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1
Bhutta, Salman Ahmed. "Analytical modeling of hybrid composite beams." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-11102009-020112/.
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Megharief, Jihad Dokali. "Behavior of composite castellated beams." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ37273.pdf.
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Molenstra, Nadia Julia. "Ultimate strength of composite beams." Thesis, University of Warwick, 1990. http://wrap.warwick.ac.uk/34713/.
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The study of composite beams is characterised by the connection between the two components: the concrete slab and the steel girder. In this thesis, two different problems, related to this connection were studied: the problem of partial interaction in composite beams of long spans with low degrees of shear connection, and the problem of transverse flexibility of the stud connection 'joint' between the concrete slab and the steel beam as part of a discrete inverted U-frame. This thesis is therefore divided into two separate parts. The study of beams with partial shear connection and solid slabs or slabs with metal decking is considered in the first part. Such beams, with a uniform stud spacing over each shear span, with spans longer than 10 m - generally propped during construction, and with low degrees of shear connection, could fail prematurely and suddenly in shear rather than gradually in bending, due to the limited slip deformation capacity of the studs in shear. In order to investigate the behaviour of simply supported and continuous composite beams with different degrees of shear connection, different geometry and different shear spans under design ultimate loading conditions, a numerical computer simulation program was written. The program takes account of the relative displacement between the slab and the beam and the non-linear behaviour of steel, concrete and stud connectors. A data bank of maximum slip results for different beams is obtained for ultimate beam loads designed to the interpolation method in Eurocode 4. The computer simulation gives a conservative but safe assessment of the suitability of the degree of interaction for a specific design ultimate load . The results were used to formulate a tentative design method for composite beams with solid slabs and partial shear connection. Discrete inverted U-frame action exists between composite bridge beams with intermittent vertical web stiffeners which provide lateral restraint to the bottom flange in the hogging bending region near the internal supports. The design method in BS 5400:Part 3 for discrete U-frame action gives values for the transverse flexibility of a number of standard structural steel connections which are used in the calculation of the effective buckling length and the lateral deflection of the compression flange. To obtain similar values for steel-concrete joints, tests were done to scale 1:1 on six flange-slab connections with different stud configurations, but constant conservative dimensions for the steel flange and the concrete slab. Their crack patterns can be predicted by using a truss analogy. All test specimens either failed in shear or by puffing out of the studs, and shear cracking and shear failure criteria for concrete beams can be used to predict the cracking and failure loads. The transverse elastic flexibiities of the joints in these tests only represent the behaviour of the same joints in a complete structure up to the point where the shear cracks propagated over the full width of the specimens. Based on these few test results, a limited tentative design equation is proposed for the transverse flexibility of these type of stud connections, although further research is required into the influence of the increased flexibility on the buckling mode and the variation of the flexibility with variables other than the stud configurations.
4
Fan, Chun Keung Roger. "Buckling in continuous composite beams." Thesis, University of Warwick, 1990. http://wrap.warwick.ac.uk/106724/.
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Two aspects of the buckling behaviour of continuous composite beams of steel and concrete are considered. The first part relates to the study of moment redistribution in braced slender beams (Class 3 draft Eurocode 4) due to local buckling in the hogging moment regions. The second part describes the experimental work to investigate the ultimate load behaviour of unbraced compact beams (Classes 1 and 2 draft Eurocode 4) in the hogging moment regions. For a braced continuous slender composite beam, local buckling at an internal support allows a redistribution of bending moment from the hogging regions to the sagging regions, in addition to material nonlinearity. This effect was studied by a computer simulation on two-span beams. The program takes into account not only the effect of local buckling, but also material nonlinearity and residual stresses, on moment redistribution. The ultimate loads designed to the less conservative method for Class 3 beans in the draft Eurocode 4 were used as a datum in the parametric study. The simulation then gave an independent assessment of the appropriateness and safety of these loads at the ultimate limit state. It is shown that the design method is slightly conservative. Residual stresses have very little effect on the ultimate carrying capacity. Furthermore, in design to the draft Eurocode 4, unpropped construction is more restrictive than propped construction, and hence the results are also more conservative. Lateral buckling of continuous unbraced composite beams in the hogging moment regions can only occur in a distortional mode, and is most unlikely to happen in practical building or bridge structures using hot-rolled steel sections of span up to about 30m. Various design methods based on numerical studies now exist to predict the ultimate strength of continuous composite beams affected by distortional lateral buckling, but few experimental results are available to validate their theoretical assumptions and accuracy. Tests at realistic scale on two T-beams and two inverted U-frames at the Class 2-3 Interface, in accordance with the draft Eurocode 4, are reported. Their results are compared with predictions by five design methods, four of which are satisfactory for the beams tested except BS5400:Part 3. Due to premature fracture of reinforcing fabric in one of the U-frame tests, it is recommended not to include their contribution in moment resistance, when the composite cross-section is plastic and a design requires a large amount of rotation capacity in the hogging moment regions. Based on limited test results, a tentative method is proposed to provide a quick check, whether distortional lateral buckling needs to be considered or not, for continuous composite beams with Class 1 or 2 cross-sections.
5
Jamal, Dany. "Solution methods of composite beams." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-264913.
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Solutions of composite beams encounter some specific problems, such as shrinkage and creep of concrete, cracking of concrete and plasticity of steel, partial interaction of elements or history of erection and loading process. These factors and others affect the distribution of internal forces along the beam, the distribution of stresses along the cross-section and also stiffness and deflection of beams. The goal is to describe and compare methods for analysis of composite steel and concrete beams by more simplified approaches allowed by Eurocode with more advanced techniques. The studies will be carried out on the simply supported and continuous beams designed with respect to Eurocode 1, 2, 3 and 4.
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Do, Nascimento Oliveira Jose Emidio. "Deformation and damage analysis of composite beams equipped with polyvinylidene fluoride film sensors /." [S.l. : s.n.], 2008. http://dk.cput.ac.za/cgi/viewcontent.cgi?article=1001&context=td_cput.
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Kong, Yow Wai. "Computer aided design of composite beams." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63364.
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Rakib, Saad Namik. "The behaviour of continuous composite beams." Thesis, Cardiff University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425983.
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BARROS, LUIS PAULO FRANCO DE. "PIEZOELECTRIC PATCHES MODELING FOR COMPOSITE BEAMS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1998. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=26509@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOREsta dissertação trata da modelagem dos esforços transmitidos por atuadores piezoelétricos, colados ou embutidos em vigas compósitas laminadas. O trabalho é motivado por aplicações na área de materiais e estruturas inteligentes. Em particular, procura-se avaliar o comportamento de diferentes teorias aproximadas nas faixas de médias e altas frequências, quando os comprimentos de onda podem ser da ordem da espessura da viga. Nestes casos, teorias tradicionais de vigas deixam de representar com acuracidade a resposta dinâmica de estruturas compósitas. Além disso, modelos convencionais que procuram representar os esforços gerados pelo atuador por forças e momentos fletores equivalentes, geralmente resultantes de uma análise estática, deixam de ser efetivos. São estudados modelos baseados na Teoria Clássica de Laminação (hipótese cinemática de Bernoulli-Euler) e na Teoria de Deformação Cisalhante de Primeira Ordem (hipótese cinemática de Timonshenko) e na Teoria discreta de Laminação proposta por Reddy (Reddy’s Layerwise Theory). Os três modelos são escritos na forma de equações de estado, e um método de solução é proposto para se obter a matriz de impedância dos atuadores. Resultados dos modelos estudados são comparados com os obtidos pelo método dos elementos finitos (código ANSYStm). São apresentados resultados para atuadores formados por camadas de PZT e Alumínio, bem como por camadas intercaladas de PZT, Aramide-Epóxi e Alumínio.
This dissertation addresses the problem of modeling the excitation of laminated composite beams by piezoelectric patches bonded or embedded in the structure. This work has been motivated by applications in the field of smart structures and materials. In particular, attention is paid to the electromechanical response in the high-frequency range. An attempt is made to evaluate the capabilities of different laminate theories in the medium and high-frequency ranges, where traditional models, such as the Classical (Bernouli-Euler) or First Order Shear Deformation (Timoshenko) theories, fail to provide accurate assessments of the structural dynamic response. Also, at these frequency ranges, conventional approaches to model the piezoelectric excitation via equivalent forces and bending moments, usually resulting from static analysis, are no longer satisfactory. Three different laminate theories are investigated: Classical, First Order Shear Deformation, and Reddy’s Layerwise theories. In the frequency domain, the governing electro-elastodynamic equations are written in a common state space formulation. A general method of solution is presented where the impedance matrix for the actuator is analytically evaluated. Comparisons are also made with numerical models obtained from a commercial finite element code.
10
Adhikari, Samiran. "High-definition Modeling of Composite Beams." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1627666419572229.
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Wang, Qi. "Asymptotic Multiphysics Modeling of Composite Beams." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/1066.
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A series of composite beam models are constructed for efficient high-fidelity beam analysis based on the variational-asymptotic method (VAM). Without invoking any a priori kinematic assumptions, the original three-dimensional, geometrically nonlinear beam problem is rigorously split into a two-dimensional cross-sectional analysis and a one-dimensional global beam analysis, taking advantage of the geometric small parameter that is an inherent property of the structure.
The thermal problem of composite beams is studied first. According to the quasisteady theory of thermoelasticity, two beam models are proposed: one for heat conduction analysis and the other for thermoelastic analysis. For heat conduction analysis, two different types of thermal loads are modeled: with and without prescribed temperatures over the crosssections. Then a thermoelastic beam model is constructed under the previously solved thermal field. This model is also extended for composite materials, which removed the restriction on temperature variations and added the dependence of material properties with respect to temperature based on Kovalenoko’s small-strain thermoelasticity theory.
Next the VAM is applied to model the multiphysics behavior of beam structure. A multiphysics beam model is proposed to capture the piezoelectric, piezomagnetic, pyroelectric, pyromagnetic, and hygrothermal effects. For the zeroth-order approximation, the classical models are in the form of Euler-Bernoulli beam theory. In the refined theory, generalized Timoshenko models have been developed, including two transverse shear strain measures. In order to avoid ill-conditioned matrices, a scaling method for multiphysics modeling is also presented. Three-dimensional field quantities are recovered from the one-dimensional variables obtained from the global beam analysis.
A number of numerical examples of different beams are given to demonstrate the application and accuracy of the present theory. Excellent agreements between the results obtained by the current models and those obtained by three-dimensional finite element analysis, analytical solutions, and those available in the literature can be observed for all the cross-sectional variables. The present beam theory has been implemented into the computer program VABS (Variational Asymptotic Beam Sectional Analysis).
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Lam, Wai-yin. "Plate-reinforced composite coupling beams experimental and numerical studies /." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37311797.
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Dorosh, Mark Norman. "Damage growth in bending of composite beams." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28376.
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A study has been made of glass fibre reinforced plastic beams in three-point bending. In recent years, the importance of flexural loading in composites has manifested itself in the form of composite leaf springs, helicopter rotors, and other applications. This study is directed at the initiation, growth, characterization and measurement of damage in unidirectional and cross-ply composite beams.
Beams were tested in three-point static and cyclic bending. Following damage initiation, either by a machined notch or by repeated cycling, damage growth has been characterized by two damage parameters: a damage depth encompassing a number of broken fibres on the tensile surface at the central load point, and a damage length or delamination parallel to the beam longitudinal axis.
A model was developed to predict the compliance, or deflection under applied load, as a function of beam properties and damage dimensions. The model is able to predict the compliance of damaged beams with reasonable accuracy. From fracture mechanics concepts it is shown that the two damage dimensions, depth and length, are related. It is concluded that the increase in compliance, a result of the growing damage dimensions, is related to the growth of the damage depth; the damage length follows from the relation between damage parameters and the compliance follows from the compliance model.
The damage state can thus be determined by compliance measurements if the relevant material properties and loading conditions are known. However, in service, compliance measurements may not be practical. Therefore a section of this study is devoted to an alternative damage measurement technique, namely acoustic emission monitoring. Damage initiation, compliance, damage length and damage depth were measured with AE monitoring techniques.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
14
Ball, Ryan. "Experimental analysis of composite reinforced concrete beams." Ohio : Ohio University, 1998. http://www.ohiolink.edu/etd/view.cgi?ohiou1177002341.
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Chen, Shiming. "Instability of composite beams in hogging bending." Thesis, University of Warwick, 1992. http://wrap.warwick.ac.uk/4009/.
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This work is concerned with local buckling and lateral distortional buckling, two aspects of instability that govern the design of composite beams in hogging regions. Local buckling in hogging regions of a continuous composite beam was modelled by moment curvature characteristics of a cantilever, modified by two curvature ratios, K1 and K2. Test based expressions for K1 and K2, in terms of a combined slenderness λc, were developed, and subsequently used in numerical analyses of 50 two-span composite beams to assess moment redistribution allowed for Class 2 beams by draft Eurocode 4. The analyses include effects of non-linear material properties, residual stresses and local buckling. The parametrical studies include adverse values, in relation to practice, of relative length of adjacent spans, span-to-depth ratio, and ratio of hogging to sagging moment of resistances. It is concluded that the redistribution of elastic bending moments allowed by the draft Eurocode 4 is safe and economical. Distortional lateral buckling of composite beams with both continuous and discrete U-frame actions was studied experimentally. Distortional lateral buckling was found in the tests of two composite beams with inverted U-frame actions. Web distortion was effectively reduced by vertical web stiffeners, which form a part of discrete U-frames together with the slab and the connection of U-frame. The work provides background to assess lateral buckling strength for composite beams with both continuous and discrete U-frame actions. A further theoretical approach on the topic of discrete inverted U-frame action was presented. Strength and stiffness of discrete U-frame connections were also studied. The strength of a discrete U-frame connection was found to be influenced by both the shear failure of concrete, and the yielding of steel top flange in the connection. A simple rule to assure strength of U-frame connections is proposed by checking these two failures separately. The prediction of shear failure of a U-frame connection is based on a truss model, and the prediction of failure in the steel top flange is based on a rigid plastic mechanism. A semi-empirical formula for flexibility of a U-frame connection was derived. They were all checked against test results. Interactive U-frame force and U-frame stiffness were also studied. A tentative design method for discrete U-frame composite beams was proposed.
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Wali, Abbas Ahmed Abdul. "The behaviour of semi-continuous composite beams." Thesis, University of Sheffield, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312777.
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Da, Silva Vellasco Pedro Colmar Goncalves. "Local web buckling in tapered composite beams." Thesis, Imperial College London, 1992. http://hdl.handle.net/10044/1/29499.
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Recent demand for very heavily serviced widespan office floors has led, as a natural development of the concept of haunched and tapered frames, to the use of composite flooring systems supported by tapered (varying web depth) beams. These systems are very attractive from an economic point of view, combining wide spans, rapid erection and easy access to services between the shallow parts of the beam and the ceiling below. One of the most pressing needs is for a better understanding of the local buckling behaviour of the relatively deep slender web at changes of slope in the lower flange, in particular at the slope change which occurs at the centre of a beam whose depth increases linearly from each support. In the past, with plate girders, this failure mechanism was less relevant than lateral torsional buckling. With the substantial top flange of a composite section, lateral buckling is less likely, and local buckling more likely to govern the design. The tapered beam sections are fabricated from plates by welding and are susceptible to imperfection effects and residual stresses. These phenomena may interact with the localized compressive stress field which is generated in the web at any slope change in the flange to cause local web buckling. The provision of local stiffening is technically feasible, but very expensive. The beam itself is produced fully automatically and the subsequent hand installation of stiffeners consumes man-hours out of all proportion to the weight of steel involved. The prime objective of the present study was to iucntify the relative importance of several parameters that influence the phenomenon, such as angle of taper, web thickness, flange area and others. For practical reasons, the experiments were executed at half-scale and the models simulated the concrete slab of the composite beam by a heavy steel top flange. Three tapered models have been tested with different web thicknesses i.e, 3, 5, and 7 millimetres. Three more specimens with different plastic neutral axis positions were also tested. An extensive parametric study has been made using a non-linear elastoplastic finite element program. This study covered practical ranges of the important parameters including the area of the tension flange and the position of the plastic neutral axis. Moment-rotation relations, peak moments and failure mechanisms have been predicted. Very good correlation was obtained between the results of the parametric study and the experiments. It has become apparent that in the great majority of practical cases it is possible to avoid the use of the expensive hand welded stiffeners. A design formulation has been developed to produce a very simple test of the need for stiffeners.
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Maheri, M. R. "Vibration damping in composite/honeycomb sandwich beams." Thesis, University of Bristol, 1991. http://hdl.handle.net/1983/d96ba3e9-edb0-4a07-ac6e-69328ed22678.
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Senne, Jolyn Louise. "Fatigue Life of Hybrid FRP Composite Beams." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/33982.
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As fiber reinforced polymer (FRP) structures find application in highway bridge structures, methodologies for describing their long-term performance under service loading will be a necessity for designers. The designer of FRP bridge structures is faced with out-of-plane damage and delamination at ply interfaces. The damage most often occurs between hybrid plys and dominates the life time response of a thick section FRP structure. The focus of this work is on the performance of the 20.3 cm (8 in) pultruded, hybrid double web I-beam structural shape. Experimental four-point bend fatigue results indicate that overall stiffness reduction of the structure is controlled by the degradation of the tensile flange. The loss of stiffness in the tensile flange results in the redistribution of the stresses and strains, until the initiation of failure by delamination in the compression flange. These observations become the basis of the assumptions used to develop an analytical life prediction model. In the model, the tensile flange stiffness is reduced based on coupon test data, and is used to determine the overall strength reduction of the beam in accordance the residual strength life prediction methodology. Delamination initiation is based on the out-of-plane stress sz at the free edge. The stresses are calculated using two different approximations, the Primitive Delamination Model and the Minimization of Complementary Energy. The model successfully describes the onset of delamination prior to fiber failure and suggests that out-of-plane failure controls the life of the structure.Master of Science
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Derian, Edward J. "Large deformation dynamic bending of composite beams." Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/45678.
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The large deformation response of composite beams subjected to a
dynamic axial load was studied. The beams were loaded with a moderate
amount of eccentricity to promote bending. The study was primarily
experimental but some finite element results were obtained. Both the
deformation and the failure of the beams were of interest. The static
response of the beams was also studied in order to determine the
difference between the static and dynamic failure. Twelve different
laminate types were tested. The beams tested were 23 in. by 2 in. and
generally 30 plies thick. The beams were loaded dynamically with a
gravity-driven impactor traveling at 19.6 ft./sec. and quasi-static
tests were done on identical beams in a displacement controlled
manner. For laminates of practical interest, the failure modes under
static and dynamic loadings were identical. Failure in most of the
laminate types occurred in a single event involving 40% to 50% of the
plies. However, failure in laminates with 30° or 15° off axis plies occurred in several events. All laminates exhibited bimodular
properties. The compressive flexural moduli in some laminates was
measured to be 1/2 the tensile flexural modulus. No simple relationship
could be found among the measured ultimate failure strains of the
different laminate types. Using empirically determined flexural
properties, a finite element analysis was reasonably accurate in
predicting the static and dynamic deformation response.Master of Science
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Abdelnaser, Ahmad Shehadeh. "Random vibrations of composite beams and plates." Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/37691.
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The response characteristics of beams and plates made from composite laminates are strongly affected by the shear deformations of their layers. However, incorporation of the shear deformation further complicates the equations of motion and their analysis. As a result the vibration analysis of such structures have been limited to simple free vibration studies such as determination of their frequencies. The forced vibration problems of these structures have been solved by exact methods for only some very simple cases. In this study, a generalized modal approach is presented to solve more general vibration problems of composite beams and plates. The coupled systems of partial differential equations, representing the equations of motion, are uncoupled into modal equations by utilizing the eigenfunctions of the system and its adjoint. A method is presented to obtain these eigenfunctions for beams with arbitrary boundary conditions and for plates with Levy-type boundary conditions. The forced vibration solutions obtained by this method are then used to calculate the random response characteristics of beams and plates subjected to spatially and temporally correlated random loads.
In the analysis of beams, both symmetric cross-ply and angle-ply configurations have been considered. In the symmetric cross-ply configuration with no torsional loads, of course, the warping effects are absent. The angle-ply case, however, includes torsion-warping effects and coupled bending-torsion motions. A simple displacement field is introduced to reflect warping in the third-order shear deformation theory. In the analysis of plates also two configurations of the laminates have been considered: symmetric cross-ply and antisymmetric angle-ply. At this time, these are the only two configurations which can be solved by the closed-form modal analysis approach for the Levy-type boundary conditions.
In both cases of the beams and plates, the numerical results with and without shear deformations are obtained and compared. The results for no shear deformation are obtained with the classical lamination theory. The results have also been obtained for the first-order shear deformation theory with a somewhat simpler displacement field which has been commonly used in the past by several investigators. The numerical results are obtained for the global response quantities such as frequencies, displacements and crossing rates as well as for the local response quantities such as normal and shear stresses across a cross section. The numerical results obtained with various deformation theories for the frequencies as well as response quantities are compared to evaluate the effect of the shear deformations. For thicker and rigid beams and plates, one observes large differences in the frequencies and responses obtained with (the first- and third-order shear deformation theories) and without consideration of shear deformations (classical theory). For the frequencies and global responses both the first- and third-order theories give about the same results. But for the local response quantities, the results obtained with the two shear deformation theories can also be quite different in some cases. In any case, the results clearly point out the importance of including the shear deformations in thick and rigidly constrained composite beams and plates.
Although, in this study only uniform cross section or uniform thickness beams and plates have been considered, it is felt that the eigenfunctions developed herein can also be conveniently utilized with advantage as comparison functions in approximate Rayleigh-Ritz type of approaches to analyze non uniform structures.Ph. D.
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Abdelnaser, Ahmad Shehadeh. "Random vibrations of composite beams and plates /." This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-05042006-164514/.
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Savic, Vesna. "Design optimization of thin-walled composite beams /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/7036.
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Bahadori-Jahromi, Ali. "Development and evaluation of composite insulated beams." Thesis, Edinburgh Napier University, 2006. http://researchrepository.napier.ac.uk/Output/2.
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Decline in supplies of old growth wood coupled with increased demand for structural timber by the construction industry led to creation of engineered timber products (EWPs) comprising wood waste. The author designed, fabricated and tested composite insulated beams (CIBs) which are foam filled sandwich panels constructed from EWPs. CIBs in many cross-sections and materials were limit-tested for structural performance, long-term durability, thermal and dynamic behaviours. Varaiation in material properties was overcome by statistical sorting of beams with different stiffness. Some types of CIB were found to provide better structural performance than equivalent timber and glulam I-beam sections and the CIBs maintained a high strength to weight ratio. A parametric study based on Eurocode 5 determined the governing design criteria for CIBs. The study showed that in identical loading conditions CIBs offer longer spans than conventional EWP I-beams, together with lower beam depths for similar spans. Injected polyurethane foam improved long-term durability, bearing capacity and damping ratio of beams, but reduced thermal loss and reduced weakening effect of a web opening on shear strength of beams.
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do, Nascimento Oliveira Jose Emidio. "Deformation and damage analysis of composite beams equipped with polyvinylidene fluoride film sensors." Thesis, Cape Peninsula University of Technology, 2008. http://hdl.handle.net/20.500.11838/1284.
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In many engineering applications, it is desirable to know the behaviour of structures and
systems under loading conditions. One reason is to help optimize the design and prevent
damage and failure which might occur during in service and operation. Damage represents a
serious problem which can cause catastrophic failure of structures, machines and systems.
Therefore for safe operation, efficient and reliable methods for inspection and monitoring of
damage are required. Different methods for health monitoring of structures such as non
destructive testing (NDT) and strain gauges are widely used. These methods have proven to
be efficient in terms of resolution and response. However, some disadvantages associated
with them include the vicinity of the area under inspection which must be well known,
equipment to acquire the necessary information is expensive and in many cases high skills
are required for operation. On the other hand, advances in materials science and MEMS
systems has promoted the use of new materials with piezoelectric properties. This include
mainly polymeric and ceramic materials which after processed can be used for structural
health monitoring. These materials offer a number of advantages such as lightweight,
sensitivity, toughness, durability, and low cost.
The present research work investigates the feasibility of using a polymeric material,
Polyvinylidene Fluoride (PVDF) as a sensor for deformation and defect detection in
structures. The sensors are embedded in composite cantilevered type beams to detect
defects at distinct locations along the beam’s length. The defect detection method proposed
is based on experimental tests and Finite Element simulations.
Experimental tests on defect free and beams with manufactured internal flaws were
conducted. Numerical (FEM) simulations of defect free and flawed beam models containing
sections of reduced elastic modulus to represent the damage were conducted using ANSYS
software. The experimental tests have been used for the validation of the numerical solution.
Results have shown that the defect location changes the stiffness and indeed the frequency
of vibration. For flaws near the fixed end of the beams, lower frequencies are obtained as
compared to flaws away from the fixed end. PVDF sensors were used to acquire the natural
frequencies of the beams for the first mode of vibration. Good agreement was verified
between experimental and numerical simulation results. The work has demonstrated that
PVDF film sensors can be used as possible candidates for defect detection.
The analysis of the behaviour embedded PVDF sensors near the fixed end of cantilever
beams, represents an initial and important step towards the application of measuring static
and dynamic behaviour of structures as part of a health monitoring process.
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Davis, Richard Anthony. "The Effects of a Damage Arrestment Device on the Mechanical Behavior of Sandwich Composite Beams Under Four-Point Bending." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/506.
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The demand for an insert on composite sandwich structures to aid in the arrestment of face-core delamination is of great need. This research studies the use of a damage arrestment device (DAD) that connects the carbon fiber face sheets to the foam core to find whether an increase in the structural integrity of the sandwich beam results. Experimental analysis was employed to test the samples and was verified by a theoretical and finite element approach.
The mechanical properties of LTM45/CF1803 pre-impregnated carbon fiber and Last-A-foam FR 6710 polyvinylchloride foam were experimentally analyzed using ASTM D3039 and ASTM D1621 standards respectively to verify the manufacturer’s data for the given material. With all the mechanical data, the effects of adding DAD keys to a delaminated composite sandwich beam were studied under a four-point bending test using ASTM standard D6272 and compared with non-delaminated beams to see if an increase in ultimate strength could be achieved. The initial delamination in the beams under consideration was one inch in length and located in between the loaded span of the beam. Two control beams were utilized for comparison: one with no defects, and another with a one inch delamination introduced at the face-core interface. The DAD keys were added in two different configurations to potentially stop the delamination propagation and increase the ultimate strength. In the first configuration DAD keys were added 0.25 inches on either side of the initial delamination in the transverse direction and provided a significant increase in strength over the delaminated control beam. The second configuration had a DAD key running along the longitudinal axis of the sandwich beam and resulted in a significant increase in ultimate strength over the delaminated control beam. After testing ten successful samples for each of the six different configurations, it was concluded that the addition of DAD keys in both configurations significantly increased the structural integrity of both the delaminated and non-delaminated control beams.
With all the experimental data acquired, finite element models were created in COSMOS. The purpose of the finite element analysis was to validate the experimental results by comparing the deflections of the beam subjected to four-point bending during the experiment to the deflections found numerically. The deflections for the various DAD key configurations found in the experimental work were in agreement with the finite element results.
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Dissanayake, Udaya Indrajith. "The influence of the composite beam-to-steel column joint on the behaviour of composite beams in frames." Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389752.
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Cho, Soon Ho. "Slab behaviour in composite beams at web openings." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74647.
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An explanation is provided for the slab behaviour in composite beams at web holes where the concrete slab carries heavy vertical shear. This is based on the truss concept, and requires consideration of shear studs in the hole region as vertical tension members. According to this, a structural action between the concrete slab and shear connectors for carrying or transferring vertical shear to the steel beam was clearly identified.On the basis of the slab behaviour identified, truss idealizations capable of determining the slab shear carrying capacity in a rational manner were developed. Then, the ultimate strength for composite beams at web holes was formulated including the truss idealizations. Another ultimate strength analysis accounting for the slab shear carrying capacity in a simple manner, which was also developed during this research project, is given. This provided the fundamental solution procedure for the plastic analysis used.
A series of nine tests was carried out with particular attention being directed to the verification of the proposed truss analogy. The major test parameters included the configurations of the studs in the hole region, the width of the concrete slab and stud detailing near the high moment end of the hole. The ultimate strength predictions were made by the two methods developed, and compared with previous and present test results.
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Ata, M. "Torsional analysis of thin-walled fibrous composite beams." Thesis, Cranfield University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333145.
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Ho, Teck Tuak. "Analysis of distortional buckling in continuous composite beams." Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275729.
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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.
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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.
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Farley, Gary L. "Energy-absorption capability of composite tubes and beams." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54523.
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In this study, the objective was to develop a method of predicting the energy-absorption capability of composite subfloor beam structures. Before it is possible to develop such an analysis capability, an in-depth understanding of the crushing process of composite materials must be achieved. Many variables affect the crushing process of composite structures, such as the constituent materials’ mechanical properties, specimen geometry, and crushing speed. A comprehensive experimental evaluation of tube specimens was conducted to develop insight into how composite structural elements crush and what are the controlling mechanisms
In this study, the four characteristic crushing modes, transverse shearing, brittle fracturing, lamina bending, and local buckling were identified and the mechanisms that control the crushing process defined. An in-depth understanding was developed of how material properties, affect energy-absorption capability. For example, an increase in fiber and matrix stiffness and failure strain can, depending upon the configuration of the tube, increase energy-absorption capability. An analysis to predict the energy-absorption capability of composite tube specimens was developed and verified. Good agreement between experiment and prediction was obtained.
Sine-wave and integrally stiffened composite beams were evaluated. Composite energy-absorbing beams crush in modes similar to tubular specimens that are made from the same material and have similar geometry. Energy-absorption trends of the composite beams are similar to energy-absorption trends from composite tube specimens. Composite beams are equal or superior energy absorbers to comparable geometry metallic beams. Finally, a simple and accurate method of predicting the energy-absorption capability of composite beams was developed. This analysis is based upon the energy-absorption capability of the beams’ constituent elements.Ph. D.
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Yassin, Airil Yasreen Mohd. "The development of precast cold-formed composite beams." Thesis, Imperial College London, 2007. http://hdl.handle.net/10044/1/8054.
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The aim of this project is to develop a new type of composite beam that is light and has high constructability: This is achieved herein with the development of the PCFC beam which consists of a closed cold-formed steel section embedded in concrete. The motivation of the project comes from the availability of cold-formed steel to take any general form, a vital feature as it allows for optimum satisfaction of the composite supply and demand principle. The development of the beam requires several fundamental aspects to be investigated or/and formulated. The first of these is the study of the effect of the normal stresses and the frictional stresses induced as part of the longitudinal force transfer in the composite beam. This requires the derivation and solution of the differential equations describing the partial interaction of the composite beam. It has been found that the normal stresses do not have a significant effect on the elastic performance of the beam. However, the inclusion of the frictional stresses has been found to beneficially contribute to the longitudinal shear resistance of the beam. The complexity of the beam cross-section in terms of shape and materials means that the thesis has had to address calculation procedure developments. Initially, a general procedure is developed for which the key feature is the use of functions to describe the geometrical shape of the cross-section. This allows the procedure to cater for complex shapes as well as to divide the cross-section into its matrix representations, leading to an efficient computer programming coding. However, the discrete nature of the procedure limits it use to the calculation of the plastic moment capacity based on the rectangular stress block method. This limitation is removed in the enhanced version of the procedure where Fourier Series have been used to represent the flexural stress distribution as a single-rule function. This allows the use of more realistic material models and covers various stress stages without requiring iteration. The procedure and its extended version allows for the assessment of the PCFC beam, where it has been found that, although it is slightly less sufficient when considering some serviceability aspects, the beam performs better than the equivalent composite beams in the ultimate condition.
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An, Wei 1963. "Strengthening of concrete beams with composite plastic plates." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/277246.
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This study investigates the feasibility of strengthening reinforced concrete beams with epoxy-bonded Glass-Fiber-Reinforced-Plastic (GFRP) plates. The composite plate is epoxy-bonded to the tension flange of the beam to increase its stiffness and strength. Seven rectangular and one T-beam, retrofitted with composite plates, were tested to failure under symmetrical 4-point bending. The load versus deflection and the load versus strain in the composite plate, steel rebar and the extreme compression fiber of concrete were measured and plotted for the midspan section throughout the entire range of loading up to failure. Analytical models based on the equilibrium of forces and compatibility of deformations were developed to predict the stresses and deformations of the beam in the linear and nonlinear regions. The predicted and measured results correlated well. The analytical models were used in a parametric study to investigate the effects of design variables such as, plate area, plate strength and stiffness, reinforcement ratio, etc., on the moment-curvature relationships of typical rectangular and T cross sections.
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Harrison, Christopher. "The detection of delaminations in vibrating composite beams." Thesis, University of Bath, 2000. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323574.
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Obst, Andreas W. "Nonlinear static and transient analysis of generally laminated beams." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-10102009-020113/.
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Lam, Wai-yin, and 林慧賢. "Plate-reinforced composite coupling beams: experimental and numerical studies." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37311797.
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Nagappan, Govindan. "Analysis of composite moving beams using higher order shear deformation theory." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3463.
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Thesis (M.S.)--West Virginia University, 2004.Title from document title page. Document formatted into pages; contains xi, 126 p. : ill. Includes abstract. Includes bibliographical references (p. 123-126).
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MOUSSA, ALBERT ELIAS. "EFFECTIVE WIDTH AND ULTIMATE STRENGTH OF CONTINUOUS COMPOSITE BEAMS." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184084.
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The primary objective of this study has been to examine the behavior of continuous composite beams. The investigation has been based on a nonlinear analysis of 15 composite floor systems. New design criteria have been proposed to calculate the effective width at mid-span and supports, at yield and at ultimate loads. New design equations have been developed to calculate the ultimate strength of a composite section in both positive and negative moment regions. Ductility and deflection characteristics have been studied and equations are proposed to calculate the deflection at service load.
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Lam, Wai-yin, and 林慧賢. "Experimental study on embedded steel plate composite coupling beams." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B26643352.
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Heidarpour, Amin Civil & Environmental Engineering Faculty of Engineering UNSW. "Behaviour of steel and steel-concrete composite beams and beam-to-column connetions at elevated temperatures." Awarded by:University of New South Wales. Civil & Environmental Engineering, 2007. http://handle.unsw.edu.au/1959.4/40555.
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The current research work investigates the behaviour of steel and composite beams as well as beam-to-column connections at elevated temperatures. Significant attention is needed to identify the main issues. as the behaviour is profoundly different from that at ambient temperature. Local buckling of the beam flange outstands has been found to be highly significant in accelerating the development of catenary action in fire, since this action is reliant on hinges forming which may result from local buckling. Local buckling of the beam web, which experiences a non-uniform temperature variation, is also important because the mechanical properties of the steel are degraded non-uniformly from their ambient values. Current formulations for web buckling at ambient temperature therefore need substantial revision at elevated temperatures. Very large compressive forces are developed within the beams initially and these induce large stresses in the column web; hitherto this has not been considered. Developing a formulation representing the mechanics of this potential failure zone in the column web in the compression region of the connection is a useful and needed addition to research in the topic. Predicting the critical temperature in a connection that causes failure of the bolts, end plate and column flange in the tension zone of the connection is considered in this research work. An elastic analysis of a panel zone in a rigid or semi-rigid joint in a steel frame, which is based on simple equilibrium considerations that takes into account the shear and flexural deformations of the panel zone, is developed at elevated temperatures. In order to model the structural response of a composite beam restrained by cooler members in a steel compartment fire in a frame structure at elevated temperature, recourse is needed to a geometric nonlinear formulation, since the beam transverse deflections are not negligible and the axial eompressive force in the member is also substantial at the early stages of the fire. This thesis presents such a formulation, which incorporates partial interaction between the concrete slab and steel component, as well as the degradation of the stiffnesses of the components of the composite beam prior to yield at elevated temperature.
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Babamohammadi, Sajjad. "Mechanical Assessment of Fiber Reinforced Composite Hollow Circular Beams." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
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This thesis presents a study on fiber reinforced hollow beams. The theoretical background is based on published works and some extensions to the present researches.
For some, simple, cases exact solutions are made available, however hollow composite beams have to be studied using 3D modeling in order to capture their actual anisotropic behavior.
At first, we start to investigate if we have enough information to successfully design a structure using FRP materials. Then after studying some published works in this field, we understood that there is a lack of some important details.
We tried to fill this void by first understanding the behavior of FRP beams and prepare a fast and easy way for engineers to use these composite beams and design structures. To do that, we used existing analytical methods. Although analytical, these methods are limited for studying fiber reinforced beams.
Thus, a new approach is here presented based on an equivalent 3D shell model which is used to defined a 3D finite element beam element for frame structural analysis.
This approach is simple and clearly considers the anisotropy inherited in such profiles.
Applications of this procedure are given which show the quality of the present results and the advantages of using composite beams with respect to classical steel beams in civil applications.
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Couchman, Graham H. Couchman Graham. "Design of continuous composite beams allowing for rotation capacity /." Lausanne : EPFL, 1995. http://library.epfl.ch/theses/?nr=1308.
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Hicks, Stephen James. "Longitudinal shear resistance of steel and concrete composite beams." Thesis, University of Cambridge, 1997. https://www.repository.cam.ac.uk/handle/1810/252318.
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Inniss, Clifton F. "Analytical and experimental modelling of timber-concrete composite beams." Thesis, University of Surrey, 1994. http://epubs.surrey.ac.uk/842780/.
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This thesis investigates the behaviour of timber-concrete composite beams with mechanical shear connectors. The analysis of these structures is complex due to the discontinuity caused by slip at the interface between the timber and concrete and can only be achieved by the use of sophisticated analytical techniques. A literature review has been carried out highlighting the fact that only a limited amount of theoretical and experimental work exists on timber- concrete composite beams. The fundamental objectives of this study were to develop suitable analytical and experimental models so as to better understand the behaviour of these structures. Fifty seven push-out specimens and seven beams were tested in order to determine the load/slip characteristics of the coach screw connectors and how these influence the behaviour of the beams. It was found that the bond and friction at the timber-concrete interface had a significant effect on the behaviour of the joints and beams. Analyses were carried out using a fully non-linear finite element package, LUSAS. The finite element model developed consisted of standard two dimensional elements and the results from the beam tests were used in a validation exercise. In general, good agreement was obtained for the stiffness of the beams throughout their loading history. Studies were carried out using the analytical model to determine the influence of the main parameters on the stiffness of the beams. The connector stiffness and timber properties were found to have a strong influence while the concrete properties were not significant at working load level. Further analytical studies were carried out for a wide range of geometric properties. The information obtained was used in the formulation of a design procedure which allowed for slip at the interface of the beams. Recommendations are included for future research on timber-concrete composite beams.
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Lentz, W. Karl. "Optimum coupling in thin-walled, closed section composite beams." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/12018.
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Jackson, Rahsean LaNaul. "Vibration and Flexural Strength Characteristics of Composite Castellated Beams." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/31242.
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With the development of lightweight concrete and design optimizations, floor vibration problems are becoming a serious serviceability problem. The castellated beam is a prime example and was the focus of this study. The vibration and flexural strength performance were verified in this paper.
The vibration characteristics of castellated beams were examined using experimental and analytical test methods. The effective moment of inertia is essential to accurately predict the frequency and deflection of a floor system due to human occupancy. Since castellated beams have non-prismatic cross-sections, their effective moment of inertia is an uncertainty and was verified in this study. This paper confirmed the accuracy of the AISC Design Guide procedures used in for prismatic beam, when applied to castellated beams.
The flexural strength of various composite castellated beam were studied. Three full-scale specimens were tested to failure to evaluate their yield and maximum applied load. Each specimensâ moment strength was verified based on span, beam properties, concrete slab, and amount of shear connection.
Master of Science
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Kim, Seunghwan. "Creep and Shrinkage Effects on Steel-Concrete Composite Beams." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/48427.
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Predicting the long-term behavior of steel-concrete composite structures is a very complex systems problem, both because obtaining reliable information on material properties related to creep and shrinkage is not straightforward and because it is not easy to clearly determine the correlation between the effects of creep and shrinkage and the resultant structural response. Slip occurring at the interface between the steel and concrete may also make prediction more complicated. While the short-term deflection of composite beams may be easily predicted from fundamental theories of structural mechanics, calculating the long-term deflection is complicated by creep and shrinkage effects on the concrete deck varying over time. There are as yet no comprehensive ways for engineers to reliably deal with these issues, and the development of a set of justifiable numerical standards and equations for composite structures that goes beyond a simple commentary is well overdue. As the first step towards meeting this objective, this research is designed to identify a simple method for calculating the long-term deformations of steel-concrete composite members based on existing models to predict concrete creep and shrinkage and to estimate the time-varying deflection of steel-composite beams for design purposes. A brief reexamination of four existing models to predict creep and shrinkage was first conducted, after which an analytical approach using the age-adjusted effective modulus method (AEMM) was used to calculate the long-term deflection of a simply-supported steel-concrete composite beam. The ACI 209R-92 and CEB MC90-99 models, which adopt the concept of an ultimate coefficient, formed the basis of the models developed and examples of the application of the two models are included to provide a better understanding of the process involved. For the analytical approach using the AEMM, the entire process of calculating the long-term deflections with respect to both full and partial shear interactions is presented here, and the accuracy of the calculation validated by comparing the model predictions with experimental data. Lastly, the way the time-dependent deflection varies with various combinations of creep coefficient, shrinkage strain, the size of the beam, and the span length, was analyzed in a parametric study. The results indicate that the long-term deflection due to creep and shrinkage is generally 1.5 ~ 2.5 times its short-term deflection, and the effects of shrinkage may contribute much more to the time-dependent deformation than the effect of creep for cases where the sustained live load is quite small. In addition, the composite beam with a partial interaction exhibits a larger mid-span deflection for both the short- and long-term deflections than a beam with a full shear interaction. When it comes to the deflection limitations, it turned out that although the short-term deflections due to immediate design live load satisfy the deflection criteria well, its long-term deflections can exceed the deflection limitations.Master of Science
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Allen, Aaron Andrew. "Stability results for damped multilayer composite beams and plates." [Ames, Iowa : Iowa State University], 2009.
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Baharom, Shahrizan. "Composite beams with openings in metal-ribbed decking slabs." Thesis, Swansea University, 2010. https://cronfa.swan.ac.uk/Record/cronfa42871.
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