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A construtibilidade como requisito para avaliação de componentes para a edificação: o caso do Elemento de Integração alvenaria/esquadriaZucchetti, Lais January 2010 (has links)
Atualmente a utilização de sistemas modulares na indústria da construção tem crescido significativamente, e, dentre estes, destaca-se o sistema construtivo de alvenaria estrutural. Entretanto, diversos estudos apontam para um grande número de manifestações patológicas relacionadas a este sistema, em especial com a interface alvenaria/ esquadria como um dos locais de maior incidência, além de representar um gargalo construtivo, pela necessidade de realização de inúmeras atividades dependentes. Dentro deste contexto, a equipe do projeto COMPOHIS (FINEP) desenvolveu uma nova proposta de solução a estas questões, denominada Elemento de Integração (EI). Para a implementação deste novo elemento, foram necessárias avaliações que garantissem o comportamento adequado do produto nas construções e, um dos requisitos considerados foi a construtibilidade, visto que sua consideração e implementação trazem benefícios relacionados ao custo, tempo e qualidade das construções. Desta forma, o objetivo principal desta pesquisa foi avaliar a construtibilidade do EI. Para que esta avaliação fosse realizada, foram identificados, a partir de revisão bibliográfica, vinte e sete requisitos de construtibilidade. Dentre estes, foram selecionados vinte e dois e, agrupados em dez requisitos básicos. Estes dez requisitos foram utilizados na análise ao longo do desenvolvimento da pesquisa, considerando protótipos virtuais e físicos (construídos com diferentes materiais). Mais especificamente, foram utilizados quatro protótipos virtuais e três protótipos físicos do EI, sendo um em MDF e dois em GRC, e duas modelagens de seqüências construtivas, sendo uma com o EI e a outra com o método tradicional de construção. Sendo que, na última fase, foi construída uma parede experimental real com o EI e, submetida ao ensaio estrutural. Os principais resultados demonstram a adequação e aplicabilidade, formal, funcional e conceitual do EI ao sistema construtivo considerando os requisitos selecionados, com algumas ressalvas quanto à conexão entre o Elemento e a alvenaria (devido às fissuras identificadas nesta interface), quanto à dificuldade de manutenção dos componentes em GRC (considerando a necessidade de execução de substituições), quanto à exclusão de ajustes em canteiro, com relação à necessidade de cuidado com as arestas do EI e, finalmente com relação à segurança (pela instabilidade do EI logo que assentado). / Nowadays, the use of modular systems in the construction industry has grown substantially and, among those, the structural masonry system gains relevance. However, several studies point to a high incidence of pathological manifestations related to this system, particularly the interface between masonry and windows being one of the places with the highest number of problems, besides being a constructive bottleneck, since several activities depend on it. Within this context, the COMPOHIS project developed new solutions to these problems, named Element of Integration (EI). However, to implement this new element, performance evaluations were needed to ensure the adequate performance of the product in buildings, and one of these performance requirements that must be considered is the constructability of the solution. The use of this requirement brings benefits related to cost, time and quality of constructions. Thus, the main objective of this research is to evaluate the constructability of the EI. For this evaluation, 27 constructability requirements were identified in the literature. From those, 22 were selected and grouped into 10 major requirements. These 10 requirements were considered for analysis along the preparation and execution phases of this work, and the analysis was carried out considering physical and virtual prototypes (built with different materials). More specifically, 4 virtual prototypes and three physical prototypes of EI we used - one in MDF and two in GRC - and two sequences of constructive modeling, one with the EI and the other with the traditional method of construction. The last GRC prototype was used to build a wall, which was used for a structural resistance test. The main results demonstrated the formal, functional and conceptual adequacy of EI to the selected requirements, with some reservations about the connection between the element and the structural masonry, due to cracks observed in this interface, the difficulty of maintenance of GRC components, considering the need for repairs and replacements, the need to use protective elements at the edges of the GRC components and finally, in regard to safety, due to the instability of the EI when set in place.
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Avaliação de incertezas em modelo de dano com aplicação a prismas de alvenaria sob compressão / Evaluation of model uncertainties of a damage model with application in masonry prisms under compressionGonçalves Júnior, Luiz Aquino 27 August 2008 (has links)
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.
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Análise experimental e numérica do comportamento de junta em painéis de contraventamento de alvenaria estrutural / Experimental and numerical analysis of the joint behavior of masonry shear wallMata, Rodrigo Carvalho da 14 June 2011 (has links)
A avaliação da capacidade de carga das estruturas de alvenaria submetidas a ações horizontais depende da confiabilidade dos modelos de dimensionamento utilizados. De fato, a alvenaria é um material heterogêneo com característica ortotrópicas. Além disso, por possuir juntas de argamassa que acarretam planos de fraqueza, geralmente a modelagem computacional desse tipo de estrutura apresenta grandes dificuldades. Um modelo robusto para alvenaria só pode ser desenvolvido por meio de uma descrição suficientemente precisa do comportamento mecânico individual de cada um dos seus componentes (unidades de alvenaria e a argamassa) e sobretudo nas juntas de argamassa, as quais são responsáveis pela maior parte dos fenômenos não-lineares que ocorrem na estrutura. Entretanto, diante da escassez de resultados experimentais, descrever esses comportamentos com a precisão e o rigor necessários é uma tarefa bastante difícil. Diante desta motivação, este trabalho se propôs a identificar e quantificar a influência da ligação unidade-argamassa, denominada junta, no comportamento estrutural de painéis de contraventamento de alvenaria estrutural executados com blocos de concreto. Assim, foram obtidos dados experimentais do comportamento da ligação unidade-argamassa e das partes componentes que posteriormente foram utilizados em modelagens computacionais realizadas para prever o comportamento estrutural de painéis de contraventamento submetidos a esforços horizontais no plano. Posteriormente, a partir dos resultados obtidos dos ensaios de painéis submetido a força horizontal e vertical e das modelagens numéricas propostas foi possível comparar os resultados experimentais e numéricos com os resultados obtidos pelo procedimento de dimensionamento da norma brasileira NBR 15812-1 (ABNT, 2010). Assim pode-se concluir que os valores da força horizontal máxima determinados a partir das recomendações da NBR 15812-1 (ABNT, 2010) apresentaram valores mais conservadores que os resultados experimentais e numéricos, como seria esperado. / The evaluation of load bearing capacity of masonry structures subjected to horizontal actions depends on the reliability of the dimensional models used. Masonry is indeed a heterogeneous material with orthotropic characteristics. In addition, due to its weak mortar joints, in general, the computational modeling of this type of structure presents major difficulties. A robust model for masonry structures can only be developed through a fairly accurate description of the individual mechanical behavior of each of its constituents (masonry units and mortar) and, especially, in the mortar joints, which are responsible for most nonlinear phenomena occurring in the structure. However, due to the lack of experimental data, describing these behaviors with the accuracy and rigor required is a rather difficult task. Hence, the objective of this study is to identify and quantify the influence of mortar-unit bond, also called joint, on the structural behavior of concrete block masonry shear walls. Accordingly, the experimental data of the behavior of the mortar-unit bond and the constituents, which were further used in the numerical modeling developed to predict the structural behavior of shear wall subjected to horizontal forces in the plane, were obtained. Subsequently, from the results obtained in the assays of shear walls subjected to a horizontal and vertical force and the numerical modeling proposed it was possible to compare the experimental and numerical results with those obtained by mean of the Brazilian Code NBR 15812-1 (ABNT, 2010). Therefore, it can be concluded that the values of maximum horizontal force determined according to the recommendations of Brazilian Code design criterion are more conservative values than the experimental and numerical values, as expected.
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Base Isolation of a Chilean Masonry House: A Comparative StudyHusfeld, Rachel L. 16 January 2010 (has links)
The objective of this study is to reduce the interstory drifts, floor accelerations,
and shear forces experienced by masonry houses subject to seismic excitation. Ambient
vibration testing was performed on a case study structure in Maip�, Chile, to identify
characteristics of the system. Upon creating a multiple degree-of-freedom (MDOF)
model of the structure, the effect of implementing several base isolation techniques is
assessed. The isolation techniques analyzed include the use of friction pendulum
systems (FPS), high-damping rubber bearings (HDRB), two hybrid systems involving
HDRB and shape memory alloys (SMA), and precast-prestressed pile (PPP) isolators.
The dynamic behavior of each device is numerically modeled using analytical
formulations and experimental data through the means of fuzzy inference systems (FIS)
and S-functions. A multiobjective genetic algorithm is utilized to optimize the
parameters of the FPS and the PPP isolation systems, while a trial-and-error method is
employed to optimize characteristic parameters of the other devices.
Two cases are studied: one case involves using eight devices in each isolation
system and optimizing the parameters of each device, resulting in different isolated
periods for each system, while the other case involves using the number of devices and
device parameters that result in a 1.0 sec fundamental period of vibration for each baseisolated
structure. For both cases, the optimized devices are simulated in the numerical
model of the case study structure, which is subjected to a suite of earthquake records.
Numerical results for the devices studied indicate significant reductions in
responses of the base-isolated structures in comparison with their counterparts in the
fixed-base structure. Metrics monitored include base shear, structural shear, interstory drift, and floor acceleration. In particular, the PPP isolation system in the first case
reduces the peak base shear, RMS floor acceleration, peak structural shear, peak
interstory drift, and peak floor acceleration by at least 88, 87, 95, 95, and 94%,
respectively, for all of the Chilean earthquakes considered. The PPP isolation system in
the second case (yielding a 1.0 sec period) and the FPS isolation systems in both cases
also significantly reduce the response of the base-isolated structure from that of the
fixed-base structure.
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Comparison Of Elastic And Inelastic Behavior Of Historic Masonry Structures At The Low Load LevelsOzen, Onder Garip 01 September 2006 (has links) (PDF)
Conventional methods used in the structural analysis are usually insufficient for the analysis of historical structures because of the complex geometry and heterogeneous material properties of the structure. Today&rsquo / s computing facilities
and methods make FEM the most suitable analysis method for complex structural geometry and heterogeneous material properties. Even the shrinkage, creep of the
material can be considered in the analysis. Because of this reason Finite Element Method (FEM) is used to analyze such structures. FEM converts the structure into finite number of elements with specific degree of freedoms and analyses the
structure by using matrix algebra. However, advanced FEM methods considering the inelastic and time dependent behavior of material is a very complex and difficult task and consumes considerable time. Because of this reason, to analyze every historical structure is not feasible by applying advanced inelastic FEM, whereas elastic FEM analysis at low load levels is very helpful in understanding the behavior of the structure.The analysis of a masonry gate in the historical city, Hasankeyf is the case study of this thesis. Different common software are used in FEM to compare the
stresses, deformations, modal shapes etc. of the same structure. Besides the inelastic behavior of the structure is investigated and compared with the elastic behavior of the structure. The study is intended to show that at the low load levels elastic FEM analysis is sufficient to understand the response of the structure and is preferable to the inelastic FEM analysis unless a very complex analysis is required
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A Comparative Study On Earthquake Resistance Of Reinforced Concrete And Masonry Residential Buildings In Small-scale Cities Of TurkeyEr Akan, Asli 01 May 2008 (has links) (PDF)
Today the vast majority of urban population in Turkey is living in multi-story apartment blocks constructed of reinforced concrete due to the fact that in the late 19th century concrete and steel took the place of traditional materials such as masonry. However, it cannot be denied that masonry is still a crucial material for load bearing walls, internal walls and cladding of buildings. In addition to this masonry construction system has many advantages. From the architectural point of view, it provides flexibility in plan, spatial composition, wide variety of colours and textures and an impressive appearance for external walls. From the construction point of view, masonry system eliminates the cost of the frame because the structure is also the enclosing wall. In spite of these advantages, until recently, masonry was not considered to be a convenient material for building construction in seismic zones of Turkey. Thus, in 1950&rsquo / s for the residential building reinforced concrete started to be used as a construction material in every region of Turkey. This building material first became popular and was widely used but after a short while it was also used in smaller cities. Before the construction of reinforced concrete residential buildings each of these small-scale cities had their own local characteristics but after a rapid urbanization period all of these cities became similar to each other.
Therefore, in this study firstly residential building typologies in some small-scale cities (Bolu, Dü / zce, Ç / ankiri, Ç / orum, Kastamonu, Kirikkale) are investigated and for these cities 4-storey masonry residential buildings is proposed instead of multi-story reinforced concrete apartment blocks. Here, it is aimed to enliven the use of masonry again in these regions. To achieve this aim it is necessary to verify the fact that it is possible to construct a four-story residential building with masonry bearing walls instead of reinforced concrete beam and column skeleton system keeping the existing plan scheme in other words without changing its architectural characteristics. In order to do this, 3D models are created to compare the behaviours of the masonry building and reinforced concrete building. The behavioural investigation of the two models is performed in the finite element platform with the help of SAP 2000. Finally it is certified that this proposal is successfully efficient.
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Structural Modelling, Analysis, Evaluation And Strengthening Of Perge Southern Gate Hellenistic TowersIsikoglu, Orhan Mete 01 February 2012 (has links) (PDF)
The successive struggle of Perge Antique City to resist against aging is clearly signified by Hellenistic Towers Ruins, parts of which still reaches up to 20 m high. Being a most reflecting example located at Anatolia, it clearly signifies its construction period and function compared to other examples that constitutes the same features.
However, There exist a certain requirement of detailed and wide ranging conservation study for finding remedy to cope with risk of further collapse, which is originated from the slender geometry of Towers Remains. Therefore, the need of a survey on the structural behaviour of towers with non-linear analytical modelling techniques is fulfilled in this study.
Preliminary analytical modelling (linear-elastic, macro models) was performed by using SAP2000 while, following detailed discrete stone element modelling examinations were performed with ANSYS-Ls DYNA, ABAQUS Software. Verification for simulations were made with results related with ambient vibration dynamic testing performed at Eastern Tower and Closed-form, simple calculations.
In the light of results bound to structural behaviour investigation on reconstitution, stability performance of today' / s ruins was examined against seismic activities. Four different strengthening methods were considered and their contributions to stability were compared in order to reach at the most appropriate intervention scheme obeying contemporary restoration criteria. The study formed a significant sub branch work of a restoration project of which charge was undertaken by SAYKA Restoration, Architecture Ltd. Co. Being a part of multi-disciplinary teamwork, structural investigation research was concluded to an optimum solution, which foreseen &ldquo / minimum intervention to the building&rdquo / assuring performance under seismic loading of large earthquakes.
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Evaluating CFRP-Masonry Bond Using Thermal ImagingRoss, Joseph Christopher 01 January 2013 (has links)
This study presents results from non-destructive testing to evaluate the degradation of the CFRP-masonry bond using thermal imaging. The goal of the research was to identify locations where there was evidence of bond deterioration that could subsequently be verified through destructive pull-off testing.
Four full-scale masonry walls were built outdoors at the University of South Florida in 1995 to evaluate the effectiveness of CFRP for repairing settlement damage. Two of the settlement-damaged walls were repaired using single layer, commercially available unidirectional CFRP systems that used Tonen (wall 3) and Henkel (wall 2) epoxies. These two walls were the subject of this investigation.
Before non-destructive tests were initiated, historical site data on temperature, humidity and rainfall variation was compiled. Over seventeen years, the walls experienced ambient temperatures as high as 98°F and as low as 25°F. The average rainfall in Tampa is about 34 inches and the annual average high humidity is around 87%#37;. Because of the high temperature and humidity, the CFRP-masonry bond was exposed to a particularly aggressive environment.
Three types of thermal evaluation were carried out: thermocouple monitoring and both passive (solar) and active (localized heating) infrared thermal imaging. Twenty-four thermocouples were used to observe the spatial variations in temperature on the wall. Data showed that the surface temperatures of the wall are uneven with one end being hotter than the other. Measurements indicated that the wall temperatures went as high as 103°F during the week of data collection in late March and early April of 2012. In contrast, the highest ambient temperature over the same period was 92°F. The high temperature experienced by the wall is below the glass transition temperature for the epoxies, which ranges from 140°F to 180°F.
A FLIR Tau 320 thermal imaging camera was used to identify localized de-bonding. Solar radiation heated the walls and the goal of thermal imaging was to detect hot spots which are indicative of de-bonding. Although this technique is ideal for exterior applications, initial attempts were unsuccessful. Once de-bonds were located by sounding, the camera was capable of confirming two hot spots on wall 2.
A thermal scanner built by the university from a series of ten Omega OS137 thermal sensors was used to obtain more complete thermal images of the walls. This scanner had a heating element which supplied heat and allowed for active thermography. The scanner detected 16 hot spots not seen with the thermal camera. Ten of the twelve spots on wall 2 are concentrated on a region of the wall which experienced the highest daily changes in temperature, which indicates that higher thermal and environmental cycling has caused greater de-bond.
Based on the number of hot spots found using both active and passive thermography the Tonen epoxy is performing better than the Henkel epoxy. In general, the bond has endured; however, there are a few localized areas that have de-bonded. Pull-off tests are recommended on walls 2 and 3. Five locations in regions suspected to have poor bond and five locations in regions suspected to have good bond are identified for each wall.
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The Effect of Splice Length and Distance between Lapped Reinforcing Bars in Concrete Block Specimens2014 April 1900 (has links)
The tensile resistance of No. 15 lap spliced reinforcing bars with varying transverse spacing and lap splice length was evaluated in full-scale concrete block wall splice specimens. The range of the transverse spacing between bars was limited to that which allowed the bars to remain within the same cell, and included the evaluation of tied spliced bars in contact. Two-and-a-half block wide by three course tall double pullout specimens reinforced with contact lap splices were initially used to determine the range of lap splice length values to be tested in the wall splice specimens such that bond failure of the reinforcement occurred. The double pullout specimens were tested in direct tension with six replicates per arrangement. Three values of lap splice length: 150, 200, and 250 mm, were selected from the testing of the double pullout specimens and tested in the wall splice specimens in combination with three values of transverse spacing: 0, 25, and 50 mm, with three replicates per configuration. A total of twenty-seven two-and-a-half block wide by thirteen course tall wall splice specimens reinforced with two lap splices were tested in four-point loading. Both the double pullout and the wall splice specimens were constructed in running bond with all cells fully grouted.
The tensile resistance of the lap spliced bars in the double pullout specimens was measured directly. The contact lap splices with a 150, 200, and 250 mm lap splice length developed approximately 38, 35 and 29% of the theoretical yield load of the reinforcement, respectively. The difference between the mean tensile resistances of the three reinforcement configurations tested in the double pullout specimens was found to be statistically significant at the 95% confidence level. Different than expected, the tensile resistance of the lap spliced reinforcing bars in the double pullout specimens was inversely proportional to the lap splice length provided. For the short lap splice lengths used in this investigation, the linear but not proportional relationship between bond force and lap splice length known from reinforced concrete is believed to have caused this phenomenon.
An iterative sectional analysis using moment-curvature response was used to calculate the tensile resistance of the lap spliced reinforcement in the wall splice specimens. The calculated mean tensile resistance of the reinforcement increased with increasing lap splice length, and was greater when the bars were in contact. Securing the bars in contact may have influenced the tensile capacity of the contact lap splices as higher stresses are likely to develop as a result of the bar ribs riding over each other with increasing slip. Results of the data analysis suggest that the tensile resistance of non-contact lap splices within the same cell is generally independent of the spacing between the bars. A comparison of the experimental results for the wall splice specimens with the development and splice length provisions in CSA S304.1-04 and TMS 402-11 indicate that both the Canadian and U.S. design standards are appropriate for both contact and non-contact lap splices located within the same cell given the limited test database included in this investigation.
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Vertikalarmering i tegelbalkar ur arbetsmiljöperspektiv / Vertical Reinforcement in Brick Spandrels with Emphasis on Occupational Safety and HealthHansson, Carl, Langvall, John January 2014 (has links)
Statistics of occupational injuries show that bricklayers are among the most exposed, with heavy lifting by far the most common cause of long-term sick leave. Prefabricated brick beams create yet another risk of injuries that can be prevented by auxiliary equipment or alternative solutions. From articles, interviews with masons and from a survey carried out in conjunction with this report, it appears that there are frequently difficulties in the use of available means for lifting and handling. Previous studies on the subject of transverse reinforcement in masonry beams indicate a viable method for bridging large openings in masonry walls. This bachelor thesis delves into whether the idea could be realized in today's brick construction with a view to improving occupational health and safety. Within the project a method, applicable in today's manufacturing of pre-stressed brick beams enabling mounting of vertical reinforcement, was developed and tested.
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