construction, maintenance, and processing/interpretation of the measurements for such a system.
Flexural Performance of Two-Way Concrete Slabs Reinforced with Carbon Fiber Grid
Authors: Aljazaeri Zena R. , Alghazali Hayder H. , Myers John J.
Published: February 2021

Fiber-reinforced polymers (FRP) were recently used as a replacing reinforcement in concrete structures in view of their excellent resistance to corrosion, light weight, and high specific strength. A state of art of using carbon fiber grids as an internal reinforcement with self- consolidate concrete in two-way slab systems is presented here. The experimental program included studying the flexural performance of the carbon fiber grid as in comparison with the conversional welded steel wire mesh. This work is expected to find its application in parking garages to enhance the durability performance and extend the service life of the concrete slab members. The load –deflection curves, ultimate loads, energy absorption, and failure mode of simply supported slabs with different aspect ratios are discussed. The test results for simply supported slabs with aspect ratio of (1:1) showed that the FRP grid tended to fall within the criteria of minimum load requirements per ASCE7 as the steel wire reinforcement did. In addition, the slabs observed a limit of deflection (L/360) at approximately 50% of their ultimate loads.
Key Techniques for Performance-based design of metro depot covered structure
Authors: Jia Jian , Liu Chuanping , Xu Xiaobing , Zhang Zhibin , Xie Xiaolin , Liu Kai
Published: February 2021

The challenges of developing superstructures on metro train depots include abrupt changes of structural stiffness, discontinuities of vertical structural elements, out-of-current codes, different architectural types, and different construction sequences. This study analyses design process of superstructures on a metro train depot in Shanghai area. The performance-based seismic design is used to design the key structural components. The laboratory shaking table tests are used to simulate seismic responses of depot and superstructure subject to earthquakes. The theoretical analysis and shaking table simulations show the superstructure and depot deformed elastically in moderate earthquakes and will not fail in strong earthquakes. The main factors affecting development of superstructure above metro train depot are analysed. The paper provides useful insights to similar projects.
The imminent Future of Parametric Nodes
Authors: Mohsen Alamir , Knaack Ulrich
Published: February 2021

Complex geometries are undeniable nowadays, according to the enormous progress in parametric software. Giving a close look to the complex geometries; one can easily define the most critical points of any geometry, which are the connecting nodes. These represent a challenge for any project, based on the flow of geometry mesh; each connecting node could have a completely different form.

Accordingly integrating additive manufacturing to the process of facade manufacturing will have prosperous results. Additive manufacturing is a growing trend based on what it could offer. Some claim that Additive manufacturing has severe limitations to be applied in facade industry. On the other hand, the question should be; how should facade engineers/manufacturers expand their horizons so they could get into the process and start to trust and utilize.

The author claims that what is missing is the tool that can be utilized during the planning phase of any project. The absence of the tool that can solve the intersecting points/nodes of any project leads to certain repetitive workload.

The tool from the author point of view is defined as the parametric node, which could adapt to any geometrical condition. The first idea was to design a parametric node that could be manufactured traditionally. The idea achieved a success reaching the point that “parametric node” is conceivable. The challenge showed up in the kernel of the node as it could only adapt to clear geometrical forms, which presented a mind shifting strategy starting to look at Additive manufacturing and topology optimization to ease the developing process of the node.

The effect of connection type (Bolted – Welded) had been done to check the effect on the topology optimization process – as a factor of cost reduction - and Material testing for 3d printed steel specimens is in progress.
Fretting Fatigue Analysis of Bridge Stay Cables at Saddle Supports using Multiaxial Stress-Based Approaches
Authors: Mohareb Sherif , Goldack Arndt , Schlaich Mike , Walbridge Scott
Published: February 2021

Saddle systems have been used in recent projects to support the cables in cable-stayed and extradosed bridge structures. With this approach, the cable is anchored to the bridge deck on one side of the pylon, extended over a “saddle” within the pylon, and then fixed on the other end to the deck on the opposite side. A major design consideration for this type of anchorage system, where several significant gaps in the current state-of-knowledge have recently been identified, is the in-service fretting fatigue behaviour of the cables within the pylon saddle. In order to begin to address these knowledge gaps, a research project was recently undertaken at Technische Universität Berlin, wherein analytical tools for understanding and calculating the displacements and contact forces were developed, fatigue tests were performed on large-scale test specimens of cables draped over a round saddle, and fretting fatigue analysis was performed using various models, including several employing multiaxial stress-based approaches. In this paper, these fatigue models are described, and the input parameters required for their application are discussed. Predictions made using the described models are then presented. The paper concludes by identifying the future work needed to further develop this modelling approach, so that it may serve as a useful tool for tasks such as: optimizing design parameters including the saddle radius and contact surface material, and developing improved, reliability-based design guidelines, which will enable the safe and economic design of this connection type, while at the same time reducing the number of large-scale proof tests required at the design stage by the current standards.