Influence of the nonlocal parameter on the transverse vibration of double-walled carbon nanotubes

A high-order nonlocal continuum beam model is proposed, which can be applied to study the transverse vibrations of double-walled carbon nanotubes (DWCNTs), including those that could have initial deformations due to defects or external actions. A beam element is developed adopting Hermite cubic polynomials as shape functions, and mass and elastic stiffness matrix are presented. The influence of the nonlocal parameter on the vibrational properties of DWCNTs is studied. Using the proposed model, it was found that the nonlocal parameter has a strong influence on the natural frequencies.Fil: de Borbon, Fernanda Maria. Universidad Nacional de Cuyo. Facultad de Ingeniería. Instituto de Mecánica Estructural y Riesgo Sísmico. Maestría en Ingeniería Estructural; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: Ambrosini, Ricardo Daniel. Universidad Nacional de Cuyo. Facultad de Ingeniería. Instituto de Mecánica Estructural y Riesgo Sísmico. Maestría en Ingeniería Estructural; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentin

Effects of underground explosions on soil and structures

Much effort has been dedicated to the study of underground explosions because they pose a major threat to people and structuresbelow or above the ground. In this regard, it is especially important to model the propagation of blast waves in soil and their effectson structures. The main phenomena caused by underground explosive detonation that must be addressed are crater or camouflet forma-tion, shock wave and elastic?plastic wave propagation in soil, and soil-structure interaction. These phenomena can be numerically sim-ulated using hydrocodes, but much care must be taken to obtain reliable results. The objective of this study is to analyze the ability of ahydrocode and simple soil models that do not require much calibration to approximately reproduce experimental and empirical resultsrelated to different buried blast events and to provide general guidelines for the simulation of this type of phenomena. In this regard,crater formation, soil ejecta, blast wave propagation in soil, and their effects on structures below and above the ground are numericallysimulated using different soil models and parameters; the results are analyzed. The properties of soil have a significant effect on struc-tures, the ejecta, and the propagation of shock waves in soil. Thus, the model of the soil to study these phenomena must be carefullyselected. However their effect on the diameter of a crater is insignificant.Fil: Ambrosini, Ricardo Daniel. Universidad Nacional de Cuyo. Facultad de Ingeniería. Instituto de Mecánica Estructural y Riesgo Sísmico. Maestría en Ingeniería Estructural; ArgentinaFil: Luccioni, Bibiana Maria. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Instituto de Estructuras "Ing. Arturo M. Guzmán"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentin

On the influence of the shear deformation and boundary conditions on the transverse vibration of multi-walled carbon nanotubes

The vibrational properties of multi-walled carbon nanotubes (MWCNTs) are studied, especially the influence of the shear deformation and the boundary conditions on the non-coaxial frequencies. A high order continuum beam model is proposed, which can be applied to study the transverse vibrations of MWCNTs, including those that could have initial deformations due to defects or external actions. Using the model it was found that the non-coaxial intertube frequencies are independent of the shear deformation and the boundary conditions. This result is important considering that the concentric structure of MWCNTs is a crucial geometrical characteristic and a non-coaxial vibration would affect their electronic and optical properties.Fil: Ambrosini, Ricardo Daniel. Universidad Nacional de Cuyo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: de Borbon, Fernanda Maria. Universidad Nacional de Cuyo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentin

Muros de mamposteria sometidos a explosiones

Las organizaciones terroristas de todo el mundo han utilizado explosivos en muchas ocasiones para llevar a cabo atentados en centros urbanos. Algunas de las víctimas y los heridos en estos tentados suelen deberse a colapsos estructurales y al impacto de escombros. Esta amenaza obliga a los nvestigadores a estudiar el comportamiento de los sistemas de construcción ordinarios expuestos a cargas impulsivas extremas. La mampostería encadenada es un sistema de construcción muy utilizadon en zonas sísmicas de muchas partes del mundo, ampliamente estudiados bajo cargas sísmicas. En cambio, son escasos los estudios sobre su respuesta a cargas impulsivas fuera del plano, como las causadas por explosiones intencionadas o accidentales. En este trabajo se estudian 2 explosiones con diferentes distancias escaladas. Se utilizaron explosivos apoyados el suelo cerca de muros de mampostería encadenada con una abertura. Se analizó la compleja interacción entre las ondas de presión y la estructura. Se modela usando codigos comerciales las sobrepresiones, impulsos y la respuesta estructural.Fil: Codina, Ramon Humberto. Universidad Nacional de Cuyo. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: Ambrosini, Ricardo Daniel. Universidad Nacional de Cuyo. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaXXVII Congreso Argentino de Mecánica ComputacionalResistenciaArgentinaUniversidad Nacional del Nordeste. Facultad de IngenieríaAsociación Argentima de Mecánica Computaciona

Colapso estructural bajo cargas explosivas

Las estructuras civiles no son generalmente diseñadas para resistir cargas dinámicas de muy corta duración y gran amplitud como las generadas por explosiones e impacto. Hasta hace muy poco tiempo, la consideración de cargas explosivas debidas a un ataque terrorista se limitaba principalmente a estructuras tales como estructuras militares, centrales nucleares, embajadas, etc. En este trabajo se presenta la simulación del proceso de destrucción de estructuras de hormigón producido por la detonación de cargas explosivas. Dicho estudio se realiza mediante un hidrocódigo que considera la interacción fluido (aire)- estructura. Se describen en el trabajo los modelos materiales utilizados para el hormigón y mampostería.Dichos modelos incluyen la simulación del fenómeno de desintegración o fractura del material que permite eliminar al mismo del cálculo para simular erosión o discontinuidades producidas en el material por la carga explosiva. Se presentan, además, las distintas estrategias de calculo utilizadas en la simulación del proceso completo, desde la detonación del explosivo, hasta la caída del edificio.Fil: Luccioni, Bibiana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Instituto de Estructuras "Ing. Arturo M. Guzmán"; ArgentinaFil: Ambrosini, Ricardo Daniel. Universidad Nacional de Cuyo. Facultad de Ingeniería. Instituto de Mecánica Estructural y Riesgo Sísmico; ArgentinaFil: Danesi, Rodolfo Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucuman. Facultad de Cs.exactas y Tecnología. Laboratorio de Estructuras; Argentin

Anales del III Congreso Internacional de Vivienda y Ciudad "Debate en torno a la nueva agenda urbana"

Acta de congresoEl III Congreso Internacional de Vivienda y Ciudad “Debates en torno a la NUEVa Agenda Urbana”, ha sido una apuesta de alto compromiso por acercar los debates centrales y urgentes que tensionan el pleno ejercicio del derecho a la ciudad. Para ello las instituciones organizadoras (INVIHAB –Instituto de Investigación de Vivienda y Hábitat y MGyDH-Maestría en Gestión y Desarrollo Habitacional-1), hemos convidado un espacio que se concretó con potencia en un debate transdisciplinario. Convocó a intelectuales de prestigio internacional, investigadores, académicos y gestores estatales, y en una metodología de innovación articuló las voces académicas con las de las organizaciones sociales y/o barriales en el Foro de las Organizaciones Sociales que tuvo su espacio propio para dar voz a quienes están trabajando en los desafíos para garantizar los derechos a la vivienda y los bienes urbanos en nuestras ciudades del Siglo XXI

Computational modelling in protective engineering research: Recent advances and good practice

Protective engineering has attracted significant renewed research interest in recent years. In the development to tackle the challenges arising from the needs of in-depth and detailed information about the complex dynamic structural and material responses, the use of sophisticated computational modelling has become a seemingly indispensable means. Apart from being driven by the traditional difficulties when it comes to performing physical experiments for the types of extreme loads concerned, the trend has been fuelled by the rapid advancement in the computing power and software capabilities. It is not difficult nowadays for an analyst to model even quite complex loading and nonlinear responses using just a desk-top computer. On the balancing side, however, we should always be reminded that the ability to exploit the modelling capabilities and make good sense of the results is still and will remain to be dependent upon sound comprehension of the underlying mechanics and physical processes, as well as calibration of the models by comparison with experimental results.Fil: Lu, Yong. University of Edimburg. School of Ingeenering; Reino UnidoFil: Ambrosini, Ricardo Daniel. Universidad Nacional de Cuyo. Facultad de Ingenieria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mendoza; Argentin

Experimental study of confined masonry walls under blast loading

Terrorist organizations around the world have used explosives on many occasions to carry out attacks in urban centers. The victims and injuries in these attacks are often due to structural collapses and the impact of debris. This threat leads researchers to study the performance of ordinary building systems exposed to extreme impulsive loads. Confined masonry buildings are a widely used construction system in seismic zones in many parts of the world and have been widely studied under seismic loads. On the other hand, studies of the response to out-of-plane impulsive loads, such as those caused by intentional or accidental explosions, are scarce. In this paper, results of three experimental explosions at different scaled distances are presented. The explosives on and 1 m above the ground were used. Confined masonry walls with and without openings were tested. The complex interaction between air blast and ground shock was analyzed. Levels of damage obtained with different scaled distances are presented. The results are compared with iso-damage curves.Fil: Codina, Ramon Humberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Nacional de Cuyo. Facultad de Ingeniería; ArgentinaFil: Ambrosini, Ricardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Nacional de Cuyo. Facultad de Ingeniería; Argentin

Full-scale testing of leakage of blast waves inside a partially vented room exposed to external air blast loading

For the last few decades, the effects of blast loading on structures have been studied by many researchers around the world. Explosions can be caused by events such as industrial accidents, military conflicts or terrorist attacks. Urban centers have been prone to various threats including car bombs, suicide attacks, and improvised explosive devices. Partially vented constructions subjected to external blast loading represent an important topic in protective engineering. The assessment of blast survivability inside structures and the development of design provisions with respect to internal elements require the study of the propagation and leakage of blast waves inside buildings. In this paper, full-scale tests are performed to study the effects of the leakage of blast waves inside a partially vented room which is subjected to different external blast loadings. The results obtained may be useful for proving the validity of different methods of calculation, both empirical and numerical. Moreover, the experimental results are compared with those computed using the empirical curves of the US Defense report/manual UFC 3-340. Finally, results of the dynamic response of the front masonry wall are presented in terms of accelerations and an iso-damage diagram.Fil: Codina, Ramon Humberto. Universidad Nacional de Cuyo. Facultad de Ingeniería. Instituto de Mecánica Estructural y Riesgo Sísmico; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: Ambrosini, Ricardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Nacional de Cuyo. Facultad de Ingeniería. Instituto de Mecánica Estructural y Riesgo Sísmico. Maestría en Ingeniería Estructural; Argentin

Numerical and analytical study of overpressures and impulses inside a masonry box subjected to external blast loading

Blast loads have attracted considerable attention in recent years due to accidental or intentional events involving important structures, which have occurred around the world. The activities related to terrorist attacks have increased and, unfortunately, the current trend suggests that they will continue to rise in the future. In relation to the design of structures subjected to blast loadings, there are still many uncertainties in the specialized technical literature. Particularly, the overpressures and impulses inside constructions are difficult to estimate due to many reflections of the shock wave. The main objective of this work is to study the propagation of the blast wave inside constructions subjected to external loadings. An experimental study was performed using a masonry box with reinforced concrete beams and columns and a typical window. The results were previously presented. In this article, numerical models are developed in order to compare results and to obtain design guidelines. Explosive charges of equivalent 1?5 kg of TNT and elevated 1m above the ground were detonated at different distances from the window, and overpressures and impulses were obtained at five points inside and outside the room. However, empirical?analytical results using a well-known technical manual are also obtained and compared. The obtained results are useful to evaluate numerical codes and empirical formulas.Fil: Codina, Ramon Humberto. Universidad Nacional de Cuyo. Facultad de Ingeniería. Instituto de Mecánica Estructural y Riesgo Sísmico; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: Ambrosini, Ricardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Nacional de Cuyo. Facultad de Ingeniería. Instituto de Mecánica Estructural y Riesgo Sísmico; Argentin