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1
Czmoch, Ireneusz. "Influence of structural timber variability on reliability and damage tolerance of timber beams". Doctoral thesis, Luleå tekniska universitet, 1998. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16865.
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The thesis addresses two main problems: 1) Probablistic modelling of lengthwise variability in structural timber, 2) Reliability and damage tolerance analysis of beams made of structural timber. Timber is considered as an elastic-brittle material. Dependence of timber properties on time and environment conditions is neglected. The presented statistical analysis of MOE is based on experimental data. An original method for determination of the MOE function on the basis of a measured deflection curve has been developed. The Log-normal, Gumbel or Normal distributions can be recommended as the probability distribution model of the homogeneous random field of MOE with the scale of fluctuation equal to 1.5-2.5 m. The variability of bending strength of timber beams has been studied with help of a weak-zone model. Assuming a marked Poisson random field as a probabilistic model of bending strength, analytical solutions have been derived for a number of particular problems. The influence of the correlation between strengths of weak zones has been studied with help of the Monte Carlo simulation. Time invariant reliability indices and damage tolerance indices have been computed for the weak-zone model and the corresponding homogeneous modelof a timber beam. The difference in reliability indices between the homogeneous and weak-zone models depends more on the probability model of the weak-zone strength than on the mean distance between the weak zones. There is no significant difference in the damage tolerance indices computed for the two considered models of a timber beam.Godkänd; 1998; 20061122 (haneit)
2
Gentile, Christopher John. "Flexural strengthening of timber bridge beams using FRP". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0027/MQ51711.pdf.
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Spellman, Phillip Michael. "The Fire Performance of Post-Tensioned Timber Beams". Thesis, University of Canterbury. Department of Civil and Natural Resources Engineering, 2012. http://hdl.handle.net/10092/7429.
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Post-tensioned timber frames have recently been undergoing heavy research and development at the University of Canterbury. The recently developed post-tensioned timber system utilises engineering wood products such as Laminated Veneer Lumber (LVL) and glue laminated timber (Glulam), which are formed into box sections and post-tensioned with high strength steel tendons made from stranded steel wire or solid steel bars. The post-tensioning serves to counteract some of the bending actions imposed on the timber beam from loading through a variety of mechanisms. Previous research has focused on the seismic performance and gravity frame performance of post-tensioned timber, both of which yielded promising results. There is however a commonly perceived increase in fire risk with timber building, particularly multi-storey timber buildings, and the fire
performance of post-tensioned timber had not previously been investigated. Therefore, the focus of this research was to investigate the fire performance of post-tensioned timber beams. This was completed through a series of full-scale furnace tests, and the development of a fire resistance design method. Three 4.36m span post-tensioned timber beams were exposed to the ISO 834 standard fire. Each of the test beams were glued box beams made from 63mm LVL and were of varying external dimensions. Each beam was intended to demonstrate a specific failure
mechanism at approximately 60 minutes of fire exposure. The failure mechanisms demonstrated were a shear failure in the lower corner of due to corner rounding, and a combined bending and compression failure at the end of the beam. These failure mechanisms are unique to post-tensioned timber in fire. The results of the experimental testing were used to validate and refine the proposed
fire resistance calculation. Also tested during the full-scale testing were five different forms of anchorage fire protection. These were tested as a secondary objective, but useful thermal data was collected. Through the full-scale testing and the calculation method development it was found that it is important to consider shear during fire design. The post-tensioning increases the bending capacity of
a beam but doesn’t affect its shear capacity, therefore when more loading is applied to utilise the increased bending capacity the shear action is increased which leads to shear governing the design in many cases. It is also important to consider shear not only in the webs at the centroid where the shear flow is greatest but also in the lower corners, which can become much thinner than the webs. Without calculation it is not possible to determine where the shear stress will be greatest and therefore both the web and the lower corners need to be checked. It was also found that as the timber section chars on three sides the post-tensioning eccentricity increases which can lead to the moment at the end of the beam becoming critical. Other failure mechanisms which need to be checked include, combined bending and compression at mid span, and tension in the bottom most fibre at mid span. It was found that the proposed calculation method, when used with a char rate of 0.72mm/min and an additional allowance of 7mm for temperature-affected timber beneath the char layer, provided good predictions of the failure times for the full-scale experiments.
4
Habite, Tadios Sisay. "Moisture-induced crack development in timber beams : a parametric study performed on dowelled timber connections". Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-68610.
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A problem has been observed by many researchers regarding the cracks caused mainly by moisture variation in timber structures. However, this effect has been neglected over the past decades. In addition, many design codes do not have a room for a realistic formulation of the moisture diffusion and its effect in causing internal stress, deformation, and cracks. Moreover, if this effect occurs in connection areas, usually the weakest structural section, it has and also had shown a devastating effect on the service life of many wooden structures. In the current work, a Fickian moisture diffusion model is implemented by use of finite element simulation with the help of the commercial software ABAQUS for a dowelled beam column connection. The results of such moisture diffusion were used to analyse the stress situation inside the timber section. Moreover, an extended finite element method was applied in ABAQUS to investigate how moisture induced crack develops into the timber section. Furthermore, a parametric study was performed by using Python scripting to investigate the effect of dowel spacing (horizontal and vertical) and critical energy release rate on the development of the moisture-induced crack. The results obtained revealed that for the same material property when the dowel spacing increases (either horizontal or vertical) the crack length increases significantly. Likewise, the crack length increases when the critical energy release rate requirement of the timber is decreasing.
5
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.
6
Zhu, Enchun. "Modelling the structural behaviour of OSB webbed timber I-beams". Thesis, University of Brighton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289477.
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Talukdar, Sudip. "Strengthening of timber beams using externally-bonded sprayed fibre reinforced polymers". Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/920.
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The use of Fibre Reinforced Polymers (FRP) has grown in popularity in the construction industry. FRP has proven useful in the retrofit of various types of structural elements. It may be used for the strengthening of beams, the seismic upgrade of walls panels, as well as the jacketing of columns to provide confinement. There exist several methods of FRP application for the case of structural retrofits. These include the application of pre-prepared FRP mats, or application of FRP via the wet lay-up process. However, a new technique developed at the University of British Columbia allows for the application of FRP in the form of a spray.
Externally bonded Sprayed FRP (SFRP) is known to increase strength and energy absorption capacity of a retrofitted member as well as, or better than, FRP sheets. However, tests have primarily been carried out on concrete members only. An area of interest, into which not much research has been conducted, is the application of SFRP to timber. Timber bridges are extensively used in many parts of the world. Often due to remoteness and practical constraints, it is impossible to apply FRP sheets to retrofit these bridges. SFRP would be a much easier method of FRP application.
This study looked at the application of SFRP to Douglas Fir (D.Fir) Beam specimens subjected to 3-Point Flexural Loading only. The specimens were treated with either a water based (Borocol) or oil borne (Creosote) antifungal preservative prior to being sprayed with FRP. Different combinations of adhesives/bonding agents including Hydroxymethylated Resorcinol and Polymeric Isocyanates were used to try to develop a strong bond.
When considering using only chemical adhesives to obtain a proper bond between the two constituents of the composite, use of HMR is recommended for timber which is untreated or has been treated with a water borne preservative such as Borocol, while a pMDI adhesive such as AtPrime 2 is recommended for timber treated with an oil borne preservative such as Creosote. For Non Creosoted beams, adhesives did not generate as significant of a strength gain. For Creosoted beams, adhesives may be sufficient to generate significant strength gain when SFRP is applied to a beam. Considering that most structures in use would probably have been treated with a preservative similar to Creosote, in practice, AtPrime 2 or some other some sort of pMDI would probably be the adhesive of choice.
Based on the results of the study, it is possible to say that the application of SFRP to retrofit/rehabilitate timber structures shows considerable promise. If a decent bond is achieved between the composite constituents, it is possible to substantially increase the ultimate flexural strength of the member, as well as drastically increase its ductility and energy absorption capacity. It is recommended that further tests be carried out using different types of loading schemes, geometrical configurations of SFRP, other types of anchorage, and development of a proper analytical model before the method is adopted for widespread use.
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Ong, Chee Beng. "Performance of glue-laminated beams from Malaysian Dark Red Meranti timber". Thesis, University of Bath, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760973.
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In this study, Malaysian Dark Red Meranti (DRM) was used to manufacture glulam beams, following closely the requirements of BS EN 14080:2013 so as to emulate commercial production. Phenol resorcinol formaldehyde (PRF), commonly used in structural glulam production, was used in the fabrication of finger joints and laminations of the glulam beams. Factors influencing the mechanical properties of finger joints and bonding performance of laminations were investigated. Full size glulam beams were manufactured and tested in bending with partial and complete carbon fibre reinforced polymer (CFRP) reinforcement on the tension face and compared with the performance of unreinforced beams. A bench-scale fire test was proposed to describe the behaviour of DRM finger joints in tension under fire condition, in order to simulate the failure of finger joints on the tension side of a glulam beam in a standard fire test. Overall, DRM finger joints exhibited better bending strength than Spruce finger joints which represented softwood used in European glulam. Wood density and end pressure were shown to affect the strength properties of the finger joints. Higher cramping pressure was needed to produce DRM laminations with higher shear strength. The glulam beam with CFRP reinforcement had a higher bending strength than the unreinforced glulam beams but partial reinforcement had an adverse effect on beam strength. In the bench-scale fire test, DRM finger-jointed specimens exhibited lower charring rate than Spruce. Furthermore, PRF finger-jointed specimens showed better fire performance than finger-jointed specimens bonded with polyurethane (PUR) adhesive. In conclusion, it is hoped that results from this research will motivate engineers and architects in Malaysia to design and build structures from less-utilised local timber, specifically in the form of glulam, encouraging the timber industry in Malaysia to produce them commercially.
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Anshari, Buan. "Structural behaviour of glued laminated timber beams reinforced by compressed wood". Thesis, University of Liverpool, 2012. http://livrepository.liverpool.ac.uk/9115/.
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As an engineered wood product, glued laminated timber (Glulam) is produced to minimise several natural weaknesses such as knots and non-uniform strength in order to enhance its stiffness and load carrying capacity. Many reinforcement methods have been tested, with promising results in increasing the strength and stiffness of beam. Recently, with increasing concern on environmental protection there is a growing trend in construction to use as many natural materials as possible. Therefore, conventional types of reinforcement using metals and/or synthetic materials do not fit well with this trend. A new approach to strengthen Glulam beams using pure natural materials has been established through this research. Glulam beams were strengthened by inserting compressed wood (CW) blocks into the pre-cut rectangular holes on the top of the beams. This practice was to make use of moisture-dependent swelling nature of the compressed wood. As a result, a pre-camber was produced in the mid-span of the beam reinforced. Significant initial tensile and compressive stresses were generated at both the top and the bottom extreme fibres of the beam, respectively. Material tests have been done to investigate material properties of compressed Japanese cedar with different compression ratios. Structural tests were undertaken for short and long Glulam beams strengthened by CW blocks after gained the pre-camber. 3-D finite element models have also been developed by using commercial code ABAQUS to simulate the pre-stressing behaviour of Glulam beams reinforced using compressed wood blocks. The finite element models were used to simulate the structural behaviour of the pre-stressed beams subjected to subsequent destructive bending tests. All computer models developed were validated against corresponding experimental results of the free moisture-dependent swelling, pre-stressing processes and the destructive tests for both the short and long beams. Reasonably good correlation was obtained in terms of the free swelling, the pre-camber, initial stress state of the Glulam beams reinforced and load-deflection relationships. Using validated computer models, parametric studies were further carried out to provide design information for such a reinforcing technique. The results have indicated that the reinforcing techniques using compressed wood blocks are very effective means to enhance the initial stiffness, bending strength and load carrying capacity of Glulam beams. The technology is ready to be applied in practice.
10
Khokhar, Aamir Muhammad. "The evaluation of shear properties of timber beams using torsion test method". Thesis, Edinburgh Napier University, 2011. http://researchrepository.napier.ac.uk/Output/4406.
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Williams, Walter Ray. "Stress analysis of a glued timber beam". Master's thesis, Mississippi State : Mississippi State University, 2009. http://library.msstate.edu/etd/show.asp?etd=etd-04032009-085801.
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Bretschneider, Tino. ""Assessment of existing glued laminated timber beams by probability-based updating" with considerations to the effects of updating to safety analysis of timber beams and applications to advanced test routines". Tönning Lübeck Marburg Der Andere Verl, 2007. http://d-nb.info/985324139/04.
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van, Beerschoten Wouter Adrian. "Structural Performance of Post-tensioned Timber Frames under Gravity Loading". Thesis, University of Canterbury. Department of Civil and Natural Resources engineering, 2013. http://hdl.handle.net/10092/8735.
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A new structural system for multi-storey timber buildings has been developed over the last seven years at the University of Canterbury. The system incorporates large timber structural frames, whereby semi-rigid beam-column connections are created using post-tensioning steel tendons. This system can create large open floor plans required for office and commercial buildings.
Several material properties of the engineered timber used were determined based on small-scale experimental testing. Full-scale testing of beams, connections and frames resulted in a more comprehensive understanding of the behaviour of such systems. Numerical, analytical and framework models also led to the development of design equations and procedures which were validated with the acquired experimental data.
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Choamnak, Sitdhichai. "Nondestructive and destructive testing of covered timber bridge members". Ohio : Ohio University, 1997. http://www.ohiolink.edu/etd/view.cgi?ohiou1177444570.
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Fawwaz, Maha y Adnan Hanna. "Structural behavior of notched glulam beams reinforced by means of plywood and FRP". Thesis, Linnéuniversitetet, Institutionen för teknik, TEK, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-19479.
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Nowadays, timber is widely used in construction industry thanks to its availability and good properties. The use of solid (sawn) timber is not always proper since it is only available up to certain dimensions. Therefore, the so-called Engineered WoodProducts (EWPs) have been introduced to cope with the different design needs of structures. The Glued laminated Timber (glulam) is a type of EWPs that consists of smallsections of timber laminates glued together to form beams and columns. Glulam can be manufactured in almost any size and shape; it can also be tapered or notched. However, notching a beam at its end leads to a stress concentration at the re-entrantcorner of the notch due to the sudden change in the notched beam’s cross section. The concentration of shear and tensile stresses perpendicular to the grain can lead to a catastrophic brittle failure caused by the crack propagation from the notch corner. Crack opening due to tensile stresses perpendicular to grain is the most common failure at the notch corner and it is always taken into design consideration. However,shear component is usually exists and must be also considered in design to guarantee the safety of the structure. Currently, only the normal forces perpendicular to the beam’s axis are considered in the design of the reinforcement in design handbooks. The aim of this thesis was to study the structural behavior of notched glulam beams reinforced by adhered plywood panels and FRP. The carrying capacity of the notched glulam beams at their ends is the main subject of this thesis. In addition, a review of the notched beams design, reinforcements, and analysis theories are included. Experimental series of three point bending tests with notched glulam beams withdifferent configurations of reinforcement was carried out in lab. Deformations and forces were measured both with conventional techniques and with contact-free measurement systems - ARAMIS. On the other hand, a simple model of two dimensional plane stress element has been created of the unreinforced notchedbeam in ABAQUS. The normal and shear stresses were calculated for a horizontalpath of 100 mm in length starting from the notch tip. Afterwards, the mean stresseswere determined for the same path and have been used in calculations. The Mean Stress Approach has been adopted in the hand calculations to calculate the crack length and the failure load according to the ABAQUS model. Accordingly, the failure load was about 40 kN for the unreinforced beams. Also, Eurocode 5 has been used to calculate the failure load which gave a value of 20.2 kN for the unreinforced beams. The average maximum applied load in tests was 30 kN for the unreinforced beams while it reached about two and a half times this value for the CF-reinforced and the plywood-reinforced beams.Tack vare sina goda egenskaper används trä i byggnadskonstruktioner i allt storeomfattning. Konstruktionsvirke (sågade trävaror) kan dock inte alltid användas pågrund av de begränsade dimensioner som finns tillgängliga. På grund av bl a dettahar ett flertal så kallade engineer wood products (EWP) utvecklats. Limträ är en typav EWP som består av sammanlimmade lameller som bygger upp tvärsnitt i balkareller pelare. Limträ kan tillverkas i nästan godtycklig storlek och form och kan enkeltförses med t ex urtag. Vid urtag i balkändar nära upplag uppstår högaspänningskoncentrationer vid urtagets horn på grund av geometrin. Koncentrationenav normalspänningar och skjuvspänningar kan leda till plötsligt brott på grund avsprickpropagering från urtagets hörn, något som måste tas hänsyn till viddimensionering. Dagens dimensioneringsmetoder är baserade på att man tar hänsyntill enbart normalspänningarna vinkelrät fiberriktningen.Målet med detta arbete har varit att studera beteendet hos limträbalkar med urtag vidupplag som förstärkts med fiberarmering eller plywood. Huvudmålet har varit attbestämma balkarnas bärförmåga, vilket skett genom att genomföra försök med olikakonfigurationer vad gäller förstärkningsmaterial och dess utformning. Vidare harolika dimensioneringsmetoder från litteraturen studerats.Kraft och förskjutning under provningarna uppmättes dels med traditionellamätmetoder, men deformationerna mättes även med beröringsfri metod, ARAMIS.En enkel tvådimensionell finit elementmodell skapades och analyserades i ABAQUSför analys av oförstärkt balk. Normalspänningar och skjuvspänningar beräknades ochmedelspänningarna längs en på förhand definierad sträcka beräknades.Medelspänningskriteriet användes sedan för att uppskatta balkens bärförmåga.Enligt FE-beräkningarna uppskattades bärförmågan för de oförstärkta balkarna till ca40 kN. Provningarna gav ett medelvärde på balkarnas bärförmåga på ca 30 kN,medan de förstärkta balkarna hade en 2,5 gånger högre bärförmåga. Skillnadenmellan FE-beräkningarna och provningarna kan förklaras med den osäkerhet somfinns vad gäller det aktuella trämaterialets egenskaper.Beräkningar enligt Eurokod 5 gav en karakteristisk bärförmåga på 20,2 kN.
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Mohammadianfar, Omid y Lambert Imanizabayo. "Study of the Bonding Properties for Timber – Glass Composite Beams : The influence of viscoelastic adhesives on the load-bearing capacity". Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-77549.
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The study of the influence of viscoelastic adhesives on timber-glass composite beams addresses the development of new and innovative load bearing structures. Hybrid timber-glass beams, comprising of timber flanges and a glass web, were considered. The solutions proposed in this study are based on utilizing viscoelastic adhesive bond lines to obtain optimal structural interaction between timber and glass. For hybrid timber-glass beams, numerical simulations have been developed with Abaqus, Finite element software which are verified by analytical methods according to the Eurocode 5 (EN 1995). In this study, three different bond-line geometries and three adhesives (epoxy, silicone and acrylate) have been investigated. The beams were analyzed under four-point bending. This report summarizes theoretical investigations, background studies, numerical modelling and analytical solution that have been performed. Guidance is presented which can be used for the design of timber-glass composite beams. The study has shown that the viscoelastic properties of the adhesive had no significant influence for the selected epoxy adhesive, but it can slightly affect the beam behavior with the silicone and acrylate adhesives used. From the three geometries studied, the design with an epoxy bond-line on both sides and on top of glass is regarded the best way, leading to good load-bearing structural elements where the response of the adhesive was highly influenced by its near incompressible behavior.
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Resch, Ludovic. "Développement d'éléments de construction en bois de pays lamellés assemblés par tourillons thermo-soudés". Thesis, Nancy 1, 2009. http://www.theses.fr/2009NAN10142/document.
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Le soudage du bois constitue un nouveau procédé d’assemblage, deux pièces de bois sont assemblées sans aucun adhésif, ni organe métallique. Ce travail étudie la faisabilité d’éléments de construction en bois lamellé à échelle 1 comme des poutres, des parois et des planchers, en utilisant le soudage de chevilles (Fagus sylvatica) dans des avivés (Picea abies) des forêts locales (VOSGES). La maîtrise du procédé étant primordiale pour étudier sa reproductibilité, une machine prototype est développée. Les paramètres d’asservissement et la mesure des efforts appliqués sont maîtrisés précisément par un logiciel. La fabrication contrôlée d’échantillons et de poutres soudées permet de caractériser les propriétés mécaniques élémentaires.L’étude du comportement des poutres et des planchers fait appel à la théorie des poutres à connexions imparfaites. Une approche par éléments finis montre que le modèle analytique de KREUZINGER n’approche pas suffisamment la distribution des contraintes dans la section composite, un modèle analytique est développé selon l’approche de GIRHAMMAR : le modèle exact généralisé. Les essais de poutres montrent une trop grande souplesse de la liaison et sa sensibilité au fluage. Les essais sur le plancher conduisent à des caractéristiques intéressantes en termes de rigidité et de confort. Les parois, non optimisées, montrent des résultats prometteurs pour le contreventement. Les premiers éléments sur l’utilisation du soudage du bois dans la construction sont présentés. Cette technologie se révèlerait compétitive dans la réalisation d’éléments constructifs en 3D. Dans un contexte de développement durable, cette approche constructive est porteuse d’avenirWood welding is a new assembly concept; two pieces of wood can be connected without any adhesive or any metal fastener. This study present the feasibility in usable scale, to produce laminated elements for construction like beams, walls and floors, using welded dowels (Fagus sylvatica) to connect planks (Picea abies) from local forests (Vosges). To be used, it is essential that the welding process has to be reproducible; a prototype machine was designed in this aim. It mastered the main parameters of welding like rotation speed and efforts. A convivial software pilot efficiently the machine. This allows a controlled fabrication of welded samples and beams to characterize their basic resistance properties. The behaviour of beams and floors is given by composite beam with interlayer slip theory. A finite elements approach showed that the KREUZINGER’s analytical model does not allow to describe well enough the stress distribution in a multi layer composite section, an analytical model is then develop from GIRHAMMAR’s composite beams theory: the so call generalized exact model. Tests of beams show that the dowel connection is too weak and will have then a great sensitivity to creep. Tests on floor provide interesting features in terms of rigidity and comfort. The walls which are not optimized show encouraging results for racking resistance. The first items for the use of wood welding in construction are presented. This technology will be competitive in achieving constructive elements in 3D. In a context of sustainable development, this constructive approach takes its full meaning
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Mahjoub, Musaab. "FE modeling of glulam beams with mechanical slotted-in steel plate connections". Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-105430.
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The mechanical behavior of timber beams with a slotted-in steel plate is studied by creating anumerical model that can simulate the global bending behavior and the load carrying capacity aswell as the nonlinear plastic fastener force distribution. Experimental results from Material TestingInstitute (MPA), University of Stuttgart were compared with simulation results done at LinnaeusUniversity. The modeling of the timber beams and the mechanical connections is performed withshell, beam, and nonlinear connector elements. Three models were created, where the first modelwas a single-dowel double shear joint model to study the ability to use structural elements in themodeling of the test beams. It was used to simulate some of the basic failure modes in Eurocode5 (EC5). The second model was a beam model used to simulate the bending of a jointed timberbeam with a slotted-in steel plate, where only two connector elements are used to model the jointbehavior of each dowel group. It can be used to study the global deflection and the load carryingcapacity of the timber beams. The third model was a combined beam-shell model where the beamelements are used for the timber parts outside the connection area and the fasteners, while the shellelements are used for the slotted-in steel plate and the timber parts within the connection area.It uses two nonlinear connectors to connect each dowel to the wood and pure coupling to connectthe dowels to the slotted-in steel plate. This model can simulate same things as model two andalso the development of the elasto-plastic shear force distribution in all the dowels. All the modelswere created using parameterized Python scripts, which makes it possible to easily change differentinput parameters.Most of the modeling results show good agreement with both experimental results and with calculated load carrying capacity results for individual dowels according to EC5. The use of thesestructural elements (beam, shell, and connector elements) was found to result in much less computational time compared to the use of solid elements.
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Alcântara, Segundinho Pedro Gutemberg de [UNESP]. "Análise teórico-experimental de um tabuleiro misto madeira-concreto composto por vigas circulares". Universidade Estadual Paulista (UNESP), 2005. http://hdl.handle.net/11449/91482.
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O estudo em estruturas mistas é dedicado ao emprego do material madeira-concreto em estruturas de pontes, mais precisamente no seu tabuleiro. No entanto, a aplicação desse material no Brasil não está regulamentada por normas que permitam ao engenheiro civil fazer sua aplicação nas estruturas correntes. Com a proposta de viabilizar o uso desse material madeira-concreto esse estudo vem contribuir com um melhor entendimento do comportamento físico da ligação entre os materiais madeira e concreto. O estudo dessa ligação foi realizado quantificando o módulo de deslizamento em corpos-de-prova do tipo push-out, vigas T e tabuleiro de madeira-concreto. Os resultados experimentais do módulo de deslizamento obtidos por esses três tipos de ensaios foram comparados com os resultados obtidos teoricamente pelo Eurocode 5 (1993). Também, no seguinte estudo foi feito uma simulação numérica do tabuleiro de madeira-concreto usando um programa para análise estrutural baseado no Método dos Elementos Finitos (MEF). Na conclusão dessa pesquisa verificou-se que o comportamento estrutural desse material misto pode-ser calculado usando o Eurocode 5 (1993) e o Método dos Elementos Finitos (MEF).
The study of mixed structures is dedicated to the use of timber-concrete material in bridges' structures, more precisely in its tray. However, the application of this material in Brazil is not regulated by standards that allow the civil engineer to make its application in the current structures. With the proposal to make possible the use of this timber-concrete material this study contributes to understand better the physical behavior of the linking between wood and concrete. The study of this connection was carried through quantifying the slip's module in specimens of push-out type, T beams and timber-concrete's tray. The experimental results of the slip's module from these three kinds of tests had been compared with the results obtained theoretically for Eurocode 5 (1993). Also, in the following study it was made a mathematical simulation of the wood-concrete's tray using a numerical analysis' program based on the Finite Elements' Method (MEF). In the conclusion of this research it was verified that the structural behavior of this mixed material can to be calculated using Eurocode 5 (1993) and the Method of the Finite Elements (MEF).
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Bianchi, Lorenzo. "Strenght prediction of the glulam beams based on the information of knots in single lamellas". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18176/.
Texto completoResumen
In this thesis the effect of knots on the structural behaviour in terms of stiffness and strength was studied, in a linear elastic analysis, using Abaqus. Test setups from European standard EN 408 and tests performed in the research centre “Holzforschung München” were modelled, in order to compute mechanical properties and have a qualitative and quantitative estimation of the effect of knots.
The attention was then led to the effect of the adhesive layer on the numerical model, for which there is little available literature. Different types of adhesive were used in the modelling procedure to study their effects on the mechanical behaviour of wood. It is shown that the adhesive effect is generally negligible and failure is occurring in wood. All tests results and simulations are referred to thin layers of adhesive.
The last part of the study focused on the effect of stress concentrations next to knots. The maximum longitudinal stress was used to predict the glulam strength through the correlation between stress from analysis and strength from tests on single boards. The accuracy of results is not high for slightly defected boards, because other different phenomena outer than knots should be taken into account (fiber deviation, microcracks ecc.). However, predictions are relatively good for the boards with knots and not clusters. The objective of this study was finding an estimation of strength starting from a computationally efficient model, in which few input data are required.
Other researches in literature developed tools and models for an accurate analysis of strength, however the required computational resources and input parameters are sensitively increasing.
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Andersson, Isac y Niklas Ek. "Temperature distribution and charring penetrations in timber assemblies exposed to parametric fire curves : Comparisons between tests and TASEF predictions". Thesis, Luleå tekniska universitet, Byggkonstruktion och brand, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-62725.
Texto completoResumen
Four furnace tests have been performed using two different parametric fire curves and the results are compared with computer simulations and Eurocode calculations. What differentiates the parametric fire curve from other fire curves is in particular the cooling phase, something that has proven to be hard to model for timber structures. A literature study and computer simulations were followed by experimental work performed at SP Wood Building Technology in Stockholm. The computer simulations were performed using the computer code TASEF. The predictions from TASEF were compared with measurements from the fire tests to evaluate how well the program can predict temperature distribution using a parametric fire curve. The four fire tests were executed at SP Wood Building Technology, glued laminated timber beams were used in all tests. When preparing the test specimens thermocouples were installed to measure temperature distribution, the thermocouples were installed in drilled holes. A deviation study regarding these drill-holes was performed as a part of the preparations. The temperature distributions measured during the tests were compared with the temperature distribution predicted by TASEF. Charring rate and charring depth were obtained from the fire tests, from the TASEF simulations but also by using equations given in the Eurocode. Since TASEF simulates temperature distribution and not charring depth, the 300 °C isotherm was assumed to represent the charring depth. The results from all three methods were compared and evaluated. The agreement between experiments and TASEF predictions regarding temperature distribution and charring depth were in general very good. Parametric fire curves with opening factors of 0.02 m1/2 and 0.04 m1/2 were used in four fire tests. TASEF performed more accurate predictions regarding the temperature distribution for the small opening factor but looking at the charring depth the predictions were better for the bigger opening factor. It is recommended to perform further studies and find out the reason for this behaviour. Comparing the charring depths measured at the tests with values calculated using Eurocode 5 there were some differences in charring depths. Charring depths for the horizontal direction of the beams were much alike, but when comparing the charring depths for the vertical direction there is a significant difference. The equations regarding charring depth for wood exposed to parametric fire curves in Eurocode 5 underestimate the charring depth. It is recommended to evaluate these equations further. For one of the timber beams delamination occurred, this has previously been assumed not to occur to glued laminated beams. More studies should be performed regarding delamination of glued laminated beams exposed to fire.Fyra brandtester i en brandprovningsugn har genomförts med två olika parametriska brandkurvor och resultatet har jämförts med datorsimuleringar och Eurocode-beräkningar. Det som särskiljer parametriska brandkurvor från andra brandkurvor är nedkylningsfasen, något som har visat sig svårt att modellera för träkonstruktioner. Litteraturstudier och datorsimuleringar följdes av experimentellt arbete som utfördes vid SP Träbyggande och Boende i Stockholm. Datorsimuleringarna har utförts med datorkoden TASEF. Simuleringsresultat från TASEF jämfördes med mätningar från brandtesterna för att utvärdera hur bra TASEF kan förutse temperaturdistributionen då en parametrisk brandkurva används. De fyra brandtesterna förbereddes och utfördes på SP Träbyggande och Boende, limträbalkar användes i samtliga tester. När testbalkarna förbereddes inför brandtesterna installerades termoelement för att mäta temperaturdistributionen. Termoelementen installerades i borrhål. Som en del av förberedelserna gjordes en avvikelsestudie för dessa borrhål. Temperaturdistributionen som uppmättes under testerna jämfördes med temperaturdistributionen från TASEF-simuleringar. Från brandtester, TASEF-simuleringar och från ekvationer i Eurocode erhölls förkolningshastighet och förkolningsdjup. Eftersom TASEF simulerar temperaturer och inte förkolningsdjup användes 300 °C isotermen som då antogs representera förkolningsdjupet. Resultatet från alla tre metoder jämfördes och utvärderades. Generellt stämde temperaturdistributionen och förkolningsdjupen från TASEF-simuleringarna väldigt bra överens med de experimentella resultaten. Under testerna användes parametriska brandkurvor med öppningsfaktorer av 0.02 m1/2 och 0.04 m1/2. TASEF simulerade mer noggranna resultat gällande temperaturdistributionen för kurvan med den lägre öppningsfaktorn medan simuleringar för kurvan med den högre öppningsfaktorn gav bättre resultat för förkolningsdjupet. Det rekommenderas att göra fler studier för att ta reda på anledningen till detta beteende. Genom att jämföra förkolningsdjup som uppmättes efter brandtesterna med beräknade värden från Eurocode förekom vissa skillnader. Förkolningsdjup för bredden av balkarna var likartade, medan förkolningsdjupet för höjden av balkarna hade en signifikant skillnad. Ekvationerna i Eurocode underskattade förkolningsdjupet, det rekommenderas därför att utvärdera dessa ekvationer ytterligare. För en av limträbalkarna inträffade delaminering, detta har tidigare antagits vara osannolikt för limträbalkar. Fler studier borde utföras angående delaminering av limträbalkar exponerade för parametriska brandkurvor.
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Sjödin, Johan. "Strength and Moisture Aspects of Steel Timber Dowel Joints in Glulam Structures : An Experimental and Numerical Study". Doctoral thesis, Växjö universitet, Institutionen för teknik och design, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-2002.
Texto completoResumen
Joints are critical parts of timber structures, transmitting static and dynamic forces between structural members. The ultimate behavior of e.g. a building depends strongly on the structural configuration and the capacity of its joints. The complete collapse of a building or other less extensive accidents that may occur usually start as a local failure inside or in the vicinity of a joint. Such serious failures have recently occurred in the Nordic countries. Especially the collapses of two large glued-laminated timber (glulam) structures clearly indicate the need of an improved joint design. The trend toward larger and more complex structures even further increases the importance of a safer design of the joints. One aim of this partly experimentally and partly numerically based work has been to investigate if the short term capacity of steel-timber dowel joints loaded parallel to the grain is affected by an initial drying exposure. The experimental results showed that the load-bearing capacity of the joints is indeed reduced by such moisture changes. Moisture induced stresses was mentioned to be the explanation. The key point is that the climates chosen in the present work (20°C / 65% RH and 20°C / 20% RH) are equivalent to service class 1 according to EC5 (Eurocode 5 2004). Thus, EC5 predicts no decrease in load-bearing capacity, in relation to the standard climate used during testing. A decrease in load-bearing capacity in the range of 5-20%, which was found in the present work, is of course not negligible and, therefore, there could be a need to introduce the effect of drying in design codes. Because similar results were also observed for a double-tapered glulam beam, further work should consider timber structures in general. Two numerical methods in order to predict the capacity of multiple steel-timber dowel joints loaded parallel to the grain were tested in the thesis. For the first method, where fracture mechanics (LEFM) concepts were implemented, a good correlation with the experimental results was seen. Also for the second method, where the capacity for a single dowel-type joint as given in EC5 was used as a failure criterion, a good correlation to traditional EC5 calculations of multiple dowel-type joints was seen. One advantage of using numerical methods in design is that the capacity of the joint can be calculated also for cases when the dowels are placed in more complex patterns. From both a structural and an architectural point of view this can be very important. In addition, such numerical methods are effective tools for the structural engineer when considering complicated loading situations in joints, i.e. eccentric loading giving moments in the joint.
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Moraes, Victor Marcuz de. "Ponte mista de madeira-concreto em vigas treliçadas de madeira /". Ilha Solteira : [s.n.], 2007. http://hdl.handle.net/11449/91472.
Texto completoResumen
Orientador: José Antônio MatthiesenBanca: José Luiz Pinheiro Melges
Banca: Antonio Alves Dias
Resumo: As pontes mistas com vigas de madeira e tabuleiro de concreto, que constituem uma técnica já bastante estudada pelo meio acadêmico brasileiro, vêm ganhando cada vez mais espaço entre os projetistas e construtores de pontes em estradas vicinais do interior do Brasil. Entretanto, o vão dessas pontes é limitado pelo comprimento das peças de madeira, cujos valores máximos, em geral, ficam em torno de 6 metros para vigas serradas e 12 metros para vigas roliças. Neste contexto, a presente pesquisa propõe um novo sistema estrutural de pontes mistas para vencer vãos da ordem de 15 a 20 metros, constituído por vigas treliçadas de madeira que suportam a laje de concreto armado. O tabuleiro do sistema proposto pode ser executado utilizando, como pré-laje, painéis treliçados pré-moldados auto-portantes, evitando-se escoramentos e, conseqüentemente, reduzindo o tempo e os custos de construção. A laje final é solidarizada às treliças de madeira por intermédio de pinos metálicos de cisalhamento, que fazem com que ambos os materiais trabalhem solidariamente na resistência aos esforços solicitantes, buscando, portanto, a otimização do uso estrutural desses materiais. A principal abordagem desta pesquisa é experimental, com a construção e análise de um modelo físico reduzido na escala 1:4... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Timber-concrete composite structures - TCCS - constitute a technique well studied by the Brazilian academy and have been each time more present among the designers and constructors of bridges in secondary roads in the interior of Brazil. However, the span of these bridges is limited by the length of the timber beams, whose maximum values, in general, are around 6 meters for sawed beams and 12 meters for round beams. In this context, the present research suggests a new structural system of composite bridges, to overcome spans from 15 to 20 meters, built by trussed timber beams that support a reinforced concrete deck. The deck of the system can be executed using precast self-supported trussed panels, preventing props and, consequently, reducing time and costs of construction. The final slab is connected to the trussed beams by metallic shear bolts, which make that both the materials (timber and concrete) work together in the resistance to the requesting efforts, aiming the optimization of the structural use of these materials. This research was based on an experimental approach, with the construction and analysis of a reduced physical model in the scale 1:4, based on a bridge design classified as 30t with a free span of 16 meters. The model was instrumented with strain gauges and... (Complete abstract click electronic access below)
Mestre
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Lehmann, Martin [Verfasser], Karl [Akademischer Betreuer] Rautenstrauch, Parviz [Gutachter] Navi y Jan-Willem van de [Gutachter] Kuilen. "Investigations of the Loadbearing Behaviour of Timber Bending Beams Reinforced Using Prestressed CFRP-Lamellas / Martin Lehmann ; Gutachter: Parviz Navi, Jan-Willem van de Kuilen ; Betreuer: Karl Rautenstrauch". Weimar : Professur Holz- und Mauerwerksbau, 2015. http://d-nb.info/1116366657/34.
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Alves, Nívea Mara Pereira. "Análise de pontes de madeira protendidas transversalmente formadas por vigas-T". Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-11082016-164531/.
Texto completoResumen
Neste trabalho é estudada uma variação do sistema estrutural de ponte de madeira com tabuleiro laminado protendido, em que a seção transversal é formada por vigas-T. As nervuras destas vigas são de madeira laminada colada e o tabuleiro de madeira serrada. São analisadas pontes da classe 30, com uma ou duas faixas de tráfego, dimensionando-se os elementos estruturais para diversas situações de projeto, e avaliando-se as influências das espécies e classes de resistência das madeiras e dos fatores geométricos (largura da nervura, altura do tabuleiro e espaçamento entre nervuras) na altura das nervuras. O procedimento de cálculo utilizado no dimensionamento das pontes de madeira formadas por vigas-T baseia-se no método WVU. Para o desenvolvimento deste trabalho, o método foi adaptado aos critérios da Associação Brasileira de Normas Técnicas, \"NBR 7188/84 - Cargas móveis em pontes rodoviárias e passarelas de pedestres\" e \"NBR 7190/97 - Projeto de estruturas de madeira\", e programado em software MATHCAD©. Os resultados obtidos indicam que não existe influência significativa na altura da nervura, ao se utilizar madeira da classe C 30 ou C 40 no tabuleiro, ou ao se variar a altura do tabuleiro de 15 até 25 cm. O modelo teórico é avaliado experimentalmente, por meio de modelo reduzido na escala geométrica de 1:5, obtendo-se boa concordância entre os valores experimentais e os teóricos.In this work it is studied a variation of the structural system of timber bridge with transversely laminated deck, in which the transversal section is composed of T-beams. The stringers of those beams are made of glued laminated timber and the deck of sawed timber. Bridges of class 30 are analyzed, with one or two traffic lanes, where the structural elements are designed for different project situations, and evaluated the influences of specimens and wood classes and geometric factors (width of stringer, depth of deck and spacing of stringers) in the depth of stringers. The calculus procedure used in the design of the timber bridges composed of T-beams is based on the WVU Method. To the development of this work, the method was adapted to the criteria of the Brazilian standards \"NBR 7188/84 - Live Loads in Highway Bridges and Pedestrian Bridges\" and \"NBR 7190/97 - Project of Timber Structures\" and programmed in MATHCAD© software. The results obtained show that there is no significant influence in the depth of stringer, either by using wood class C 30 or C 40, or by varying the height of the deck from 15 to 25 cm. The theoretical model is evaluated experimentally, by means of a reduced model at 1:5 geometric scale, being obtained well agreement between experimental and theoretical values.
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Alcântara, Segundinho Pedro Gutemberg de. "Análise teórico-experimental de um tabuleiro misto madeira-concreto composto por vigas circulares /". Ilha Solteira : [s.n.], 2005. http://hdl.handle.net/11449/91482.
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Orientador: José Antônio MatthiesenBanca: Renato Bertolino Junior
Banca: Antonio Alves Dias
Resumo: O estudo em estruturas mistas é dedicado ao emprego do material madeira-concreto em estruturas de pontes, mais precisamente no seu tabuleiro. No entanto, a aplicação desse material no Brasil não está regulamentada por normas que permitam ao engenheiro civil fazer sua aplicação nas estruturas correntes. Com a proposta de viabilizar o uso desse material madeira-concreto esse estudo vem contribuir com um melhor entendimento do comportamento físico da ligação entre os materiais madeira e concreto. O estudo dessa ligação foi realizado quantificando o módulo de deslizamento em corpos-de-prova do tipo "push-out", vigas T e tabuleiro de madeira-concreto. Os resultados experimentais do módulo de deslizamento obtidos por esses três tipos de ensaios foram comparados com os resultados obtidos teoricamente pelo Eurocode 5 (1993). Também, no seguinte estudo foi feito uma simulação numérica do tabuleiro de madeira-concreto usando um programa para análise estrutural baseado no Método dos Elementos Finitos (MEF). Na conclusão dessa pesquisa verificou-se que o comportamento estrutural desse material misto pode-ser calculado usando o Eurocode 5 (1993) e o Método dos Elementos Finitos (MEF).
Abstract: The study of mixed structures is dedicated to the use of timber-concrete material in bridges' structures, more precisely in its tray. However, the application of this material in Brazil is not regulated by standards that allow the civil engineer to make its application in the current structures. With the proposal to make possible the use of this timber-concrete material this study contributes to understand better the physical behavior of the linking between wood and concrete. The study of this connection was carried through quantifying the slip's module in specimens of "push-out" type, T beams and timber-concrete's tray. The experimental results of the slip's module from these three kinds of tests had been compared with the results obtained theoretically for Eurocode 5 (1993). Also, in the following study it was made a mathematical simulation of the wood-concrete's tray using a numerical analysis' program based on the Finite Elements' Method (MEF). In the conclusion of this research it was verified that the structural behavior of this mixed material can to be calculated using Eurocode 5 (1993) and the Method of the Finite Elements (MEF).
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Adolfs, Daniel Veiga. "Análise de confiabilidade de peças de madeira fletidas dimensionadas segundo a NBR 7190/97". Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-06022012-081149/.
Texto completoResumen
A passagem do método das tensões admissíveis para o método dos estados limites na NBR 7190 - Projeto de Estruturas de Madeira, ocorrida em 1997, foi feita por meio de calibração determinística que teve como ponto central a resistência da madeira na compressão paralela às fibras. Um dos aspectos modificados foi o dimensionamento de peças fletidas no tocante à verificação das tensões normais devidas ao momento fletor, em que é utilizada a resistência à compressão paralela às fibras. Com a intenção de averiguar o grau de segurança do modelo de cálculo para esse caso, foram realizadas análises de confiabilidade para vigas fletidas de madeira. Foram coletados dados de 549 testes de flexão de vigas, obtendo-se valores relativos à ruptura, e também foram obtidas informações estatísticas a respeito como a média e o desvio-padrão da resistência à compressão paralela às fibras, das mesmas espécies usadas nas vigas. Nas análises de confiabilidade foram utilizadas 5 variáveis aleatórias, com 5 tipos de combinações diferentes, analisadas com e sem erro de modelo para cada um dos 16 grupos de resultados levantados, totalizando 2752 análises de confiabilidade. Os resultados das análises sem o erro de modelo mostram que a norma não atinge valores suficientes para o índice de confiabilidade e que, com a introdução do erro de modelo, os resultados são mais adequados. Também se verificou que o modelo adotado pela norma é muito conservador, no caso de peças de madeira de Pinus SP classificadas.The transition of allowable stress to limit state design methods in \"NBR 7190 - Projeto de Estruturas de Madeira\", in 1997, was made considering the strength in compression parallel to the grain as central point of deterministic calibration. One of the aspects modified was the design of beams, related to tension and compression; in this case is used the strength in compression. A reliability analysis was made for timber beams to determine the security level of the theoretical model. Were collected data related to failure from 549 bending tests in beams, and statistical information about the mean and standard deviation of the strength in compression of the wood species used in the beams. In reliability analysis were used 5 random variables, with 5 different types of combinations, analyzed with and without model error for each of the 16 groups of results collected, resulting 2752 reliability analysis. The results of the analysis without the model error show that the standard doesnt achieve sufficient values for the reliability index and, with the introduction of model error, the results are more adequate. It was also verified that the theoretical model is very conservative in the case of graded members of Pine species.
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Moraes, Victor Marcuz de [UNESP]. "Ponte mista de madeira-concreto em vigas treliçadas de madeira". Universidade Estadual Paulista (UNESP), 2007. http://hdl.handle.net/11449/91472.
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moraes_vm_me_ilha_prot.pdf: 4456756 bytes, checksum: 70a028ea28db2cfaed1abecec234c525 (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
As pontes mistas com vigas de madeira e tabuleiro de concreto, que constituem uma técnica já bastante estudada pelo meio acadêmico brasileiro, vêm ganhando cada vez mais espaço entre os projetistas e construtores de pontes em estradas vicinais do interior do Brasil. Entretanto, o vão dessas pontes é limitado pelo comprimento das peças de madeira, cujos valores máximos, em geral, ficam em torno de 6 metros para vigas serradas e 12 metros para vigas roliças. Neste contexto, a presente pesquisa propõe um novo sistema estrutural de pontes mistas para vencer vãos da ordem de 15 a 20 metros, constituído por vigas treliçadas de madeira que suportam a laje de concreto armado. O tabuleiro do sistema proposto pode ser executado utilizando, como pré-laje, painéis treliçados pré-moldados auto-portantes, evitando-se escoramentos e, conseqüentemente, reduzindo o tempo e os custos de construção. A laje final é solidarizada às treliças de madeira por intermédio de pinos metálicos de cisalhamento, que fazem com que ambos os materiais trabalhem solidariamente na resistência aos esforços solicitantes, buscando, portanto, a otimização do uso estrutural desses materiais. A principal abordagem desta pesquisa é experimental, com a construção e análise de um modelo físico reduzido na escala 1:4...
Timber-concrete composite structures - TCCS - constitute a technique well studied by the Brazilian academy and have been each time more present among the designers and constructors of bridges in secondary roads in the interior of Brazil. However, the span of these bridges is limited by the length of the timber beams, whose maximum values, in general, are around 6 meters for sawed beams and 12 meters for round beams. In this context, the present research suggests a new structural system of composite bridges, to overcome spans from 15 to 20 meters, built by trussed timber beams that support a reinforced concrete deck. The deck of the system can be executed using precast self-supported trussed panels, preventing props and, consequently, reducing time and costs of construction. The final slab is connected to the trussed beams by metallic shear bolts, which make that both the materials (timber and concrete) work together in the resistance to the requesting efforts, aiming the optimization of the structural use of these materials. This research was based on an experimental approach, with the construction and analysis of a reduced physical model in the scale 1:4, based on a bridge design classified as 30t with a free span of 16 meters. The model was instrumented with strain gauges and... (Complete abstract click electronic access below)
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Stamato, Guilherme Corrêa. "Ligações em estruturas de madeira compostas por chapas de madeira compensada". Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-03062016-100611/.
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As estruturas de madeira composta com alma em compensado já vem sendo amplamente utilizadas em diversos países onde as estruturas de madeira estão tecnologicamente mais desenvolvidas, oferecendo aos engenheiros civis mais uma opção de sistema construtivo eficiente, seguro e duradouro. Nesse trabalho são apresentados estudos teóricos e experimentais referentes às estruturas de madeira compostas utilizando compensado nas almas, e em especial as estruturas cuja ligação alma mesa é feita por pinos metálicos. O objetivo desse trabalho é desenvolver critérios de dimensionamento dessas estruturas para serem aplicados no Brasil. Vários critérios de dimensionamento de elementos compostos foram encontrados na bibliografia, alguns com simplificações que desconsideram efeitos de composição parcial e outros mais completos, que consideram deformações por cisalhamento, composição parcial etc. Com os resultados dos ensaios de vigas compostas pregadas foi possível comparar valores experimentais com resultados teóricos, concluiu-se que os critérios de dimensionamento do EUROCODE 5 são adequados. Os ensaios de rigidez de nó de pórtico de seção composta permitiram o desenvolvimento de metodologia para o cálculo da rigidez dessas ligações, visto que não existe formulação equivalente na bibliografia internacional. Concluiu-se que as ligações por pinos metálicos apresentam boa eficiência para serem utilizadas nas seções compostas com alma em compensado. As ligações de nó de pórtico com ligação alma/mesa pregadas podem ser consideradas rígidas na maioria dos casos estudados.Plywood webbed structures have been applied in at several countries where timber structures are commonly used, giving civil engineers and builders one more option when looking for a safe, efficient and durable construction system. This work presents theoretical and experimental studies about plywood-webbed structures, with emphasis on nailed plywood webbed structures. The aim of this work is to develop design criteria for these structures to be used in Brazil. Several design criteria where found in the bibliography, some of them using simplifications for shear deflexions and joint deformations. Experimental results of nailed plywood webbed beams were compared with theoretical values from formulations found in the bibliography, concluding that EUROCODE 5 gives the best design criteria for nailed composite beams. Based on plywood webbed knee joints tests, a methodology to calculate the joint rigidity was proposed. The conclusions show the efficiency of this system and that nailed plywood webbed knee joints can be considered fixed for the majority of the specimens tested.
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Karagiannis, Vasileios. "Behaviour of hybrid timber-steel beam-to-column connections". Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/59187.
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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.
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Kavaliauskas, Saulius. "Behaviour of timber-concrete composite beam interconnection with inclined screws". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20100317_151205-00517.
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The dissertation investigates the behaviour of timber-concrete connections with inclined screws – the load carrying capacity and deformability. The essen¬tial objects of investigation are the load carrying capacity of inclined screws; the modules of connection slip deformation, and the mechanical properties of mate¬rials and ware of which the connection is made. The load-carrying capacity of the connection depends on the properties of the material of connected member and the connectors, on which depends the strength and stiffness of the composite member. The main aim of dissertation is to create the connection load carrying capacity predicting model, based on the more realistic behaviour of the material of connected members; to prepare the simplified approach for load-carrying capacity predicting model for composite timber-concrete connections within at any angle in respect to timber grain in¬clined crews. The paper approaches a few major tasks such as the choice of suitable load-carrying capacity predicting base model; preparing it to composite timber-con¬crete connections with inclined screws; the experimental investigation of con¬nection with inclined screws under long- and short term loading; the experi¬mental investigation of properties of connected materials and type of used con¬nectors; the evaluation of created predictive model based on results also of other researchers experimental investigations.Disertacijoje nagrinėjama kompozitinės medinės-betoninės jungties su įžambiai šlyties plokštumai orientuotais medsraigčiais elgsena – laikomoji galia ir deformacinės savybės. Pagrindiniai tyrimų objektai yra įžambiai medienos pluoštui orientuotų medsraigčių laikomoji galia, slinkties deformacijų moduliai ir mechaninės jungtį sudarančių elementų savybės, veikiančios jungties elgseną. Nuo medsraigčio ašies posvyrio kampo, deformacinių po medsraigčiu glemžiamos ir ištraukiamos medienos ir lenkiamo medsraigčio savybių priklauso ir jungties irties pobūdis, laikomoji galia ir slinkties deformacijų moduliai, o nuo pastarųjų – kompozitinio elemento stiprumas ir standumas. Pagrindinis disertacijos tikslas yra sukurti skaičiavimo modelį tokių jungčių laikomajai galiai nuspėti, kuo tiksliau atsižvelgiant į medžiagų ir elementų mechanines savybes; pateikti supaprastintą skaičiuojamąjį modelį, skirtą bet kokiu kampu medienos pluošto atžvilgiu įsriegtų medsraigčių laikomajai galiai nuspėti. Darbe sprendžiami keli pagrindiniai uždaviniai: tinkamo pamatinio jungties laikomąją galią vertinančio skaičiuojamojo modelio parinkimas, jo pritaikymas įžambiai medienos pluoštui orientuotiems medsraigčiams; trumpalaikis ir ilgalaikis eksperimentinis įžambinės medsraigtinės jungties laikomosios galios tyrimas ir vertinimas; kitų autorių eksperimentinių rezultatų vertinimas sukurtajam jungties laikomąją galią vertinančiam modeliui pagrįsti.
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Scaliante, Ricardo de Mello. "Pontes em vigas e tabuleiros em painéis de madeira laminada colada (MLC)". Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-27042015-094721/.
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O Brasil, um país de dimensões continentais e inúmeros rios em seu território, tem uma enorme carência de pontes para pequenos e médios vãos. Atualmente, a elevada produção de madeira de reflorestamento traz à engenharia uma opção de material renovável e ecologicamente correto para se utilizar em prol do ser humano nas obras de infraestrutura, mais especificamente na construção de pontes, uma vez que a madeira possui ótimo desempenho quando sujeita a cargas de curta duração. A utilização de Madeira Laminada Colada (MLC) permite a fabricação de peças de grandes dimensões, com excelente estabilidade, e com elevado controle de qualidade, proporcionando segurança e confiabilidade à estrutura. Este trabalho tem como objetivo o estudo teórico de pontes em vigas de MLC e tabuleiros em painéis de MLC utilizando procedimentos desenvolvidos por pesquisadores internacionalmente renomados e adequando estes procedimentos para as normas e condições brasileiras. Apresentam-se neste trabalho tabelas para pré-dimensionamento deste tipo de ponte para vãos de 8m a 20m para TB-30 e TB-45. Além disso, analisam-se numérica e experimentalmente os ganhos de rigidez e redução de deslocamentos relativos proporcionados pela utilização de vigas de enrijecimento, bem como a influência da seção destas vigas e a quantidade de parafusos utilizados para interligar ao tabuleiro. Por fim, apresentam-se algumas disposições construtivas não estruturais fundamentais para o bom funcionamento deste tipo de estrutura.Brazil, a continental size country and with many rivers in its territory, has a huge necessity for short and medium spans bridges. Nowadays, the high production of reforestation wood allows to engineering an option of renewable material and ecologically correct to be used in favor to humans in infrastructure works, most specifically in bridges construction, once timber has a great performance in quick loads. The use of Glued-Laminated Timber (Glulam) enable the manufacture of large sizes members, with excellent stability, and a high control of quality in its production, providing a safety and reliability structure. This work aim the theoretical study of glulam stringers bridge and glulam panels deck using procedures developed by international researchers and adapting those procedures for Brazilian conditions and normalizations. Pre-design tables are presented in this work for 8m to 20m spans for TB-30 and TB-45. In addition to, analyses numerical and experimentally the gain of stiffness and the reduction of relative displacements between panels provided by the use of stiffener beams, besides the influence of those beams section size and number of bolts used for deck interconnection. Finally, it is presented some not structural constructive arrangements essential for good performance of this kind of structure.
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Fernandes, Felipi Pablo Damasceno. "Análise numérica de vigas mistas de madeira e concreto em situação de incêndio". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-18062018-120514/.
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As vigas mistas de madeira e concreto são formadas pela união de vigas de madeira a lajes de concreto armado por meio de conectores de cisalhamento. Quando os pisos mistos de madeira e concreto são comparados aos pisos construídos unicamente em madeira ou àqueles confeccionados somente em concreto armado é possível destacar algumas vantagens, incluindo o bom desempenho em situações de incêndio. Os elementos estruturais quando submetidos a ações térmicas sofrem redução de resistência e rigidez, sendo, desta forma, necessário conhecer as modificações sofridas por cada um de seus componentes, que para o caso estudado são: a madeira, o concreto e os conectores de cisalhamento. Desta forma, foi elaborada uma estratégia de modelagem numérica para o estudo de vigas mistas de madeira e concreto em situação de incêndio, utilizando o programa computacional ABAQUS, o qual é baseado no método dos elementos finitos. Em uma primeira etapa da pesquisa foram realizadas modelagens numéricas de vigas de madeira e mistas de madeira e concreto em temperatura ambiente, encontrando-se boa correlação entre as curvas força versus deslocamento no meio do vão obtida numericamente e por meio de ensaios disponíveis na literatura. Em seguida procedeu-se a calibração das propriedades térmicas e mecânicas da madeira brasileira, alcançando-se resultados numéricos próximos aos experimentais, seja em relação às temperaturas do elemento analisado seja em relação à curva de deslocamento vertical em função do tempo de incêndio. Por fim, a estratégia de modelagem termoestrutural desenvolvida para a viga mista de madeira e concreto forneceu curva de deslocamento vertical em função do tempo de incêndio semelhante à curva obtida por meio de modelo analítico disponível na literatura. Por meio do modelo elaborado foi possível observar que a elevação do nível de carregamento reduz o tempo de resistência do elemento estrutural e que a proteção térmica do concreto é essencial para aumentar o tempo até a ruptura da viga.Timber-concrete composite beams are formed by the union of timber beams to reinforced concrete slabs through of shear connectors. When timber-concrete composite floors are compared to timber floors or reinforced concrete floors it is possible to highlight some advantages, including good performance in fire situations. When subjected to thermal actions, structural elements suffer strength and stiffness reductions, being, therefore, necessary to know the modifications suffered by each of its components, which for the case studied are: timber, concrete and shear connectors. Thus, it is developed a numerical modeling strategy using the computational program ABAQUS, which is based on the finite element method, for the study of timber-concrete composite beams in fire situation. In the first stage of the research it was carried out a numerical modeling of timber beam and timber-concrete composite beam at room temperature, finding good correlation between the force versus displacement curves in the middle of the span obtained numerically and through tests available in the literature. Then, it was carried out the calibration of the thermal and mechanical properties of the Brazilian wood, reaching numerical results close to the experimental ones, either in relation to the temperatures of the analyzed element or in relation to the vertical displacement curve as a function of the fire time. Finally, the thermo-structural modeling strategy developed for the timber-concrete composite beam provided a vertical displacement curve as a function of the fire time similar to the curve obtained through an analytical model available in the literature. Through of the elaborated model it was possible to observe that the load level increase reduces the resistance fire time of the structural element and that the thermal protection of the concrete is essential to increase the rupture time of the beam.
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Viau, Christian. "Investigation and Optimization of Connections in Timber Assemblies Subjected to Blast Loading". Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40405.
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The majority of research on high strain-rate effects in timber structures has been limited to the study of the load-bearing members in isolation. Limited work has been conducted on timber connections and full-scale timber assemblies under blast loading, and these have generally been constrained to qualitative observations. In North America, the increasing prevalence of mid- and high-rise timber structures makes them susceptible to blast effects. In addition, questions remain on how to design and optimize these timber assemblies, including the connections, against blast loads, due in part to the limitations on comprehensive design provisions.
The effects of far-field blast explosions were simulated using the University of Ottawa shock tube. A total of fifty-eight dynamic tests were conducted on connection-level and full-scale specimens. The research program aimed to investigate the behaviour of heavy-timber connections when subjected to simulated blast loads. The experimental results showed that connections with a main failure mechanism consisting of wood crushing experienced significant increases in dynamic peak load when compared to the static peak load. In contrast, connections where steel yielding and rupturing occurred experienced no statistically significant increase in dynamic peak load. Full-scale glulam specimens with bolted connections designed to yield via wood crushing and bolt bending performed better than those with overdesigned connections. Bolted connections which failed in splitting led to premature failure of the glulam assembly. Reinforcement with self-tapping screws allowed these bolted joints to fail in a combination of bolt yielding and wood crushing, and provided more ductility when compared to unreinforced specimens. Specially designed energy-absorbing connections significantly increased the energy dissipation capabilities of the timber assemblies. The basis of these connections was to allow for connection yielding while delaying failure of the wood member. This was achieved via elastoplastic connection behaviour, which effectively limited the load imparted onto the wood member. Based on the experimental results, limitations in the current Canadian blast provisions were highlighted and discussed. A two-degree-of-freedom blast analysis software was developed and validated using full-scale and connection-level experimental results and was found to adequately capture the system response with reasonable accuracy. Sensitivity analyses regarding the applicability of using single-degree-of-freedom analysis were presented and discussed.
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MATSUDA, HYLTON. "Monitoracao do feixe externo do ciclotron cyclone 30 do IPEN-CNEN/SP". reponame:Repositório Institucional do IPEN, 2002. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10995.
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Made available in DSpace on 2014-10-09T12:46:40Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T13:58:16Z (GMT). No. of bitstreams: 1 07535.pdf: 5658873 bytes, checksum: bfc9a035eb51ae184a489a4570c8c827 (MD5)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Mmari, Winston. "Modeling of nailed timber connection : Displacement path dependency in sheathing-to-framing connections". Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-66956.
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Connections in wood have been investigated and advanced ever since the ground-breaking work of Johansen in the early nineteenth century. Nevertheless, not much investigation has been undertaken on the existence of load-displacement path dependency in a sheathing-to-framing connection. Herein, a sheathing-to-framing connection is investigated in relation to displacement path dependency. This work uses 3D Finite Element beam-on-foundation models of an Oriented Strand Board (OSB/2) sheathing nailed to a C24 wood framing, to study possible strategies to numerically simulate the displacement path dependency. The models are used to study if non-linear elastic or elastic-plastic embedment properties of an annular-ringed shank nail in the wood-based materials bring about the path dependency using Connector elements in combination with different material models in the FE software Abaqus. Numerical results are compared with corresponding experimental test results of the connection together with the Eurocode 5 approach. The outcome of the numerical study both; confirms the existence of displacement path dependency and shows that this property in the connection can be described by plasticity properties in nail, sheathing material and the wood framing.
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Matuška, Martin. "Dřevěná nosná konstrukce víceúčelové haly". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226078.
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This Master’s thesis is focused on the design and structural analysis of load-bearing structure of a multipurpose hall that is strained by the permanent load, working load and climatic load. The hall has the shape of an elliptical dome. Maximum margin of the structure is 60,0m and maximum height is 18,0m. Main carrier elements of the structure are radially arranged curved beams made of glued laminated timber, class SA(GL24).
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Thajudeen, Shamnath. "Supporting the design phase of industrialised house building using a product platform approach : A case study of a timber based post and beam building system". Licentiate thesis, Jönköping University, JTH, Konstruktion och produktutveckling, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-48266.
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In recent years, industrialised house building has gained shares on the Swedish house building market. The market demands for industrialised house building are exceeding the available supply of housing and experiencing a substantial increase in the housing production costs. For industrialised house building, the design has been identified as a critical phase with the systematization of the design a necessary part of industrialisation. Therefore, companies strive towards the inclusion of standardization and controlled processes in the design phase. Product platforms have proved to be related to the standardization of processes and products. Introducing a product platform approach in the design phase of house building could be a way to improve the design and ensure value creation in entire processes. Thus, the aim of this research is to outline means to support and improve the design phase of industrialised house building by using a product platform approach. A Swedish multi-storey house building company that uses glulam post and beam building system with a focus on platform development was used as the single case study in this research. The company intends to achieve increased efficiency by moving towards industrialized approaches. Empirical data were mainly gathered from interviews, observations, workshops, and document analysis. The findings present the existing challenges in the housing building industry and outlines twenty critical success factors that need to be considered in the design phase. Also, the result outlines support methods and tools that can be used for the improvement of the design phase when applying a product platform approach. Moreover, a flexible product platform can be developed with the support of parametric modelling and used to design building components having an engineer-to-order characteristic. Finally, the results show that a building system can be considered as part of a product platform in light of the necessity of an adequate support in the design process to maintain a sustainable platform. Thus, the contribution includes the addition of knowledge to platform theory in general and its application on the design phase of industrialised house building.Under de senaste åren har det industriella husbyggandet tagit andelar på den svenska husbyggnadsmarknaden. Behovet av bostäder på marknaden överstiger tillgången och med ökning av bostadsproduktionskostnaderna som konsekvens. För det industriella husbyggandet har projekteringen identifierats som en avgörande fas och dess systematisering är en nödvändig för industrialiseringen. Som en följd strävar företag i segmentet efter att inkludera standardisering och kontrollerade processer i projekteringen. Produktplattformar har kunnat kopplas till standardisering av processer och produkter. Införandet av produktplattformar i projekteringen kan vara ett sätt att förbättra designen och säkra värdeskapandet igenom hela processen. Således är syftet i denna avhandling att ta fram medel för att stödja och förbättra projekteringen för industriellt husbyggande genom att tillämpa en ansats med produktplattformar. Ett svenskt byggnadsföretag med flera våningar som använder limträ- och balksystem med fokus på plattformsutveckling användes som en enda fallstudie i denna forskning. En fallstudie har genomförts på ett företag som bygger flervåningshus med ett pelar-balksystem i limträ med fokus på plattformsutveckling. Företaget har ambitionen att nå högre effektivitet genom att röra sig mot ett mer industriellt tillvägagångssätt. Data samlades in från intervjuer, observationer, workshops och dokumentanalyser. Resultaten visar vilka de befintliga utmaningarna är för husbyggandet och presenterar tjugo kritiska framgångsfaktorer som ska beaktas i projekteringen. Studien har även tagit fram supportmetoder och verktyg som kan användas för att förbättra projekteringen vid tillämpning av produktplattformar. Vidare, en flexibel produktplattform kan utvecklas med stöd av parametrisk modellering och användas för att projektera byggnads-komponenter med engineer-to-orderegenskaper. Slutligen, resultaten pekar mot att ett byggsystem kan betraktas som en del av en produktplattform ur perspektivet att tillräckligt med stöd i projekteringen krävs för att underhålla en hållbar plattform. Således, arbetet har bidragit med kunskap till teori om plattformar i allmänhet och dess tillämpning på projekteringen för industriellt husbyggande.
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Allahverdiyev, Rovshan. "Effects of beam configuration on dynamic properties and seismic performances of multi-storey frame building models". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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The present study aims at comparing the dynamic properties and seismic performances offered by reinforced concrete frame structures characterised by different beams distribution.
Multi-storey regular frame buildings are considered as reference structures. Different models are then developed according to various layout of the beams (x-direction is the longitudinal direction, whilst y-direction is the transversal one): (1) beams placed along the x-direction at the odd storeys and placed along the y-direction at the even storeys; (2) beams placed along the y-direction at the odd storeys and placed along the x-direction at the even storeys; (3) and (4) alternating beams every two storeys; (5) beams placed along the x-direction at all storeys; (6) beams placed along the y-direction at all storeys; (7) complete three-dimensional frame with beams placed along both the x- and the y-direction at all storeys. In all models, smaller perimeter beams are placed along the direction orthogonal to the one of the main beams.
Modal analysis has been conducted to evaluate the influence of beams distribution on the period of vibration. Response spectrum and time-history dynamic analyses have been carried out to assess the effects of beams distribution on the base shear and base bending moments, top-storey displacements, interstorey displacements and floor accelerations.
On the contrary of what could be expected, the results indicate that structures with beams alternating every storey do not behave unfavorably with respect to the complete three-dimensional frames. In more detail, two effects may be clearly recognized: one associated to the period and one associated to the static scheme. The former acting basically on the base shear; the latter acting mainly on the base bending moment. The understanding of the influence of beams distribution on frame structures is useful when dealing with seismic vulnerability assessment of existing buildings and design of new buildings.
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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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Řihák, Pavel. "Stavebně technologický projekt pavlačového domu v České Třebové". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227435.
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The thesis is focused on building and technological project balcony house in the Czech Třebové. The project contains all the essentials of building technology project that can be used for project implementation in practice. Instead of a plot is real and if the city Czech Třebová allow this construction, will be implemented by this work.
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Hinkle, Stephen Dock. "Investigation of Time-Dependent Deflection in Long Span, High Strength, Prestressed Concrete Bridge Beams". Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/34740.
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Accurate camber prediction in prestressed concrete bridge beams is important to all parties involved in bridge design and construction. Many current prestress loss prediction methods, necessary for proper camber calculation, were developed many years ago and are predicated on assumptions that may no longer be valid as higher strength concrete, wider beam spacing, and longer span lengths become more commonplace. This throws into question which models are appropriate for use in camber calculation by the bridge engineers and contractors of today.
Twenty-seven high-strength concrete modified 79 in. Bulb Tee beams with a design compressive strength of 9,000 psi were periodically measured to determine camber growth. Most available models for concrete creep and shrinkage were used to calculate creep and shrinkage strain. The modulus of elasticity equation of each model was used to predict modulus of elasticity of the studied mix. The Shams and Kahn compressive strength and modulus of elasticity equations were modified in order to approximate measured modulus of elasticity. The creep, shrinkage, and modulus of elasticity equations were used as inputs to an incremental time step method. The time-dependent change in beam curvature calculated by the time step method was used to calculate theoretical camber using the Moment-Area method. Predicted camber, using inputs from each considered model, was then compared with measured camber to determine the most accurate camber prediction models. Season of casting was also examined to determine what, if any, affect ambient temperature has on camber growth.
For the studied beams, the Shams and Kahn Model for creep, shrinkage, and modulus of elasticity, used as inputs for an incremental time step analysis, were found to most accurately predict camber values. Lower concrete compressive strength was observed for test cylinders from beams cast in summer versus beams cast in winter. Differences in beam deflection based on season of casting showed mixed results.Master of Science
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Slavíková, Michaela. "Rekreační jezdecké středisko". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240107.
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This final thesis projects an areal of riding center with four objects. The first one is complex of stabels ,the second one is riding hall, , and the last two area family house and litte apartment for accomodation of employeers and visiters. For objects one and two is complete documentation, the other ones are processed as a studie. All the buildings are designed as a timber structure, the ridding hall is created by glue laminated timber girders.
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Redgrave, Giles David. "Spin spectroscopy of YbF using molecular beam interferometry". Thesis, University of Sussex, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285125.
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Kubášková, Barbora. "Horský hotel v Beskydech". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226642.
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This thesis solves design of timber structure of mountain hotel in Beskydy. The hotel is two-storey building with residential attic and no cellar. The ground plan of the building is about 15x26 m and height of the building is 14,76 m. The type of roof timbers was chosen from two options. There was used structural timber of the strength class C24, glued laminated timber of the strength class GL24 and steel S235. Program Scia Engineer was used for the static analysis of the structure. There was made only linear calculation.
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Quintana, James R. A. "Frequency Responsive Beam Tracing". Oberlin College Honors Theses / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=oberlin1462957979.
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Baingo, Darek. "A Framework for Stochastic Finite Element Analysis of Reinforced Concrete Beams Affected by Reinforcement Corrosion". Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23063.
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Corrosion of reinforcing bars is the major cause of deterioration of reinforced concrete (RC) structures in North America, Europe, the Middle East, and many coastal regions around the world. This deterioration leads to a loss of serviceability and functionality and ultimately affects the structural safety. The objective of this research is to formulate and implement a general stochastic finite element analysis (SFEA) framework for the time-dependent reliability analysis of RC beams with corroding flexural reinforcement. The framework is based on the integration of nonlinear finite element and reliability analyses through an iterative response surface methodology (RSM). Corrosion-induced damage is modelled through the combined effects of gradual loss of the cross-sectional area of the steel reinforcement and the reduction bond between steel and concrete for increasing levels of corrosion. Uncertainties in corrosion rate, material properties, and imposed actions are modelled as random variables. Effective implementation of the framework is achieved by the coupling of commercial finite element and reliability software. Application of the software is demonstrated through a case study of a simply-supported RC girder with tension reinforcement subjected to the effects of uniform (general) corrosion, in which two limit states are considered: (i) a deflection serviceability limit state and (ii) flexural strength ultimate limit state. The results of the case study show that general corrosion leads to a very significant decrease in the reliability of the RC beam both in terms of flexural strength and maximum deflections. The loss of strength and serviceability was shown to be predominantly caused by the loss of bond strength, whereas the gradual reduction of the cross-sectional area of tension reinforcement was found to be insignificant. The load-deflection response is also significantly affected by the deterioration of bond strength (flexural strength and stiffness). The probability of failure at the end of service life, due to the effects of uniform corrosion-induced degradation, is observed to be approximately an order of magnitude higher than in the absence of corrosion. Furthermore, the results suggest that flexural resistance of corroded RC beams is controlled by the anchorage (bond) of the bars and not by the yielding of fully bonded tensile reinforcement at failure. This is significant since the end regions can be severely corroded due to chloride, moisture, and oxygen access at connections and expansion joints. The research strongly suggests that bond damage must be considered in the assessment of the time-dependent reliability of RC beams subjected to general corrosion.
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Janoušek, Martin. "Vícepodlažní budova". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227818.
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This master's thesis deals with design of the timber structure four-storey building. Plan dimensions of the hall are 20 x 30 m. The structure is designed for the Třebíč. The structure is designed as a heavy timber frame. The axial distance of arches is 5 m. The timber structure is placed between the reinforced concrete towers.
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Mu, Xiangkui. "Clinical application of intensity and energy modulated radiotherapy with photon and electron beams". Doctoral thesis, Umeå : Strålningsvetenskaper, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-443.
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Gurkšnys, Kęstutis. "Kompozitinių medienos-betono sijų ir jungių kūrimas ir bandymai". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2006. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2006~D_20060306_092600-78837.
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Recently more and more buildings of light structures have been built in Lithuania as well as in other European and world countries. Nevertheless, timber products are not widely used for floors in this share of construction market. Traditional light timber frame floors are characterized by vibrations, acoustic transmission and low fire resistance. The above-mentioned problems can be rationally solved by using timber-concrete composite (hereinafter TCC) floors. In comparison with entirely timber floors such type of floors are characterised not only by increased strength and stiffness but also by increased fire resistance and better sound insulation. In comparison with reinforced concrete floors manufactured of non-regenerative sources TCC floors are lighter and more economic. These characteristics stimulate usage of TCC floors in newly built buildings. It should also be noted that usage of timber in building structures instead of concrete or steel could substantially decrease energy demand and emission of carbon dioxide during production.
In this work author presents TCC structural solution when thin-webbed beams (I-joists) used for timber floor beams instead of solid or glued rectangular beams. Thin-webbed beams are without upper flange of structural timber. Embedding in concrete a part of web of oriented strand board (hereinafter OSB) connects the OSB web and the concrete slab.
This concept allows to save structural materials and production costs. Nevertheless, not so many... [to full text]