Tesi sul tema "Behavior of connectors"
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1
Rambo-Roddenberry, Michelle. "Behavior and Strength of Welded Stud Shear Connectors". Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/26989.
Abstract (sommario):
The behavior and strength of welded shear studs are subjects of ongoing study. In recent years, research has shown that the American Institute of Steel Construction (AISC) specification equations for shear stud strength are unconservative for studs placed in deck with ribs transverse to the steel beam. Twenty-four solid slab push-out tests, 93 composite slab push-out tests, and bare stud tests were performed to study the effects on stud strength of friction, normal load, position of studs in the ribs of steel deck, concrete strength, and stud properties. Stud diameters ranged from 3/8 in. to 7/8 in., deck heights ranged from 2 in. to 6 in., and both single and pairs of studs were tested. The push-out test results from this study were combined with other studies to propose a new stud strength prediction model. Three new beam tests were performed to study the effect of the stud position in the ribs of the steel deck. The results of these tests, along with 61 other beam tests, were used to verify the new stud strength prediction model. A reliability study was performed to determine resistance factors for stud strength and beam strength.Ph. D.
2
Sullivan, Sean Robert. "Construction and Behavior of Precast Bridge Deck Panel Systems". Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/27479.
Abstract (sommario):
A bridge with precast bridge deck panels was built at the Virginia Tech Structures Laboratory to examine constructability issues, creep and shrinkage behavior, and strength and fatigue performance of transverse joints, different types of shear connectors, and different shear pocket spacings. The bridge consisted of two AASHTO type II girders, 40 ft long and simply supported, and five precast bridge deck panels. Two of the transverse joints were epoxied male-female joints and the other two transverse joints were grouted female-female joints. Two different pocket spacings were studied: 4 ft pocket spacing and 2 ft pocket spacing. Two different shear connector types were studied: hooked reinforcing bars and a new shear stud detail that can be used with concrete girders.
The construction process was well documented. The change in strain in the girders and deck was examined and compared to a finite element model to examine the effects of differential creep and shrinkage. After the finite element model verification study, the model was used to predict the long term stresses in the deck and determine if the initial level of post-tensioning was adequate to keep the transverse joints in compression throughout the estimated service life of the bridge. Cyclic loading tests and shear and flexural strength tests were performed to examine performance of the different pocket spacings, shear connector types and transverse joint configurations. A finite element study examined the accuracy of the AASHTO LRFD shear friction equation for the design of the horizontal shear connectors.
The initial level of post-tensioning in the bridge was adequate to keep the transverse joints in compression throughout the service life of the bridge. Both types of pocket spacings and shear connectors performed exceptionally well. The AASHTO LRFD shear friction equation was shown to be applicable to deck panel systems and was conservative for determining the number of shear connectors required in each pocket. A recommended design and detailing procedure was provided for the shear connectors and shear pockets.Ph. D.
3
Kloak, David G. "Strong Emotive Connectors| A Study of a Social Skill and Effective Team Performance". Thesis, Alliant International University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10267146.
Abstract (sommario):
Organizational success and outcomes rely on good teamwork. The study question asked if teams can be more successful with a greater number of socially skilled team members? Evolving research indicates composing teams based on intrinsic social skills, such as personality, values, and psychological roles may generate greater team outcomes than teams based solely on vocational roles, competencies, and cognitive ability. When teams are first formed, people connect instinctively and warm to other team members using their social skills. Only later do people appraise others for competencies and skills. This study examined whether the number of strong emotive connectors (SEC) can increase team outcomes. The study hypothesis tested whether teams with a greater number of high SECs, a socioemotional role construct, would increase their team task-completion rates (TTCR). Regression analysis showed the low and high SEC with an adjusted R2 = .52 correlation were both predictive of the TTCR. Additional analysis using 2 one-way ANOVAs for high and low SECs showed between-team (groups) and within teams (groups) results were statistically significant at the p = .00 level. The study found teams having 2 of 5 high SECs made a difference in team performance. Additional high SECs had no impact on team performance. An interesting study result found 2 of 5 low SECs had an adverse impact on team performance. Additional low SECs did not harm team performance. Ensuring at least 2 of 5 high SECs on teams can lessen gaps, diminish conflicts, and elevate team outcomes.
4
Rao, Yang. "Mechanical behavior characterization of some new materials for high density interconnect substrates". Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/19286.
5
Mujagic, Ubejd. "Design and Behavior of Composite Steel-Concrete Flexural Members with a Focus on Shear Connectors". Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/26745.
Abstract (sommario):
This study consists of three self-standing parts, each dealing with a different aspect of design of composite steel-concrete flexural members.
The first part deals with a new type of shear connection in composite joists. Composite steel-concrete flexural members have increasingly become popular in design and construction of floor systems, structural frames, and bridges. A particularly popular system features composite trusses (joists) that can span large lengths and provide empty web space for installation of typical utility conduits. One of the prominent problems with respect to composite joists has been the installation of welded shear connection due to demanding welding requirements and the need for significant welding equipment at the job site. This part of the study presents a new type of shear connection developed at Virginia Tech â standoff screws. Results of experimental and analytical research are presented, as well as the development of a recommended design methodology.
The second part deals with reliability of composite beams. Constant research advances in the field of composite steel-concrete beam design have resulted in numerous enhancements and changes to the American design practice, embodied in the composite construction provisions of the AISC Specification (AISC 1999). Results of a comprehensive reliability study of composite beams are presented. The study considers specification changes since the original reliability study by Galambos et al. (1976), considers a larger database of experimental data, and analyses recent proposals for changes in design of shear connection. Comparison of three different design methods is presented based on a study of 15,064 composite beam cases. A method to consider effect of degree of shear connection on strength reduction factor is proposed.
Finally, while basic analysis theories between the two are similar, requirements for determining the strength of composite beams in Eurocode 4 (CEN 1992) and 1999 AISC Specification (AISC 1999) differ in many respects. This is particularly true when considering the design of shear connections. This part of the dissertation explores those differences through a comparative step-by-step discussion of major design aspects, and accompanying numerical example. Several shortcomings of 1999 AISC Specification are identified and adjustments proposed.Ph. D.
6
Tabet-Derraz, Moulay Idriss. "Comportement et modélisation des connecteurs dans une structure mixte (acier-béton)". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0092.
Abstract (sommario):
Le principe des poutres mixtes acier-béton est d'associer une dalle de béton et une poutre en acier pour un travail en commun. Les connecteurs de cisaillement sont des outils mécaniques qui ont le rôle d'assurer la connexion entre les deux matériaux à l'interface des poutres mixtes. Une variété de connecteurs de cisaillement a été proposée dans la littérature afin de fournir un comportement approprié à l'interface acier-béton. Les connecteurs à goujon à tête sont les plus largement utilisés dans la construction mixte en raison des recommandations des codes du bâtiment. Cependant, ces derniers présentent des inconvénients notables en termes de performances structurelles et de praticabilité sur les chantiers. Dans cette présente thèse, un nouveau type de connecteur innovant en forme d'OMEGA a été proposé en deux conceptions géométriques (forme primaire et forme améliorée) pour être une alternative aux connecteurs conventionnels. En plus d'avoir un processus de fabrication simple et une installation pratique à l'interface de la poutre mixte, la forme de ce connecteur permet une grande surface de béton confiné, le rendant ainsi plus résistant au cisaillement et au soulèvement de la dalle. Dans cette recherche, des tests expérimentaux de push-out ont été effectués sur le connecteur OMEGA avec différentes configurations pour étudier leur résistance, leur ductilité et leur mode de ruine dans la connexion acier-béton. Des spécimens de push-out supplémentaires avec les connecteurs conventionnels de type goujon à tête ont également été testés dans le but de comparer les performance des connecteurs OMEGA avec celles des goujons à tête standard. Les résultats ont démontré que le connecteur en forme d'OMEGA proposé présente un comportement intéressants dans la connexion acier-béton et pourrait donc être utilisé comme connecteur de cisaillement alternatif pour les poutres mixtes. De plus, un modèle numérique EF de l'essai de push-out sur les connecteurs OMEGA a été développé dans cette thèse à l'aide du logiciel Abaqus. Le but est d'approfondir les investigations sur ce connecteur proposé, en menant une étude paramétrique qui vise à évaluer les influences des dimensions du connecteur et de la résistance de la dalle de béton sur le comportement interne de la connexion acier-béton. En outre, en exploitant les résultats de l'étude paramétrique, une équation de prédiction de la résistance au cisaillement des connecteurs OMEGA a également été développée. Par ailleurs, des essais de poutre mixte avec les connecteurs OMEGA disposés à l'interface ont également été réalisés dans le cadre de cette thèse, en réalisant un spécimen de poutre mixte avec une connexion complète et un autre avec une connexion partielle. L'objectif de cette étude est d'analyser l'influence du comportement des connecteur OMEGA dans la connexion sur le comportement global de la poutre mixte. Les résultats ont affirmé que l'utilisation des connecteur OMEGA assure un comportement adéquat aux poutres mixtes, même avec un degré de connexion réduitThe principle of steel-concrete composite beams is to combine a concrete slab and a steel beam for joint work. Shear connectors are mechanical tools that have the role of ensuring the connection between the two materials at the interface of the composite beams. A variety of shear connectors have been proposed in the literature to provide suitable behavior at the steel-concrete interface. Headed stud connectors are most widely used in composite construction due to building code recommendations. However, the latter have significant drawbacks in terms of structural performance and practicability on construction sites. In this present thesis, an innovative new type of OMEGA-shaped connector has been proposed in two geometric designs (primary shape and improved shape) to be an alternative to conventional connectors. In addition to having a simple fabrication process and convenient installation at the composite beam interface, the shape of this connector allows for a large confined concrete zone, making it more resistant to shear and slab uplift. In this research, experimental push-out tests were performed on OMEGA connector with different configurations to study their strength, ductility and failure mode in the steel-concrete connection. Additional push-out specimens with conventional headed stud type connectors were also tested in order to compare the performance of OMEGA connectors with that of standard headed studs. The results demonstrated that the proposed OMEGA-shaped connector exhibited interesting behavior in steel-concrete connection and which can be used as an alternative shear connector for composite beams. In addition, an FE numerical model of the push-out test on OMEGA connectors was developed in this thesis using Abaqus software. The goal is to deepen the investigations on this proposed connector, by conducting a parametric study that aims to evaluate the influences of connector dimensions and concrete slab strength on the internal behavior of the steel-concrete connection. Moreover, by exploiting the parametric study results, an equation for predicting the OMEGA connectors shear strength was also developed. Furthermore, composite beam tests with OMEGA connectors arranged at the interface were also carried out as part of this thesis, by producing a composite beam specimen with a complete connection and another with a partial connection. The objective of this study is to analyze the influence of OMEGA connectors mechanism in the connection on the overall behavior of the composite beam. The results affirmed that the use of OMEGA connectors ensure adequate behavior to composite beams, even with a reduced degree of connection
7
Harman, Kelly. "Structural integrity of lightweight wood truss assemblies exposed to fire : an insight to the behavior of metal truss plate connectors /". Available to subscribers only, 2006. http://proquest.umi.com/pqdweb?did=1136091331&sid=23&Fmt=2&clientId=1509&RQT=309&VName=PQD.
8
Perrinet, Olivier. "Analyse de l'endurance de contacts électriques Sn, Au et Ag soumis à des sollicitations complexes de fretting usure". Thesis, Ecully, Ecole centrale de Lyon, 2014. http://www.theses.fr/2014ECDL0009.
Abstract (sommario):
Dans les applications automobiles et dans d'autres domaines (énergie, aviation, etc), le nombre d'appareils électroniques a augmenté de façon significative au cours des dernières décennies. La sécurité des systèmes et des personnes repose sur la qualité de connecteurs électriques. Toutefois, soumis à des vibrations (moteur de la voiture, de l'environnement) des microdéplacements sont induits à l’interface. La problématique du contact électrique est principalement liée à l'altération de la conduction de faible courant (5mA) dans les interfaces soumises à des contraintes mécaniques de glissement répétitifs engendrant un phénomène bien connu de fretting par l’usure. La sollicitation de fretting usure apparait comme un processus de dégradation très pénalisant. Outre la détérioration des surfaces, ce processus conduit à une augmentation de la résistance électrique des contacts et à une possible perte du signal électrique. Ceci est particulièrement le cas pour les connecteurs bas niveau très sensibles aux fluctuations de la résistance électrique. Pour remédier à cela, les acteurs de la connectique développent de nouveaux dépôts pour limiter l’utilisation de dépôts nobles tels que l’or. Les objectifs de cette thèse sont d’établir une "table d’utilisation" des revêtements en fonction de sollicitations précises et de mettre en place une méthodologie dans le choix des dépôts en vue d’optimiser la durée de vie des connecteurs. L’étude aborde différents aspects tels que les influences des conditions de chargements mécaniques, des épaisseurs de dépôts, du type de dépôt (noble, non noble, dopé), de l’amplitude de débattement (micro-déplacement et grand déplacement) et la formalisation de l’endurance électrique (loi puissance et approche énergétique)In automotive applications and in other areas (energy, aviation, etc.), the number of electronic devices has increased significantly in recent last decades. Systems and people securities are based on the quality of electrical connectors. However, submitted to vibrations (car engine, environment) micro-displacements are induced at the interface. The problem of electrical contact is mainly due to the impairment of low current conduction (5mA) in interfaces subjected to repetitive sliding displacement generating a well-known fretting wear phenomenon. Fretting wear solicitation appears as a process of very detrimental degradation. Besides surface deterioration, this process leads an increase of the electrical contact resistance and a possible loss of the electrical signal. This is particularly the case of the low level connectors which are very sensitive to electrical contact fluctuations. To remedy, connections actors develop new deposits to limit the use of noble ones such as gold. The objectives of this thesis are to establish a "table of use" coatings based on specific solicitations and define a methodology for the selection of deposits to optimize the lifetime connectors. The study covers different aspects such as the mechanical loading conditions influence, the thickness deposits influence, the type of deposit (noble, non-noble, doped), the displacement amplitude (microdisplacement and large displacement) and the electrical endurance formalization (energetic approach and power law)
9
Rehman, Naveed Ur. "Behaviour of demountable shear connectors in composite structures". Thesis, University of Bradford, 2017. http://hdl.handle.net/10454/14790.
Abstract (sommario):
The research presented in this thesis is to evaluate the feasibility of demountable shear connectors as an alternative to welded shear connectors in composite structures through push off tests and composite beam tests. Push off tests were conducted to examine the shear strength, stiffness and ductility of demountable shear connectors in composite structures. The experimental results showed that demountable shear connectors in composite structures have very similar shear capacity to welded shear connectors. The shear capacity was compared against the prediction methods used for the welded shear connections given in Eurocode 4 and AISC 360-10 and the methods used for bolted connections in Eurocode 3 and ACI 318-08. It was found that the AISC 360-10 and ACI 318-08 methods overestimated the shear capacity in some cases. The Eurocode method is conservative and can be utilised to predict the shear capacity of demountable connectors in composite structures. The experimental studies of two identical composite beams using demountable shear connectors and welded shear connectors showed very similar moment capacity. However, the specimen with demountable shear connectors was more ductile compared to the welded specimen. The experimental study suggests that the methods available in Eurocode 4 and BS 5950 for predicting moment capacity and mid span deflection can be adopted for composite beam with demountable shear connectors. In addition, a finite element analysis of push off test and beam test with demountable shear connectors was also conducted for parametric studies and results are used to evaluate the behaviour of composite structures.
10
Rehman, Naveed. "Behaviour of demountable shear connectors in composite structures". Thesis, University of Bradford, 2017. http://hdl.handle.net/10454/14790.
Abstract (sommario):
The research presented in this thesis is to evaluate the feasibility of
demountable shear connectors as an alternative to welded shear connectors
in composite structures through push off tests and composite beam tests.
Push off tests were conducted to examine the shear strength, stiffness and
ductility of demountable shear connectors in composite structures. The
experimental results showed that demountable shear connectors in
composite structures have very similar shear capacity to welded shear
connectors.
The shear capacity was compared against the prediction methods used for
the welded shear connections given in Eurocode 4 and AISC 360-10 and the
methods used for bolted connections in Eurocode 3 and ACI 318-08. It was
found that the AISC 360-10 and ACI 318-08 methods overestimated the
shear capacity in some cases. The Eurocode method is conservative and
can be utilised to predict the shear capacity of demountable connectors in
composite structures. The experimental studies of two identical composite beams using
demountable shear connectors and welded shear connectors showed very
similar moment capacity. However, the specimen with demountable shear
connectors was more ductile compared to the welded specimen. The experimental study suggests that the methods available in Eurocode 4 and
BS 5950 for predicting moment capacity and mid span deflection can be
adopted for composite beam with demountable shear connectors.
In addition, a finite element analysis of push off test and beam test with
demountable shear connectors was also conducted for parametric studies
and results are used to evaluate the behaviour of composite structures.EPSRC and the University of Bradford
11
Lloyd, Robert Mitchell. "The behaviour of through deck welded stud shear connectors". Thesis, Cardiff University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402848.
12
Chikho, Abdul Hakim. "Frame behaviour with semi-rigid connections". Thesis, University of Sheffield, 1989. http://etheses.whiterose.ac.uk/3067/.
Abstract (sommario):
In this thesis both analytical and design studies have been conducted on the behaviour of fully and semi-rigidly connected multistorey steel frames. Many topics have been addressed, current design approaches examined and new design methods proposed to allow for such effects based upon a first order linear elastic analysis, which is the most commonly used in normal design. These topics are as follows: 1) The well known amplified sway method (see BS 5950: 1985: Part 1) which can be used to incorporate the effect of the presence of axial loads on the behaviour of sway frames was studied. A modification to this method has been proposed and the validity of the proposed method was checked using an existing computer program [1] to verify the proposed method against a second order analysis. 2) The influence of the action of semi-rigid connections on frame behaviour was examined and the need to conduct a systematic investigation into the problem verified. A simple hand calculation method to incorporate this influence to any of the conventional design methods has been proposed. A second computer program [2] was slightly modified to suit the university of Sheffield IBM3083 mainframe machine and this program was later used in this study. 3) The stiffening effect due to partial sway bracing resulting from the presence of block or brickwork walls in a practical multistorey frame accompanied by the weakening effect due to the finite stiffness of semi-rigid joints on frame serviceability was investigated and a suitable design method is recommended. 4) The behaviour of columns in sway frames with and without partial sway bracing, resulting from the presence of infill panels in practical frames, has been examined. Design charts which can be used to predict a reasonably conservative estimation of the inelastic ultimate load of a framed column in a sway structure are given. These charts are particularly helpful in assisting a designer to make a reasonably good initial selection for the column section sizes in a flexibly connected frame. In addition an empirical formula has been proposed to incorporate the beneficial effect on the column behaviour resulting from the presence of infill panels in real steel frames. In order to conduct this study a computer program developed by Rifai [3] has been modified to simulate the behaviour of a flexibly connected sway subassemblages. 5) Finally general conclusions and recommendations for future work are given.
13
Italiano, Vincenza M. "Behavior of Diagonal Knee Moment End-Plate Connections". Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/32478.
Abstract (sommario):
An experimental and analytical investigation was conducted to study the behavior of diagonal knee moment end-plate connections and a multiple row extended moment end-plate connection. Diagonal knee moment end-plate connections differ from typical moment end-plate connections because of the large pitch distance required between the top flange and first row of tension bolts. The large pitch distance is outside of the geometric parameters of all previous research. Design solutions are presented for five moment end-plate connections with provisions added to accommodate these parameters.
The analytical investigation focused on the limit states of end-plate yielding and bolt rupture. Yield-line analysis was used to predicted end-plate yielding and a simplified Kennedy method proposed by Borgsmiller and Murray (1995) was used to predict bolt rupture including and excluding prying forces. An experimental investigation was conducted to verify the design solutions. Five knee area specimens and one plate girder specimen were tested in this study.
The analytical and experimental results are analyzed and compared. For the test specimens that failed in the connection, the predicted results proved to be conservative. Recommendations are presented at the end of the study as well as sample calculations.Master of Science
14
VIANNA, JULIANA DA CRUZ. "ASSESSMENT OF PERFOBOND CONNECTOR BEHAVIOUR FOR COMPOSITE BEAMS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2009. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=14993@1.
Abstract (sommario):
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
As vigas mistas são um exemplo das cada vez mais difundidas estruturas mistas, e resultam da associação de uma viga de aço com uma laje de concreto ou mista, ligadas por meio dos conectores de cisalhamento. Dentre os diversos tipos existentes pode-se citar os pernos com cabeça (stud bolts), perfis C e o Perfobond. Um conector alternativo foi proposto para estruturas mistas, o TPerfobond, que deriva do conector Perfobond acrescentando a componente da mesa, que trabalha como um bloco. Combina portanto a alta resistência do conector tipo bloco com a ductilidade e resistência ao levantamento dos furos do Perfobond. Para determinação da sua capacidade resistente foi realizado um programa experimental envolvendo cinquenta e dois ensaios do tipo push-out com conectores Perfobond, T-Perfobond e T, um ensaio em escala real e uma modelagem numérica. Os ensaios push-out estabeleceram a carga máxima e a capacidade de deformação dos conectores. Procurou-se com o ensaio em escala real determinar a resistência última da estrutura, o modo de ruína, as deflexões e as deformações, e validar o comportamento do conector TPerfobond em uma estrutura real. Os resultados indicaram que o modelo de plastificação total pode ser adotado para a determinação do momento fletor resistente em vigas mistas bi-apoiadas com conectores T-Perfobond. Os modelos numéricos auxiliaram no estudo da capacidade de deformação da mesa do conector T-Perfobond, e na investigação das vigas com interação total ou parcial ao cisalhamento. Sob o ponto de vista econômico, um estudo comparativo dos custos dos conectores Perfobond, T-Perfobond e Studs foi conduzido e concluiu-se que os conectores Perfobond e T-Perfobond são mais econômicos em até 33% que os conectores Studs. Dentre as vantagens estruturais e construtivas de utilizar os tipos de conectores alternativos destacam-se: a alta resistência, a fácil produção e instalação no perfil de aço através de solda corrente, e bom comportamento à fadiga.
Steel and composite beams have been extensively used in buildings and bridges. The component that assures the shear transfer between the steel profile and the concrete deck, enabling the composite action to develop, is the shear connector. Among the different types of connectors the headed studs, C sections and the Perfobond may be referred. An alternative connector has been proposed for composite structures, the T-Perfobond. The main difference between the studied Perfobond and T-Perfobond connectors is the presence of a flange, providing a further anchorage to the system. This connector combines the high strength of the block connector with ductility and resistance to uplift of the Perfobond holes. To evaluate their shear capacity an experimental programme that consisted of fifty-two push-out test and one full-size test, and some numerical analysis were performed. The push-out tests have established the maximum load capacity and deformation of the connectors. The full-size test has determined the composite beam load carrying capacity, typical failure modes, associated stresses and displacements, and has validated the behaviour of the T- Perfobond connector in an actual structure. The results indicated that the plastic distribution can be adopted for T- Perfobond connectors. The numerical analysis helped in the assessment of the deformation capacity of the T-Perfobond flange connector, and the investigation of the composite beam with total or partial connection. From the economic point of view, a comparative study of the cost of Perfobond, TPerfobond and Studs connectors was conducted and it was concluded that the Perfobond and T-Perfobond connectors lead to an economy of up to 33% when comparing to the Studs connectors. Among the structural and constructive advantages of the use of alternative types of connectors, an high resistance, easy manufacturing and installation of steel beam by current welding and good performance to fatigue may be referred.
15
Kharouf, Nourhene. "Post-elastic behavior of bolted connections in wood". Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36970.
Abstract (sommario):
A nonlinear finite element model is developed to study the behavior of single- and double-bolted timber connections with relatively low member thickness-to-fastener diameter ratios. These structural joints tend to fail in a brittle fashion. The established model is capable of predicting the post-elastic deformations of the connections locally and globally, and the unequal load fractions transferred by each bolt in a two-fastener connection.The ADINA software package is used to generate the model. The problem presents two types of non-linearity. The first is due to geometric effects caused by increased sliding contact between the bolts and the oversized holes in the wood member. Contact is simulated using the Lagrange Multiplier algorithm available in ADINA. This algorithm enforces the compatibility of surface displacements at the wood member which is the contactor surface, and Coulomb frictional conditions over the contact segments, with a coefficient of friction of 0.7. The second non-linearity results from the material post-elastic behavior adjacent to the contact points. A plasticity-based compressive constitutive material model is developed to represent wood as elasto-plastic orthotropic according to the Hill yield criterion in regions of bi-axial compression. Linear elastic orthotropic response is applied otherwise. The model is incorporated as a user-supplied material model of ADINA to carry out the analysis.
The performance of the program and the effectiveness of the elasto-plastic material model are first verified with examples from the literature. Thereafter, numerical simulations of the post-elastic deformations of one- and two-bolt connections are compared to experimental results from tensile tests undertaken on glued-laminated timber connections with stocky bolts and subject to monotonic loading. Characterization tests are undertaken to obtain stiffness and strength for compression and tension parallel and perpendicular to grain, and shear, required as input in the new material model. Five configurations of single-bolt connections and four configurations of double-bolt connections have been tested with different combinations of end distance, edge distance, and spacing between bolts. Reasonable agreement is found between numerical and experimental load vs. strains obtained using single axis strain gages and strain rosettes mounted in regions of stress concentrations. The model is capable of tracing the post-elastic global deformation as obtained from experimental load vs. displacements of LVDT's mounted on specimens. The non-linearity of these load-slip curves is primarily caused by the inelastic wood deformation beneath the bolts at low load levels. This behavior explains the redistribution of load proportions among the bolts in a double-bolt connection. Under test configurations forces are unequally shared between the bolts even at the ultimate load. As a consequence, joint capacity as estimated with the proposed elasto-plastic material model is bounded by the so-called European Yield Model, which assumes equal load distribution among the bolts at ultimate, and the linear elastic model. Observed shear-out brittle failures of wood bolted connections are believed to be caused by excessive combined shear and tension perpendicular to grain along the sides of the contact zone.
16
Sadasivan, Sridhar. "Mathematical Modeling of Behavior of T-Stub Connections". University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1092837126.
17
Burguete, R. L. "Aspects of the behaviour of threaded connections". Thesis, University of Sheffield, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429869.
18
Ramli, Sulong Nor Hafizah. "Behaviour of steel connections under fire conditions". Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424307.
19
Ramli, Sulong Nor Hafizah. "Behaviour of steel connections under fire conditions". Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424307.
20
Rex, Clinton O. "Behavior of composite semi-rigid beam-to-girder connections". Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-07102009-040338/.
21
Rex, Clinton O. "Behavior and modeling of partially restrained beam-girder connections". Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-06062008-151614/.
22
Dale, Kenneth William 1971. "Behaviour of tubular connections under variable repeated loads". Monash University, Dept. of Civil Engineering, 2001. http://arrow.monash.edu.au/hdl/1959.1/8848.
23
Lo, Clifford Fook Leong. "Behaviour and design of eccentrically loaded bolted connections". Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63986.
24
Hasan, Sarakot. "Behaviour of discontinuous precast concrete beam-column connections". Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/12269/.
Abstract (sommario):
The study investigates experimentally and theoretically the behaviour of an internal precast concrete beam-column connection, where both the column and beam are discontinuous in construction terms. The aim was to modify the behaviour mechanisms within the connection zone by introducing a beam hogging moment resistance capacity under dead loads and limiting the damage within the connection. This is to offer permanent dead load hogging moments that could counterbalance any temporary sagging moment generated under sway loads, enhance the rotational stiffness, balance the design requirements for the beam-end and beam mid-span moments, provide efficient continuity across the column, and reduce the deflection at the beam mid-span. Three full-scale beam-column connection tests subjected to gravity loads were conducted taking the connection reinforcement detail as the main variable. The configuration of the three main interfaces within the connection was based on the experimental results of small-scale tests. The results of the full-scale tests showed that, by using the strong connection concept, it was possible to produce equivalent monolithic behaviour, control the crack width within the connection zone, and force the final damage to occur outside of this zone, which comprises the interfaces and parts of the adjoining elements. The strong connection consisted of using additional short steel bars crossing the connection at the top of the beam, horizontal U-shaped links at the beam-ends, and additional column links. In addition, the experimental programme included two full-scale tests to investigate the behaviour of the connection under sway loads using two different connection reinforcement details. The results of this study showed that the proposed modification in the reinforcement details was able to mobilise the beam sagging moment through the dowel action of the column main bars but it was also accompanied by large relative beam-column rotations (low rotational stiffness). The evaluation of the behaviour of the connections was carried out by incorporating the experimental rotational stiffnesses in semi-rigid frame analyses using the ANSYS software package and a Visual Basic program based on the conventional semi-rigid analysis approach. In addition, a simplified technique has been validated against these two methods to replicate the semi-rigid behaviour. In the same respect, the study is proposing a new approach for classifying precast concrete beam-column connections as rigid by relating the connection fixity factor with the moment redistribution. It has been shown that the connection could be classified as rigid if the fixity factor is not less than 0.73 and the available moment redistribution from the midspan to the supports is not less than the required moment redistribution resulting from semi-rigid frame analysis. In the theoretical part, an analytical tool has been calibrated to predict the rotational stiffness of the specimens with semi-rigid behaviour under gravity loads. The model showed a reasonable agreement with the experimental results. To help the modelling, two pull-out tests were conducted to determine the bond-slip relation of steel bars embedded in cement-based grout. Moreover, a finite element numerical simulation model using the ANSYS software package was carried out to replicate the experimental results of the semi-rigid specimens tested under gravity loads. In spite of providing results close to experimental values prior to yielding, the FE model was not able to predict the failure mode and consequently the correct ultimate load. This is due to the simplified way of modelling the interaction between the corrugated sleeves and the surrounding concrete as perfect bond. The research concludes that the precast beam-column connection investigated in the current study can be treated as an emulative monolithic connection under gravity loads through using the strong connection concept; however, it is not suitable to resist beam net sagging moments. Besides, the study concludes that to consider a precast concrete beam-column connection as rigid, it is required to correlate the fixity factor with the moment redistribution.
25
Anderson, Kate Rachel. "Effects of connections on structural behaviour in fire". Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/6233.
Abstract (sommario):
The behaviour of connections in fire has become of particular interest to the structural engineering community following the possible link of connection failure to the collapse of the World Trade Centre building 7 and the failures and huge distortion of some connections after the Cardington full scale tests. In order to widen the understanding of the complex behaviour of connections in fire this thesis discusses a number of specific issues relating to connections in fire and their influence on structural response. The first part of this work presents a finite element model for predicting connection temperature profiles. A parametric study is then carried out to investigate which factors have the greatest influence on temperature prediction. This method is compared to the currently available methods for connection temperature prediction presented in the Eurocodes: using a percentage of the beam mid-span lower flange temperature to estimate the temperature across the connection and a lumped capacitance method to calculate average joint temperature based on the mass of material and surface area. In each case, along with the predicted temperatures, the influence on connection material strength is also presented. The three methods have varying levels of accuracy. The finite element model provides detailed and accurate results due to the thorough consideration given to the input parameters. The percentages method gives reasonable estimates in the heating phase but is less accurate in cooling and the lumped capacitance method is only suitable for crude estimations. The remainder of the thesis is concerned with how a number of phenomena affect the overall structural behaviour of buildings: the inclusion of detailed connection models within larger, less complex, finite element models; the effects of connection rotational capacity and the composite beam-slab shear connection. A finite element model for isolated joints is presented in detail for a number of heating regimes and connection types. The influence of the bolt shear and tensile properties is considered in detail and the need for further testing on bolts at high temperatures is discussed. The model has the capacity to predict a number of failure modes and also shows a good comparison between experimental and theoretical deflected shapes. This connection model is then inserted into a large model. It is shown that whilst the inclusion of the shell connection has a small influence on the residual deflections of a structure after cooling when compare to a model where connections are simple and fixed, the difference between heating and not heating the connection does effect structural deflections. Following on from the previous full scale model, simple connections are then exclusively included where the connection rotational capacity is varied. Results show that there is not a large effect on the structural deflections or beam axial and shear forces when rotational behaviour is changed. However column bending moments are hugely increased during heating both in the fire compartment and away from it and fixed connections result in larger bending moment that pinned ones. Finally, the shear interaction between the slab and beams is investigated. The detailed development of both an ambient temperature and then an elevated temperature model of a beam-slab system including explicit shear studs are presented. A study is then carried out looking at the effects on deflections and beam forces when the strength and ductility of the studs are altered. It is found that more ductile studs with a high shear capacity are beneficial for reducing forces in beams and limiting their deflections. Finally the shear studs are included in the larger model used in previous chapters where results are similar to those seen in the beam-slab model, but are less pronounced.
26
Restrepo-Posada, José I. "Seismic behaviour of connections between precast concrete elements". Thesis, University of Canterbury. Civil Engineering, 1992. http://hdl.handle.net/10092/7666.
Abstract (sommario):
Several precast concrete systems have been in use in New Zealand in the construction of moment resisting frames designed for earthquake resistance, despite the lack of code design guidelines. The two design codes for buildings, NZS 4203 (1984) and NZS 3101 (1982), deal only with the design of monolithic concrete construction.
The use of precast concrete in moment resisting frames in New Zealand assumes that this method of construction behaves the same as monolithic reinforced concrete structures. A test programme was devised to provided experimental evidence on the seismic behaviour of the most commonly used precast concrete arrangements. Six full-scale subassemblages were quasi-statically tested under reverse load conditions with increasing displacements to failure. Four tests were conducted in H-shaped specimens connected at the beam midspan. The remaining two specimens were cruciform-shaped and had the connection detail in the critical region at the beam-column joint. It was found that neither of the connection detail nor the construction joints have a detrimental effect on the seismic performance. Hence, the assumption of designing these systems as if monolithic is adequate.
Theoretical work was undertaken to give simple design recommendations for the design of different connecting details, including the design of interior beam-column joints. Truss models and the concept of shear friction were extensively used.
This report also discusses in some detail the stress-strain behaviour of the two grades of New Zealand manufactured reinforcing steel. Test results on the effects of bar deformations, strain ageing and strain rate on the cyclic behaviour of reinforcing steel are presented. An analytical model based on test results is postulated
27
Xiao, Yong. "Behaviour of composite connections in steel and concrete". Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239931.
28
Aritenang, Wendy. "Behaviour of composite tubular connections in offshore structures". Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47336.
29
Huynh, Minh Toan. "Structural Behaviour of Cold-Formed Steel Screwed Connections". Thesis, The University of Sydney, 2020. https://hdl.handle.net/2123/22098.
Abstract (sommario):
This thesis presents a study on the behaviour of connections using screws in cold-formed steel structures. The first part of the thesis studies the behaviour of the screw connectors using simple connection tests and Finite Element (FE) modelling. Specimens were assembled by using 2 or 3 screws connecting two cold-reduced sheet steels with various grades and thicknesses. Two types of limit states were investigated: (i) screw shear failure and (ii) bearing and tilting failure. A set of revised design equations for strength of screwed connections in bearing and tilting is proposed. A reliability analysis is performed using the proposed equations, which allow for an improvement in the capacity reduction factor in current design standards. Furthermore, an FE model, which contains fracture characteristics of both the screws and the sheet steels, is developed to give better understanding of the screw behaviour with respect to different limit states. In the second stage of the research, a dual-actuator test apparatus was set up in order to test shear connections from cold-formed steel channels to hollow sections. Each connection contained an angle cleat and two screws. Different amount of shear force and connection rotation to transfer into the connection in each test. Two limit states involving failure of the screws and failure of the sheets were investigated. Finally, an analytical model for the connection is developed using the relation between bearing force and deformation of individual screws from the first stage of the thesis. An FE model is also developed, which demonstrates how to apply actual geometry of the screws into a simulation at a structure scale. It is concluded that a simple connection carrying shear with bearing and tilting failure mode has better strength conserving capability when dealing with high rotation compared with a connection with shear fracture of the screws.
30
Mahmood, Salih Qasim. "Behavior of Lap Shear Connections with Thermally Insulating Filler Plates". PDXScholar, 2017. https://pdxscholar.library.pdx.edu/open_access_etds/4159.
Abstract (sommario):
This research consists of experimental load tests and numerical simulations of structural steel connections with various filler materials to study the effect of non-steel fillers on the connection strength. Non-steel fillers are used in the steel connections to provide thermal insulation by reducing thermal bridging. Eight specimens having steel and polypropylene filler plates of various thicknesses were tested in the laboratory. The collected data were compared to a Finite Element Analysis (FEA) using ABAQUS to validate the numerical results. After validation, three parametric studies were conducted using ABAQUS to provide insight into general behavior of connections with a variety of fillers that could be used as thermal breaks. In addition, an extreme case of having air gaps instead of alternative fillers was also considered.
The Research Council on Structural Connections (RCSC 2014) suggests a reduction in the bolt shear strength when undeveloped fillers with a thickness of more than 0.25 inch are used while using any non-steel material is prohibited due the limited research available.
Most research studies have investigated the mechanical behavior of thermal breaks in either end-plate moment connections or slip-critical connections. No data is available for thermal breaks in bearing-type connections up to failure.
This research aims to study the effects of filler material properties such as modulus of elasticity and strength on bolt strength, as well as investigate whether the current equation in RCSC 2014 is applicable for alternative filler materials like polypropylene that has less than 0.5% of the steel modulus of elasticity and less than 10% of steel strength.
31
Albarram, Ahmed. "Behaviour of headed stud connectors in composite beams with very deep profiled sheeting". Thesis, University of East London, 2018. http://roar.uel.ac.uk/8079/.
Abstract (sommario):
Lack of design rules and no past research on the behaviour of composite beams with steel decks deeper than 80 mm is a major knowledge gap. Thus, this research provides fundamental information on the behaviour of headed stud connectors with narrow and very deep decks. After a series of extensive validation, a vast number of 3-D push-off tests are modelled using ABAQUS/Explicit package. Both secondary and primary composite beam systems are investigated. Critical examination is conducted on the existing design equations to assess their accuracy in predicting the shear stud capacity with the use of narrow and very deep decks. The numerical analysis regarding the secondary composite beams showed that the shear stud capacity with narrow and very deep decks (i.e. 100 and 146 mm deep) was almost 65% of that obtained from the traditional steel decks (60-80 mm deep). The shear stud capacity was mainly affected by the concrete embedded within ribs. Reinforcing that area by a unique wire-mesh bars layout, which has not been investigated before, led the load bearing capacity to increase by 24%. For the primary composite beams, the numerical analysis indicated that the correlation between very deep decks and traditional ones regarding the shear stud capacity can not be represented through the rib deck geometry as it was believed in the past. A new concept was introduced to more accurately explain that correlation. This was through the effective cross-sectional area of concrete. The existing design equations, when validated, did not account for narrow and very deep decks. As a result, a big discrepancy up to 50% was noticed between the predicted strengths and FE results in some cases, especially among EC4 and ANSI/AISC provisions. This necessitated to introduce more effective formulae. The developed equations regarding the secondary composite beams covered for the first time a wide range of ribbed geometries including narrow and very deep decks. For the primary composite beams, the correlation between different types of decks was established in the new equations through the effective cross-sectional area of concrete. The reliability of the new equations was proven against many previous experiments. The accuracy in results remained within ±10%. Besides the accuracy, the new equations are easy to use. This will help the designers to directly apply these equations in the practice.
32
Ahmadi, Danesh Ashtiani Fakhreddin. "Seismic behaviour of steel frames with semi-rigid connections". Thesis, Imperial College London, 1996. http://hdl.handle.net/10044/1/8455.
33
Zhang, Jinwu 1970. "Structural behaviour of washerless bolted connections loaded in shear". Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79276.
Abstract (sommario):
The general bearing mode of failure often controls the capacity of cold-formed steel bolted connections loaded in shear. Previous research has shown that the absence of washers can significantly lower the bearing resistance of these connections. Experimental studies have also revealed that the bearing capacity can be formulated with a gradated bearing coefficient that is governed by the ratio of fastener diameter to sheet thickness.A gradated bearing coefficient method, which was based on an investigation of bolted connections composed of mild steel as well as thin high strength steel, has recently been proposed to cold-formed steel design code committees in North America, Australia and New Zealand. However, the new bearing method does not include provisions for the design of washerless bolted connections. For this reason a total of 168 bolted connection shear tests designed to fail by bearing were performed. The test program included connections with and without washers, which were divided into single and double shear, as well as high strength steel (Grade 550) and mild sheet steel (Grade 230) categories. The thickness of the sheet steel material ranged between 0.43 mm and 1.53 mm. In addition, data for 381 washerless bolted connection specimens from previous experimental investigations was included in an evaluation of current cold-formed steel design standards and specifications. Modifications to the connection design procedure contained in the 2001 North American Specification were proposed.
34
Mahdi, Ali Abdulkarim. "Moment-rotation behaviour of connections in precast concrete structures". Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387185.
35
Celikag, Murude. "Moment-rotation behaviour of steel beam-to-column connections". Thesis, University of Sheffield, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361708.
36
Kuttab, Atallah Shafic. "Behaviour of grouted dowelled connections between precast concrete columns". Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/38076.
37
Karagiannis, Vasileios. "Behaviour of hybrid timber-steel beam-to-column connections". Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/59187.
Abstract (sommario):
This thesis studies the behaviour of hybrid systems consisting of tubular steel columns and laminated glulam timber beams. The research includes experimental investigations at the material and structural system levels as well as several numerical and assessments. Firstly, an extensive experimental programme is conducted on the determination of the material properties of the glulam. This involve compressive, tensile, shear and bending material tests. In addition, one-dowel connection tests are carried out to examine the interaction between the steel fastener and the timber volume around the fastener hole with the aid of Digital Image Correlation (DIC) techniques. Subsequently, detailed three-dimensional detailed models are constructed and their results are compared with the experimental tests. To account for the material damage, the foundation zone approach was used. This model was shown to be able to correctly simulate the crushing response of wood in the embedding region. The implementation of this region into the model allows an accurate simulation of the damage accumulation process. To this end, new relationships were formulated as part of this thesis, that can be used to estimate the material characterisation as a function of the crushing volume. The proposed model allows for a relatively low dependence on the radius of the foundation volume adopted making it applicable to a wider range of varying geometrical configurations. The validity and accuracy of the proposed modified foundation models were examined against the experimental force-displacement curves, and good agreement was found between the experimental response and the numerical simulations The second experimental programme is concerned with the performance of timber beam-steel column assemblages. Two timber beam-to-steel column alternatives are examined: a) top and seat angle connection and b) slotted-in T-stub connection with bolts. The configuration of the connections and their set-up are presented, followed by detailed results in the form of figures and tables as well as observations from the tests. The main behavioural patterns are identified and key response characteristics such as stiffness, capacity and failure mechanisms are discussed. Detailed finite element models were created to simulate the experimental timber beam-to-steel column connection tests. The models included advance features such as contact phenomena, bolt pretension and orthotropic material definitions. The foundation zone approach developed in this thesis was implemented. The results of the models were validated against the experimental results and good agreement was found. Additionally, component-based models were also formulated for the prediction of the flexural response of the connection types tested. These expressions were developed to estimate the stiffness, capacity and ultimate loads of the connections and the results were validated against the experimental and numerical findings. The component models proposed were able to predict the response of the connection accurately including those cases where screws and bottom-wedge angles were involved. In the concluding part of the thesis, the developed finite element models are employed in a parametric assessment in order to highlight the influence of key geometric and material considerations. The dearth of information on timber-steel hybrid connection of this type, design methodologies must be developed to offer a preliminary assessment on the prediction and evaluation of the key characteristics and hence the results are also compared with simplified analytical expressions. Finally, the last section of the thesis summarised all the findings and numerous possible future research are identified.
38
Görgün, Halil. "Semi-rigid behaviour of connections in precast concrete structures". Thesis, University of Nottingham, 1997. http://eprints.nottingham.ac.uk/11294/.
Abstract (sommario):
Multi-storey precast concrete skeletal structures are assembled from individual prefabricated components which are erected on-site using various types of connections. In the current design of these structures, beam-to-column connections are assumed to be pin jointed. This current research work focuses on the flexural behaviour of the beam-to-column connections and their effect on the behaviour of the global precast concrete frame. The experimental work has involved the determination of moment-rotation relationships for semi-rigid precast concrete connections both in full scale connection tests and smaller isolated joint tests. This has been done using the so called "component method" in which the deformation of various parts of the connection and their interfaces are summated, and compared with results from full scale sub-frame connection tests. The effects of stress redistribution, shear interaction etc. are taken of by linear transformation in the results from the full scale tests, enabling parametric equations to be formulated empirically in order to describe the semi-rigid behaviour. Eight full scale column-beam-slab assemblages were tested to determine the (hogging) moment-rotation behaviour of double (balanced loading) and single sided in-plane connections. Two of the most common types of connection were used, the welded plate and the billet type. Proprietary hollow core slabs were tied to the beams by tensile reinforcing bars, which also provide the in-plane continuity across the joint. The strength of the connections in the double sided tests was at least 0.84 times the predicted moment of resistance of the composite beam and slab. The strength of the single sided connections was limited by the strength of the connection itself, and was approximately half of that for the double sided connection, even though the connection was identical. The secant stiffness of the connections ranged from 0.7 to 3.9 times the flexural stiffness of the attached beam. When the connections were tested without the floor slabs and tie steel, the reduced strength and stiffness were approximately a third and half respectively. This remarkable contribution of the floor strength and stiffness to the flexural capacity of the joint is currently neglected in the design process for precast concrete frames. Measurements of the extent of damaged zones near to the connection in full scale tests showed that, unlike steel connections, semi-rigid behaviour in precast concrete does not occur at a single nodal position. In general the double sided connections were found to be more suited to a semi-rigid design approach than the single sided ones. Analytical studies were carried out to determine empirical design equations for column effective length factors β in unbraced and partially braced precast concrete frames. The main variables were the relative flexural stiffness α of the frame members, and the relative linear rotational stiffness Ks of the connection to that of an encastre beam. The variation of β factors with Ks and α are presented graphically and in the form of design equations similar to those currently used in BS 8 110. The change in the response of a structure is greatest when 0< Ks <1.5 where β is found to be more sensitive to changes in Ks than α. When Ks >2 the changes in the behaviour are so small that they may be ignored within the usual levels of accuracy associated with stability analysis. This is an important finding because the experiments have found Ks to be generally less than 2 for typical sizes of beam. The results enable designers to determine β factors for situations currently not catered for in design codes of practice, in particular the upper storey of a partially braced frame. A design method is proposed to extend the concrete column design approach in BS 8110 and EC2, whereby the strength and semi-rigid stiffness of the connection enables column bending moments to be distributed to the connected beams. However, the suitability of each type of connection towards a semi-rigid design approach must be related to the stiffness and strength of the frame for which it is a part.
39
Sarraj, Marwan. "The behaviour of steel fin plate connections in fire". Thesis, University of Sheffield, 2007. http://etheses.whiterose.ac.uk/3035/.
Abstract (sommario):
Steel joints have always been considered as important parts of any structural steel building because they provide the strong links between the principal structural members. The properties and behaviour of joints in both steel and composite structures have been widely studied for some time. The focus has recently been on improving the design of structural frames by taking advantage of realistic connection moment-rotation response. This has necessitated the development of an effective and practicable methodology to describe steel connection behaviour, despite its inherent complexity. Although, the evaluation of steel connections' performance at ambient temperature has been a continuous research topic, the investigation of steel connections at elevated temperatures has only recently been tackled by researchers. However, the determination of the behaviour, available strength and stiffness of moment connections in fire conditions has been a dominant theme in these research works. Moreover, over a number of years the Component Method has been developed to describe the moment-rotation characteristics of end-plate connections, and the method is now included in Eurocode 3. To date, most of the research conducted on steel connections using the component method has focused on relatively stiff and strong connections - flush end-plates and extended end-plates. The modelling of more flexible ("pinned") connections using the Component Method has not received much attention, since the benefits arising from consideration of their behaviour in overall frame response are usually modest. However, in fire conditions connections are subject to complex force combinations of moment and tying forces, as well as vertical shear forces, and the real behaviour, even of nominally pinned connections, can have a significant effect on the overall response of the frame. To date very little information on the behaviour and the resistance of simple shear connections in fire conditions has been generated. Fin plate shear connections, which are economic to fabricate and easy to use in erection, are among these shear connections which are assumed to act as pins in normal service conditions In this research, the behaviour and robustness of simple fin plate beam-to-column connections has been investigated, under the conditions of catenary tension from highly deflected beams which occurs in fire. In addition, detailed investigations have been made on applying the component method approach to this connection at both ambient and elevated temperatures. ABAQUS software has been selected to create a very detailed 3D finite element model. This is a complex model accounting for material nonlinearity, large deformation and contact behaviour. The connection model has been analysed through the elastic and plastic ranges up to failure. Bolt shear and bending, plate and web bearing have been observed as failure modes. A comparison between available experimental data at ambient and elevated temperatures and FEA results shows that the model has a high level of accuracy. However, by implementing the FE model the opportunity was then available to explore the connection tying resistance and the application of the Component Method to the fin plate connection. An intensive investigation has been conducted to develop a representation of this connection type via a simplified component model, enabling prediction of the connection response at both ambient and elevated temperatures. The three main components of a fin-plate connection have been identified as plate bearing, bolt shearing and web-to-plate friction. These components have been described in detail at ambient and elevated temperatures via intensive parametric FE analyses, leading to a simplified component model of a fin plate connection. This model has been evaluated against FE models of complete fin plate joints. Eventually, a fin plate connection spring model is proposed and successfully evaluated for tying, rotation, and shear actions. The Component Model presented in this research offers an opportunity to explore complicated behaviour of fin plate shear joints, and can be incorporated into frame analysis in fire conditions.
40
Bird, Patricia E. "Hearing God- peer coaching and the role of high quality connections in spiritual development". Thesis, United Theological Seminary, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10055451.
Abstract (sommario):
The context for this qualitative case study evaluation was a 400 member United Methodist Church in southwest Michigan. Incongruence existed between the congregants' claimed spiritual development and minimal supernatural manifestations. Significant instruction has not resulted in change. The purpose of this project was to develop, implement, and evaluate a leadership training. The hypothesis was that peer coaching is an effective method to accelerate spiritual intimacy as measured by hearing God. Data analysis revealed three themes related to hearing God: hindrances, helps, and hearing. Hindrances must be addressed through helps in order to hear.
41
Rifai, Abdussalam Mahmud. "Behaviour of columns in sub-frames with semi-rigid joints". Thesis, University of Sheffield, 1987. http://etheses.whiterose.ac.uk/3050/.
Abstract (sommario):
The behaviour of limited subassemblages with flexible beans and semi-rigid beam to column connections was studied using a computer program in which the finite element method was employed in a non-linear analysis which accounts for the presence of semi-rigid connections and the inelastic behaviour of frames. The program accounts for many other factors such as initial imperfections and residual stresses. The theoretical background to the present computer program has been presented along with the program layout. The program was used to simulate some of the experimental results obtained from tests on rigidly and flexibly connected frames with different combinations of beam and column loads. The analytical results were found to compare reasonably well with the experimental results. The program was also used to simulate a series of I-shaped subassemblages that were tested at the University of Sheffield. Comparisons were made between the analytical and experimental results characterized by the maximum loads, load-deflection curves and load- moment curves. Good agreement was obtained between the analytical and the experimental load-deflection curves for all of the cases considered. The general trends of the measured and calculated load- moment curves for most cases were found to be comparable. The recommendations given in B35950 for the design of columns in simple construction were applied to all cases in the last series and were found unconservative in the cases of balanced loading and conservative in the cases of unbalanced loads. A limited parametric study was conducted to study the effects of semi-rigid joints, bean flexibility and type of loading. In this study, an I-shaped subassemblage was analysed for different load types and different types of beam to column connections. A substantial effect was recognized due to the presence of semi-rigid connections whether or not a beam load was applied. Beam flexibility was also seen to affect the carrying capacity of the subassemblage under the action of column load only although this effect was less noticeable than that of the connection flexibility. The presence of beam load was found to result in an unexpected interaction curve which relates the total force in the column to the moment that is transmitted to the column's end. An almost linear relationship with negative gradient seems to exist between the column and beam loads. It is pointed out that all the findings of the present study are based on the range of cases considered in the parametric study but it is suggested that they serve as indicators to the behaviour of any the subassemblage under axial load oniy or axial load combined with beam loads. A few recommendations for future work are presented.
42
Pons, Aguilera Hector Feliciano. "Dynamic behavior of tubular bracing members with single plate concentric connections". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ29395.pdf.
43
Fang, Demi L. "Timber joinery in modern construction: Mechanical behavior of wood-wood connections". Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127868.
Abstract (sommario):
Thesis: S.M. in Building Technology, Massachusetts Institute of Technology, Department of Architecture, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (pages [107]-112).
Timber joinery is a method of geometrically interlocking timber elements prevalent in historic cultures around the world, including North America, Europe, and East Asia. The use of joinery as structural connections faded with the development of metallic screws and nails. Two recent developments offer the opportunity to revive this historic timber connection type: 1) the increasing desire to reduce embodied carbon in buildings by replacing more components with timber as a low-carbon structural material, and 2) recent digital fabrication capabilities which enable the precise milling of complex geometries as an alternative to the time- and labor-intensive handiwork required previously. How can joinery connections be designed in modern structural joints? Can we quantify the sustainability advantage of using these all-timber joints in lieu of the modern convention of metallic fasteners? This thesis addresses both questions as applied to the Japanese Nuki joinery type, though the workflows may be applied to any joinery geometry. First, the rotational stiffness of the Nuki joint is characterized and cross-verified using multiple methods. Second, the embodied carbon of a gravity frame using Nuki joints is compared to that of a gravity frame using conventional metallic fasteners. The use of Nuki joints not only eliminates the use of steel and aluminum but also provides rotational stiffnesses that enable smaller beam sections to be used. It is shown that gravity frames designed with Nuki joints could reduce embodied carbon by over 70% compared to gravity frames designed using conventional beam hanger connections. The findings make a case for all-timber joinery connections to be implemented as a sustainable alternative to conventional metallic connections used in modern timber construction.
by Demi L. Fang.
S.M. in Building Technology
S.M.inBuildingTechnology Massachusetts Institute of Technology, Department of Architecture
44
Kenyon, Elizabeth Mary. "Predicting the Seismic Behavior of the Dywidag Ductile Connector (DDC) Precast Concrete System". DigitalCommons@CalPoly, 2008. https://digitalcommons.calpoly.edu/theses/36.
Abstract (sommario):
Structural engineering is heavily dependent on the use of computers. When creating a building model using structural analysis software, it is required that the designer have an understanding of the system behavior and the modeling program capabilities.
Some engineers in the Southern California region are taking steps towards incorporating the Dywidag ductile connector (DDC) and super hybrid systems into building practice due to the advantages found in these systems’ construction methods and seismic performance.
As the DDC and super hybrid systems reach industry, the design engineer will need to model these systems using structural analysis programs. This report describes two DDC specimens that were each modeled two ways: (1) using elastic members in conjunction with nonlinear rotational hinges (lumped plasticity model), and (2) using finite elements (fiber model). The experimental pushover curve for each test specimen was compared to the corresponding analytical backbone curves.
The fiber modeling focuses on providing a means to study the joint behavior as the parameters of the system change. The lumped plasticity model provides the design engineer with a means for modeling a three-dimensional DDC building in order to get acceptable global demand values. This project offers modeling suggestions for both the fiber models and the lumped plasticity models used to predict the seismic behavior of the DDC precast concrete system.
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Siegel, Angeline M. "Unspoken connections| Scientists' intersubjective experiences with animals". Thesis, Saybrook University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3711355.
Abstract (sommario):
Little is known about the scientist-animal relationship; therefore, the aim of this study was to learn how moments of intersubjectivity, or "oneness" are created and experienced by scientists. It is by appreciating the risks and vulnerabilities intrinsic to human-animal relationships that propel the present investigation. The current cultural bias of valuing objectification and detachment as the predominant form of scientific investigation overlooks relational subtleties intrinsic to deriving meaning from humananimal studies. By examining scientists and their descriptions of intersubjectivity with their animal participants, a greater understanding of society's philosophical and ethical deliberations on the human-animal relationship may be revealed. An exploratory, sequential mixed-method design was utilized to phenomenologically examine intersubjectivity, as well as to measure the prevalence of its dimensions within the larger academic population. Phenomenological analysis from ten interviews identified humananimal intersubjectivity as having four significant phases: joint mindfulness, synchronized embodiment, intrinsic belonging , and transcendental awareness. Spearman correlational analysis from fifty-four responses to the online survey supported these findings, as well as identified a potential link with the variables of proximity (r s = .469, p < .05, n=25), closeness (rs = .483, p < .01, n=25), similarity (rs = .483, p < .01, n=25) and embodied awareness (rs = .421, p < .01, n=25) that account for variation in the scientific population. When examining past behavior as it related to current scientific practices, gender differences emerged that resemble those reported by neuroanatomical studies. Lastly, further mixed analysis identified academic and cultural risks that were met by employing concealment and silencing strategies. These results add valuable depth in the interpretation of intersubjectivity and its relationship with scientific behavior, as well as insight into the role of intersubjectivity within ethical and philosophical debates.
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Biddah, Ashraf Mahmoud Samy. "Seismic behaviour of existing and rehabilitated reinforced concrete frame connections". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ30074.pdf.
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Moussa, Maged Abdel-Ghaffar. "Behaviour of semi-rigid composite connections subject to wind loads". Thesis, University of Southampton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240964.
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Mohamed, Sherif Ali Mohtady. "Behaviour of sleeved bolt connections in precast concrete building frames". Thesis, University of Southampton, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315403.
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Reynolds, Thomas Peter Shillito. "Dynamic behaviour of dowel-type connections under in-service vibration". Thesis, University of Bath, 2013. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608327.
Abstract (sommario):
This study investigated the vibration serviceability of timber structures with dowel-type connections. It addressed the use of such connections in cutting-edge timber structures such as multi-storey buildings and long-span bridges, in which the light weight and flexibility of the structure make it possible that vibration induced by dynamic forces such as wind or footfall may cause discomfort to occupants or users of the structure, or otherwise impair its intended use. The nature of the oscillating force imposed on connections by this form of vibration was defined based on literature review and the use of established mathematical models. This allowed the appropriate cyclic load to be applied in experimental work on the most basic component of a dowel-type connection: a steel dowel embedding into a block of timber. A model for the stiffness of the timber in embedment under this cyclic load was developed based on an elastic stress function, which could then be used as the basis of a model for a complete connector. Nonlinear and time-dependent behaviour was also observed in embedment, and a simple rheological model incorporating elastic, viscoelastic and plastic elements was fitted to the measured response to cyclic load. Observations of the embedment response of the timber were then used to explain features of the behaviour of complete single- and multiple-dowel connections under cyclic load representative of in-service vibration. Complete portal frames and cantilever beams were tested under cyclic load, and a design method was derived for predicting the stiffness of such structures, using analytical equations based on the model for embedment behaviour. In each cyclic load test the energy dissipation in the specimen, which contributes to the damping in a complete structure, was measured. The analytical model was used to predict frictional energy dissipation in embedment, which was shown to make a significant contribution to damping in single-dowel connections. Based on the experimental results and analysis, several defining aspects of the dynamic response of the complete structures, such as a reduction of natural frequency with increased amplitude of applied load, were related to the observed and modelled embedment behaviour of the connections.
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Muniasamy, D. "Behaviour of semi-rigid composite connections for steel framed buildings". Thesis, Engineering systems department, 2009. http://hdl.handle.net/1826/3974.
Abstract (sommario):
During propped construction the steel-concrete composite action resists dead as well as
imposed loads. Conversely, the steel section alone resists the floor self-weight in unpropped
beams. The major difference between propped and unpropped composite beams lies in the
ductility requirements rather than in the strength requirements. Relatively few studies have
been carried out to assess the rotation requirements for unpropped semi-continuous
composite beams. The outstanding critical factor in the case of unpropped construction is the
dead load stress that must be carried by the steel beam alone prior to hardening of the
concrete.
This research overcomes the difficulties involved in modelling the composite and noncomposite
stages by using a numerical integration technique developed from the basic
principles of structural mechanics. The method incorporates the fully non-linear material
properties and requires very little assumption. The technique was initially validated using the
experimental results from plain steel beam bending tests. The subsequent comparison
between the model predictions and the results from the large-scale frame test carried out for
this research purpose, showed that the method is capable of predicting non-elastic load vs.
end rotation behaviour within a high degree of accuracy. Thus the model can be used with
confidence in order to predict the connection rotation requirements for a wider range of
loading configurations than is practically possible from experimental testing alone.
A parametric study is carried out using the numerical integration technique developed for the
semi-continuous composite beam on a total of 2160 different beam configurations, utilising
different steel grades and loading conditions. In this study the influence of dead load stress on
the connection rotation requirement has been thoroughly evaluated along with several other
factors including span to depth ratio, location within the building frame, ratio between the support (connection) moment capacity and span (beam) moment capacity, loading type, steel
grade and percentage of the beam strength utilised during design. The connection rotation
capacity requirements resulting from this study are assessed to establish the scope for
extending the use of composite connections to unpropped beams.
The large-scale experiment that has been carried out provided an opportunity to investigate
the behaviour of a modified form of composite connection detail for use at perimeter
columns (single-sided composite connections) with improved rebar anchorage.
Additionally, another extensive parametric study is carried out using the numerical
integration technique developed for the steel beam to establish the influence of strainhardening
on elastic-plastic frame instability design.