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1
Jelvehpour, Ali. "Development of a transient gradient enhanced non local continuum damage mechanics model for masonry." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/93365/1/Ali_Jelvehpour_Thesis.pdf.
Повний текст джерелаАнотація:
Due to the advent of varied types of masonry systems a comprehensive failure mechanism of masonry essential for the understanding of its behaviour is impossible to be determined from experimental testing. As masonry is predominantly used in wall structures a biaxial stress state dominates its failure mechanism. Biaxial testing will therefore be necessary for each type of masonry, which is expensive and time consuming. A computational method would be advantageous; however masonry is complex to model which requires advanced computational modelling methods. This thesis has formulated a damage mechanics inspired modelling method and has shown that the method effectively determines the failure mechanisms and deformation characteristics of masonry under biaxial states of loading.
2
Pelà, Luca. "Continuum damage model for nonlinear analysis of masonry structures." Doctoral thesis, Universitat Politècnica de Catalunya, 2009. http://hdl.handle.net/10803/30327.
Повний текст джерелаАнотація:
The present work focuses on the formulation of a Continuum Damage Mechanics model for nonlinear analysis of masonry structural elements. The material is studied at the macro-level, i.e. it is modelled as a homogeneous orthotropic continuum.
The orthotropic behaviour is simulated by means of an original methodology, which is based on nonlinear damage constitutive laws and on the concept of mapped tensors from the anisotropic real space to the isotropic fictitious one. It is based on establishing a one-to-one mapping relationship between the behaviour of an anisotropic real material and that of an isotropic fictitious one. Therefore, the problem is solved in the isotropic fictitious space and the results are transported to the real field. The application of this idea to strain-based Continuum Damage Models is rather innovative.
The proposed theory is a generalization of classical theories and allows us to use the models and algorithms developed for isotropic materials. A first version of the model makes use of an isotropic scalar damage model. The adoption of such a simple constitutive model in the fictitious space, together with an appropriate definition of the mathematical transformation between the two spaces, provides a damage model for orthotropic materials able to reproduce the overall nonlinear behaviour, including stiffness degradation and strain-hardening/softening response.
The relationship between the two spaces is expressed in terms of a transformation tensor which contains all the information concerning the real orthotropy of the material. A major advantage of this working strategy lies in the possibility of adjusting an arbitrary isotropic criterion to the particular behaviour of the orthotropic material. Moreover, orthotropic elastic and inelastic behaviours can be modelled in such a way that totally different mechanical responses can be predicted along the material axes.
The aforementioned approach is then refined in order to account for different behaviours of masonry in tension and compression. The aim of studying a real material via an equivalent fictitious solid is achieved by means of the appropriate definitions of two transformation tensors related to tensile or compressive states, respectively. These important assumptions permit to consider two individual damage criteria, according to different failure mechanisms, i.e. cracking and crushing. The constitutive model adopted in the fictitious space makes use of two scalar variables, which monitor the local damage under tension and compression, respectively. Such a model, which is based on a stress tensor split into tensile and compressive contributions that allows the model to contemplate orthotropic induced damage, permits also to account for masonry unilateral effects. The orthotropic nature of the Tension-Compression Damage Model adopted in the fictitious space is demonstrated. This feature, both with the assumption of two distinct damage criteria for tension and compression, does not permit to term the fictitious space as “isotropic”. Therefore, the proposed formulation turns the original concept of “mapping the real space into an isotropic fictitious one” into the innovative and more general one of “mapping the real space into a favourable (or convenient) fictitious one”. Validation of the model is carried out by means of comparisons with experimental results on different types of orthotropic masonry.
The model is fully formulated for the 2-dimensional case. However, it can be easily extended to the 3-dimensional case. It provides high algorithmic efficiency, a feature of primary importance when analyses of even large scale masonry structures are carried out. To account for this requisite it adopts a strain-driven formalism consistent with standard displacement-based finite element codes. The implementation in finite element programs is straightforward.
Finally, a localized damage model for orthotropic materials is formulated. This is achieved by means of the implementation of a crack tracking algorithm, which forces the crack to develop along a single row of finite elements. Compared with the smeared cracking approach, such an approach shows a better capacity to predict realistic collapsing mechanisms. The resulting damage in the ultimate condition appears localized in individual cracks. Moreover, the results do not suffer from spurious mesh-size or mesh-bias dependence. The numerical tool is finally validated via a finite element analysis of an in-plane loaded masonry shear wall.
3
PELA', Luca. "CONTINUUM DAMAGE MODEL FOR NONLINEAR ANALYSIS OF MASONRY STRUCTURES." Doctoral thesis, Università degli studi di Ferrara, 2009. http://hdl.handle.net/11392/2389195.
Повний текст джерелаАнотація:
The present work focuses on the formulation of a Continuum Damage Mechanics
model for nonlinear analysis of masonry structural elements. The material is
studied at the macro-level, i.e. it is modelled as a homogeneous orthotropic
continuum.
The orthotropic behaviour is simulated by means of an original methodology,
which is based on nonlinear damage constitutive laws and on the concept of
mapped tensors from the anisotropic real space to the isotropic fictitious one. It is
based on establishing a one-to-one mapping relationship between the behaviour of
an anisotropic real material and that of an isotropic fictitious one. Therefore, the
problem is solved in the isotropic fictitious space and the results are transported to
the real field. The application of this idea to strain-based Continuum Damage
Models is rather innovative.
The proposed theory is a generalization of classical theories and allows us to use
the models and algorithms developed for isotropic materials. A first version of the
model makes use of an isotropic scalar damage model. The adoption of such a
simple constitutive model in the fictitious space, together with an appropriate definition of the mathematical transformation between the two spaces, provides a
damage model for orthotropic materials able to reproduce the overall nonlinear
behaviour, including stiffness degradation and strain-hardening/softening response.
The relationship between the two spaces is expressed in terms of a transformation
tensor which contains all the information concerning the real orthotropy of the
material. A major advantage of this working strategy lies in the possibility of
adjusting an arbitrary isotropic criterion to the particular behaviour of the
orthotropic material. Moreover, orthotropic elastic and inelastic behaviours can be
modelled in such a way that totally different mechanical responses can be predicted
along the material axes.
The aforementioned approach is then refined in order to account for different
behaviours of masonry in tension and compression. The aim of studying a real
material via an equivalent fictitious solid is achieved by means of the appropriate
definitions of two transformation tensors related to tensile or compressive states,
respectively. These important assumptions permit to consider two individual
damage criteria, according to different failure mechanisms, i.e. cracking and
crushing. The constitutive model adopted in the fictitious space makes use of two
scalar variables, which monitor the local damage under tension and compression,
respectively. Such a model, which is based on a stress tensor split into tensile and
compressive contributions that allows the model to contemplate orthotropic
induced damage, permits also to account for masonry unilateral effects. The
orthotropic nature of the Tension-Compression Damage Model adopted in the
fictitious space is demonstrated. This feature, both with the assumption of two
distinct damage criteria for tension and compression, does not permit to term the
fictitious space as “isotropic”. Therefore, the proposed formulation turns the
original concept of “mapping the real space into an isotropic fictitious one” into
the innovative and more general one of “mapping the real space into a favourable (or convenient) fictitious one”. Validation of the model is carried out by means of
comparisons with experimental results on different types of orthotropic masonry.
The model is fully formulated for the 2-dimensional case. However, it can be easily
extended to the 3-dimensional case. It provides high algorithmic efficiency, a
feature of primary importance when analyses of even large scale masonry
structures are carried out. To account for this requisite it adopts a strain-driven
formalism consistent with standard displacement-based finite element codes. The
implementation in finite element programs is straightforward.
Finally, a localized damage model for orthotropic materials is formulated. This is
achieved by means of the implementation of a crack tracking algorithm, which
forces the crack to develop along a single row of finite elements. Compared with
the smeared cracking approach, such an approach shows a better capacity to predict
realistic collapsing mechanisms. The resulting damage in the ultimate condition
appears localized in individual cracks. Moreover, the results do not suffer from
spurious mesh-size or mesh-bias dependence. The numerical tool is finally
validated via a finite element analysis of an in-plane loaded masonry shear wall.
4
Saloustros, Savvas. "Tracking localized cracks in the computational analysis of masonry structures." Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/461714.
Повний текст джерелаАнотація:
Numerical methods aid significantly the engineering efforts towards the conservation of existing masonry structures and the design of new ones. Among them, macro-mechanical finite element methods based on the smeared crack approach are commonly preferred as an affordable choice for the analysis of large masonry structures. Nevertheless, they usu-ally result in a non-realistic representation of damage as smeared over large areas of the structure, which hampers the correct interpretation of the damage pattern. Additionally, a more critical pathology of this approach is the mesh-dependency, which influences nota-bly the safety and stability predictions.
To overcome these limitations, this thesis proposes a novel computational tool based on the {enrichment} of the classical smeared crack approach with a local tracking algorithm. The objective of this localized damage model is the realistic and efficient non-linear anal-ysis of masonry structures with an enhanced representation of cracking.
The non-linear behaviour of masonry is simulated through the adoption of a continuum damage mechanics model with two damage indices, allowing the differentiation between the tensile and compressive mechanical responses of masonry. In this context, a novel explicit formulation for the evolution of irreversible strains is proposed and implemented. Two new expressions are derived for the regularization of the tensile and compressive softening responses according to the crack-band approach, ensuring the mesh-size objec-tivity of the damage model.
The simulation of the structural behaviour of masonry structures under versatile loading and boundary conditions necessitates some developments in the context of local tracking algorithms. To this end, this thesis presents the enhancement of local tracking algorithms with novel procedures that make possible the simulation of multiple, arbitrary and inter-secting cracking under monotonic and cyclic loading. Additionally, the effect of different crack propagation criteria is investigated and the selection among more than one potential failure planes is tackled.
The proposed localized damage model is validated through the simulation of a series of structural examples. These vary from small-scale tests on concrete specimens with few dominant cracks, to medium and large-scale masonry structures with multiple tensile, shear and flexural cracking. The analyses are compared with analytical, experimental and numerical results obtained with alternative methods available in the literature. Overall, the localized damage model developed in this thesis largely improves the mesh-independency of the classical smeared crack approach and reproduces crack patterns and collapse mech-anisms in an efficient and realistic way.Los métodos numéricos son decisivos en la ingeniería para la conservación de estructuras de mampostería existentes y el diseño de estructuras nuevas. Entre ellos, los métodos macro-mecánicos de elementos finitos, basados en el concepto de fisuras distribuidas, son habitualmente los preferidos como opción asequible para el análisis de grandes estructuras de mampostería. Sin embargo, suelen resultar en a una representación poco realista del daño, distribuido en grandes áreas de la estructura, lo que impide la correcta interpretación del patrón de daño. Además, esta metodología presenta una patología más crítica, la dependencia de la malla, que influye notablemente en las predicciones de seguridad y estabilidad. Para superar estas limitaciones, esta tesis propone una nueva herramienta numérica basada en el enriquecimiento del clásico enfoque de fisuras distribuidas con un algoritmo de trazado local. El objetivo de este modelo de daño localizado es el análisis no-lineal de las estructuras de mampostería de manera realista y eficiente con una representación mejora-da de fisuras. El comportamiento no lineal de la mampostería se simula a través de la adopción de un modelo de mecánica de daño continuo con dos índices de daño, permitiendo la diferenciación entre las respuestas mecánicas de tensión y compresión de la mampostería. En este contexto, se propone e implementa una nueva formulación explícita para la evolución de deformaciones irreversibles. Se derivan dos nuevas expresiones para la regularización del ablandamiento de tracción y compresión según el ancho de banda de la fisura, garantizan-do la objetividad del modelo de daño al respecto del tamaño de la malla. La simulación del comportamiento estructural de las estructuras de mampostería en condiciones de carga y contorno generales precisa de algunos desarrollos en el contexto de los algoritmos locales de trazado. Con este objetivo, se presenta la mejora de los algoritmos locales de trazado con nuevos procedimientos que posibilitan la simulación de fisuración múltiple, arbitraria e secante bajo cargas monótonas y cíclicas. Además, se investiga el efecto de diferentes criterios de propagación de fisuras y se aborda la selección entre más de un plano de falla posible. El modelo de daño localizado propuesto se valida mediante la simulación de una serie de ejemplos estructurales. Éstos van desde pruebas a pequeña escala en probetas de hormigón, con pocas fisuras dominantes, hasta estructuras de mampostería de mediana y gran escala con fisuración múltiple de tracción, de cortante y de flexión. Los análisis se comparan con los resultados analíticos, experimentales y numéricos obtenidos con métodos alternativos disponibles en la literatura. El modelo de daño localizado mejora en gran medida la independencia de la malla del clásico método de fisuras distribuidas y reproduce patrones de daño y mecanismos de colapso de una manera eficiente y realista
5
Kalkbrenner, Philip. "A machine learning based material homogenization technique for masonry structures." Doctoral thesis, Universitat Politècnica de Catalunya, 2021. http://hdl.handle.net/10803/673191.
Повний текст джерелаАнотація:
Cutting-edge methods in the computational analysis of structures have been developed over the last decades. Such modern tools are helpful to assess the safety of existing buildings. Two main finite element (FE) modeling approaches have been developed in the field of masonry structures, i.e. micro and macro scale. While the micro modeling distinguishes between the masonry components in order to accurately represent the typical masonry damage mechanisms in the material constituents, macro modeling considers a single continuum material with smeared properties so that large scale masonry models can be analyzed. Both techniques have demonstrated their advantages in different structural applications. However, each approach comes along with some possible disadvantages. For example, the use of micro modeling is limited to small scale structures, since the computational effort becomes too expensive for large scale applications, while macro modeling cannot take into account precisely the complex interaction among masonry components (brick units and mortar joints).
Multi scale techniques have been proposed to combine the accuracy of micro modeling and the computational efficiency of macro modeling. Such procedures consider linked FE analyses at both scales, and are based on the concept of a representative volume element (RVE). The analysis of a RVE takes into account the micro structural behavior of component materials, and scales it up to the macro level. In spite of being a very accurate tool for the analysis of masonry structures, multi scale techniques still exhibit high computational cost while connecting the FE analyses at the two scales.
Machine learning (ML) tools have been utilized successfully to train specific models by feeding big source data from different fields, e.g. autonomous driving, face recognition, etc. This thesis proposes the use of ML to develop a novel homogenization strategy for the in-plane analysis of masonry structures, where a continuous nonlinear material law is calibrated by considering relevant data derived from micro scale analysis. The proposed method is based on a ML tool that links the macro and micro scales of the analysis, by training a macro model smeared damage constitutive law through benchmark data from numerical tests derived from RVE micro models. In this context, numerical nonlinear tests on masonry micro models executed in a virtual laboratory provide the benchmark data for feeding the ML training procedure. The adopted ML technique allows the accurate and efficient simulation of the anisotropic behavior of masonry material by means of a tensor mapping procedure. The final stage of this novel homogenization method is the definition of a calibrated continuum constitutive model for the structural application to the masonry macro scale.
The developed technique is applied to the in-plane homogenization of a Flemish bond masonry wall. Evaluation examples based on the simulation of physical laboratory tests show the accuracy of the method when compared with sophisticated micro modeling of the entire structure. Finally, an application example of the novel homogenization technique is given for the pushover analysis of a masonry heritage structure.En las últimas décadas se han desarrollado diversos métodos avanzados para el análisis computacional de estructuras. Estas herramientas modernas son también útiles para evaluar la seguridad de los edificios existentes. En el campo de las estructuras de la obra de fábrica se han desarrollado principalmente dos técnicas de modelizacón por elementos finitos (FE): la modelización en escala micro y en escala macro. Mientras que en un micromodelo se distingue entre los componentes de la obra de fábrica para representar con precisión los mecanismos de daño característicos de la misma, en un macromodelo se asignan las propiedades a un único material continuo que permite analizar modelos de obra de fábrica a gran escala. Ambas técnicas han demostrado sus ventajas en diferentes aplicaciones estructurales. Sin embargo, cada enfoque viene acompañado de algunas posibles desventajas. Por ejemplo, la micromodelización se limita a estructuras de pequeña escala, puesto que el esfuerzo computacional que requieren aumenta rápidamente con el tamaño de los modelos, mientras que la macromodelización, por su parte, es un enfoque promediado que no puede por tanto tener en cuenta precisamente la interacción compleja entre los componentes de la fábrica (unidades de ladrillo y juntas de mortero). Hasta el momento, se han propuesto algunas técnicas multiescala para combinar la precisión de la micromodelización y la eficiencia computacional de la macromodelización. Estos procedimientos aplican el análisis de FE vinculado a ambas escalas y se basan en el concepto de elemento de volumen representativo (RVE). El análisis de un RVE tiene en cuenta el comportamiento microestructural de los materiales componentes y lo escala hasta el nivel macro. A pesar de ser una herramienta muy precisa para el análisis de obra de fábrica, las técnicas multiescala siguen presentando un elevado coste computacional que se produce al conectar los análisis de FE de dos escalas. Además, diversos autores han utilizado con éxito herramientas de aprendizaje automático (machine learning (ML)) para poner a punto modelos específicos alimentados con grandes fuentes de datos de diferentes campos, por ejemplo, la conducción autónoma, el reconocimiento de caras, etc. Partiendo de los anteriores conceptos, este tesis propone el uso de ML para desarrollar una novedosa estrategia de homogeneización para el análisis en plano de estructuras de mampostería, donde se calibra una ley de materiales continua no lineal considerando datos relevantes derivados del análisis a microescala. El método propuesto se basa en una herramienta de ML que vincula las escalas macro y micro del análisis mediante la puesta a punto de una ley constitutiva para el modelo macro a través de datos producidos en ensayos numéricos de un RVE micro modelo. En este contexto, los ensayos numéricos no lineales sobre micro modelos de mampostería ejecutados en un laboratorio virtual proporcionan los datos de referencia para alimentar el procedimiento de entrenamiento del ML. La técnica de ML adoptada permite la simulación precisa y eficiente del comportamiento anisotrópico del material de mampostería mediante un procedimiento de mapeo tensorial. La etapa final de este novedoso método de homogeneización es la definición de un modelo constitutivo continuo calibrado para la aplicación estructural a la macroescala de mampostería. La técnica desarrollada se aplica a la homogeneización en el plano de un muro de obra de fábrica construido con aparejo flamenco. Ejemplos de evaluación basados en la simulación de pruebas físicas de laboratorio muestran la precisión del método en comparación con una sofisticada micro modelización de toda la estructura. Por último, se ofrece un ejemplo de aplicación de la novedosa técnica de homogeneización para el análisis pushover de una estructura patrimonial de obra de fábrica.
Enginyeria de la construcció
6
Yao, Chicao. "Failure mechanisms of concrete masonry." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/29323.
Повний текст джерелаАнотація:
The behaviour of concrete masonry under in-plane compression combined with out-of-plane bending was examined both experimentally and analytically.
Ungrouted and grouted masonry, both fully bedded or face-shell bedded, were included in the study. It was found that the masonry under the above stated loading conditions may suffer loss of capacity either due to splitting or shear type of material failure, or by instability. Different loading conditions yield different failure mechanisms, which in turn correspond to different apparent strengths. Theoretical developments are presented leading to estimates of capacity for each of these cases. An extensive experimental program involving 104 masonry prism specimens, was conducted to assist and to verify these analyses.
Theoretical developments include those directed to explain splitting failure phenomena, to investigate the mortar joint effect, the deformation compatibility of grouted masonry, and to examine the slenderness of tall masonry wall. Experimental measurements and observations made on the specimens include capacity, deformation and failure pattern.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
7
Mallinder, Peter Alan. "Constitutive-based masonry vault mechanisms." Thesis, Sheffield Hallam University, 1997. http://shura.shu.ac.uk/20007/.
Повний текст джерелаАнотація:
The objective of the research programme has been to investigate the behaviour of masonry arch vault collapse mechanisms in the context of the problems besetting the national bridge stock. The programme has primarily involved masonry constitutive theoretical studies, supported by laboratory experimentation, which have led to the formulation of novel masonry hinge modelling. The modelling has been developed for practical application in a four hinge masonry vault mechanism analysis and subjected to testing. The technique has been applied in the field supported by a novel application of information technology (IT) image processing, reflecting the growing importance of IT within the construction industry. All theoretical studies have been mounted as micro-computer software with graphics. The accent is upon engineering requirements in practice. Chapter One reviews the context and history of the masonry vault structural form, whose presence has long been commonplace in the United Kingdom, especially on the nation's road network. It is noted that elderly arched road bridges are under continual pressure to carry ever greater loads yet their strength is uncertain. Historically, structural analysts have attempted to resolve the arch's behaviour but present methods are still inexact. Chapter Two describes how, traditionally, masonry has been assumed to possess either a linear stress-strain property or infinite stiffness and strength. An alternative, novel equation for modelling masonry stress-strain laws is presented which may be configured to mimic the behaviour of real materials as well as that of the infinite strength and linear laws it replaces. A numerical analytical procedure has been developed to 'solve' rectangular masonry sections under combined bending and thrust thereby rendering the earlier approximations unnecessary. Chapter Three develops the theme further leading to the numerical determination of limit state hinge characteristics which furnish a static limit state axial thrust/bending moment interaction diagram and a corresponding serviceability limit state, prevention of cracking interaction diagram. Differentiation is thus made possible between hitherto identically-treated though varying natural materials and comparisons made. It is further postulated that any point on a static limit state interaction diagram locus represents a masonry hinge and an extensive series of laboratory model hinge tests is undertaken to demonstrate the point by testing the foregoing theoretical studies. Chapter Four describes the incorporation of the hinge theory into a mechanism-type computer analytical tool. Crucially, the analysis is different from other mechanism analyses by virtue of the hinge modelling, enabling the effects of material properties on arch behaviour to be studied. The software is tested in Chapter Five against prototype data for laboratory model and full size masonry bridges. Chapter Six introduces computer vision, an IT technique that is relatively novel to the structures field. It is adapted to monitor the above laboratory model arch tests and then extended to the monitoring of a multi-span arch bridge test in the field. Computer vision permits the formulation of a hypothesis regarding the unusual mode of failure that occurred and this is supported by a generalisation of the mechanism hinge theory, thereby demonstrating the merits of both techniques. Finally, Chapter Seven draws conclusions on the foregoing and makes suggestions for further work. Supporting documentation is given in the Appendices.
8
Júnior, Luiz Aquino Gonçalves. "Avaliação de incertezas em modelo de dano com aplicação a prismas de alvenaria sob compressão." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-21102008-101410/.
Повний текст джерелаАнотація:
A norma brasileira de cálculo de alvenaria é baseada no método de tensões admissíveis e passa por revisão para ser escrita no método dos estados limites. A confiabilidade estrutural é um ramo da engenharia que mede segurança das estruturas, sendo muitas vezes empregada para calibrar fatores de segurança. Para medir a confiabilidade de uma estrutura deve-se conhecer as incertezas que envolvem o problema. A incerteza de modelo estima a tendência do modelo (que pode ser eventualmente ser eliminada) e a variância do modelo (uma medida da sua variabilidade). O presente trabalho propõe um método de cálculo da incerteza de um modelo numérico de um prisma formado por três unidades concreto sujeito à compressão. O estudo numérico é feito em elementos finitos com análise não-linear baseada em dano. A incerteza é avaliada através de variáveis de projeto: tensão máxima, deformação na tensão máxima e módulo de elasticidade. São aplicados métodos probabilísticos para comparar resultados numéricos e ensaios experimentais disponíveis na literatura. Confronta-se a probabilidade de falha resultante de resistências corrigidas, sem correção e obtidas experimentalmente. Conclui-se que a incerteza de modelo é importante para quantificar a medida de segurança e deve ser levada em conta na análise da confiabilidade de uma estrutura. O procedimento também é útil para qualificar e comparar modelos de cálculo, com aplicações em alvenaria ou quaisquer outros tipos de estruturas.The brazilian masonry code is based on the allowable stress method and is currently in revision to be written in the partial safety factor format. Structural reliability is a branch of engineering which allows quantitative evaluation of the safety of structures, being useful in the calibration of safety factors. To measure structural safety, it is necessary to know the uncertainties present in the problem. Model error variables estimate the bias of the model (wich can eventually be eliminated) and the variance of the model (a measure of the model variability). The present work suggests a method for evaluation of modeling uncertainty of the resistence of a prism made of three concrete units subject to compression. The numerical study is based on the finite element method and nonlinear analysis with damage mechanics. The uncertainty is evaluated by design variables: maximum stress, deformation in maximum stress and elasticity modulus of the prism. A probabilistic method is used to compare numerical results with experimental results taken from the literature. The probability of failure based on experimental resistances are compared with the probability of failure based on the model and corrected resistances. It is concluded that the model uncertainty is important to quantify safety and must be taken into account in structural reliability analysis. The procedure is also useful to qualify and compare different models, with application to masonry or other kinds of structural materials.
9
Shapiro, Elaine Elizabeth. "Collapse mechanisms of small-scale unreinforced masonry vaults." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/72648.
Повний текст джерелаАнотація:
Thesis (S.M. in Building Technology)--Massachusetts Institute of Technology, Dept. of Architecture, 2012.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 61-63).
The structural behavior of masonry arches under various forms of loading is well-studied; however, the three-dimensional behavior of barrel vaults and groin vaults is not as well understood. This thesis aims to address this problem by performing scale model testing of barrel and groin vaults as a complement to analytical solutions. The behavior of the model vaults are observed in four cases: (1) spreading supports, (2) vertical point loads applied at various locations of the vault's geometry, (3) point loads applied to an initially deformed vault, and (4) horizontal acceleration through tilting. In all cases, extensive experimental testing is carried out on a subset of three model vaults: two barrels and one groin vault, all with the same radius and thickness ratio but with different angles of embrace. High-speed cameras are used to capture the collapse mechanism of the vaults. The analyses include equilibrium methods executed through Excel and Matlab programs, publicly available online applets for arch stability, and hand calculations. The testing and analysis carried out in this thesis reveal several properties that can be used by engineers studying existing structures. First, a groin vault's spreading capacity is determined by the constituent barrel vault that is spreading. This simplifies the analysis to a two-dimensional problem. Second, the load capacity of a barrel vault is linearly proportional to the initial deformation in span. So, if a vault experiences a span increase that is 25% of the maximum it can withstand, its load capacity decreases by 25%. Nearly all vaults have experienced deformations due to settlement over time and will therefore respond differently to loading than a perfect vault which is the common starting point in analysis. This work can be applied to the understanding and maintenance of masonry vaults in service throughout the world.
by Elaine Elizabeth Shapiro.
S.M.in Building Technology
10
Marino, Salvatore. "Mechanical behaviour of composite spandrels in unreinforced masonry buildings." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amslaurea.unibo.it/5951/.
Повний текст джерелаАнотація:
La presente tesi tratta il comportamento meccanico delle fasce di piano in muratura composite. Con tale termine ci si riferisce alle fasce di piano che hanno al di sotto un elemento portante in conglomerato cementizio armato, come ad esempio cordoli o solai. Assieme ai maschi murari, le fasce di piano costituiscono gli elementi portanti di una parete in muratura. Tuttavia, in caso di analisi sismica di un edificio in muratura, l’effetto fornito da tali elementi è trascurato e si considera solamente il contributo dei maschi murari. Ciò è dovuto anche alla scarsa conoscenza che ancora oggi si possiede sul loro comportamento meccanico. Per questo motivo diversi gruppi di ricerca tutt’ora sono impegnati in tale studio. In particolare, il lavoro di questa tesi, s’inserisce nel più ampio progetto di ricerca condotto dalla professoressa Katrin Beyer, direttrice del Laboratorio di Ingegneria Sismica e Dinamica Strutturale del Politecnico di Losanna (Svizzera).
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Tayer, André Del Negro. "Modelagem numérica de juntas de argamassa em estruturas de alvenaria utilizando elementos finitos com alta razão de aspecto." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-27082018-102403/.
Повний текст джерелаАнотація:
Este trabalho apresenta um novo modelo numérico para simulação de juntas de argamassa em estruturas de alvenaria no plano via método dos elementos finitos. Neste modelo, blocos de alvenaria e juntas de argamassa são representados separadamente. Elementos finitos com alta razão de aspecto são utilizados para representar as juntas de argamassa e são inseridos na malha de elementos finitos através de uma técnica de fragmentação de malha. A principal vantagem desta técnica consiste na utilização de modelos constitutivos contínuos para representar regiões descontínuas, uma vez que seu campo de deformações quando a altura do elemento de interface tende a zero é semelhante ao apresentado pela abordagem de aproximação contínua de descontinuidades fortes. Um modelo constitutivo contínuo baseado na mecânica do dano foi desenvolvido para representar o comportamento dos elementos de interface. Este modelo consegue representar a abertura e fechamento de fraturas, bem como o efeito de atrito em função da tensão de confinamento nas interfaces. Como o objetivo deste trabalho consiste na simulação da formação e propagação de fraturas ao longo das juntas de argamassa, comportamento elástico linear foi atribuindo aos elementos triangulares de três nós utilizados na discretização dos blocos de alvenaria. Vários exemplos numéricos são apresentados. Inicialmente, testes básicos são realizados para demonstrar as principais características do modelo quando submetido a carregamentos de tração, compressão e cisalhamento. Posteriormente, estruturas de alvenaria submetidas a carregamentos estáticos são analisadas e os resultados comparados com as respostas experimentais a fim de validar o modelo proposto. A técnica proposta se mostrou bastante promissora para simulação da formação e propagação de fratura em juntas de argamassa de estruturas de alvenaria.This work presents a novel numerical model to simulate the failure process in masonry structures subjected to static loads via finite element method. Brick and mortar joints are modeled separately with their own constitutive equations. Interface finite element with high aspect ratio are used to simulate the mortar interface and inserted by the mesh fragmentation technique. The main advantage of this strategy is supported by the fact that, as the aspect ratio of a standard low-order solid finite element increases, the element strains also increase, approaching the same kinematics as the Continuum Strong Discontinuity Approach. A constitutive model was developed, based on the continuum damage mechanics, in order to represent the behavior of the interface finite elements. This model is able to simulate the creation and propagation of cracks, as well as, the frictional effects in dependence on stress confinement on the interfaces. Furthermore, as the objective of this work aims to simulate the failure in the mortar joints, the brick elements are assumed as linear elastic material. Three node standard triangular finite element are used to represent the bricks. Several numerical models are carried out. Initially, basics tests are show in order to demonstrate the main characteristics of the proposed model subjected to tensile, compression and shear loads. Subsequently, masonry structures are subjected to static loads are analyzed and the results compared with the experimental responses in order to validate the proposed model. This technique proved to be very promising for the simulation of failure onset and propagation in mortar joints of masonry structures.
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Ruvalcaba, Ayala Fabian Rene. "Mechanical properties and structural behaviour of masonry at elevated temperatures." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/mechanical-properties-and-structural-behaviour-of-masonry-at-elevated-temperatures(1e2424f0-ab1b-4895-b71c-398783b4a7fb).html.
Повний текст джерелаАнотація:
The variation in the compressive strength of concrete block masonry was studied at elevated temperatures. Small specimens known as wallettes were used to obtain the compressive strength under steady state conditions. Eighteen wallettes were made of lightweight concrete blocks and 1:1:5 mortar proportion. The target temperatures were 20°C, 200°C, 400°C, 600°C, 700°C and 800°C. Initially load-deflection relationships were determined from the experimental wallettes and later they were converted into stress-strain relationships. Although the goal was to determine the compressive strength, other parameters were also studied such as modulus of elasticity, temperature-time relationships, modes of failure, material degradation, and change of colour.Lightweight concrete blocks were also tested to determine the compressive strength at equal temperatures applied for the wallettes. The blocks belonged to the same batch used for the wallettes. The tensile behaviour of mortar was determined at 20°C, 200°C and 400°C.Once the mechanical properties of the masonry wallettes, units and mortar were determined, they were used as input data to develop finite element models to simulate the same behaviour of the experimental wallettes. Finally, using the experimental and numerical results from the wallettes, they were used to predict the behaviour of 3m height walls.
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Silveira, Dora Susana Gomes da. "Constructive and mechanical characterisation of adobe masonry walls of existing buildings." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/17313.
Повний текст джерелаАнотація:
Doutoramento em Engenharia CivilEarthen construction has been widely used throughout the world, since approximately 10000 years ago and until the present day. A significant part of the world earthen built heritage – including many properties inscribed on the UNESCO’s World Heritage List –, however, is at risk. In Portugal, earth was also a widely used construction material until the middle of the 20th century. In Aveiro district, in particular, adobe construction was very common. Currently, there are still a great number of adobe constructions in this region, a large part of which are in use. Many of the existing buildings are of social, cultural, and architectural value. Despite their value, however, many of these buildings are in a poor state of conservation, suffering from various structural and non-structural defects. The problems observed in existing adobe buildings result in large part from a lack of knowledge regarding the materials and building systems used in this type of construction. There is, in particular, a lack of knowledge about the properties and behaviour of adobe masonry walls, which are key structural elements that influence the overall behaviour of buildings. The main aim of the research developed and discussed in this thesis is thus to contribute to this knowledge, focusing, in particular, on the adobe buildings of Aveiro district. For this purpose, a visual and dimensional inspection of the facade walls of twenty-one representative adobe buildings was conducted. With this inspection, it was possible to carry out a detailed analysis of the facade walls – including their structural system, coatings, and traditional masonry materials – and to assess the vulnerabilities, common defects, and state of conservation of these elements. A series of experimental tests were also carried out. Simple compression tests were performed on cylindrical and cubic adobe specimens, flexural tests on adobe bricks, and splitting tests on cylindrical specimens. Simple compression and diagonal compression tests were also conducted on ten full-scale adobe masonry wall panels, built with adobes taken from an existing construction. Finally, an in-plane horizontal cyclic test was performed on a full-scale double-T shaped adobe wall, also built with adobes from an existing construction. With the tests carried out, it was possible to characterise the strength, stiffness, stress-strain relationships, and common damage pattern of the test specimens, and to assess correlations between different mechanical properties. It was also possible to develop a comparison between the strength values obtained and the limits indicated in existing standards for earthen construction, and between the results obtained and those determined by other authors for test specimens representative of adobe construction in other countries. The results presented and discussed in this thesis contribute to the enrichment of knowledge that is considered essential to support the conservation and rehabilitation of existing adobe buildings, not only in Portugal, but also in other regions of the world.
A construção em terra tem sido muito utilizada em todo o mundo, desde há cerca de 10000 anos atrás e até aos dias de hoje. Uma parte significativa do património mundial construído com terra, incluindo vários bens inscritos na Lista de Património Mundial da UNESCO, encontra-se, no entanto, em risco. Em Portugal, a terra foi também um material de construção muito utilizado até meados do século XX. No distrito de Aveiro, em particular, a construção em adobe era muito comum. Atualmente, existe ainda um elevado número de construções em adobe nesta região, grande parte das quais se encontram em uso. Muitos dos edifícios existentes são de valor social, cultural e arquitetónico reconhecido. No entanto, apesar do seu valor, muitos destes edifícios estão em mau estado de conservação, apresentando anomalias estruturais e não estruturais variadas. Os problemas observados nos edifícios existentes de adobe resultam, em grande parte, de falta de conhecimento sobre os materiais e sistemas de construção utilizados neste tipo de edificação. Há, em particular, falta de conhecimento sobre as propriedades e o comportamento das paredes de alvenaria de adobe, que são elementos estruturais principais que influenciam o comportamento global dos edifícios. Assim, o trabalho de investigação desenvolvido e discutido nesta tese tem como principal objetivo contribuir para este conhecimento, debruçando-se, em particular, sobre as construções em adobe do distrito de Aveiro. Para este efeito, foi realizada uma inspeção visual e dimensional das paredes de fachada de vinte e um edifícios de adobe representativos. Com esta inspeção, foi possível analisar de forma detalhada as paredes de fachada – incluindo o seu sistema estrutural, revestimentos e materiais de alvenaria tradicionais – e avaliar as vulnerabilidades, anomalias comuns e estado de conservação destes elementos. Uma série de ensaios experimentais foi também levada a cabo. Foram realizados ensaios de compressão simples sobre provetes cilíndricos e cúbicos de adobe, ensaios de flexão sobre blocos de adobe e ensaios de compressão diametral sobre provetes cilíndricos. Foram ainda realizados ensaios de compressão simples e compressão diagonal sobre dez painéis de alvenaria de adobe à escala real, construídos com adobes recolhidos de uma construção existente. Por fim, realizou-se o ensaio de uma parede à escala real em forma de ‘duplo T’, construída também com adobes de uma construção existente, sob a ação de uma carga horizontal cíclica, aplicada no plano da parede. Com os ensaios realizados, foi possível caracterizar a resistência, a rigidez, as relações de comportamento tensão-deformação e o padrão comum de dano dos elementos ensaiados, e avaliar as correlações entre diferentes propriedades mecânicas. Foi ainda desenvolvida uma comparação entre os valores de resistência obtidos e os limites indicados nas normas existentes para a construção em terra, bem como entre os resultados obtidos e aqueles determinados por outros autores para a alvenaria de adobe representativa da construção em adobe noutros países. Os resultados apresentados e discutidos nesta tese contribuem para o enriquecimento de conhecimento que é considerado essencial para apoiar a conservação e reabilitação dos edifícios de adobe existentes, não só em Portugal, mas também noutras regiões do mundo.
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Panizza, Matteo. "FRP strengthening of masonry arches: analysis of local mechanisms and global behaviour." Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3427075.
Повний текст джерелаАнотація:
In the last two decades, FRP (Fibre-Reinforced Polymers) composite materials have been adopted for strengthening and repair of both modern and historic masonry constructions (buildings, bridges, towers) and structural components (walls, arches and vaults, piers and columns).
Strengthening of masonry brick arches and vaults with FRP laminates can contribute significantly in the improvement of their structural capacity at a limit state, by activating local mechanisms both at material and interface levels, but also modifies the collapse mechanisms of the original structures, as the reinforcement prevents the typical brittle failure due to the formation of hinge-mechanisms.
Despite the increasing number of specific studies on FRP reinforcement of masonry structures, investigations are still limited if compared to reinforced concrete applications. Moreover, few codes and recommendations are currently available.
Starting from these points, the present work deals with experimental investigations on three local mechanisms involved by the collapse of FRP-reinforced masonry arches: the interface behaviour in the case of stresses normal to the surface (FRP detachment observed in structures with intrados reinforcement) has been investigated through the execution of a large number of combined tests on solid clay bricks (flexural, compressive, splitting and pull-off tests) aimed at experimentally calibrate possible correlations among the corresponding strength parameters and to observed possible influences of the fibres type and the presence of primer on the pull-off behaviour; the bond behaviour has been investigated by performing ten Double-lap Shear Tests on solid clay bricks, aimed at calibrating fracture energy value and bond-slip law for both carbon FRP and glass FRP reinforcement (moreover, a simple exponential-based bond-slip law has been proposed); the mixed-mode behaviour (fourteen tested samples) has been investigated by adapting a test setup developed for FRP applications on reinforced concrete, known as V-shape Peel Test, to clay substrate, in order to reproduce on a local scale the conditions related to the shear sliding failure of arches with extrados reinforcement.
Finally, several case studies, concerning real-scale or scaled brick masonry arches and vaults reinforced at their intrados or extrados, have been collected from literature in order to compare the experimental results to the available interpretative models of the global behaviour of the structure at failure.Negli ultimi due decenni, i materiali compositi FRP (Fibre-Reinforced Polymers) sono stati adottati anche nel rinforzo di costruzioni murarie sia moderne sia antiche (edifici, ponti, torri), nonché di vari elementi strutturali (pareti, archi e volte, pile e colonne). Il rinforzo di archi e volte in muratura con FRP può contribuire in modo significativo a migliorare la loro portanza in stato limite, attivando meccanismi locali a livello di materiali e interfaccia, ma comporta anche un cambiamento dei meccanismi di collasso della struttura originale, dal momento che il rinforzo impedisce la tipica rottura fragile causata dalla formazione di meccanismi a cerniera. Nonostante un crescente numero di studi riguardanti il rinforzo di strutture murarie con FRP, le indagini sono tuttavia ancora limitate, se confrontate con applicazioni su calcestruzzo armato. Inoltre, pochi codici e raccomandazioni sono attualmente disponibili. Partendo da questi punti, il presente lavoro affronta l'indagine sperimentale di tre meccanismi locali coinvolti nel collasso di archi rinforzati con FRP: il comportamento dell’interfaccia nel caso di tensioni normali alla superficie (distacco del composito osservato in strutture rinforzate all’intradosso) è stato investigato mediante l’esecuzione di un ampio numero di prove combinate eseguite su mattoni pieni in laterizio (prove a flessione, compressione, trazione indiretta e pull-off), allo scopo di calibrare sperimentalmente eventuali correlazioni fra i relativi parametri di resistenza e di osservare eventuali influenze del tipo di fibra e della presenza del primer sul comportamento nella prova di pull-off; il comportamento nel caso di azioni tangenziali è stato studiato mediante l’esecuzione di dieci Double-lap Shear Tests su mattoni pieni in laterizio, al fine di calibrare energia di frattura e legge bond-slip per rinforzo in fibra di carbonio e fibra di vetro (inoltre, è stata proposta una semplice legge bond-slip); il comportamento nel caso di azioni miste (quattordici prove eseguite) è stato investigato mediante l’adattamento di una prova sviluppata per applicazioni di FRP su calcestruzzo armato, nota come V-shape Peel Test, a mattoni in laterizio usati come substrato, allo scopo di riprodurre a scala locale le condizioni relative allo scorrimento a taglio sul giunto di archi con rinforzo estradossale. Infine, vari casi studio, riguardanti archi e volte in muratura, a dimensioni reali oppure scalate, sono stati raccolti da letteratura al fine di comparare i risultati sperimentali con i modelli interpretativi del comportamento globale della struttura a collasso attualmente disponibili.
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MacMullen, James. "Novel nano-particulate/polymer treatment systems for masonry enhancement and protection." Thesis, University of Portsmouth, 2012. https://researchportal.port.ac.uk/portal/en/theses/novel-nanoparticulatepolymer-treatment-systems-for-masonry-enhancement-and-protection(b2a572a6-690e-4c45-bb61-2c4dc02b9f7b).html.
Повний текст джерелаАнотація:
Fundamental issues associated with addressing the UK housing shortage problem are climate change and the lack of usable building space. Conservation of old buildings, maintaining green land and a country filled with single walled older properties mean that the UK government has to retrofit existing older building stock. This would make a significant impact on reducing the carbon footprint of each household as well as to alleviate energy supply problems. The investigation of novel zinc oxide and titanium dioxide nanoparticulates in aqueous silane/siloxane oil-in-water (O/W) emulsions for practical exterior facade applications is presented. An initial emulsion was developed and optimised before further improvement through nanoparticulate incorporation was achieved. Nanoparticulates of zinc oxide and titanium dioxide were dispersed respectively using ultrasonication in n-isooctyltriethoxysilane before being incorporated into a base emulsion. Once formulations were optimised, applied studies and fundamental assessment of these emulsions were conducted. The aim of the work presented was to produce a practical facade emulsion that could be used in the retrofitting of existing building stock or for heritage remedial treatments. Initial research indicated that water was the governing factor in a diverse range of facade degradation mechanisms; improving water repellence, thermal envelope efficiency while reducing biofouling was recognised as being of key interest in this field. The study gives insight into aqueous water repellent emulsions, nanoparticulate integration by commercially practical means, and assessment of the attributes exhibited by such treatments. Rheological and morphological characterisation concluded that a gelled network structure is produced by the incorporation of the fabricated nanoparticulate colloids. The emulsions retained shear-thinning characteristics, ideal for deep treatment penetration to be achieved for porous silicate substrates. Accelerated ageing tests showed that the nanoparticulate emulsions were substantially more thermodynamically stable than the emulsion control while also being physically more stable due to surfactant-particulate stabilisation mechanisms of the polar phases. From further investigation it was also found that hydroxyl terminated siloxane could be integrated into these emulsions, helping to improve the ‘green credentials’ of such systems through the replacement of conventionally used trimethoxy terminated siloxanes, that release harmful methanol upon curing, thus substitution is preferential and in line with current European policy. Treatments improved thermal envelope efficiency of structures through the reduction of retained water in various forms including rising damp. Assessment was carried out using model houses exposed to various temperature and humidity scenarios under controlled heating. The findings showed that water was the root cause of heat loss and thus a key parameter when considering the improvement of a structures’ carbon footprint. These treatments allow water vapour to permeate out of a structure passively, reducing internal humidity issues including microbiological degradation and health related problems experienced by occupants. Investigation of bioreceptivity conducted though an 8 week algal culture streaming study concluded that treatments with <0.1wt% of the aforementioned nanoparticulates could reduce biofouling through photo-induced sanitisation. Furthermore, it was also found that while water repellence may vary at the facade interface due to the respective metal oxides photocatalytic nature, substrate interior water contact angles should remain high due to the absence of UV light. This is of key importance as it implies that simultaneous antifouling and rising damp remediation may be achieved by such treatments. One of the major advantages of the treatments presented is that they do not effectively alter the aesthetics of the substrate, unlike photo-induced ‘self-cleaning’ coatings that turn the facade white. In addition, these treatments are not susceptible to problems related to the cracking or chipping of coated surfaces, allowing them to provide better protection. From the above points it is clear that these treatments are the next paradigm in facade protection, complying with current social, ecological, political and industrial needs. This study presents the inception, development and investigation of key attributes and mechanisms of these novel treatments while showing critically that such emulsion treatments are practical with great potential to enhance the lives of UK residents.
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Mehrotra, Anjali Abhay. "A computational tool for seismic collapse assessment of masonry structures." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/287464.
Повний текст джерелаАнотація:
Earthquakes represent a serious threat to the safety of masonry structures, with failure of these constructions under the influence of seismic action generally occurring via specific, well-documented collapse mechanisms. Analysis and assessment of these collapse mechanisms remains a challenge - while most analysis tools are time-consuming and computationally expensive, typical assessment methods are too simplified and often tend to underestimate the dynamic resistance of the structures. This dissertation aims to bridge the gap between the two through the development of a computational tool for the seismic collapse assessment of masonry structures, which uses rocking dynamics to accurately capture large displacement response, without compromising on computational efficiency. The tool could be used for rapid evaluation of critical mechanisms in a structure in order to prioritise retrofit solutions, as well as for code-based seismic assessment. The framework of the tool is first presented, wherein the rocking equations of motion are derived for a range of different collapse mechanisms, for any user-defined structural geometry, using as a starting point a geometric model of the structure in Rhino (a 3D CAD software). These equations of motion are then exported for solution to MATLAB. As a number of collapse mechanisms take place above ground level, a methodology to account for ground motion amplification effects is also proposed, while in the case of comparison of multiple different mechanisms, an algorithm to automatically detect critical mechanisms is presented. These developments make it possible to rapidly conduct a seismic analysis of structures with complicated three-dimensional geometries. However, the rocking equations of motion utilised thus far assume that the interfaces between the masonry macro-elements are rigid, which is not the case in reality. Thus, a flexible interface model is introduced, where the interfaces are characterised by a finite stiffness and compressive strength. This modelling strategy results in an inward shift of the rocking rotation points, and expressions are derived for these shifting rotation points for different interface geometries. The rocking equations of motion are also re-derived to account for the influence of the continuously moving hinges. However, the new equations tend to be highly non-linear - especially in the case of more complex collapse mechanisms. Thus to reduce computational burden, the semi-flexible interface model is proposed, which accounts for the shifting hinges in a more simplified manner than its fully-flexible counterpart. These new analytical models enable more accurate prediction of the seismic response of real-world structures, where interface flexibility tends to have a significant influence on dynamic response, while material damage in the form of crushing of the masonry also reduces dynamic resistance. The ability of the tool to be used for both seismic analysis and assessment is finally demonstrated by using it to perform a rocking dynamics-based analysis as well as a code-based seismic assessment of the walls of a historic earthen structure.
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Albattah, Abdulraheem. "Masonry Train Bridge Evaluation Using Finite Element Technique." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Знайти повний текст джерелаАнотація:
This paper explores the application of finite element methods to a masonry rail bridge. And Identifying which elements need strengthening – and planning suitable interventions – requires not merely an assessment of load-carrying capacity but moreover a thorough understanding of the structural behavior of the bridge.
The scope and impact of this thesis is better framed recalling a masonry rail bridge In Italy , and modelling it using Sap2000 Software , Reviewing the assessment methods used ,Evaluating the behavior of the bridge for static (Dead load only) and Modal analysis .
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Rudoltz, Hannah R. "Commercialization of a masonry tool designed in a senior-capstone class through a licensing agreement." Thesis, Massachusetts Institute of Technology, 2018. https://hdl.handle.net/1721.1/122879.
Повний текст джерелаАнотація:
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018Cataloged from PDF version of thesis.
Includes bibliographical references.
Many seemingly viable products are designed and built in MIT Mechanical Engineering's senior capstone design class, 2.009, but a small fraction make it to real markets. The 2017 2.009 Orange Team is commercializing their product through the company Rhino Tools and Equipment (RTE). The product, a rotary hammer attachment that guides the chisel bit as it moves within a mortar joint, was designed with the aim of improving the repointing work done by masons on brick exteriors. Given the real constraints on a team of soon-to-be graduating students and analysis of the market and the product, a licensing business model was chosen. The licensing business model is heavily reliant on intellectual property. Thus, an extensive prior art search was carried out to determine the product's novelty. By this analysis the product is patentable. Cash flows were projected to determine a fair allocation of economic benefit in a licensing agreement; RTE should expect to receive about 4.5% royalty on revenue. Moving forward, RTE should pursue funding to complete the patent process as well as a pilot program with masons, and continue to develop its connections within the tool industry.
by Hannah R. Rudoltz.
S.B.
S.B. Massachusetts Institute of Technology, Department of Mechanical Engineering
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Al-Sibahy, Adnan Flayih Hassan. "Thermo-mechanical behaviour of a novel lightweight concrete and its application in masonry walls." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/thermomechanical-behaviour-of-a-novel-lightweight-concrete-and-its-applicationin-masonry-walls(a803fcb4-a33c-4594-8622-87e565a7ceb4).html.
Повний текст джерелаАнотація:
The development of lightweight concretes has made a contribution to advances in structural design. It would be useful to further improve the mechanical properties of lightweight concrete formulations whilst enhancing their resistance to fire degradation and reduced thermal conductivity. Improving the sustainability of any new proposed lightweight concrete formulation is desirable, for example by the inclusion of waste stream components into the formulation.This thesis describes an investigation of the mechanical, thermal and fire resistance properties of a new type of expanded clay lightweight concrete formulation in which varying quantities of sand are replaced by crushed glass aggregate, in conjunction with the addition of metakaolin (which may be available as a waste component from the manufacture of paper) as a partial replacement for the cement. The investigation involved short and long-term laboratory testing of a range of mechanical and thermal properties of individual concrete formulations and small scale structural elements consisting of masonry blocks made from these formulations (so called wallettes). An extensive programme of Finite Element Analysis using Abaqus was also performed.The results obtained show that it is possible to produce a structural expanded clay lightweight concrete that possesses good thermal properties by incorporating of ground glass and metakaolin. Compressive and splitting tensile strengths, as well as the modulus of elasticity, increased with an increase in the metakaolin content, while concrete density decreased. Reductions in thermal conductivity and improvements in fire resistance criteria were also observed in comparison with conventional lightweight concrete mixtures. For example, measured thermal conductivity values ranged from 0.092 W/m.K to 0.177 W/m.K, and the insulation criterion (an indicator of resistance to fire) reached up to 110 minutes for a concrete member with a thickness of 29 mm. The highest resistance to the effects of high temperatures was observed for concrete mixes containing either 15% or 30% recycled glass with 10% metakaolin.The maximum axial loads at failure were 474 kN and 558 kN for reference and modified wallettes respectively, implying corresponding bearing capacities of 7.1 MPa and 8.3 MPa. The critical path of the failure mode was similar for all of the wallettes tested and normally began underneath the load point, then passed through the concrete blocks and head joint to reach the toe of the wallette. The masonry wallettes formulated using reference lightweight concrete blocks exhibited failure due to explosive spalling at 400 oC with no applied mechanical load, whereas the second type of masonry wallettes (the modified wallettes) did not show such behaviour.The results of Finite Element Analysis showed that the coefficient of thermal convection had the most influence upon the insulation criterion. From a structural perspective, the key parameters were the value of penalty stiffness and imperfections in wallette construction. In general, a close agreement between the measured and simulated results was observed for both the thermal and structural finite element models at ambient and high temperatures.
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Foscan, Tiziana. "Mechanical characterization of double-wythe masonry walls with a view to in-situ testing methods." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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Unreinforced masonry is one of the most commonly used structure typologies for the construction of residential buildings, which is why the estimation of its mechanical parameters is of primary importance. The main techniques to acquire them are based on destructive methods, however less invasive tests have been studied in the past years in order to obtain the same parameters in-situ: the core testing method is one of those. While monotonic compression tests on single-wythe cores provided good results, tests performed on double-wythe cores have given a significant overestimation of the compressive strength, supposedly due to the excessive stiffness of the high strength mortar cap used to perform the tests, that doesn’t allow the opening of the collar joint. An experimental campaign was conducted at Delft University of Technology in order to identify a new configuration of the cap suitable to use in moderately destructive tests to retrieve the mechanical properties of masonry under compression. An initial Finite Element Analysis is performed to anticipate the behaviour of the different configurations in order to choose the right prototypes. Four different models are developed, and the most significant ones are implemented and tested in the laboratory. In particular, a configuration with high strength mortar cap is tested as a comparison with previous tests on double-wythe cores, while a configuration with a high strength mortar cap separated from the core by a neoprene sheet is chosen in an attempt to reduce the confinement in the direction perpendicular to the collar joint. Finally the results obtained from the monotonic compression tests on cores are compared with the results from destructive tests on companion wallets, which were carried out in a previous experimental campaign on the same masonry.
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Elzokra, Ahmed Adel Emhemed. "Damage mechanisms in porous building materials due to salt crystallization: formulation of equivalent materials for masonry." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Знайти повний текст джерелаАнотація:
An equivalent material approach is presented for the computation of the elastic properties of brick masonry and for the assessment of salt crystallization in masonry structures. A stacked brick-mortar system consisting of a series of parallel layers which behave elastically is introduced. This is extended such that masonry with two sets of mortar joints (bed and head joints) can be represented by an equivalent homogeneous orthotropic elastic material. It is then extended to salt deteriorated brick masonry by including salt crystals induced within the pores. In terms of the elastic properties of the brick and mortar, as well as relative thicknesses, expressions for the equivalent material's elastic properties are derived. The mechanical properties of salt deteriorated masonry are computed in terms of effective porosity and saturation ratio. Using this derivation, the stresses in the brick-and-mortar joints are calculated for a masonry wall partial deteriorated by salt and subjected to thermal stress variation.
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Gabrielli, Elena <1982>. "Experimental assessment of environmental decay effects in masonry via non destructive diagnostic techniques and mechanical tests." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6653/1/Tesi_Gabrielli.pdf.
Повний текст джерелаАнотація:
Environmental decay in porous masonry materials, such as brick and mortar, is a widespread problem concerning both new and historic masonry structures. The decay mechanisms are quite complex dependng upon several interconnected parameters and from the interaction with the specific micro-climate. Materials undergo aesthetical and substantial changes in character but while many studies have been carried out, the mechanical aspect has been largely understudied while it bears true importance from the structural viewpoint. A quantitative assessment of the masonry material degradation and how it affects the load-bearing capacity of masonry structures appears missing.
The research work carried out, limiting the attention to brick masonry addresses this issue through an experimental laboratory approach via different integrated testing procedures, both non-destructive and mechanical, together with monitoring methods. Attention was focused on transport of moisture and salts and on the damaging effects caused by the crystallization of two different salts, sodium chloride and sodium sulphate.
Many series of masonry specimens, very different in size and purposes were used to track the damage process since its beginning and to monitor its evolution over a number of years Athe same time suitable testing techniques, non-destructive, mini-invasive, analytical, of monitoring, were validated for these purposes. The specimens were exposed to different aggressive agents (in terms of type of salt, of brine concentration, of artificial vs. open-air natural ageing, …), tested by different means (qualitative vs. quantitative, non destructive vs. mechanical testing, punctual vs. wide areas, …), and had different size (1-, 2-, 3-header thick walls, full-scale walls vs. small size specimens, brick columns and triplets vs. small walls, masonry specimens vs. single units of brick and mortar prisms, …). Different advanced testing methods and novel monitoring techniques were applied in an integrated holistic approach, for quantitative assessment of masonry health state.
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Gabrielli, Elena <1982>. "Experimental assessment of environmental decay effects in masonry via non destructive diagnostic techniques and mechanical tests." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6653/.
Повний текст джерелаАнотація:
Environmental decay in porous masonry materials, such as brick and mortar, is a widespread problem concerning both new and historic masonry structures. The decay mechanisms are quite complex dependng upon several interconnected parameters and from the interaction with the specific micro-climate. Materials undergo aesthetical and substantial changes in character but while many studies have been carried out, the mechanical aspect has been largely understudied while it bears true importance from the structural viewpoint. A quantitative assessment of the masonry material degradation and how it affects the load-bearing capacity of masonry structures appears missing.
The research work carried out, limiting the attention to brick masonry addresses this issue through an experimental laboratory approach via different integrated testing procedures, both non-destructive and mechanical, together with monitoring methods. Attention was focused on transport of moisture and salts and on the damaging effects caused by the crystallization of two different salts, sodium chloride and sodium sulphate.
Many series of masonry specimens, very different in size and purposes were used to track the damage process since its beginning and to monitor its evolution over a number of years Athe same time suitable testing techniques, non-destructive, mini-invasive, analytical, of monitoring, were validated for these purposes. The specimens were exposed to different aggressive agents (in terms of type of salt, of brine concentration, of artificial vs. open-air natural ageing, …), tested by different means (qualitative vs. quantitative, non destructive vs. mechanical testing, punctual vs. wide areas, …), and had different size (1-, 2-, 3-header thick walls, full-scale walls vs. small size specimens, brick columns and triplets vs. small walls, masonry specimens vs. single units of brick and mortar prisms, …). Different advanced testing methods and novel monitoring techniques were applied in an integrated holistic approach, for quantitative assessment of masonry health state.
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Dorji, Jigme. "Strength and serviceability assessment of aged masonry arch bridges." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/213050/1/Jigme_Dorji_Thesis.pdf.
Повний текст джерелаАнотація:
This thesis investigated strength and serviceability of aged masonry arch bridges which exist in rail track networks in Australia. The method is based on the measurement of structural responses under operating loads and experimental tests. Two typical bridges were investigated for Australian Rail and Track Corporation Ltd (ARTC) and found that the bridges are safe against the operating loads, despite having undergone aging phenomenon.
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Franceschelli, Stefano. "Experiments on Chinese historical brick and masonry to evaluate their physical and mechanical properties after freeze-thaw cycles." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
Знайти повний текст джерелаАнотація:
Ultrasonic Pulse Velocity (UPV) and Rebound test as non-destructive techniques may effectively contribute to in situ analysis of bricks and masonries elements for the restoration, rehabilitation and strengthening of historic buildings.
Fired-clay bricks were commonly used in buildings in ancient China, but there is few knowledge on their behaviour in environmental conditions. Moisture is one of the main factors that cause deterioration in historic building, in particular in areas with natural freeze-thaw cycles.
In this work, two laboratory experiments were carried out, at Tongji University, China, and DICAM Department of Bologna University, Italy, respectively. Fired-clay bricks about 200 years old were collected from demolished buildings in Changzhi City in Shanxi Province, belonging to the Yellow River Region, where the climate involves natural freeze-thaw cycles.
The aim was to evaluate how the frost damage changes the physical and mechanical properties of Chinese historical bricks and masonries. Several non-destructive methods were used, focusing on the effectiveness of Ultrasonic Pulse Velocity (UPV) for evaluating physical and mechanical properties of Chinese historic grey bricks and masonries. Destructive tests were also used to evaluate compressive strength and static elastic modulus.
The samples showed a reduction of their properties due to freeze-thaw cycles. The presence of water affected the values of the analysed parameters, leading to a decrease of UPV.
The trend determined by these methods can be used to assess the uniformity of bricks and to detect areas of poor quality or deteriorated masonry structures.
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Taforel, Paul. "Apport de la Méthode des Éléments Discrets à la Modélisation des Maçonneries en Contexte Sismique : Vers une Nouvelle Approche de la Vulnérabilité Sismique." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2012. http://tel.archives-ouvertes.fr/tel-00801814.
Повний текст джерелаАнотація:
L'évaluation des risques naturels et du risque sismique en particulier a pris une importance croissante pour les autorités publiques ces dernières années, entraînant une adaptation importante des outils utilisés jusqu'à présent dans l'étude de la vulnérabilité du bâti. Il est nécessaire de mieux évaluer ces risques afin de mieux y faire face. De nouvelles approches doivent être proposées pour répondre à ces objectifs dont les approches numériques font partie. Parmi les méthodes numériques développées pour tenir compte de la spécificité du bâti maçonné figurent les approches par éléments discrets comme la méthode NSCD (" Non Smooth Contact Dynamics "). Les travaux présentés dans cette thèse visent à mieux appréhender le comportement mécanique et dynamique des ouvrages maçonnés en utilisant ce type de méthode implémenté dans le code de calcul LMGC90, afin d'affiner la compréhension et la caractérisation de la vulnérabilité sismique des édifices en maçonnerie. La méthodologie que nous cherchons à mettre en place vise à traiter la vulnérabilité sismique de bâtiments spécifiques ou au contraire d'ensembles de bâtiments de même typologie.
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Cannella, Alfio. "Definizione di un "codice di pratica" per la sicurezza e la conservazione dell'edilizia rurale tradizionale nell'area etnea." Doctoral thesis, Università di Catania, 2015. http://hdl.handle.net/10761/3780.
Повний текст джерелаАнотація:
In Italia, l'edilizia rurale tradizionale costituisce un patrimonio architettonico, storico e culturale da preservare e tramandare alle generazioni future. In particolare, il presente lavoro, ha posto l'attenzione sui fabbricati rurali di tipo tradizionale dell'area etnea, realizzati con tecniche costruttive e materiali radicati nel contesto territoriale di appartenenza che caratterizzano fortemente il "genius loci". Gli interventi atti a preservare e migliorare tali edifici, di conseguenza, consentono di salvaguardare la valenza paesaggistica ed ambientale del territorio in cui essi sorgono.
Le attività di studio ed analisi delle tecniche di costruzione tradizionale e dei materiali impiegati hanno costituito una fase propedeutica alla individuazione degli interventi di recupero e conservazione e di miglioramento sismico più appropriati per gli edifici rurali tradizionali dell'area presa in esame.
Le schede tecniche proposte per gli interventi sugli elementi strutturali e decorativi dei fabbricati rurali rilevati sono rispettose delle tecniche costruttive e dei materiali impiegati e, soprattutto, del valore estetico degli edifici. L impostazione grafica di tali schede, inoltre, è stata studiata con l obiettivo di agevolare la scelta dell intervento più appropriato.
Infine, l applicazione numerica per il calcolo dei coefficienti di sicurezza relativi a un edificio campione, tra quelli rilevati, soggetto a meccanismo di collasso di primo modo ha rappresentato un applicazione finalizzata all individuazione di interventi di miglioramento del livello di sicurezza coerenti con quanto dettato dalle Norme Tecniche per le Costruzioni (D.M. 14 gennaio 2008) e dalla relativa Circolare (n. 617/2009).
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Sánchez, Tizapa Sulpicio. "Experimental and numerical study of confined masonry walls under in-plane loads : case : guerrero State (Mexico)." Phd thesis, Université Paris-Est, 2009. http://tel.archives-ouvertes.fr/tel-00537380.
Повний текст джерелаАнотація:
This research work proposes methods to rises the resistance and to evaluate the behavior of confined masonry walls built from clay solid bricks. These elements are widely used in Guerrero State (México) to build masonry structures, which should resist high lateral loads because of the serious seismic hazard. Therefore, a large experimental program to evaluate the mechanical properties of bricks and masonry currently required in the design process and masonry analysis was developed. To rises the masonry resistance and to counteract the influence of the compressive strength of the pieces on the masonry behavior, a high compressive strength mortar and a metallic reinforcement inside the joints were used. With respect to referenced values of the mechanical properties, some were similar and others were twice bigger. In this country zone, the first three tests under lateral load on full-scale confined masonry walls built from clay solid bricks were carried out in order to evaluate its behavior. A reinforcement composed by metallic hexagonal mesh-mortar coat was placed on the faces of two walls to rise or to restore the resistance. The walls showed good behavior and the reinforcement had adequate structural efficiency. Numerical models of panels and walls built by using the experimental data evaluated the envelope resistance, the failure mode and showed the influence of the mechanical properties of the pieces and joints on the global behavior. Two models had metallic reinforcement inside the joints. In addition, a constitutive law of the masonry defined from experimental results allowed to elaborate a simple model, which results were concordant with respect to the experimental results and similar to those calculated by complex models. Finally, two simplified models to evaluate the resistance of confined masonry walls by considering the failure plane on the wall diagonal were developed. One supposes the masonry failure by shear effect and the other supposes the masonry failure by induced tension. The ratio theoretical resistance vs. experimental resistance was adequate for walls built from different materials and tested under different loads, which had ratio Height/Length ranging from 0.74 to 1.26
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Ragnucci, Beatrice. "Data analysis of collapse mechanisms of a 3D printed groin vault in shaking table testing." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22365/.
Повний текст джерелаАнотація:
The aim of this novel experimental study is to investigate the behaviour of a 2m x 2m model of a masonry groin vault, which is built by the assembly of blocks made of a 3D-printed plastic skin filled with mortar. The choice of the groin vault is due to the large presence of this vulnerable roofing system in the historical heritage. Experimental tests on the shaking table are carried out to explore the vault response on two support boundary conditions, involving four lateral confinement modes. The data processing of markers displacement has allowed to examine the collapse mechanisms of the vault, based on the arches deformed shapes. There then follows a numerical evaluation, to provide the orders of magnitude of the displacements associated to the previous mechanisms. Given that these displacements are related to the arches shortening and elongation, the last objective is the definition of a critical elongation between two diagonal bricks and consequently of a diagonal portion. This study aims to continue the previous work and to take another step forward in the research of ground motion effects on masonry structures.
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Llorens, Sulivera Joan. "Experimental study of simple and multi-leaf masonry slender elements under compressive stress loaded parallel to the face." Doctoral thesis, Universitat de Girona, 2020. http://hdl.handle.net/10803/671027.
Повний текст джерелаАнотація:
The thin-tile vault is a structural system widely used in the Mediterranean area. The most spectacular development took place through modernist-style buildings designed by architects such as Antonio Gaudí o Luís Domènech and Muntaner among the others.
Thin-tile vault, from a morphological standpoint, is made up of one or more leaf of thin-tile lay flat, and joined with plaster or mortar. As a particularity of this arrangement, the load is applied parallel to the face of the thin-tile as opposed to the load-bearing walls masonry, where the load is applied perpendicularly to it. Deepening the knowledge of this type of masonry is the main objective of this thesis.
In masonry, normally the compressive strength of the constituent materials is used to analytically establish the compressive strength of the masonry. This thesis, and based on the experimental results on one-, two- , and three-leaf thin-tile specimens, analyse stress-strain law, failure modes, and mechanical properties and compared with those corresponding to different masonries presented in the literatureLa volta catalana és un sistema estructural àmpliament utilitzat en l'àrea mediterrània. Es a través d'edificis d'estil modernista d’arquitectes com Antoni Gaudí o Lluís Domènech i Muntaner que presenta el seu màxim esplendor. La volta catalana, des d'un vessant morfològica, està constituïda per una combinació d'una o diverses fulles de rajoles col·locades planes, i unides amb guix o morter. Una particularitat d'aquesta fàbrica és l’aplicació de la càrrega paral•lela a la cara de la rajola en contraposició a la fàbrica de rajol de parets on aquesta és aplicada perpendicular. Aprofundir en el coneixement d’aquest tipus de fàbrica es el principal objectiu d’aquesta tesis. En fàbrica, habitualment la determinació analítica de la resistència a compressió es determina a partir dels materials constituents (peça i morter). La tesi, i a partir dels resultats experimentals sobre provetes de fàbrica de rajola d'una, dues i tres fulles, analitza el comportament tensió-deformació, el mode de falla i les propietats mecàniques i els compara amb diferents fàbriques presents en la literatura
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Kuchař, Martin. "Stanovení modulu pružnosti zdiva ve směru ložné spáry." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227159.
Повний текст джерелаАнотація:
The determination of strain properties of masonry in the direction parallel to bed joints is a fundamental pre-requisite for designing structures, where masonry is subjected to horizontal stresses (e. g. strengthening with prestressing). The diploma thesis summarized techniques of determination of masonry modulus of elasticity presented in available literature. The goal is to suggest suitable methodology of determination of masonry modulus in direction parallel to the bed joints. In the practical part of the diploma thesis is that methodology verified by experimental test and results of tests are analyzed and discussed.
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Portuguez, Vinces Martha Helen, and Trujillo Bryan Anthonny Calderón. "Influencia de la fibra de lana de oveja en las unidades de adobe para mejorar las propiedades mecánicas de la mampostería." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2020. http://hdl.handle.net/10757/654176.
Повний текст джерелаАнотація:
A lo largo de la historia se han usado distintos materiales de construcción, tal es el caso de la tierra en adobes el cual ha sido utilizado en el ámbito de la construcción por mucho tiempo, debido a su bajo costo y fácil aplicación. Sin embargo, las distintas construcciones se han visto afectadas por diferentes eventos sísmicos causando muchas pérdidas humanas. Por ello, la presente investigación propone implementar una dosificación de 1% fibra de lana con respecto al volumen del suelo y con una longitud de 3 cm, con la finalidad de mejorar las propiedades mecánicas de las unidades y la mampostería de adobe. Para ello, se elaboró 6 unidades patrón y 6 unidades con fibra de lana para someterlas a ensayos de compresión. Asimismo, se elaboraron pilas y muretes para obtener los resultados de los ensayos de compresión en albañilería y compresión diagonal de la mampostería. De esta forma, se obtuvo que la fibra de lana aumenta en un 75% la resistencia a la compresión de la unidad patrón al obtener una resistencia de 2.22 MPa y la una resistencia de 1.27 MPa. De la misma manera, se tiene un incremento del 13% con respecto a la compresión de la pila al obtener una resistencia de 0.51 MPa; no obstante, no cumple con la mínima resistencia de 0.60 MPa estipulada en la norma E0.80. Por último, la fibra de lana aumenta la resistencia a la compresión diagonal en un 25% con respecto a las muestras patrón al obtener una resistencia al corte de 0.059 MPa. Los resultados mencionados indicaron que la incorporación de la fibra de lana mejora significativamente el comportamiento del adobe frente a eventos telúricos.Throughout history, different construction materials have been used, such is the case of adobe earth, which has been used in the construction field for a long time, due to its low cost and easy application. However, the different constructions have been affected by different seismic events causing many human losses. Therefore, the present research proposes to implement a dosage of 1% wool fiber with respect to the volume of the soil and with a length of 3 cm, in order to improve the mechanical properties of the units and the adobe masonry. For this, 6 standard units and 6 units were made with wool fiber to subject them to compression tests. Likewise, piers and walls were made to obtain the results of the masonry compression tests and the diagonal compression of the masonry. In this way, it was obtained that the wool fiber increases the compressive strength of the standard unit by 75% by obtaining a resistance of 2.22 MPa and a resistance of 1.27 MPa. In the same way, there is an increase of 13% with respect to the compression of the pile when obtaining a resistance of 0.51 MPa. However, it does not comply with the minimum resistance of 0.60 MPa stipulated in the E0.80 standard. Finally, the wool fiber increases the resistance to diagonal compression by 25% with respect to the standard samples, obtaining a shear strength of 0.059 MPa. The aforementioned results indicate that the incorporation of the wool fiber significantly improves the behavior of adobe in the face of telluric events.
Trabajo de investigación
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Barbosa, Claudius de Sousa. "Resistência e deformabilidade de blocos vazados de concreto e suas correlações com as propriedades mecânicas do material constituinte." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-09022007-152735/.
Повний текст джерелаАнотація:
O trabalho tem como objetivo correlacionar as propriedades mecânicas de blocos vazados com as do concreto que o constitui. Moldam-se blocos vazados e corpos-de-prova de dimensões distintas com concreto plástico em três níveis de resistência (10, 20 e 30 MPa) e caracterizam-se as propriedades mecânicas por meio de ensaios à compressão axial e à tração. Ensaiam-se à compressão axial prismas constituídos por dois e três blocos de concreto sem junta de argamassa, unidos por adesivo à base de epóxi. Observa-se que a relação entre as resistências do bloco e prisma e a resistência do concreto diminui com o aumento da altura desses elementos. Obtém-se o módulo de elasticidade longitudinal do concreto, a partir de ensaios com corpos-de-prova. Analisam-se as deformações em diversos pontos do bloco quando submetidos à compressão axial. Devido à distribuição não uniforme de tensões nos blocos e prismas, obtêm-se diferentes valores de deformação ao longo das paredes dos elementos. Os blocos, por possuírem menor altura que os prismas, apresentam maior diferença entre os valores de deformação. Por meio de simulações numéricas, no regime linear, observa-se que a placa de ensaio não se desloca uniformemente, acarretando os distintos valores de deformação ao longo do bloco. Uma forma peculiar de cálculo, baseada nessas deformações, permite a previsão da capacidade resistente do bloco e conduz a valores próximos da força máxima de ensaio. Apresenta-se ainda, uma tentativa de prever a deformabilidade do bloco vazado de concreto a partir das propriedades mecânicas do concreto.This research aims to correlate the mechanical properties of hollow blocks to those of the concrete used to build them. Concrete hollow blocks and test samples of different shapes and sizes (cylinder 50 x 100, 100 x 200 and 150 x 300 mm) were molded with plastic consistency concrete in three different levels of strength (nominally 10, 20 and 30 MPa). Their mechanical properties and structural behavior in axial compression and tension tests were determined. Also two and three block prisms were built without mortar joints, pilled up with epoxy glue. It could be observed that the relationship between block strength or prism strength and concrete strength (measured in test samples) decreases with increasing of the element\'s height. Stress and strain analyses were made based on the concrete\'s modulus of elasticity obtained in sample tests and on the measured strain in the blocks\' faces and webs. By linear numerical simulations it was observed that loading plate does not show uniform displacement values, causing significant differences between theoretical and experimental behavior. A peculiar stress-strain analysis permitted to calculate the block load capacity based in its deformations. Also a tentative method to preview the block deformability from the concrete mechanical properties is described and tested.
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Tabbakhha, Maryam. "Méthodologie multi-échelle pour évaluer la vulnérabilité des structures en maçonnerie." Phd thesis, Ecole Centrale Paris, 2013. http://tel.archives-ouvertes.fr/tel-00905526.
Повний текст джерелаАнотація:
L'objectif principal de cette étude est de développer des outils de simulation numérique pour évaluer la vulnérabilité des constructions en maçonnerie sous chargements variés. Ainsi, le comportement de la maçonnerie non armée sous chargement monotone en macro- et micro-échelles est étudié. La simulation du comportement non linéaire du mur de maçonnerie avant et après le pic et la capture de son mécanisme de rupture sont les points centraux de ce travail. Tout d'abord, le mur de maçonnerie d'un panneau est remplacé par deux barres simples utilisant la stratégie des macros-éléments et un comportement tri-linéaire est proposé pour évaluer la résistance à la rupture de la paroi ainsi que son comportement avant et après le pic. L'absence de l'information sur le mécanisme de rupture du mur de maçonnerie et la relation entre le mécanisme de rupture et les propriétés mécaniques des éléments barres dans ce type de modélisation conduisent à opter pour une autre description de ces structures à savoir la stratégie de micro-modélisation. Dans cette stratégie, les unités et les mortiers sont modélisés séparément et l'ensemble du comportement inélastique du mur de maçonnerie est supposé se produire dans les mortiers. Par conséquent, une attention particulière sera accordée au développement d'une description fiable des propriétés matérielles de ces éléments à l'aide d'une loi constitutive précise. La représentation tridimensionnelle d'un mur de maçonnerie faite dans ce travail, améliore la capacité des méthodes actuelles pour prédire le comportement de la maçonnerie sous les deux chargements en plan et hors du plan. D'abord, des enveloppes de rupture comprenant la tension limite et la surface de charge de Mohr-Coulomb sont assignées à l'élément d'interface du code éléments finis GEFDyn. Ensuite, la loi de comportement est améliorée en ajoutant un seuil de compression aux surfaces de charge pour inclure l'endommagement en compression de la maçonnerie à travers l'élément d'interface. Dans le nouveau modèle élastoplastique, les écrouissages négatifs des seuils de traction et de compression ainsi que la cohésion du mortier sont pris en considération. La capacité des deux modèles pour reproduire le comportement avant et après le pic de la résistance au cisaillement du mur de maçonnerie est vérifiée en comparant les résultats numériques avec les données expérimentales. L'importance de l'interaction entre les seuils de compression et celui du cisaillement est montrée en comparant les résultats obtenus avec ceux d'un test réel. Les résultats ont révélé que le second modèle est capable de simuler le comportement du mur de maçonnerie avec une bonne précision. Ensuite, l'effet des propriétés géométriques de la paroi telles que l'existence d'une ouverture et l'élancement, les propriétés des mortiers comme la cohésion, la résistance en traction et la résistance en compression ainsi que la contrainte verticale initiale dans le mur, sur la résistance latérale et le mécanisme de rupture des murs de maçonnerie est démontré. En outre, afin de présenter l'état d'endommagement, des indices de dommage, portant sur la longueur totale des fissures dans différentes rangées et colonnes de mortiers sont introduits et comparés pour différentes configurations. Les longueurs de glissement et d'ouverture de fissures dans les mortiers horizontale et verticale respectivement, sont les paramètres les plus importants qui contrôlent le comportement du mur. Enfin, la relation entre les profils de fissuration différents et les propriétés des matériaux y contribuant sont résumées dans un tableau.
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Bui, Tan Trung. "Etude expérimentale et numérique du comportement des voiles en maçonnerie soumis à un chargement hors plan." Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00963611.
Повний текст джерелаАнотація:
Cette contribution, en s'appuyant sur expérimentation et modélisation numérique, vise à une meilleure compréhension du comportement de structures en maçonnerie. Nous traitons tout d'abord le cas des murs soumis à un chargement hors plan de type pression uniforme. Les applications en ingénierie sont multiples, par exemple le cas de la maison individuelle construite en montagne en zone bleu, zone où les structures sont susceptibles de subir un impact de type avalanche de neige ; ou encore le cas de la maçonnerie soumise à une pression latérale induite par une charge accidentelle telle qu'une explosion dans une zone Seveso ou plus généralement en ville suite à l'explosion d'une conduite de gaz. Notre étude se confine au cas quasi-statique, l'objet étant une meilleure compréhension du comportement d'un mur en maçonnerie soumis à pression latérale uniforme. Nous avons aussi testé différentes configurations de renforcement par matériau composite. Puis nous évaluons pas à pas, les possibilités de la modélisation via la méthode des éléments discrets (DEM). Des essais judicieusement choisis, maçonnerie à joint sec ou mortier, nous permettent d'en évaluer les pertinences et les limites. Nous abordons ensuite sur maquettes, les essais sous charge ponctuelle hors plan en quasi-statique et le cas de l'impact en dynamique, puis nous traitons des essais vibratoires et des sollicitations dynamiques harmoniques. La modélisation DEM est aussi évaluée dans certains cas tels que les vibrations et les sollicitations modales, voir l'application d'une sollicitation sismique unidirectionnelle. L'étude des sollicitations dynamiques est limitée à la vibration et l'impact, plus facile à gérer en laboratoire que les essais dynamiques de " type souffle ", non ici abordés mais que nous mettons en perspective
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Helán, Tomáš. "Rezidence Austerlitz, vybrané části stavebně technologického projektu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240482.
Повний текст джерелаАнотація:
Purpose of this master’s thesis is to compile structurally – technological aspects of the project of new housing building in Brno. Thesis concentrates on technological phase of upper rough construction, which involves prescriptions for masonry of walls and constructions from reinforced concrete. Thesis is also includes suggestions of constellation of machines, time plan, supplying of construction site, rules of workplace safety, quality requirements, solutions for organization of construction and maintenance of the building. Conclusion of this master’s thesis is comparison of different systematical variations of constructing peripheral wall based on many structurally – technological factors.
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Bakešová, Martina. "Stavební průzkum a diagnostika zděné konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227513.
Повний текст джерелаАнотація:
The aim of my master’s thesis is to develop a brief overview of the historical development of brick, diagnosis methodologies of masonry structures and their application in the practical part for evaluation of structural survey masonry, carried out at the Faculty of Philosophy, Masaryk University in Brno.
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Ferreira, Nélia Lopes. "Evaluation of the structural capacity of historical constructions." Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/17986.
Повний текст джерелаАнотація:
Mestrado em Engenharia CivilAs construções históricas são uma parte importante do património mundial construído, símbolos arquitetónicos das cidades, países e culturas. Os museus, monumentos, castelos, igrejas, catedrais, entre outros, são edifícios e locais que oferecem experiências únicas tornando-se difusores de conhecimento. Estes edifícios históricos são alvo da comunidade turística que representa recursos económicos importantes. Por estas razões, a sociedade realiza grandes esforços técnicos e económicos para a conservação e valorização do seu património histórico. Ao longo do tempo, desde a sua construção até aos dias de hoje, um edifício histórico é exposto a diversos fatores que afetam o seu estado de conservação tais como, a degradação e envelhecimento do material, alterações arquitetónicas, desastres naturais com grandes períodos de retorno, destruição causada por algum tipo de conflito, ações de reabilitação e reforço, entre outros. Assim, a avaliação de construções históricas é um tópico que detém alguma preocupação, não só do ponto de vista da preservação do património, mas também pela segurança estrutural e durabilidade dos edifícios ao longo do tempo. A análise estrutural é bastante importante para a identificação do motivo pela qual os edifícios exibem danos e deformações e também para compreender o seu efeito no equilíbrio estrutural do edifício. Através de uma abordagem correta e apropriada é possível avaliar a capacidade estrutural de um edifício histórico e definir e validar uma futura estratégia de reabilitação, tentando assim recuperar e manter o comportamento da estrutura original. O principal objetivo desta dissertação é avaliar a capacidade estrutural de duas construções históricas, a Catedral de Palma de Mallorca (Mallorca, Espanha) e um edifício de alvenaria que faz parte do complexo do Castelo de São Jorge (Lisboa, Portugal). Para os casos de estudo apresentados realizou-se modelação numérica recorrendo a diversos softwares de elementos finitos, desenvolvendo um estudo paramétrico para compreender a influência das propriedades dos materiais no comportamento global de uma estrutura e ainda se definiram e analisaram diferentes estratégias de reabilitação.
The historical constructions are an important part of the world built heritage, architectural valued symbols of their cities, countries and cultures. Museums, monuments, castles, churches, cathedrals, among others, are buildings and sites that offer unique experiences as centres of knowledge. These historical buildings are the target of the tourist community which represent important economic resources. For these reasons, the society holds great technical and economical effort for the conservation and value of their historical heritage. Overtime, since their construction until the present day, a historical building is exposed to several factors that could affect their state of conservation such as, the material degradation and aging, architectural alterations, natural disasters with high return periods, destruction in occasion of conflicts, retrofitting actions, amongst others. Therefore, the assessment of historical constructions is a concerning subject, not only from the heritage safeguarding point of view, but also from the structural safety and durability over time. The structural analysis is of full importance to identify the origin of existing damage and deformations and their effect on the durability of the structure. With the correct and appropriate approach, it is possible evaluate the structural capacity of the historical construction in analysis and define/validate future rehabilitation strategies, strengthening and maintaining an improved behaviour of the original structure. The main focus of this dissertation is to evaluate the structural capacity of two historical constructions, the Palma Mallorca Cathedral (Spain) and one-story masonry arched building of the Castelo of São Jorge complex (Lisbon, Portugal). For these case studies were performed numerical modelling resourcing to different finite element software’s, developing a parametric study to understand the influence of the material properties on the overall behaviour of the structures, as well as proposing and analysing retrofitting strategies.
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Sienkiewicz, Lukasz Krzysztof. "Concept, implementation and analysis of the piezoelectric resonant sensor / Actuator for measuring the aging process of human skin." Thesis, Toulouse, INPT, 2016. http://www.theses.fr/2016INPT0047/document.
Повний текст джерелаАнотація:
L’objectif de cet projet est la conception, réalisation et caractérisation d’un actionneur / capteur piézoélectrique piézorésonant destiné à la mesure du vieillissement de la peau humaine. L’étude présentée est le fruit d’une collaboration entre le groupe de recherche de l'Electrodynamique du INP-ENSEEIHT (Toulouse), LAPLACE Laboratoire de Recherche et l'École Polytechnique de Gdask, Département Génie Electrique et Automatique. Un concept d’actionneur / capteur pour la caractérisation des propriétés mécaniques des tissus mous a été présenté. Un actionneur piézoélectrique résonant, appelé "unimorphe" a été choisi parmi les différentes structures piézoélectriques fondées sur le cahier des charges. L'innovation du projet réside dans l'intégration de la méthode d'indentation dynamique en utilisant un unimorphe comme dispositif d'indentation. Ceci permet l'utilisation d'un certain nombre de propriétés électromécaniques favorables des transducteurs piézo-électriques. Ce mémoire est divisé en 7 chapitres. Le chapitre 1 présente la thèse et ses objectifs. Le chapitre 2 présente le phénomène piézoélectrique et les applications piézoélectriques dans les domaines de la médecine et de la bio ingénierie. Le chapitre 3 décrit le cahier des charges pour le transducteur développé. Le choix du transducteur unimorphe est ainsi justifié. Le chapitre 4 présente une description analytique du transducteur unimorphe, y compris les calculs de déformations statiques, la description du circuit équivalent de Mason, et la description des conditions de contact entre la sonde d'indentation et les matériaux testés. Le chapitre 5 contient l'analyse numérique du transducteur unimorphe en utilisant le modèle virtuel MEF. Les résultats de simulations statiques et modales sont décrits par deux géométries considérées du transducteur. Le chapitre 6 décrit le processus de vérification expérimentale des modèles analytiques et numériques développés pour le transducteur unimorphe. Enfin, le dernier chapitre comprend des conclusions générales concernant les résultats de recherche obtenus, ainsi que les travaux futurs possibles. Afin de vérifier la thèse d'un cycle complet de recherche a été effectuée, qui a couvert: étude analytique, l'analyse numérique (simulations MEF), réalisation de prototype, et la vérification expérimentale des actionneurs / capteurs piézoélectriques considérésThe main goal of the dissertation was following: preparation of a new concept, implementation and analysis of the piezoelectric resonant sensor/actuator for measuring the aging process of human skin. The research work has been carried out in the framework of cooperation between the INP-ENSEEIHT-LAPLACE, Toulouse, France, and at the Gdansk University of Technology, Faculty of Electrical and Control Engineering, Research Group of Power Electronics and Electrical Machines, Gdask, Poland. A concept of transducer for the characterization of mechanical properties of soft tissues was presented. The piezoelectric resonant, bending transducer, referred to as “unimorph transducer” was chosen from different topologies of piezoelectric benders based on the fulfillment of the stated requirements. The innovation of the project lies in the integration of the dynamic indentation method by using a unimorph as an indentation device. This allows the use of a number of attractive electromechanical properties of piezoelectric transducers. The thesis is divided into seven chapters. Chapter 1 states the thesis and goals of the dissertation. Chapter 2 presents piezoelectric phenomenon and piezoelectric applications in the fields of medicine and bioengineering. Chapter 3 describes the requirements for the developed transducer. The choice of unimorph transducer is justified. Chapter 4 presents an analytical description of the unimorph transducer, including the calculations of static deformations, equivalent circuit description, and description of the contact conditions between the transducer and the tested materials. Chapter 5 contains the numerical analysis of the unimorph transducer using FEM virtual model. Results of static and modal simulations are described for two considered geometries of the transducer. Chapter 6 describes the experimental verification process of analytic and numerical models developed for unimorph transducer. The final chapter includes general conclusions concerning obtained research results and achievements, as well as possible future works. In order to verify the proposition of the thesis a full research cycle was carried out, that covered: analytical study, numerical analysis (FEM simulations), prototype realization, and experimental verification of the considered (developed) piezoelectric sensor/actuator structures
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Gallienne, Nicolas. "Modélisation thermomécanique de maçonneries : endommagement d’un piédroit de cokerie sous l’effet de la poussée du charbon." Thesis, Orléans, 2014. http://www.theses.fr/2014ORLE2032/document.
Повний текст джерелаАнотація:
Afin de répondre aux besoins du marché de l’acier, le procédé de cokéfaction du charbon doit s’adapter. Cependant, changer les paramètres de cokéfaction du charbon, tels que la température du four, le temps de cuisson ou la composition de la pâte à coke enfournée, peut générer un endommagement prématuré de la maçonnerie des fours. En effet, la transformation du charbon en coke s’accompagne d’une poussée sur les parois du four fortement dépendantes d’un grand nombre de paramètres. Afin d’anticiper ce problème, un projet européen nommé « Swelling PRessure In a coke oven, Transmission on oven walls and COnsequences on wall » a été mis en place. Cette thèse s’inscrit dans ce programme et vise à déterminer la poussée maximale pouvant être admise par un piédroit de cokerie lors de la pyrolyse du charbon. Pour modéliser ces structures composées de plusieurs centaines de milliers de briques, le point de vue macroscopique est le plus approprié. La maçonnerie est remplacée par un matériau homogène équivalent dont le comportement varie en fonction de l’état d’endommagement de la maçonnerie, ramené localement à un état d’ouverture des joints de mortier. Afin de détecter ces ouvertures, un critère de type Mohr-Coulomb en contraintes est utilisé. Il repose sur la comparaison des limites à rupture d’un sandwich brique-Mortier déterminé expérimentalement à haute température avec les contraintes mésoscopiques issues de la simulation. Un protocole expérimental novateur a été développé pour caractériser la tenue en traction du sandwich brique / mortier / brique jusqu’à 1000°C. Les limites à rupture issues de cet essai de traction directe ont été comparées à celles obtenues par des essais de fendage réalisés à l’université de Leoben. Les résultats sont concordants et confirment l’importance de l’état de surface avant maçonnage. Selon l’état d’endommagement considéré, les contraintes mésoscopiques sont obtenues grâce à un tenseur de localisation ou grâce à une sous-Structuration. Cette étape de sous-Structuration consiste à simuler localement une cellule à l’échelle mésoscopique en lui appliquant le champ de déplacement macroscopique obtenu grâce à la simulation. L’outil numérique a été validé par confrontation avec un cas test de référence. Pour finir, l’outil numérique développé a été utilisé pour caractériser l’influence de différents paramètres tels que la prise en compte de la thermique, la mise en compression de la structure…. Enfin, la simulation de cuissons sur des piédroits complets (sains ou initialement endommagés) a été réalisée. L’importance de l’endommagement initial est clairement soulignée par les résultats. Enfin, un nouveau modèle, appelé « deux carneaux avec poutres», est proposé pour réduire le coût de calcul. Plus complet que le modèle « deux carneaux » utilisé au CPM, il donne accès à de très bons résultats pour un coût nettement moindre que celui du piédroit complet avec homogénéisation et sous-StructurationTo face coke and steel market requirements, the coking process has to be more flexible. Changing process parameters such as coking temperature, blend composition and cooking time can damaged coke oven battery heating wall. Indeed, the coking process generates a swelling pressure on wall which depends on a lot of parameters. To study this point, a European project named « Swelling PRessure In a coke oven, Transmission on oven walls and COnsequences on wall » has been set up. This work is a part of it and aims to determine the admissible pushing pressure for the coke oven heating walls to prevent crack formation. To model large masonries composed of numerous bricks, a mesoscopic point of view is more appropriate. Bricks and mortar are replaced by a Homogeneous Equivalent Material (HEM) whose behaviour depends on the joint state. In order to represent joint opening mechanism, a Mohr-Coulomb criterion in stress is used. This criterion compares the level of stress to the ultimate tensile or shear stress at mesoscopic scale. Ultimate stresses are obtained thanks to an experimental campaign using a new protocol developed at PRISME Laboratory. The brick-Mortar behaviour is experimentally characterised at high temperature (20°C to 1000°C). To validate the tensile test developed, a second experimental campaign using “wedge splitting tests” has been done at Leoben University. Results are similar and confirm the importance of the brick surface state. Depending on the initial damage of the structures, mesoscopic stresses are obtained by localization tensor or by sub-Modelling. The sub-Modelling step aims to simulate a local part of the masonry at the mesoscopic scale. This step aims to simulate with a mesoscopic point of view a local part of the global model. This numerical tool has been validated thanks to a literature test. Finally, the numerical tool has been used to characterise the influence of some parameters (thermal, force due to the cross tie rod,..). Next, the simulation of the whole coke oven heating wall has been performed (undamaged or initially damaged masonry). These FE simulations show the influence of initial damage on the final masonry damage. Finally, a two flues model with beams is proposed to take into account compression due to cross tie rod and to limit computational cost. It permits to obtain better results than the existing two flues model used at CPM with a lower cost compared to the whole coke oven heating wall model
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Barbosa, Claudius de Sousa. "Resistência e deformabilidade de blocos vazados de concreto, prismas e paredes e suas correlações com as propriedades mecânicas dos materiais constituintes." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-21102008-102947/.
Повний текст джерелаАнотація:
O objetivo deste trabalho é identificar e correlacionar as propriedades mecânicas do concreto e da argamassa de assentamento com o comportamento estrutural de blocos vazados de concreto, prismas e paredes, por meio de modelagem física e numérica. Realizou-se detalhada investigação experimental, recorrendo à premissa metodológica de se utilizar um mesmo concreto, de consistência plástica, para a moldagem de blocos vazados e corpos-de-prova cilíndricos, para assegurar propriedades idênticas dos materiais em cada série de ensaios. Analisou-se o efeito de confinamento que se apresenta nos ensaios de blocos isolados, o qual induz uma distribuição não-uniforme de deformações e acarreta aumento da sua capacidade resistente em relação à resistência à compressão do concreto. Em ensaios nos quais se reduziu o efeito de confinamento, constatou-se que os blocos apresentam menor capacidade resistente e alteração do modo de ruína, decorrente da distribuição mais uniforme das deformações, similar àquela que se observa nos blocos centrais dos prismas e paredes. Analisou-se também a influência do efeito de confinamento e do processo de cura das juntas de argamassa e se associou parâmetros indicativos do seu comportamento à capacidade resistente e ao modo de ruína de prismas e paredes. As propriedades mecânicas dos materiais, obtidas experimentalmente, foram implementadas em um modelo numérico de elementos finitos, que se mostrou capaz de representar o comportamento dos diversos elementos de alvenaria submetidos à compressão, com boa predição da resistência, deformabilidade e modo de ruína. Com base nos resultados numéricos e experimentais, estabeleceu-se um modelo de interpretação da distribuição de tensões e deformações nos blocos vazados de concreto, o que resultou na recomendação de um procedimento para determinação de sua rigidez axial. Associou-se também o efeito da resistência e da deformabilidade da argamassa no comportamento estrutural dos prismas e paredes. Correlações e formulações algébricas foram estabelecidas para análise do comportamento e previsão quantitativa da resistência e da deformabilidade de blocos, prismas e paredes.This work aims to identify and correlate the mechanical properties of concrete and bedding mortar to the structural behavior of hollow concrete blocks, prisms and walls, by mean of physical and numerical modeling. A detailed experimental investigation was carried out by assuming as a premise the use of plastic consistency concrete to produce hollow blocks and cylindrical samples. This was done to assure the same material properties in each test series. Confinement effect in block compression tests causes a non-uniform strain distribution through face-shells and webs. This effect induces an increase of the block ultimate load. Modified block tests by reducing the confinement effect were performed. The results showed that confinement reduction brings a more uniform strain distribution, which is similar to the observed one in the central blocks of prisms and walls. A decrease of compressive strength and changes the failure mode were also evidenced. Confinement effect and influence of water loss during the curing of mortar joints were also considered. Indicative parameters about bedding mortar behavior were obtained and the resistant capacity and the failure mode of prisms and walls were associated to them. The mechanical properties of materials obtained in tests were implemented in a finite elements numerical model to analyze the behaviour of masonry elements under compression. The numerical analysis gave good predictions of strength, deformability and failure mode. Based on the numerical and experimental results, a stress and strain distribution model was realized, which enabled an experimental procedure for the determination of the block axial stiffness. Correlations and algebraic formulation were proposed for the behavior analysis and quantitative evaluation of strength and deformability of blocks, prisms and walls.
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Boleček, Richard. "Vybraná část STP Viladomy Zámostí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225614.
Повний текст джерелаАнотація:
Presented work the master's thesis is solving a build-up technology of a ional building construction . It is a study of main technological phases, focused on foundation building and masonry. The building technological project contains the technology statement and the technological phases primary model, technology procedure, time schedule and financial heftiness, machines formation, check and test plan, occupational safety and as specialism the mechanical drawing details of structure.
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Soares, Raimundo Nonato Belo. "Resíduo de construção e demolição e EPS reciclado como alternativa de agregados para a Região Amazônica: aplicação em blocos para alvenaria." Universidade Tecnológica Federal do Paraná, 2010. http://repositorio.utfpr.edu.br/jspui/handle/1/185.
Повний текст джерелаАнотація:
Trabalho desenvolvido através do projeto de mestrado interinstitucional - MINTER - entre a UTFPR e o IFAM - Manaus, financiado pela CAPES e pela SUFRAMA.Financiado pela CAPES e pela SUFRAMA.
No estado do Amazonas a questão do gerenciamento dos Resíduos de Construção e Demolição (RCD) merece atenção e soluções que sejam sustentáveis dos pontos de vista ambiental, econômico e social. O RCD gerado, bem como o Poliestireno Expandido (EPS), ainda são descartados ou conduzidos às lixeiras com os agravantes da inexistência de um projeto de gestão, visto haverem problemas com inundações, poluição dos mananciais e, significativa ocupação nos lixões controlados pelo poder público, dentre outros. Outro aspecto relevante refere-se ao uso, pela construção civil, de agregados como o seixo rolado e granito, o primeiro extraído de rios e transportado em balsas percorrendo distâncias superiores a 700 km e o segundo explorado a distâncias superiores a 150 km da cidade de Manaus, causando alto impacto ambiental e elevado custo de logística. Neste contexto, o objetivo desse trabalho foi estudar a viabilidade técnica da produção de concreto alternativo utilizando RCD e EPSR(Poliestireno Expandido Reciclado) obtido após processo de extrusão e moagem na forma de agregado graúdo ou miúdo. Os RCDs (de concreto) selecionados em obras e britados, bem como, o EPSR foram analisados granulometricamente com a finalidade de serem incorporados à concretos aplicados a fabricação de blocos de alvenaria. Os blocos produzidos foram analisados quanto a resistência mecânica e também quanto à absorção de água. O EPSR possui baixa densidade e contribui para a obtenção de blocos mais leves.
In the Amazon State, the issue of management concerning construction and demolition waste (C&D) deserves attention and solutions that are sustainable from environmental, economical and social standpoints. The RCD produced as well as the expanded polystyrene (EPS), are still discharged in inappropriate places or taken to the dumpsters with the worsening provided by the lack of a management project such as: floods pollution of the water resources (rivers lakes and others) and significant space occupation in the landfills controlled by the city council, among others. Another aspect, related with the civil engineering sector, refers to the usage of components like the pebbles and granite, the first one extracted from rivers and transported by ferries within distances over 700 km and the second one explored within distances over 150 km from Manaus City, causing high environmental impact and high logistics cost. The goal of this research was to study the technical feasibility of producing alternative concrete using RCD and post-consumpting EPS extruded and crushed to transform it in aggregate. The RCDs (of concrete) selected in construction sites and crushed, as well as the EPSR (expanded polystyrene recycled) were analyzed in its granulometric distribution to be used as aggregate on the concrete composition features to obtain wall blocks. The produced blocks were analyzed mechanically and also regarding the water absorption level. The EPSR has low density and contributing to the production of lighter blocks.
5000-11-25
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Ježowiczová, Barbora. "Nadstandardní rodinný dům v Křelově - stavebně technologický projekt." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227833.
Повний текст джерелаАнотація:
Subject of this work is pursuance technology of above-standard family house. This diploma thesis contains construction and technology report, technological prescriptions for important parts of buildings, technology report of plant building site, concepts of mechanical assembly, inspection and test plan, technology report of health and safety on the construction site. Budget, calculation and time planning, a drawing of the facilities of the construction site, description of transport relations is included in addendum. Work also contains part about use of Calcium silicate masonry and its comparation.
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Ševčík, Daniel. "Bytový dům Mrštíkova Hustopeče, Blok B - stavebně technologický projekt." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409946.
Повний текст джерелаАнотація:
This master’s thesis is focused on technological and constructional project of apartment building – Block „B“ in the Hustopeče city. Content of this thesis includes engineering report of technological project, construction site equipment, used machinery, situational concept of transport routes and technological regulations for drilled pilots. This thesis also contains construction time schledule, itemized budget and assessment of the masonry systems.
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Rada, Stanislav. "Wellness centrum Jinačovice, stavebně technologická příprava stavby." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226976.
Повний текст джерелаАнотація:
The subject of this thesis is also dealt with construction of the second phase of the congress and wellness centre in Jinačovice. The work includes technical report, time and financial plan, project site equipment, technical regulations, inspection and test plans, implementation of technology water impermeable concrete
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Vojtek, Ondřej. "Stavebně technologický projekt bytového domu v Brně - Slatině." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372271.
Повний текст джерелаАнотація:
This diploma thesis deals with construction and technological project of apartment building in Brno – Slatina, Kigginsova street. Thesis focus on technological phase of monolithic rough superstructure and masonry work. For this phases were processed technogical specifications and controlling ad testing schedules. Within this thesis was also compiled technical report, solution of transport roads, technical report and drawings of site equipmet. For main object was compiled itemized budget, which was foundation for completing time schedule. In diploma thesis are further processed safety requirements and chosen construction details.
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Malý, Martin. "Skladová hala v Měříně, příprava a organizace stavby." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372192.
Повний текст джерелаАнотація:
The aim of this work is the processing of the technological project for the ,,Skladová hala v Měříně“, which addresses the preparation and organization of construction. Construction technology the project involves the processing of time plans, economic evaluation, design of pumping sources for construction, working procedures, construction site equipment, and design of major machines and mechanisms. Further, it is processed a detailed technological regulation and inspection and test plan for a prefabricated reinforced concrete skeleton. All technological procedures are processed with regard to work safety and environment.
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Vasconcelos, Graça. "Experimental investigations on the mechanics of stone masonry: characterization of granites and behavior of ancient masonry shear walls." Doctoral thesis, 2005. http://hdl.handle.net/1822/17383.
Повний текст джерелаАнотація:
Tese de doutoramento em Engenharia CivilThe work presented in this thesis was developed at the Department of Civil Engineering of University of Minho. This work is eminently experimental and intends to be a valuable contribution to a better insight on the mechanics of stone masonry. In order to improve the knowledge on the mechanical properties of granite, the constitutive behavior of distinct granite types under tensile and compressive loading was successfully obtained through a set of experimental tests associated to suitable displacement control. Afterwards, elastic and fracture properties were derived and statistical correlations among these parameters were obtained. The selection of different types of granitic rocks made possible the analysis of the influence of some microstructural aspects, such as grain size and internal texture on the large range of elastic and fracture properties. Other aspects that can explain the variation of the tensile and compressive engineering properties, like weathering state, moisture content and physical properties were also investigated. The possibility of predicting the mechanical and physical properties of the granites by simple and economical nondestructive techniques, such as the ultrasonic pulse velocity (UPV) and the Schmidt hammer rebound number (N) was studied. A set of statistical correlations between the elastic and strength properties and the experimental data obtained through nondestructive techniques were defined. Moreover, a discussion of the factors (moisture content, weathering state and internal texture) that possibly induce variations on the velocity measurements and on the rebound number was performed. The characterization of the composite behavior of masonry materials used in the construction of the stone masonry walls was carried out by means of a set of direct shear tests conducted on dry and mortared masonry joints and of uniaxial compressive tests conducted on masonry prisms. Besides the shear and compressive strength properties, results of the influence of the bond material on the overall compressive behavior were presented. The analysis of the mechanical shear behavior of granitic masonry walls, considered representative of ancient masonry constructions, was carried out based on the experimental results of twenty-four static cyclic tests. The influence of the masonry bond and the axial load levels was analyzed by considering different masonry bonds and distinct levels of axial load. The analysis of the lateral cyclic performance of stone masonry walls was based on the results of the failure patterns and the force-displacement histeresis loops. From this information, it was possible to carry out a comparative analysis of the distinct types of walls in terms of ductility, nonlinear deformability and energy dissipation capacity. In addition, the lateral resistance was assessed by using simplified formulations for prediction of the shear strength of masonry walls under combined axial and shear loads.
O trabalho apresentado nesta tese foi desenvolvido no departamento de Engenharia Civil da Universidade do Minho. Este trabalho é eminentemente experimental e pretende ser uma contribuição para uma melhor compreensão do comportamento mecânico da alvenaria de pedra. Com o objectivo de melhorar o conhecimento das propriedades do granito, o comportamento constitutivo de diferentes tipos de granito foi obtido com sucesso através de um conjunto de ensaios experimentais realizados em controlo de deslocamento e com selecção da variável de controlo adequada. Os resultados destes ensaios permitiram determinar as propriedades elásticas e os parâmetros de fractura, obtendo-se posteriormente um conjunto de correlações estatísticas entre os mesmos que possibilitou uma melhor clarificação da gama de variação das propriedades. A selecção de diferentes tipos de granito permitiu a análise da influência de alguns aspectos micro-estruturais, como por exemplo a dimensão do grão e textura interna na diversidade das propriedades elásticas e de fractura. Foram também considerados aspectos como estado de alteração, humidade e propriedades físicas. A possibilidade de estimar as propriedades dos granitos através de técnicas não destrutivas económicas e de simples utilização foi analisada com base em medições da velocidade de propagação dos ultrassons e os valores de recuo de martelo de Schimdt. Para o efeito, foi estabelecido um conjunto de correlações estatísticas entre o módulo de elasticidade e a resistência à tracção e compressão e os valores obtidos nos ensaios não destrutivos. Adicionalmente, foram estudados os factores que potencialmente podem afectar as medidas dos ensaios não destrutivos, nomeadamente humidade, estado de alteração e anisotropia. A caracterização do comportamento compósito dos materiais usados na construção das paredes de alvenaria de pedra foi realizada através de um conjunto de ensaio de corte directo realizados em juntas de alvenaria seca e argamassada e de um conjunto de ensaios de compressão uniaxial conduzidos em prismas de alvenaria. Para além das propriedades resistentes de corte e compressão, foram também apresentados os resultados da influência do tipo de material das juntas no comportamento global à compressão. A análise do comportamento mecânico das paredes de alvenaria de granito, consideradas representativas de estruturas antigas de alvenaria, foi efectuada com base nos resultados experimentais de vinte e quatro ensaios estáticos cíclicos. A influência do aparelho e do nível de esforço axial foi analisada através da consideração de diferentes tipos de aparelho e pela variação do nível de esforço axial. A análise do desempenho cíclico das paredes de alvenaria foi realizada a partir da informação combinada dos modos de rotura e dos diagramas força-deslocamento. Através desta informação foi possível estabelecer uma análise comparativa entre os diferentes tipos de paredes em termos de ductilidade, capacidade de deformação não linear e capacidade para dissipar energia durante o carregamento cíclico. Além disso, os valores da resistência lateral obtidos experimentalmente foram comparados com os valores obtidos por aplicação de métodos analíticos simplificados.
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Pagani, Claudio. "Modeling of Masonry Structures at Multiple Scales." Doctoral thesis, 2021. http://hdl.handle.net/2158/1248578.
Повний текст джерелаАнотація:
Masonry represents the material used in the great majority of the world-building heritage structures.
Reliable tools for analysis of masonry structures are needed not only for seismic vulnerability assessment but also to properly design interventions to restore and strengthen existing buildings, which deserve to be preserved.
Masonry is a nonlinear, heterogeneous, and anisotropic material whose properties strongly depend on its microstructure, typically composed of two phases, blocks and mortar, and on the way it is assembled.
To simulate the mechanical behavior of masonry structures, numerous models have been developed, characterized by different detailing levels.
For large structures, the need for computational efficiency leads to simplified models characterized by the subdivision of masonry walls in macro-elements.
A notable example of this group of models is the equivalent-frame method, which consists of identifying the masonry wall with an ideal frame, where panels are modeled as beams characterized by proper mechanical behavior.
The detailing level can be increased by considering each macro-element as a homogenized continuum, assuming that, at the scale of representation, masonry can be treated as a continuum having mechanical properties that reproduce the overall response of a certain portion of the heterogeneous microstructure.
However, the formulation of a suitable constitutive law is not an easy task.
It should phenomenologically reproduce the material mechanics, including tension cracking, shear sliding, compressive crushing, and many other aspects.
Moreover, this approach requires a cumbersome identification of mechanical parameters that are not always easy to determine from basic experimental tests on the material.
To consider the role of each constituent and the effects of their interactions, a microscale model can be set up, where blocks, mortar joints, and mortar-block interfaces are represented explicitly.
In this work, masonry structures are studied at several detailing levels.
An issue affecting equivalent-frame models, namely the presence of irregularity in the wall opening layout, is addressed by comparing equivalent-frame results with finite-element ones, which are assumed to better represent the actual behavior of irregular walls.
A parametric analysis on masonry piers, modeled as a homogenized continuum, is carried out, aimed to assess the influence of the height-to-width ratio and the vertical compression load on the nonlinear static behavior.
The focus is then shifted to finer scales.
The localization analysis of an orthotropic macro-scale model in the framework of multi-surface plasticity is presented, deriving analytical localization conditions corroborated by finite element simulations.
Finally, a microscale model for regular masonry is developed to analyze the localization properties of the representative volume element, also by investigating the role of its size and periodicity directions.