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In-plane shrinkage strains and their effects on welding distortion in thin-wall structuresCheng, Wentao 24 August 2005 (has links)
No description available.
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Systematische Untersuchung von BIM-Workflows in einer Wechselbeziehung zwischen Objekt- und Tragwerksplanung an einem FallbeispielLawrenz, Martin 12 January 2024 (has links)
Im Rahmen dieser Masterarbeit wurden die Arbeitsmethoden der Tragwerksplanung eines Ingenieurbüros im Zusammenhang mit der fortschreitenden Digitalisierung innerhalb der Baubranche
untersucht. Konkret sollen die Einflüsse und Möglichkeiten von Building Information Modeling auf interne Prozesse und die damit verbundene Effektivität analysiert werden. Das Ziel der Arbeit ist
die Identifikation der Produktivität des bestehenden Workflows und einem anschließenden Vergleich mit dem im Zuge dieser Arbeit entwickelten angepassten Workflow, welcher sich im Optimalfall als effektiver herausstellt. Dieser Vergleich soll an einem Fallbeispiel, dem Neubau eines 16-geschossigen Wohnquartiers in Jena stattfinden.
Dafür wird der projektbezogene Bestandsworkflow in die verschiedenen Arbeitsschritte zerlegt, strukturiert und dahingehend systematisch beschrieben. Danach erfolgt in einer ähnlichen Vorgehensweise die Entwicklung eines angepassten Workflows, welcher ebenfalls zunächst vorgestellt wird. Diese beiden Workflows werden abschließend hinsichtlich verschiedener Parameter miteinander verglichen, um eine Bewertung der Effektivität treffen zu können. Dafür werden beide Arbeitsweisen der Tragwerksplanung anhand des gleichen Schemas analysiert. Im Zuge der Analyse
des angepassten Workflows erfolgt die projektbezogene Beschreibung, um eine genaue Vergleichbarkeit zu Gewährleisten.
Innerhalb der abschließenden Gegenüberstellung konnten signifikante Unterschiede bezüglich der zuvor definierten Parameter festgestellt werden. Die mit der Digitalisierung verbundene
BIM-Methode kann die Arbeitsweisen der Tragwerksplanung in einem Ingenieurbüro maßgeblich beeinflussen. Vor dem Hintergrund der begrenzten personellen und finanziellen Ressourcen kleinerer Unternehmen bietet eine Anpassung der Workflows völlig neue Potenziale und kann als
Chance angesehen werden, um die eigene Wettbewerbsposition nachhaltig zu stärken.:Abbildungsverzeichnis
Abkürzungsverzeichnis
1 Einleitung
1.1 Problemstellung
1.2 Ziele und Struktur der Arbeit
2 Bauvorhaben „Solar-Quartiers“ in Jena
2.1 Projektvorstellung – Fallbeispiel
2.2 Ökonomischer Zielkonflikt zwischen den Beteiligten
3 Erläuterung der Ausgangssituation im Ingenieurbüro Hubert Beyer
4 Erläuterung von BIM-Workflows
4.1 Workflow 1: Projektbezogener Bestandsworkflow
4.1.1 Aufstellung von statischen Berechnungen
4.1.2 Modellorientierte Kommunikation zwischen den Planungsbeteiligten
4.2 Workflow 2: Angepasster projektbezogener Workflow
4.2.1 Aufstellung von statischen Berechnungen
4.2.2 Modellorientierte Kommunikation zwischen den Planungsbeteiligten
5 Analyse der betrachteten BIM-Workflows
5.1 Bestandsworkflow
5.2 Angepasster projektbezogener Workflow
5.3 Vergleich beider Workflows und Analyse der Zielerreichung
5.4 Analyse hinsichtlich des ökonomischen Zielkonfliktes
6 Zusammenfassung und Ausblick
Literaturverzeichnis
Eidesstattliche Erklärung / As part of this master's thesis, the working methods of structural planning of an engineering office
were examined in the context of the progressive digitalization within the construction industry.
Specifically, the influences and possibilities of building information modelling on internal processes and the associated effectiveness will be analysed. The aim of the work is to identify the productivity of the existing workflow and then compare it with the adapted workflow developed in the course of this work, which in the optimal case turns out to be more effective. This comparison will
take place based on a concrete case example, the new construction of a 16-storey residential quarter in Jena.
For this purpose, the project-related inventory workflow was first broken down into the different work steps, structured and described systematically. Afterwards, an adapted workflow was developed using a similar approach, which was also presented initially. Finally, these two workflows should be compared with each other regarding different parameters to be able to make an evaluation regarding effectiveness. For this purpose, both methods of structural design were analysed below based on the same scheme. In the course of the analysis of the adapted workflow, the project-related description is carried out to ensure exact comparability.
Within the final comparison, significant differences with respect to the previously defined parameters could be observed. The BIM method associated with digitization can significantly influence the
working methods of structural planning in an engineering office. Given the limited human and financial resources of smaller companies, adapting their workflows offers completely new potential
and can be seen as an opportunity to sustainably strengthen their competitive position.:Abbildungsverzeichnis
Abkürzungsverzeichnis
1 Einleitung
1.1 Problemstellung
1.2 Ziele und Struktur der Arbeit
2 Bauvorhaben „Solar-Quartiers“ in Jena
2.1 Projektvorstellung – Fallbeispiel
2.2 Ökonomischer Zielkonflikt zwischen den Beteiligten
3 Erläuterung der Ausgangssituation im Ingenieurbüro Hubert Beyer
4 Erläuterung von BIM-Workflows
4.1 Workflow 1: Projektbezogener Bestandsworkflow
4.1.1 Aufstellung von statischen Berechnungen
4.1.2 Modellorientierte Kommunikation zwischen den Planungsbeteiligten
4.2 Workflow 2: Angepasster projektbezogener Workflow
4.2.1 Aufstellung von statischen Berechnungen
4.2.2 Modellorientierte Kommunikation zwischen den Planungsbeteiligten
5 Analyse der betrachteten BIM-Workflows
5.1 Bestandsworkflow
5.2 Angepasster projektbezogener Workflow
5.3 Vergleich beider Workflows und Analyse der Zielerreichung
5.4 Analyse hinsichtlich des ökonomischen Zielkonfliktes
6 Zusammenfassung und Ausblick
Literaturverzeichnis
Eidesstattliche Erklärung
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A study of full displacement design of frame structures using displacement sensitivity analysisAbou-Rayan, Ashraf M. 09 November 2012 (has links)
The intent of this study is to develop an algorithm for structural design based on allowable displacements for structural members, independent of stresses caused by the configurations imposed. Structural design can be based on displacement constraints applied in the same basic format as stress constraints so that convergence is based on allowable displacements rather than on stresses. / Master of Science
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Topology and Lattice-Based Structural Design Optimization for Additively Manufactured Medical ImplantsPeto, Marinela 05 1900 (has links)
Topology-based optimization techniques and lattice structures are powerful ways to accomplish lightweight components with enhanced mechanical performance. Recent developments in additive manufacturing (AM) have led the way to extraordinary opportunities in realizing complex designs that are derived from topology and lattice-based structural optimization. The main aim of this work is to give a contribution, in the integration between structural optimization techniques and AM, by proposing a setup of a proper methodology for rapid development of optimized medical implants addressing oseeointegration and minimization of stress shielding related problems. The validity of the proposed methodology for a proof of concept was demonstrated in two real-world case studies: a tibia intramedullary implant and a shoulder hemi prosthetics for two bone cancer patients. The optimization was achieved using topology optimization and replacement of solid volumes by lattice structures. Samples of three lattice unit cell configurations were designed, fabricated, mechanically tested, and compared to select the most proper configuration for the shoulder hemi prosthesis. Weight reductions of 30% and 15% were achieved from the optimization of the initial design of the tibia intramedullary implant and the shoulder hemiprosthesis respectively compared to initial designs. Prototypes were fabricated using selective laser melting (SLM) and direct light processing (DLP) technologies. Validation analysis was performed using finite element analysis and compressive mechanical testing. Future work recommendations are provided for further development and improvement of the work presented in this thesis.
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Algorithmic component and system reliability analysis of truss structuresHashemolhosseini, Sepehr 12 1900 (has links)
Thesis (MScEng)-- Stellenbosch University, 2013. / ENGLISH ABSTRACT: Most of the parameters involved in the design and analysis of structures are of stochastic nature.
This is, therefore, of paramount importance to be able to perform a fully stochastic analysis of
structures both in component and system level to take into account the uncertainties involved
in structural analysis and design. To the contrary, in practice, the (computerised) analysis of
structures is based on a deterministic analysis which fails to address the randomness of design
and analysis parameters. This means that an investigation on the algorithmic methodologies for
a component and system reliability analysis can help pave the way towards the implementation
of fully stochastic analysis of structures in a computer environment. This study is focused
on algorithm development for component and system reliability analysis based on the various
proposed methodologies. Truss structures were selected for this purpose due to their simplicity
as well as their wide use in the industry. Nevertheless, the algorithms developed in this study
can be used for other types of structures such as moment-resisting frames with some simple
modi cations.
For a component level reliability analysis of structures different methods such as First Order
Reliability Methods (FORM) and simulation methods are proposed. However, implementation
of these methods for the statistically indeterminate structures is complex due to the implicit
relation between the response of the structural system and the load effect. As a result, the
algorithm developed for the purpose of component reliability analysis should be based on the
concepts of Stochastic Finite Element Methods (SFEM) where a proper link between the finite
element analysis of the structure and the reliability analysis methodology is ensured. In this
study various algorithms are developed based on the FORM method, Monte Carlo simulation,
and the Response Surface Method (RSM). Using the FORM method, two methodologies are
considered: one is based on the development of a finite element code where required alterations
are made to the FEM code and the other is based on the usage of a commercial FEM package.
Different simulation methods are also implemented: Direct Monte Carlo Simulation (DMCS),
Latin Hypercube Sampling Monte Carlo (LHCSMC), and Updated Latin Hypercube Sampling
Monte Carlo (ULHCSMC). Moreover, RSM is used together with simulation methods. Throughout the thesis, the effciency of these methods was investigated. A Fully Stochastic
Finite Element Method (FSFEM) with alterations to the finite element code seems the fastest
approach since the linking between the FEM package and reliability analysis is avoided. Simulation methods can also be effectively used for the reliability evaluation where ULHCSMC seemed
to be the most efficient method followed by LHCSMC and DMCS. The response surface method
is the least straight forward method for an algorithmic component reliability analysis; however,
it is useful for the system reliability evaluation.
For a system level reliability analysis two methods were considered: the ß-unzipping method
and the branch and bound method. The ß-unzipping method is based on a level-wise system
reliability evaluation where the structure is modelled at different damaged levels according to its
degree of redundancy. In each level, the so-called unzipping intervals are defined for the identification of the critical elements. The branch and bound method is based on the identification
of different failure paths of the structure by the expansion of the structural failure tree. The
evaluation of the damaged states for both of the methods is the same. Furthermore, both of
the methods lead to the development of a parallel-series model for the structural system. The
only difference between the two methods is in the search approach used for the failure sequence
identification.
It was shown that the ß-unzipping method provides a better algorithmic approach for evaluating
the system reliability compared to the branch and bound method. Nevertheless, the branch and
bound method is a more robust method in the identification of structural failure sequences. One
possible way to increase the efficiency of the ß-unzipping method is to define bigger unzipping
intervals in each level which can be possible through a computerised analysis. For such an
analysis four major modules are required: a general intact structure module, a damaged structure
module, a reliability analysis module, and a system reliability module.
In this thesis different computer programs were developed for both system and component
reliability analysis based on the developed algorithms. The computer programs are presented
in the appendices of the thesis. / AFRIKAANSE OPSOMMING: Meeste van die veranderlikes betrokke by die ontwerp en analise van strukture is stogasties in
hul aard. Om die onsekerhede betrokke in ontwerp en analise in ag te neem is dit dus van
groot belang om 'n ten volle stogastiese analise te kan uitvoer op beide komponent asook stelsel
vlak. In teenstelling hiermee is die gerekenariseerde analise van strukture in praktyk gebaseer
op deterministiese analise wat nie suksesvol is om die stogastiese aard van ontwerp veranderlikes
in ag te neem nie. Dit beteken dat die ondersoek na die algoritmiese metodiek vir komponent en
stelsel betroubaarheid analise kan help om die weg te baan na die implementering van ten volle
rekenaarmatige stogastiese analise van strukture. Di e studie se fokus is op die ontwikkeling van
algoritmes vir komponent en stelsel betroubaarheid analise soos gegrond op verskeie voorgestelde
metodes. Vakwerk strukture is gekies vir die doeleinde as gevolg van hulle eenvoud asook hulle
wydverspreide gebruik in industrie. Die algoritmes wat in die studie ontwikkel is kan nietemin
ook vir ander tipes strukture soos moment-vaste raamwerke gebruik word, gegewe eenvoudige
aanpassings.
Vir 'n komponent vlak betroubaarheid analise van strukture word verskeie metodes soos die
"First Order Reliability Methods" (FORM) en simulasie metodes voorgestel. Die implementering
van die metodes vir staties onbepaalbare strukture is ingewikkeld as gevolg van die implisiete
verband tussen die gedrag van die struktuur stelsel en die las effek. As 'n gevolg, moet die algoritme
wat ontwikkel word vir die doel van komponent betroubaarheid analise gebaseer word
op die konsepte van stogastiese eindige element metodes ("SFEM") waar 'n duidelike verband
tussen die eindige element analise van die struktuur en die betroubaarheid analise verseker is. In
hierdie studie word verskeie algoritmes ontwikkel wat gebaseer is op die FORM metode, Monte
Carlo simulasie, en die sogenaamde "Response Surface Method" (RSM). Vir die gebruik van die
FORM metode word twee verdere metodologieë ondersoek: een gebaseer op die ontwikkeling
van 'n eindige element kode waar nodige verandering aan die eindige element kode self gemaak
word en die ander waar 'n kommersiële eindige element pakket gebruik word. Verskillende simulasie
metodes word ook geïmplimenteer naamlik Direkte Monte Carlo Simulasie (DMCS),
"Latin Hypercube Sampling Monte Carlo" (LHCSMC) en sogenaamde "Updated Latin Hypercube
Sampling Monte Carlo" (ULHCSMC). Verder, word RSM tesame met die simulasie
metodes gebruik. In die tesis word die doeltreffendheid van die bostaande metodes deurgaans ondersoek. 'n Ten volle stogastiese eindige element metode ("FSFEM") met verandering aan die eindige element
kode blyk die vinnigste benadering te wees omdat die koppeling tussen die eindige element
metode pakket en die betroubaarheid analise verhoed word. Simulasie metodes kan ook effektief
aangewend word vir die betroubaarheid evaluasie waar ULHCSMC as die mees doeltre end
voorgekom het, gevolg deur LHCSMC en DMCS. The RSM metode is die mees komplekse
metode vir algoritmiese komponent betroubaarheid analise. Die metode is egter nuttig vir
sisteem betroubaarheid analise.
Vir sisteem-vlak betroubaarheid analise is twee metodes oorweeg naamlik die "ß-unzipping"
metode and die "branch-and-bound" metode. Die "ß-unzipping" metode is gebaseer op 'n
sisteem-vlak betroubaarheid ontleding waar die struktuur op verskillende skade vlakke gemodelleer
word soos toepaslik vir die hoeveelheid addisionele las paaie. In elke vlak word die
sogenaamde "unzipping" intervalle gedefinieer vir die identifikasie van die kritiese elemente. Die
"branch-and-bound" metode is gebaseer op die identifikasie van verskillende faling roetes van
die struktuur deur uitbreiding van die falingsboom. The ondersoek van die skade toestande vir
beide metodes is dieselfde. Verder kan beide metodes lei tot die ontwikkeling van 'n parallelserie
model van die strukturele stelsel. Die enigste verskil tussen die twee metodes is in die
soek-benadering vir die uitkenning van falingsmodus volgorde.
Dit word getoon dat die "ß-unzipping" metode 'n beter algoritmiese benadering is vir die ontleding
van sisteem betroubaarheid vergeleke met die "branch-and-bound" metode. Die "branch-and-
bound" metode word nietemin as 'n meer robuuste metode vir die uitkenning van die falings
volgorde beskou. Een moontlike manier om die doeltre endheid van die "ß-unzipping" metode
te verhoog is om groter "unzipping" intervalle te gebruik, wat moontlik is vir rekenaarmatige
analise. Vir so 'n analise word vier hoof modules benodig naamlik 'n algemene heel-struktuur
module, 'n beskadigde-struktuur module, 'n betroubaarheid analise module en 'n sisteem betroubaarheid analise module.
In die tesis word verskillende rekenaar programme ontwikkel vir beide sisteem en komponent
betroubaarheid analise. Die rekenaar programme word in die aanhangsels van die tesis
aangebied.
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Ethics in structural design and mechanical design for live entertainment sceneryVieira, David Vincent 21 October 2014 (has links)
Scenic construction requires a strong understanding of a range of principles related to construction including: materials strength properties, mechanical components, electrical motor systems, fluid power systems, and finishing techniques. A manager of scenic construction, or a Technical Director (TD), is required to take artistic designs and ideas and create magical elements on stage that are safe for performers, installers, operators, and audiences. In order to create these onstage spectacles, a great deal of planning, engineering, and careful fabrication must take place. There are several ways for a Technical Director to gain the knowledge required to effectively work at any level of entertainment production. This mixed-methods research study asks: what are the ethical standards that guide how a TD’s work is completed? The thesis begins with a review of the job of the Technical Director in Live Entertainment and data from a survey conducted of professionals in scenic technology. Results from the survey were analyzed to provide both quantitative data, in the form of statistics, and qualitative response data. Additional discussion addresses a sample of the resources for structural design support available currently to the field, as well as challenges that some professionals confront in their typical practice. The thesis concludes a review of literature around engineering ethics and liability in engineering practice and recommendations for the incorporation of new ethical standards in live entertainment scenic production. / text
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Rekonstrukce hliněných staveb v regionu Haná / Reconstruction of earth buildings in Haná regionKarasová, Alena January 2009 (has links)
The current state of earth building in Czeh Republic is described in this work. The results are based on a research made in several villages. Reconstruction of traditional countryside building made from unburned earth should be made very sensitive with respect to architectural and technical solution and in accordance with environmental requirements and wishes of investor.
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Contribution à l’optimisation multi-objectifs sous contraintes : applications à la mécanique des structures / Contribution to multi-objective optimization under constraints : applications to structural mechanicsTchvagha Zeine, Ahmed 04 July 2018 (has links)
L’objectif de cette thèse est le développement de méthodes d’optimisation multi-objectif pour la résolution de problèmes de conception des structures mécaniques. En effet, la plupart des problèmes réels dans le domaine de la mécanique des structures ont plusieurs objectifs qui sont souvent antagonistes. Il s’agit, par exemple, de concevoir des structures en optimisant leurs poids, leurs tailles, et leurs coûts de production. Le but des méthodes d’optimisation multi-objectif est la recherche des solutions de compromis entre les objectifs étant donné l’impossibilité de satisfaire tout simultanément. Les métaheuristiques sont des méthodes d’optimisation capables de résoudre les problèmes d’optimisation multi-objective en un temps de calcul raisonnable sans garantie de l’optimalité de (s) solution (s). Au cours des dernières années, ces algorithmes ont été appliqués avec succès pour résoudre le problème des mécaniques des structures. Dans cette thèse deux métaheuristiques ont été développées pour la résolution des problèmes d’optimisation multi-objectif en général et de conception de structures mécaniques en particulier. Le premier algorithme baptisé MOBSA utilise les opérateurs de croisement et de mutation de l’algorithme BSA. Le deuxième algorithme nommé NNIA+X est une hybridation d’un algorithme immunitaire et de trois croisements inspirés de l’opérateur de croisement original de l’algorithme BSA. Pour évaluer l’efficacité et l’efficience de ces deux algorithmes, des tests sur quelques problèmes dans littérature ont été réalisés avec une comparaison avec des algorithmes bien connus dans le domaine de l’optimisation multi-objectif. Les résultats de comparaison en utilisant des métriques très utilisées dans la littérature ont démontré que ces deux algorithmes peuvent concurrencer leurs prédécesseurs. / The objective of this thesis is the development of multi-objective optimization methods for solving mechanical design problems. Indeed, most of the real problems in the field of mechanical structures have several objectives that are often antagonistic. For example, it is about designing structures by optimizing their weight, their size, and their production costs. The goal of multi-objective optimization methods is the search for compromise solutions between objectives given the impossibility to satisfy all simultaneously. Metaheuristics are optimization methods capable of solving multi-objective optimization problems in a reasonable calculation time without guaranteeing the optimality of the solution (s). In recent years, these algorithms have been successfully applied to solve the problem of structural mechanics. In this thesis, two metaheuristics have been developed for the resolution of multi-objective optimization problems in general and of mechanical structures design in particular. The first algorithm called MOBSA used the crossover and mutation operators of the BSA algorithm. The second one named NNIA+X is a hybridization of an immune algorithm and three crossover inspired by the original crossover operator of the BSA algorithm. To evaluate the effectiveness and efficiency of these two algorithms, tests on some problems in literature have been made with a comparison with algorithms well known in the field of multi-objective optimization. The comparison results using metrics widely used in the literature have shown that our two algorithms can compete with their predecessors.
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Influência de um corte na borda tracionada de uma viga maciça simulando uma emenda de topo na lâmina inferior de vigas laminadas coladas / The influence of a cut in the tensioned edge of a solid beam simulating a butt joint at the bottom lamination of glued laminated beamsAprilanti, Mônica Duarte 12 February 2010 (has links)
A madeira laminada colada (MLC) é um produto estrutural que permite racionalizar o uso da madeira sólida, pois a partir de pequenas peças selecionadas e preparadas é possível produzir grandes vigas das mais variadas formas. A utilização da madeira de reflorestamento na produção de MLC lhe confere vantagens ambientais sobre outros materiais e o Eucalyptus grandis é uma espécie que oferece grande potencial para o uso estrutural. As emendas longitudinais entre lâminas representam descontinuidades na peça de MLC e, assim como os defeitos em peças maciças, são regiões potencialmente fracas causando grande influência na resistência de vigas laminadas. O objetivo do presente trabalho foi o de estudar a influência de uma emenda de topo e de sua posição na lâmina inferior de vigas laminadas coladas (VLCs) no momento de inércia, na elástica da viga e consequentemente no módulo de elasticidade na flexão estática (EM0). Foi conduzido um estudo teórico-experimental com corpos-de-prova maciços que receberam um corte na borda tracionada simulando uma emenda de topo na lâmina inferior de VLCs. Em uma 1ª etapa da experimentação, foram realizados ensaios de flexão estática destrutivos com corposde- prova de seção transversal 2,5 x 2,5 cm não classificados com o intuito de explorar a grandeza da variabilidade das propriedades estudadas para diferentes posições da emenda ao longo da borda inferior da viga biapoiada. A 2ª etapa de ensaios consistiu na classificação de um lote de corpos-de-prova de seção transversal de 3,0 x 4,0 cm através de ensaios de flexão estática não destrutivos para minimizar o erro experimental imposto pela variabilidade natural do material. Em uma 3ª etapa, foram realizados ensaios de flexão estática destrutivos de corpos-de-prova de seção transversal 3,0 x 4,0 cm classificados para estudar o efeito de diferentes posições da emenda na borda inferior da viga num lote de menor variabilidade. Em uma 4ª etapa da experimentação foram realizadas simulações através de planilhas de cálculo com base na teoria de Garcia (2008) para a comprovação dos resultados experimentais e elaboração de novas formulações de dimensionamento de VLCs. Verificou-se que o corte não influenciou no EM0 nos ensaios da 1ª etapa quando se tratou de um lote de madeira desuniforme, mas exerceu um efeito significativo nos ensaios da 3ª etapa dentro do lote de peças classificadas. Concluiu-se que o corte influencia na rigidez da viga à flexão (EI), pois provoca uma modificação do fluxo de tensões com consequente alteração da distribuição de tensões ao longo da altura da viga e do momento de inércia. A concentração de tensões na área circundante ao corte provoca uma redução no momento de inércia que deve ser levada em consideração no dimensionamento de VLCs em que se utilizam emendas de topo nas lâminas tracionadas. O corte influencia significantemente na resistência à flexão da viga porque dá origem ao aparecimento de uma fissura paralela à grã que transporta a altura reduzida pelo corte à seção critica. Essa fissura é provocada por cisalhamento oriundo do momento fletor e não do esforço cortante. / Glued laminated timber (GLULAM) is a structural product that allows rationalizing the use of solid wood, as from small selected and prepared pieces it is possible to produce large beams in a variety of shapes. The use wood from planted forests in GLULAM production brings environmental advantages compared to other materials and Eucalyptus grandis is a species that offers great potential for structural use. The end joints that connect pieces to perform the entire laminas represent discontinuities in the GLULAM and as many defects in solid wood are potentially weak areas. The aim of the present paper is to study the influence of a butt joint and its position in the bottom lamination of glued laminated beams, on the moment of inertia, on the elastic of the beam and therefore on the modulus of elasticity in static bending (EM0). A theoretical and experimental study was conducted with solid specimens that were cut on the tensioned edge simulating a butt joint at the bottom lamination of glued laminated beams. At a first phase of testing, destructive static bending tests were performed with specimens sized 2.5 x 2.5 cm as cross-section non classified in order to explore the magnitude of the natural variability of the studied properties for different positions of the joint along the bottom edge of the biconstrainted beam. The second phase of testing consisted in classifying a batch of specimens 3.0 x 4.0 cm cross section by non-destructive static bending tests to minimize experimental error imposed by the natural variability of the material. At a third phase, destructive static bending tests were performed with 3.0 x 4.0 cm cross section classified specimens to study the effect of different positions of the joint on the bottom edge of the beam in a group of low variability. At the fourth phase simulations were performed using spreadsheets on the Garcia´s theory (2008) to verify the experimental results and the development of new formulations of glued laminated beams design. It was verified that the cut did not affect the EM0 on the first step of testing when regarding a non uniform batch of wood, but there was a significant effect on the tests of the third step over the batch of classified wood. It was concluded that the cut influences the stiffness of the bending beam (EI) by changing the flux tensions pattern and consequent change in stress distribution along the beam height and the moment of inertia. The concentration of stresses in the area surrounding the cut causes a reduction in the moment of inertia that must be taken into account for designing glued laminated beams that use butt joints in the tensioned edge. The cut significantly influence the beam bending strength because give way to appear a check in parallel to the grain and transport the reduced height to the critical cross section. Such a check is due shear stresses consequent of the bending moment and not from the shear force.
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Contribuição ao projeto de vigas delgadas de seção \"L\" de concreto pré-moldado / Contribution to the design of precast concrete slender L-shaped beamsPastore, Marcus Vinícius Filiagi 05 August 2015 (has links)
Esta dissertação tem por objetivo contribuir para o projeto estrutural de vigas delgadas de seção \"L\" de concreto pré-moldado, também conhecidas no Brasil como vigas suporte-peitoril. O projeto deste tipo de viga apresenta uma maior complexidade que o de vigas usuais pela seção transversal assimétrica, carregamento excêntrico e as várias possibilidades de ligações viga-pilar e viga-laje. Em função de sua ligação com a laje, o comportamento deste tipo de viga pode apresentar diferentes modelos: a) com torção de equilíbrio; b) sem torção de equilíbrio; e c) com restrição parcial da rotação da laje. É mostrado que para relações altura da viga/largura da mesa inferior maiores que 2,5, a variação da orientação dos eixos principais de inércia com relação aos eixos vertical e horizontal pode ser desprezada. Além disso, o centro de cisalhamento pode ser considerado situado na linha de centro da alma para grandes relações altura da viga/altura da aba. Também são discutidas as ações e efeitos a serem considerados no projeto de vigas de seção \"L\". Em relação ao estado limite último, é mostrado que os procedimentos de dimensionamento de momento fletor e força cortante não diferem dos outros tipos de vigas de concreto, entretanto, o momento de torção pode ser tratado como flexão de placa por um método recomendado na última revisão do ACI-318. O comportamento da ligação alma/aba é considerado como dente de concreto e os seguintes aspectos de seu dimensionamento são apresentados: cálculo do tirante, cálculo da suspensão, cálculo da armadura longitudinal e verificação da biela crítica. Além disso, é levada em conta a resistência à punção da aba para efeito de forças concentradas. Também são discutidas as considerações para a flexão do peitoril que pode ocorrer pela ação lateral do vento e do impacto de veículos. Em relação ao estado limite de serviço, são apresentadas duas situações exclusivas para vigas de seção \"L\" com peitoril alto e delgado: formação de fissuras na extremidade e deformação lateral excessiva. Por fim, um exemplo de aplicação é desenvolvido para ilustrar particularidades no dimensionamento de vigas delgadas de seção \"L\" de concreto pré-moldado. / This thesis aims to contribute to the structural design of precast concrete slender L-shaped beams, also known as facade beams, spandrel beams, L-shaped edge beams and others. The design of these beams shows a greater complexity than usual concrete beams due to the asymmetric cross section, eccentric loads and the various possibilities for beam-column and beam-slab connections. According to their connection with the slab, the beam behavior can be divided into different models: a) with equilibrium torsion; b) without equilibrium torsion; c) with partial restriction of the slab rotation. It is shown that for height-to-total width ratios larger than 2.5, the variation of the orientation of the principal axes with respect to the vertical and horizontal axes can be neglected. Furthermore, the shear center can be considered located at the web center line for high values of the beam height-to-ledge height ratio. It is also discussed the actions and effects to be considered in the design of L-shaped beams. Regarding the ultimate limit state, it is shown that the bending moment and shear force procedures do not differ from other types of concrete beams, however, the torsion can be treated as plate bending by a recent method recommended in the latest ACI-318 revision. The ledge is considered as dapped end beams and the following aspects of its design are presented: transverse bending; hanger requirements; longitudinal bending and shear strength, including punching shear. It is also discussed the considerations for web flexure that may occur by wind action and lateral vehicle impact. Regarding the serviceability limit state, it is presented two unique situations for precast concrete slender L-shaped beams: crack formation at end regions and excessive lateral deflection. Lastly, an example is developed to illustrate particularities of the precast concrete slender L-shaped beam design.
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