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1
Skinner, Jonathan. "Thin topping timber-concrete composite floors". Thesis, University of Bath, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.606665.
Testo completoAbstract (sommario):
A timber-concrete composite (TCC) combines timber and concrete, utilising the complementary properties of each material. The composite is designed in such a way that the timber resists combined tension and bending, whilst the concrete resists combined compression and bending. This construction technique can be used either in new build construction, or in refurbishment, for upgrading existing timber structures. Its use is most prolific in continental Europe, Australasia, and the United States of America but has yet to be widely used in the United Kingdom. To date, the topping upgrades used have been 40mm thick or greater. Depending on the choice of shear connection, this can lead to a four-fold increase in strength and stiffness of the floor. However, in many practical refurbishment situations, such a large increase in stiffness is not required, therefore a thinner topping can suffice. The overarching aim of this study has been to develop a thin (20mm) topping timber-concrete composite upgrade with a view to improving the serviceability performance of existing timber floors. Particular emphasis was given to developing an understanding of how the upgrade changes the stiffness and transient vibration response of a timber floor. Initially, an analytical study was carried out to define an appropriate topping thickness. An experimental testing programme was then completed to: characterise suitable shear connectors under static and cyclic loads, assess the benefit of the upgrade to the short-term bending performance of panels and floors, and evaluate the influence of the upgrade on the transient vibration response of a floor. For refurbishing timber floors, a 20mm thick topping sufficiently increased the bending stiffness and improved the transient vibration response. The stiffness of the screw connectors was influenced by the thickness of the topping and the inclination of the screws. During the short-term bending tests, the gamma method provided a non-conservative prediction of composite bending stiffness. In the majority of cases the modal frequencies of the floors tested increased after upgrade, whilst the damping ratios decreased. The upgrade system was shown to be robust as cracking of the topping did not influence the short-term bending performance of panels. Thin topping TCC upgrades offer a practical and effective solution to building practitioners, for improving the serviceability performance of existing timber floors.
2
Skaare, Mathilde Korvald. "Vibrations in Composite Timber-Concrete Floor Systems". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23327.
Testo completoAbstract (sommario):
Timber-concrete composite structures were originally developed for bridges and strengthening existing timber floors, but is today used extensively also in new buildings. The objective of this thesis was to look at the dynamic behavior of a timber-concrete composite system, where the concrete deck consisted of several prefabricated elements glued together. The shear connector used was a glued-in steel mesh, which had shown strong capacity in previous studies. The concrete was fibre reinforced concrete.A full-scale model was built in the laboratory, and the following tests were performed: A dynamic test (hammer impact test) and a deflection test with 1 kN load. In addition a direct shear test was performed on two asymmetrical specimen to find the stiffness of the shear connector. The fibre reinforced concrete was tested separately to find its characteristic properties. There was also made a numerical model in ABAQUS, to estimate the behavior of the composite beam.The hammer impact test showed that the composite beam satisfied the dynamic requirements sat for the beam. The shear connector proved to be weaker and more ductile than expected. It was discovered this was due to insufficient gluing during the assembly. The numerical analyses done in combination with the empirical tests proved to give good estimates on the behavior of the composite beam. The stiffness of the shear connector proved to be more decisive of the deflection of the beam than the frequency. Expanding the beam to a full-size floor in ABAQUS indicated that the composite beam gave smaller values for the frequency than what would be the case for a full floor. The overall performance of the timber-concrete composite system tested in this thesis was good. However, some adjustments should be made and more research has to be done, before developing this into a new floor system.
3
Churchill, C. E. "Direct and flanking transmission across timber concrete composite floors with cross laminated timber walls". Thesis, University of Liverpool, 2018. http://livrepository.liverpool.ac.uk/3021424/.
Testo completoAbstract (sommario):
Timber-concrete composite (HBV) floors are widely manufactured by many construction companies. Cross laminated timber (CLT) elements are an effective way to produce more homogenised timber building elements. In this thesis, the applicability of measurement-based prediction methods to calculate the apparent sound reduction index (R’) for these two types of elements was investigated. A prediction model using Statistical Energy Analysis (SEA) was developed and validated to calculate the airborne sound transmission of a HBV floor. There was additional complexity in modelling this floor system compared with other SEA models found in the literature therefore two types of model were compared. To determine the stiffness of the floor it was proposed that bending stiffness predicted using the theories of Huffington and Troitsky provide a more suitable and flexible approach than that of Kimura and Inoue. All SEA models predicted a weighted sound reduction index to within 2.0dB of the measurements. For CLT plates, an accurate measure of the elastic moduli was sought to determine direct sound transmission. A low-frequency stiffness can be determined by modal measurement and optimisation of the material constants (≤ 100Hz a thin plate model is adequate). At mid to high frequencies (>300Hz) sound transmission of CLT was predicted using a frequency-dependant modulus determined from directly measuring the bending wavespeed. Elastic moduli were extracted from wavespeed data (the Young’s modulus was measured to be approximately 50% less stiff than the low-frequency stiffness) and in the y-direction the value of the shear modulus Gyz determined that a thick plate model should be applied in this direction. Finite Element Method (FEM) models of CLT plates and junctions using the elastic moduli determined using the methods described above were validated using measurements of freely and simply supported plates and three simple junctions (L-junction, rotated L-junction and T-junction). The contribution of residual modes (higher than the frequency range of interest) to the calculated point mobility was assessed. The transition to thick plate theory occurs within the frequency range of interest (100-5000Hz). This resulted in a modal density which increases with frequency and some implications of this are discussed. The best agreement between FEM model and measured data was obtained for the simplest (unrotated) L-junction. Finally, measurement based prediction methods to assess the flanking performance of CLT combined with the HBV floor were investigated. Agreement was obtained between the structure-borne and airborne methodologies if a correction factor, which accounts both for the thick plate properties of the CLT and the fit of measured results to the HBV model, was used. The Df path was the strongest transmission path and the most accurately predicted and hence it was possible to predict the apparent sound reduction index (R’) by summing the paths.
4
O'Neill, James William. "The Fire Performance of Timber-Concrete Composite Floors". Thesis, University of Canterbury. Civil and Natural Resources, 2009. http://hdl.handle.net/10092/3912.
Testo completoAbstract (sommario):
Timber-concrete composite floors are a combination of timber joists and concrete topping, creating a flooring system to best utilise the advantages each material has to offer. Timber is used as the main tensile load bearing material due to its high strength-to-weight ratio, while concrete is used in floor slabs for its advantages in stiffness and acoustic separation. The strength of the system is dependent on the connection between timber and concrete, thus the connection must be strong, stiff, and economical to manufacture, to ensure that the flooring system is economically viable.
This research investigated the fire performance and failure behaviour of timber-concrete composite floor systems currently under development in New Zealand, resulting in a calculation method for evaluating the fire resistance of these floors. Furnace tests were performed on two full-size floor specimens at the Building Research Association of New Zealand (BRANZ). Both floor specimens were 4 m long and 3 m wide, consisting of 65 mm concrete topping on plywood formwork, connected to double LVL floor joists. They were tested over a 4 m span, subjected to a nominal design live load of 2.5 kPa. Both floors were subjected to the ISO 834 test fire for over 60 minutes. Two separate connection types were tested; concrete notches cut into the timber beams with an incorporated shear key, and metal toothed plates pressed between the double beams.
It was found that the reduction in section size of the timber beams due to the fire governed the failure mode of the floors. Due to the composite action achieved by the connections, the floor units were able to withstand prolonged exposure to the test fire, well exceeding one hour. The test data and visual observations aided in the development of a numerical model for evaluating the fire resistance of the floors. This was developed in a spreadsheet that is able to predict the expected fire resistance of these floors, taking into account some major time dependent variable properties that can have an effect on the overall performance. Load-span tables have been produced to give the estimated fire resistance of floors with differing floor dimensions, span lengths and applied loads.
5
Hong, Kwan Eui Marcel. "Structural performance of nail-laminated timber-concrete composite floors". Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62710.
Testo completoAbstract (sommario):
Nail-laminated timber-concrete composite (TCC) is a system composed of a nail-laminated timber (NLT) panel connected to a concrete slab through shear connections. When used as flexural elements such as floors, the concrete and NLT are located in the compression and tension zones, respectively. NLT panels, being constructed out of inexpensive lumber planks nailed on their sides, offer an economical advantage in mass-timber constructions that complement the structural and building physics advantages of TCC. However, the performance of nail-laminated TCC as well as efficient shear connectors for this system have not been investigated.
This thesis presents the experimental study conducted on the performance of TCC panels constructed out of NLT, mechanical fasteners, and cast-in-place concrete. First, nine different sizes of truss-plates and two configurations of self-tapping screws installed in small-scale TCC specimens were tested under shear load. The connections’ strength and stiffness were determined to evaluate its performance as TCC shear connectors. Second, four truss-plate configurations were selected for implementation in full-scale TCC panels. Two panels for each shear connection systems were tested under impact loading and a quasi-static monotonic loading to determine the vibration bending properties, respectively. Panel specifications and layouts of the connectors were designed based on the established γ-method. The test results show that nail-laminated TCC panels reached slightly higher fundamental natural frequency and elastic bending stiffness than predicted. Furthermore, failure did not occur until loading reached 5 to 7 times the serviceability requirements. The selected truss-plates shear connection demonstrated to be an efficient solution for nail-laminated TCC panels.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
6
Inniss, Clifton F. "Analytical and experimental modelling of timber-concrete composite beams". Thesis, University of Surrey, 1994. http://epubs.surrey.ac.uk/842780/.
Testo completoAbstract (sommario):
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.
7
Yeoh, David Eng Chuan. "Behaviour and Design of Timber-Concrete Composite Floor System". Thesis, University of Canterbury. Department of Civil and Natural Resources, 2010. http://hdl.handle.net/10092/4428.
Testo completoAbstract (sommario):
This Ph.D. thesis represents a summative report detailing research processes and outcomes from investigating the ultimate and serviceability limit state short- and long-term behaviour and design of timber-concrete composite floors. The project enables the realization of a semi-prefabricated LVL-concrete composite floor system of up to 15 m long using 3 types of connection. Design span tables which satisfy the ultimate and serviceability limit state short- and long-term verifications for this system form the novel contribution of this thesis.
In quantifying the behaviour of timber-concrete composite floors, 5 different experimental phases have been carried. 9 major achievements in meeting 9 sub-objectives have been concluded:
1) Three best types of connection system for timber-concrete composite floors have been identified;
2) The characteristic strength and secant slip moduli for these connections have been determined;
3) The short-term behaviour of the selected connections defined by their pre- and post-peak responses under collapse load has been established;
4) An analytical model for the strength evaluation of the selected connections based on the different possible modes of failure has been derived;
5) Easy and fast erected semi-prefabricated timber-concrete composite floor has been proposed;
6) The short-term ultimate and serviceability limit state behaviour of timber-concrete composite floor beams under collapse load has been investigated;
7) The long-term behaviour of chosen connections defined by their creep coefficient has been determined;
8) The long-term behaviour of timber-concrete composite floor beams under sustained load at serviceability limit state condition has been investigated; and
9) Design example and span tables for semi-prefabricated timber-concrete composite floors that satisfy both the ultimate and serviceability limit state in the short- and long-term using the gamma-method have been developed.
8
Ribbenstedt, Marcus, e Nick Salvati. "Simulation driven design of timber bolster in fibre composite". Thesis, KTH, Lättkonstruktioner, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-203367.
Testo completoAbstract (sommario):
The primary objective of this thesis is to investigate a simulation and optimisation based methodology using fibre composite materials to lower the weight of timber bolsters. The timber bolsters secure the timber from falling off the truck during loading and transport. A lighter forestry truck is beneficial for several reasons such as increased payload and fuel efficiency and a decreased environmental impact. This thesis includes a concept study for a bolster made of fibre composites. Carbon and glass fibres together with polyurethane were chosen as material system and the recommended manufacturing methods were pultrusion and resin transfer moulding. A study of the economy related to the timber transport was conducted during the concept phase to investigate the potential business case. The thesis also includes an optimisation of the generated concept. The optimisation focused on geometry and fibre layup. By the use of optimisation the weight was reduced from the initial 136 kg of aluminium to 87 kg of glass and carbon fibre. The optimised design was compared with today’s aluminium bolsters and indicated that the composite bolster is realistic from an economic perspective. A methodology for analysing bolted joints in fibre composites was developed. The analysis was made using the finite element method and resulted in a comparison between different failure criteria. Based on the results it can be concluded that the prediction of failure differs significantly depending on used failure criterion and tests are needed for verification. Finally a simulation was made to verify the structures response to an impact. The simulation was compared with calculations using energy equations showing a fairly good agreement.Det huvudsakliga syftet med detta examensarbete var att använda metodik baserad på simulering och optimering samt fiberkompositmaterial för att minska vikten på timmerbankar. Timmerbankar används för att lastsäkra timmer på lastbilar under lastning och transport. En lättare lastbil är fördelaktig av flera anledningar som t.ex. ökad kapacitet för nyttolast och bränsleeffektivitet samt en minskad miljöpåverkan. Examensarbetet inkluderar en konceptstudie för en timmerbanke i fiberkomposit. Kolfiber och glasfiber tillsammans med polyuretan valdes som material. Pultrusion och resin transfer moulding rekommenderades som tillverkningsmetoder. En studie av ekonomin relaterad till timmertransport genomfördes under konceptstudien för att undersöka om konceptet har potential att vara ekonomiskt gångbart. Examensarbetet innehåller även en optimering av det genererade konceptet. Optimeringen fokuserade på geometri samt kompositlaminatets fiberriktningar och stackningsordning. Genom användning av optimering minskades vikten på banken från dagens 136 kg i aluminium till 87 kg med glas och kolfiber. Den optimerade banken jämfördes med en existerande aluminiumbanke ur ett ekonomiskt perspektiv och slutsatsen är att med de givna antagandena har den optimerade konstruktionen större ekonomisk potential. En metod för att analysera skruvförband i komposit utvecklades och olika brottkriterier har undersökts. Analysen genomfördes med finita elementmetoden och resulterade i en jämförelse mellan olika brottkriterier. Baserat på resultaten kan det konstateras att prediktering av brott påverkas avsevärt av använt brottkriterium och att verifierande provning behövs. Slutligen genomfördes en simulering för att verifiera strukturens respons vid en slag last. Simuleringen jämfördes med beräkningar baserade på energiekvationer och på påvisade skaplig överenstämmelse.
9
Cameron, Tony Ray. "Alaskan timber resources for wood-plastic composites". Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Summer2009/t_cameron_070209.pdf.
Testo completoAbstract (sommario):
Thesis (M.S. in civil engineering)--Washington State University, August 2009.Title from PDF title page (viewed on Aug. 12, 2009). "Department of Civil and Environmental Engineering." Includes bibliographical references.
10
Mohamed, Ahmed S. "Photogrammetric and stereo vision techniques for evaluating material properties in timber and timber-based composite structures". Thesis, Edinburgh Napier University, 2016. http://researchrepository.napier.ac.uk/Output/462281.
Testo completoAbstract (sommario):
A fundamental requirement for efficient use of a glulam beam is an accurate knowledge of its mechanical behaviour and the material properties characterising that behaviour. It becomes extremely important to obtain accurate measurements of material properties ofglulam, but this can be challengeable, especially for commonly used properties, such as the modulus of elasticity and shear modulus. Experiment testing is the way to determine elastic properties, however, the problem of experimentally determining appropriatevalues of these properties for timber-based composite is not as simple and straightforward as in isotropic materials, and care must be taken in the experimental methods used in determining their values. There is a need to develop an appropriate method in order to evaluate these properties. Unlike the traditional methods in whichcontact devices such as inclinometers or linear variable differential transducers are used to identify the material properties of glulam by utilizing their measurements of displacements and rotations at specific points, the optical methods provide an efficient and accurate approach for measuring these properties at multi-location so that more regions of interest can be monitored simultaneously without contact. Moreover, the traditional devices are limited to give measurements in one or two dimensions whereas the optical methods can be used to gain measurements in three dimensions. Although the optical techniques were successfully applied to different structural applications, little work has been done on the area of evaluating material properties of timber, especially modulus of elasticity and shear modulus. Therefore, the primary motivation of this project will be allocated to evaluate those properties utilizing the stereo vision approach. This thesis describes the research work in which a stereo camera system combined with a photogrammetric approach was proposed to evaluate material properties of timber and timber-based composite joists. A series of experiments were conducted to investigate the applicability of the approach to evaluate different material properties of glulam beams under different types of tests, including the torsion and the compression. Remarkable findings were obtained which might help for developing an outline for a future research programme in the field of evaluating material properties of glulam, allowing investigating the relationship between these properties. The results also showed that the optical system not only allowed assessing performance and reliabilityof the traditional sensors, but also allowed monitoring the deformation of the samples at various locations by providing more information which would not be possible to obtain using the traditional techniques.
11
Gerber, Adam Reynold. "Timber-concrete composite connectors in flat-plate engineered wood products". Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57860.
Testo completoAbstract (sommario):
Timber-Concrete Composite (TCC) systems are comprised of a timber element connected to a concrete slab through a mechanical shear connection. When TCC are used as flexural elements, the concrete and timber are located in compression and tension zones, respectively. A large number of precedents for T-beam configurations exist; however, the growing availability of flat plate engineered wood products (EWPs) in North America in combination with a concrete topping has offered designers and engineers greater versatility in terms of architectural expression and structural and building physics performance. The focus of this investigation was to experimentally determine the properties for a range of proprietary, open source, and novel TCC systems in several Canadian EWPs. Strength and stiffness properties were determined for 45 different TCC configurations based on over 300 small-scale shear tests. Nine connector configurations were selected for implementation in full-scale bending and vibration tests. Eighteen floor panels were tested for elastic stiffness under a quasi-static loading protocol and measurements of the dynamic properties were obtained prior to loading to failure. The tests confirmed that both hand calculations according to the γ-method and more detailed FEM models can predict the basic stiffness and dynamic properties of TCC floors within a reasonable degree of accuracy; floor capacities were more difficult to predict, however, failure did usually not occur until loading reached 10 times serviceability requirements. The research demonstrated that all selected connector configurations produced efficient timber-concrete-composite systems.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
12
Weight, Shilo Willis. "A novel wood-strand composite laminate using small-diameter timber". Online access for everyone, 2007. http://www.dissertations.wsu.edu/Thesis/Spring2007/s_weight_050207.pdf.
Testo completo
13
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.
Testo completoAbstract (sommario):
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.
14
Jiao, Shuai. "Development of an Innovative Composite Mullion Made of Aluminium and Timber". Thesis, Griffith University, 2021. http://hdl.handle.net/10072/401641.
Testo completoAbstract (sommario):
The façade, as the envelope of a building, provides essential functions such as structural resistance against wind loading, thermal insulation and weather independence. The aluminium-glass curtain wall façade system has become a popular alternative for high-rise buildings due to its aesthetic appeal and efficient unitised installation. In a unitised glass curtain wall façade system, the vertical structural frame, named mullion, is the dominate wind load-bearing element but the critical thermal bridging element. Extruded aluminium mullions have been popularly used due to their high strength to weight ratios, high corrosion resistance and extrudability to allow the façade frames light, durable and flexibly unitised. However, the aluminium mullions might not be so good as some mullions in other aspects, e.g., in thermal performance, aesthetics and sustainability. To address these issues, several attempts to improve their performance, including introducing thermal breaks or structural timber, and hiding the exposed aluminium extrusions, were proposed and evaluated in recent decades. However, none of them could solve all the drawbacks of aluminium mullions. This thesis proposes an innovative aluminium-timber composite mullion, which is durable, unitised, structurally sound, energy-efficient, aesthetically pleasing and sustainable, and aims at its structural and thermal behaviours.
In the structural investigation, three series of experimental tests were firstly conducted to investigate and evaluate the structural behaviour of the novel composite mullions: material property tests, connection tests, and four-point bending tests. Material property tests were done to obtain the mechanical properties of aluminium and timber used in the novel composite mullions. Four types of aluminium-timber connections were subjected to shear loading in the connection tests. The results showed that the proposed adhesive bond formed the optimum connection between aluminium and timber. After determining the connection type, a series of four-point bending tests were conducted using a back-to-back restrained test set-up under both positive and negative loading cases. Furthermore, the traditional aluminium mullions were also tested for comparison. The aluminium mullions failed in local buckling under negative loading, while the composite mullions failed due to plywood compressive yielding and aluminium flange local buckling. Moreover, distortional buckling was observed during aluminium mullion tests subjected to positive loading, while the composite mullions failed due to parallel to the grain tensile failure in the plywood flanges. It was found that the composite mullion had greater structural performance subjected to bending.
Then, a numerical study using finite element models was conducted to further investigate the bending behaviour of the composite mullion based on the experimental results. Two types of finite element models, experimental models and ideal models, were used and validated with the experimental tests. Parametric studies were also performed using validated ideal models to develop the design rules of the composite mullions. The finite element analysis results were then compared with two current design methods: limiting stress method (LSM) and total moment capacity approach (TMCA). It was found that the LSM was too conservative and that the TMCA was only accurate under positive loading with a mean ratio of 1.07 and a COV of 3% for male mullions, 1.09 and 3% for female mullions. Hence, this thesis proposes a modified TMCA using an elastic-plastic approach under negative loading to improve its accuracy. The modified TMCA to predict the negative loading case reached an adequate accuracy with a mean ratio of 0.99 and a COV of 3% for male mullions, and a mean ratio of 1.00 and a COV of 3% for female mullions.
This thesis also evaluates and compares the thermal performance of this novel composite mullion with several current aluminium mullions. It showed that the composite mullion had a much greater thermal performance than the traditional mullion with an improvement of 52%, though it was less energy-efficient than thermally broken aluminium mullion. Furthermore, it was found that the thermal conductance of the composite mullion could be further reduced by four proposed energy-efficient strategies. The optimal combination could reach a reduction of 69% compared with the initial design of the innovative composite mullion. Moreover, a generic study was also performed to investigate the influence of various parameters on the thermal conductance of the composite mullions. The results and evaluation are detailed in this thesis.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Eng & Built Env
Science, Environment, Engineering and Technology
Full Text
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Voth, Christopher Ray. "Lightweight sandwich panels using small-diameter timber wood-strands and recycled newsprint cores". Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Fall2009/c_voth_120609.pdf.
Testo completoAbstract (sommario):
Thesis (M.S. in civil engineering)--Washington State University, December 2009.Title from PDF title page (viewed on Jan. 26, 2010). "Department of Civil and Environmental Engineering." Includes bibliographical references.
16
Custodio, Joao Eduardo Pereira. "Performance and Durability of Composite Repair and Reinforcement Systems for Timber Structures". Thesis, Oxford Brookes University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520921.
Testo completo
17
Alling, Joseph. "Timber vs. composite/plastic pile fender systems in Pearl Harbor maintenance cost comparison". Thesis, Monterey, California. Naval Postgraduate School, 1996. http://hdl.handle.net/10945/9075.
Testo completoAbstract (sommario):
CIVINSThe Navy has traditionally used treated timber materials for fender systems for piers and wharves in Pearl Harbor. In recent years, the costs associated with the use of timber have escalated and the Navy has begun to use plastic piles at installations around the world to replace timber fender systems. Plastic fender systems are more expensive, but have greater energy absorption capabilities and are more resilient to environmental decay. To determine whether plastic piles are a cost saving alternative to treated timber, the present study compiled and evaluated existing technical data, maintenance/ construction records and inspection reports from various Navy staff civil engineer offices and at the Navy Public Works Center Pearl Harbor (PWC). Since records at these various locations were not designed to present associated cost/ maintenance data in a format suitable for an economic analysis, field surveys of over 3 miles of waterfront in Pearl Harbor and interviews with staff civil engineers and wharf building branch managers at PWC were conducted to supplement existing historical data. Through the gathered data, the maintenance costs of timber pile fenders are estimated and compared to those of composite plastic piles using manufacturers' quotes and from reports compiled by the Navy Civil Engineering Laboratory (NCEL). For the expected life cycles of timber piles observed in Pearl Harbor this analysis shows the proposed plastic system to be more cost effective for shore facilities with remaining service lives of greater than ten years
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Schiro, Gianni. "Timber composite solutions for high performance new diaphragms and structural rehabilitation of existing floors". Doctoral thesis, Università degli studi di Trento, 2018. https://hdl.handle.net/11572/368559.
Testo completoAbstract (sommario):
The main aim of this research work was to deepen the understanding of the mechanical behaviour of timber-to-timber composite (TTC) floors with incomplete interaction in order to develop, design and test high performance solutions. Several types and arrangements of connections and different timber products, made from both softwood and hardwood species, were considered for the realisation of diaphragms suitable for a wide range of structural applications. An original assembly procedure, developed at the University of Trento, was adopted in the optimization process of these technical solutions. Such innovative procedure allows the designers to pre-stress and camber composite timber elements by simply relying on screw type connectors. The experimental tests presented in this thesis positively contributed to the calibration and validation of this assembly technique, confirming the method applicability. The test results were consistent with the numerical and analytical models, in terms of uplifts, stress levels and overall mechanical performance. The benefits from adopting the above-mentioned procedure appeared to be persistent over time, as the result of an experimental test where four composite specimens, 5.4 m long, were loaded out-of-plane and subjected to continuous monitoring under controlled environmental conditions for a period of two years. The research program was organized into two phases. The first phase was dedicated to the study of alternative strategies for retrofit interventions on timber diaphragms in historical heritage buildings. An extensive experimental campaign on the out-of-plane behaviour of the retrofitted diaphragms was performed in order to evaluate the effectiveness of the different techniques analysed. Specifically, hybrid solutions that coupled the reduced weight of softwood elements with the strength of hardwood components by means of different types of fasteners, were compared with “more common†timber-to-timber strengthening techniques. A large number of tests, covering fourteen configurations obtained by changing fasteners type, fastener arrangement and timber products, were performed to maximize the performance (cost/effectiveness) of the retrofit techniques. Test outcomes included characterization of stiffness, strength, static ductility and residual strength of the connection systems as well. The second phase of the program was devoted to the development of solutions for newly constructed diaphragms, either for new building applications or replacement of damaged/inadequate existing floors. The second phase research work included the design and testing of prefabricated timber-to-timber composite floor modules to be assembled by using laminated veneer lumber (LVL) made of beech wood. Full scale tests were performed on 6 m long and 10 m long modules, respectively designed for residential areas and offices. In addition to the full-scale testing of the modules, the connection system optimization was performed by referring to different types of test protocols, including both push-out and pull-out testing.
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Schiro, Gianni. "Timber composite solutions for high performance new diaphragms and structural rehabilitation of existing floors". Doctoral thesis, University of Trento, 2018. http://eprints-phd.biblio.unitn.it/3028/1/PhD_Thesis.pdf.
Testo completoAbstract (sommario):
The main aim of this research work was to deepen the understanding of the mechanical behaviour of timber-to-timber composite (TTC) floors with incomplete interaction in order to develop, design and test high performance solutions. Several types and arrangements of connections and different timber products, made from both softwood and hardwood species, were considered for the realisation of diaphragms suitable for a wide range of structural applications. An original assembly procedure, developed at the University of Trento, was adopted in the optimization process of these technical solutions. Such innovative procedure allows the designers to pre-stress and camber composite timber elements by simply relying on screw type connectors. The experimental tests presented in this thesis positively contributed to the calibration and validation of this assembly technique, confirming the method applicability. The test results were consistent with the numerical and analytical models, in terms of uplifts, stress levels and overall mechanical performance. The benefits from adopting the above-mentioned procedure appeared to be persistent over time, as the result of an experimental test where four composite specimens, 5.4 m long, were loaded out-of-plane and subjected to continuous monitoring under controlled environmental conditions for a period of two years. The research program was organized into two phases. The first phase was dedicated to the study of alternative strategies for retrofit interventions on timber diaphragms in historical heritage buildings. An extensive experimental campaign on the out-of-plane behaviour of the retrofitted diaphragms was performed in order to evaluate the effectiveness of the different techniques analysed. Specifically, hybrid solutions that coupled the reduced weight of softwood elements with the strength of hardwood components by means of different types of fasteners, were compared with “more common” timber-to-timber strengthening techniques. A large number of tests, covering fourteen configurations obtained by changing fasteners type, fastener arrangement and timber products, were performed to maximize the performance (cost/effectiveness) of the retrofit techniques. Test outcomes included characterization of stiffness, strength, static ductility and residual strength of the connection systems as well. The second phase of the program was devoted to the development of solutions for newly constructed diaphragms, either for new building applications or replacement of damaged/inadequate existing floors. The second phase research work included the design and testing of prefabricated timber-to-timber composite floor modules to be assembled by using laminated veneer lumber (LVL) made of beech wood. Full scale tests were performed on 6 m long and 10 m long modules, respectively designed for residential areas and offices. In addition to the full-scale testing of the modules, the connection system optimization was performed by referring to different types of test protocols, including both push-out and pull-out testing.
20
Wahlers, John Colin. "A study of the extrusion of particulate cellulosic composite materials". Thesis, Brunel University, 1988. http://bura.brunel.ac.uk/handle/2438/7868.
Testo completoAbstract (sommario):
Traditional routes to the manufacture of timber based composite materials such as particleboard rely on platen pressing a premix of carefully chosen and prepared timber particles and an adhesive to produce flat sheets. Historically such routes have made very inefficient use of forest resources, and because of the planar nature of the composite produced, the finished articles have enjoyed a reputation of being of poor quality and "cheap". The work documented in this thesis sought to examine alternatives to the traditional manufacturing methods in terms of both raw materials and processing route, and to establish technical, economic, and environmental boundaries for the use of the alternatives. Having settled upon extrusion as the most likely technique with which to proceed, the investigation was carried forward by the construction of a series of experimental instruments with the joint aims of refining the technique to a realistic working level and investigating the underlying mechanical principles behind the process. Recourse to the literature of polymer rheology, fluid mechanics, and soil mechanics gave the basis for a crude mechanism hypothesis, and iterative improvements in the instrumental techniques yielded data with which this could be refined. Although some correlation between the extrusion behaviour of this system with other more easily quantifiable systems was found, there is still considerable work required in defining the dynamic changes in the material properties as the raw material is extruded. Small scale production experiments proved successful, however, and an elementary financial model of a suitable production facility indicated that the techniques developed could be used as the basis of an environmentally acceptable, economically viable, low technology industry.
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Persaud, Richard Yajuvendra. "The structural behaviour of a composite timber and concrete floor system incorporating steel decking as permanent formwork". Thesis, University of Cambridge, 2008. https://www.repository.cam.ac.uk/handle/1810/252081.
Testo completo
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Atashipour, Seyed Rasoul. "Structural Analysis of Deep Composite Box-Type Components with application to a proprietary stabilising timber wall element". Doctoral thesis, Luleå tekniska universitet, Byggkonstruktion och -produktion, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17337.
Testo completoAbstract (sommario):
The stabilising wall element of the Trä8-system is a deep box-type beam/column element which is made of different types of timber composites including framing members of gluedlaminated timber (glulam) and sheathings of laminated veneer lumber (LVL). This element is used as a ―shear wall‖ in multi-storey buildings up to four storeys. To be able to optimise thecomposite stabilising element and use its maximum potential and efficiency, it is necessary to have sufficient fundamental knowledge and information about the structural behaviour and influences of different mechanical properties and geometrical parameters and dimensions of the sub-elements.In this thesis, structural analysis and design principles of the Trä8 stabilising wall element are discussed, including the early stage of erection during assembly to the final usage and residence. A list of required fundamental basic analyses are presented, including accurate deflection analysis for the serviceability limit state, local pre- and post-buckling of the LVL sheathings, global buckling as well as the lateral-torsional buckling of the stabilising element in different design situations. This thesis is then focused on deformations and local instability. For each type of structural problem, accurate, but simple and general methodology is employed to incorporate a large number of effective geometric and property parameters. In this way, a fast evaluation of the influence of different parameters is possible for a wide range of values without needing several time-consuming 3-D finite element (FE) simulations. In several cases, the accuracy and validity of the obtained solutions and formulae are examined and confirmed by comparing their results to those based on the 3-D FE simulations. First, different composite beam theories including shear effects are employed for deflection analysis of the stabilising timber element. Next, an accurate energy-based methodology isdeveloped rendering an explicit formula that gives accurate predictions for the deflection of the stabilising element within a medium range of sheathing or web thicknesses and/or stiffnesses. For weak shear webs, however, this model is not sufficient. Therefore, another new model based on the partial composite interaction theory is developed for accurate deflection predictions of the element having weak shear webs. This model contains simple but accurate formulae for deflection analysis of any similar composite box-type of element with an arbitrary range of geometry and property parameters.Next, shear buckling of the rectangular LVL-panel between the framing members are analysed using differential quadrature (DQ) numerical technique as well as an explicit analytical solution and a formula is established for accurate and fast prediction of the shear pre-buckling of the LVL. This study is extended by considering the effect of each individual lamina of the LVL as well as general orthotropic material properties using a laminated theoryand the DQ solution approach. Further, the post-buckling of the LVL panel is studied based on a simple analytical method with rotating stress fields together with the accurate 3-D FE simulations. A simple formula is then proposed for accurate prediction of the shear post-buckling resistance of the LVL-panel in the stabilising element. As a result of the thesis concerning the two main focus areas, deformations and local instability, explicit analytical formulae are presented for the design of the box-type stabilisingelement with respect to deflections including shear effects in the serviceability limit state and with respect to local shear buckling of the sheathings of the stabilising element including the post-critical area in the ultimate limit state.Godkänd; 2016; 20160217 (rasata); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Seyed Rasoul Atashipour Ämne: Träbyggnad/Timber Structures Avhandling: Structural Analysis of Deep Composite Box-Type Components With Application to a Proprietary Stabilising Timber Wall Element Opponent: Professor Per Johan Gustafsson, Avd för byggnadsmekanik, Lunds tekniska högskola, Lunds universitet, Lund. Ordförande: Professor Ulf Arne Girhammar, Avd för byggkonstruktion- och produktion, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet, Luleå Tid: Fredag 18 mars, 2016 kl 10.00 Plats: F1031, Luleå tekniska universitet
23
Mohammadianfar, Omid, e 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.
Testo completoAbstract (sommario):
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.
24
Carvalho, Ricardo Fernandes. ""Compósitos de fibras de sisal para uso em reforço de estruturas de madeira"". Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-10062005-184350/.
Testo completoAbstract (sommario):
O reforço em estruturas de madeira é necessário em vários edifícios com interesse cultural e histórico. Compósitos com fibra têm sido utilizados no reforço de elementos estruturais de madeira. Carbono e fibras de vidro são as fibras mais usadas como reforço. Porém, fibras naturais são uma importante alternativa considerando as seguintes vantagens: abundância, biodegradabilidade e o baixo custo comparadas com as fibras de vidro ou fibras de carbono. As fibras têxteis e os fios de sisal foram caracterizados por ensaios de tração. Um novo tecido de sisal industrializado foi desenvolvido com base nos tecidos usados em compósitos estruturais com o objetivo de melhorar o alinhamento das fibras e reduzir as deformações transversais. Ensaios de tração foram utilizados para avaliar os compósitos de sisal com matrizes epóxi e poliuretanas derivadas do óleo de mamona. Os ensaios de flexão e cisalhamento foram utilizados para avaliar a resistência e a rigidez. Também foram analisadas as interfaces entre a madeira e os compósitos e avaliados os modos de ruptura. Os resultados mostraram que os compósitos de epóxi e sisal são suficientemente rígidos e resistentes para reforçar estruturas de madeira.Many buildings of cultural and historical interest require reinforcement of their timber structures. This research focuses on fiber-reinforced composites to repair and reinforce such structural elements of wood as an alternative for carbon and glass fibers, which are the materials most commonly used for purposes of reinforcement. Natural fibers are an important alternative, offering several advantages such as their abundant availability, biodegradability and low cost compared with glass or carbon fibers. Sisal In the study reported here, textile sisal fibers and cords were characterized under tensile testing. A new sisal textile was designed based on an industrially manufactured textile for advanced composite arrangements to improve the fibers alignment and reduce transverse deformations. Composites consisting of a combination of sisal, commercial epoxy and polyurethane based on castor oil resin matrixes were tensile tested. The effect of sodium hydroxide (10%) treatments on the sisal was also evaluated. The composite material was subjected to bending and shear tests to determine its strength and stiffness, and its wood-composite interface and failure modes were investigated. The results showed that the new Sisal Fiber-Reinforced Plastic (SFRP) is sufficiently strong and stiff to serve as a reinforcement of timber structures.
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Af, Klintberg Albin, e Jonny Åkehag. "Träbjälklag med tung fyllning : Bjälklag framtaget med inspiration av byggteknik från sekelskiftet 1800–1900". Thesis, KTH, Byggteknik och design, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-213958.
Testo completoAbstract (sommario):
Denna rapport utreder möjligheterna att använda restprodukter som ljudisolering i lägenhetsskiljande mellanbjälklag av trä med spännvidd 6 m. Ett steg mot att uppfylla Sveriges byggindustris nollvision för koldioxidutsläpp är att bygga mer i trä och att återanvända/återvinna restprodukter. Det svenska entreprenadföretaget Skanska har vid sina krossanläggningar ett överskott av material i form av bergkross 0 - 0,2 mm och krossad restbetong. I denna rapport har en prototyp av ett träbjälklag tagits fram med influenser från byggtekniken från sekelskiftet 1800–1900 med avseende på nyttjandet av tung fyllningsmassa som ljudisolering i träbjälklag. Den framtagna bjälklagsprototypen uppfyller de krav som ställts i BBR efter dimensionering enligt Eurokoderna med hänsyn till brand, hållfasthet, svikt och nedböjning. Enligt en simulering i SEAWood, ett verktyg för akustiksimulering som är under utveckling vid RISE Research Institutes of Sweden, uppfylls även kraven på ljudisolering, detta stöds av de analyser som gjorts av mätresultat från liknande bjälklag. Fyllningsmaterialets höga vikt medför att prototypen är ett lågfrekvent bjälklag, detta kombinerat med att simuleringen endast är en indikation på ljudisoleringsegenskaper gör att det kommer krävas praktiska tester för att fastställa prototypens ljudisolerande och dynamiska egenskaper. Den framtagna bjälklagsprototypen är lämplig att prefabricera tack vare en konstruktion med få ingående delar. Att prefabricera bjälklaget har utöver de ekonomiska fördelar det medför stora fördelar ur ett arbetsmiljöperspektiv och är även fördelaktigt ur fuktsynpunkt. För att uppskatta bjälklagets miljöpåverkan gjordes en enklare jämförelse med ett prefabricerat betongbjälklag som visade att utsläppen av koldioxidekvivalenter fram till bruksfasen var mer än dubbelt så stor för betongbjälklaget än för prototypbjälklaget.This report investigates the possibilities of using residual products as sound insulation in apartment separating timber floors with a span of 6 m. One step towards meeting the Swedish construction industry's zero vision for carbon dioxide emissions is to build more using timber and to reuse/recycle residual products. The Swedish building contractor Skanska has at its quarries a surplus of material in the form of crushed rock of the 0 - 0.2 mm fraction and crushed residual concrete. In this report, a prototype of a timber floor has been produced with influences of construction technology from the turn of the 19 th century regarding the use of heavy filling as sound insulation in timber floors. The developed floor prototype complies with the requirements set in BBR after dimensioning according the Eurocodes regarding fire safety, strength, sagging and deflection. According to a simulation in SEAWood, a tool for acoustic simulation which is under development at RISE Research Institutes of Sweden the requirements for sound insulation are also met, which is supported by analyzes made by comparing with data on similar timber floors. The high mass of the filling material implies that the prototype is a low frequency floor, this in conjunction with the simulation only being an indication of sound insulation properties, it will require practical tests to determine the prototypes sound insulating and dynamic properties. The developed floor prototype is suitable for prefabrication thanks to a design with few components. Prefabrication of the floor has in addition to the economic benefits it brings great benefits from a working environment perspective and is also beneficial from a moisture point of view. To estimate the environmental impact of the timber flooring, a simple comparison was made with a prefabricated concrete floor which showed that carbon dioxide emissions up to the using phase were more than twice that of the concrete floor than for the prototype floor.
26
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.
Testo completoAbstract (sommario):
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
27
Archila, Santos Hector Fabio. "Thermo-hydro-mechanically modified cross-laminated Guadua-bamboo panels". Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675700.
Testo completoAbstract (sommario):
Guadua angustifolia Kunth (Guadua) is a bamboo species native to South and Central America that has been widely used for structural applications in small and large-scale buildings, bridges and temporary structures. Currently, its structural use is regulated within seismic resistant building codes in countries such as Peru and Colombia. Nevertheless, Guadua remains a material for vernacular construction associated with high levels of manual labour and structural unpredictability. Guadua buildings are limited to two storeys due to the overall flexibility of the slender and hollow culms and its connection systems. Its axial specific stiffness is comparable to that of steel and hardwoods, but unlike wood, Guadua’s hollow structure and lack of ray cells render it prone to buckling along the grain and to transverse crushing. As a result, Guadua’s mainstream use in construction and transformation into standard sizes or engineered Guadua products is scarce. Therefore, this work focussed on the development of standardised flat industrial structural products from Guadua devising replicable manufacturing technologies and engineering methods to measure and predict their mechanical behaviour. Cross-laminated Guadua panels were developed using thermohydro-mechanically modified and laminated flat Guadua strips glued with a high performance resin. Guadua was subjected to thermo-hydro-mechanical (THM) treatments that modified its microstructure and mechanical properties. THM treatment was applied to Guadua with the aim of tackling the difficulties in the fabrication of standardised construction materials and to gain a uniform fibre content profile that facilitated prediction of mechanical properties for structural design. Densified homogenous flat Guadua strips (FGS) were obtained. Elastic properties of FGS were determined in tension, compression and shear using small-clear specimens. These properties were used to predict the structural behaviour of G-XLam panels comprised of three and five layers (G-XLam3 and G-XLam5) by numerical methods. The panels were assumed as multi-layered systems composed of contiguous lamellas with orthotropic axes orientated at 0º and 90º. A finite element (FE) model was developed, and successfully simulated the response of G-XLam3 & 5 panels virtually loaded with the same boundary conditions as the following experimental tests on full-scale panels. G-XLam3 and G-XLam5 were manufactured and their mechanical properties evaluated by testing large specimens in compression, shear and bending. Results from numerical, FE predictions and mechanical testing demonstrated comparable results. Finally, design and manufacturing aspects of the G-XLam panels were discussed and examples of their architectural and structural use in construction applications such as mid-rise buildings, grid shells and vaults are presented. Overall, this research studies THM treatments applied to Guadua in order to produce standardised engineered Guadua products (EGP), and provides guidelines for manufacturing, testing, and for the structural analysis and design with G-XLam panels. These factors are of key importance for the use of Guadua as a mainstream material in construction.
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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.
Testo completoAbstract (sommario):
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
29
Voltr, Vojtěch. "Komplexní diagnostika stavebně statického stavu objektu". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372225.
Testo completoAbstract (sommario):
This diploma thesis deals with the problems of revitalization of historical objects. The theoretical part describes the technologies for static reinforcing and rehabilitation of vertical and horizontal bearing structures for a purpose of increasing the general stiffness of the object. As the practical part a static design project is made for reinforcing of the bearing walls and also for the general reconstruction of the slab. The slab is designed as the composite timber-concrete structure. The design project of the slab is economically compared with other variants. The designs are made for an existing object of the old restaurant in the village Velichovky.
30
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.
Testo completoAbstract (sommario):
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]
31
Zelený, Petr. "Experimentální a numerická analýza spřažených dřevobetonových konstrukcí". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226112.
Testo completoAbstract (sommario):
The master´s thesis deals with wood-concrete composite floors constructions. The work is divided into a theoretical and a practical part. The theoretical part describes methods of construction and materials used for wood-concrete composite constructions. The practical part describes an experimental four point bend test carried out on wood-concrete composite elements and samples. Further, manual calculation was performed according to Eurocode 5 and in program Asteres three variants of test elements were modeled. Each variant had different composite stiffness according to the working diagram of composite elements. At the end, experimental, computational and numerical results were compared.
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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.
Testo completoAbstract (sommario):
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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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Nilsson, Ida, e Dennis Svensson. "Samverkansbjälklag : En studie om KL-platta med samverkande betong". Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-49152.
Testo completoAbstract (sommario):
Purpose: The purpose of this study was to investigate whether timber-concrete composite (TCC) floors made of a CLT-deck and casted concrete could be used as a method for increasing the use of wood as a building material. Method: The methods used in this degree project were a literature study, in which a number of laws of construction and different connector systems were studied, as well as an experiment consisting of bending tests on CLT-decks with casted concrete where SFS VB-screws were used as shear connectors. Results: The TCC-beams in the experiment behaved as expected and went to bending failure. The beams displayed an almost invisible slip between the materials despite the low composite action of 40,2 %. In addition, the beams had a higher bending stiffness on average than CLT-beams of the same height would have. Conclusions: Compared to floors made entirely of wood, TCC-floors with CLT add extra mass, stiffness, and better acoustic properties to the construction while maintaining a low floor height. The three main types of connectors used in TCC floors are mechanical, notched and glued-in connectors, where the latter two generates higher composite action and stiffness. Adhesive connection is another method with great potential, but there is still more research needed for this type of connection to be used.
34
Loulou, Louisa. "Durabilité d’un assemblage mixte bois-béton collé sous chargement hydrique". Thesis, Paris Est, 2013. http://www.theses.fr/2013PEST1123/document.
Testo completoAbstract (sommario):
La mixité bois-béton est une solution intéressante dans le domaine des ouvrages d'art pour la réalisation de ponts, et dans le domaine du bâtiment dans la confection de planchers mixtes bois-béton. Le laboratoire Navier travaille depuis plusieurs années au développement du procédé par collage appliqué aux structures mixtes bois-béton. En effet, cette technique d'assemblage permet d'assurer une connexion quasi-parfaite entre le bois et le béton, contrairement aux techniques d'assemblage usuelles (connecteurs métalliques). Des travaux antérieurs ont montré la bonne performance de structures mixtes collées bois-béton du point de vue de leur tenue mécanique en fatigue. Cependant la connexion par collage nécessite une étude complémentaire concernant la durabilité de l'assemblage collé bois-béton, en particulier lorsque la structure mixte est soumise à des conditions hygrométriques variables. Les travaux menés pendant la thèse ont pour objectifs de déterminer les facteurs qui influent sur la tenue de ces assemblages collés sous chargement hydrique ; ils se divisent en 3 parties :-Deux parties expérimentales :(1)Des tests de cisaillement « Push-Out », en collaboration avec le Laboratoire Départemental d'Autun, ont permis d'évaluer l'effet des propriétés élastiques de l'adhésif sur la tenue en cisaillement de l'assemblage. L'objet de cette étude expérimentale est de valider un choix de colle pour ce type d'assemblage, prenant en compte un vieillissement hydrique, en se basant sur la capacité maximale atteinte en cisaillement, et le mode de rupture de l'assemblage. (2)Parallèlement aux tests de cisaillement, l'effet de chargements hydriques sur la tenue d'assemblages collés bois-béton a été étudié. L'analyse du comportement hydrique de la structure a été réalisée par la technique de corrélation d'image (DIC) sur des assemblages bois-béton collé de petite taille. Ces mesures de déformations locales ont permis de localiser des zones d'endommagement liées notamment aux déformations hydriques du bois empêchées par l'interface collée. Les effets des propriétés élastiques de l'adhésif, de la géométrie du bois (notamment sa structure et le sens des cernes par rapport au plan de collage) ainsi que du comportement mécanique du matériau cimentaire ont été étudiés.- Une partie numérique :(3) Un modèle numérique par éléments finis a été validé en comparant les résultats numériques aux cartes de déformation obtenues expérimentalement. L'analyse numérique a permis de quantifier les contraintes induites au niveau de l'interface en relation avec les déformations hydriques empêchées par l'interface collée et de prévoir le comportement à l'échelle 1 de structures mixtes. Ces différentes investigations ont permis de proposer des solutions optimisant ce type de connexion et de définir des conditions de mise en œuvre et d'utilisation de ces assemblagesThe wood-concrete composite is an interesting solution in the field of Civil Engineering to create high performance bending elements for bridge, as well as in the building construction for the design of wood-concrete floor systems. The Navier laboratory has been working for many years on the development of the bonding process as applied to wood-concrete composite structures. Contrary to conventional joining connectors (metal connectors), this assembling technique does ensure an almost perfect connection between wood and concrete. Previous work has already shown good performances of glued wood-concrete composite structures in terms of mechanical fatigue. However, the bonding connection requires additional research on the long-term behaviour of glued wood-concrete composites, especially when this structure is subjected to variable hygrometric conditions. The work undertaken during this thesis aims at determining the factors which induce damages on these glued wood-concrete assemblies under hygrometric loading; the research is divided into 3 parts:-Two experimental parts:(1)"Push-Out" shear tests conducted in collaboration with the Departmental Laboratory of Autun, were used to assess the effect of the elastic properties of the resin on the shear strength of the assembly. This experimental study aims at validating the adhesive of choice for this kind of connection, taking into account ageing under variable hygrometric conditions. Analysis is based on maximum shear capacity and on the failure mode of the assembly. (2)In addition to shear tests, the effect of hygrometric loading on the durability of glued wood concrete assemblies was examined. The analysis of the hydric behaviour of the structure was carried out by the digital image correlation (DIC) technique on small-sized glued wood-concrete assemblies. The measurements of the local deformations allowed us to locate areas of damage, particularly due to the hydric deformations of the wood prevented by the glued connection The effects of the elastic properties of the resin, the microstructure of the wood (including its structure and the direction of the annual rings) as well as the mechanical behaviour of the concrete material were examined.- A numerical part:(3) A numerical finite element model was validated by comparing the numerical results to the deformation maps experimentally obtained. Numerical analysis was used to quantify the stresses induced to the structure, in relation to hydric deformations prevented by glued connection. Moreover investigations at the full scale were conducted to evaluate the long-term behaviour under variable hygrometric conditions. These investigations were conducted in order to offer solutions aiming at optimizing this type of connection, and to define conditions for use of these glued assemblies
35
Hubený, Radim. "Rekonstrukce zděné budovy". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265687.
Testo completoAbstract (sommario):
The final thesis is focused on restoration masonry building. Concretely assessment of resistance joist's floors, design alternative's strengthening and impact of surcharge on pronounces constructions. The choice one of alternatives strengthening, design and check of floor structure over the second floor.
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Tichák, Tomáš. "Divadlo v Přerově". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240118.
Testo completoAbstract (sommario):
The main purpose of this work is a structural design of the building of theatre in Prerov city. The building has irregular shape. The structure is 72 m long, 54 m wide and 14,5 m high. Footprint equals to 2000 m2. Timber part of the building consists of glued laminated timber elements, as well as solid-sawn timber and steel ones. Steel part of the building includes tnasversal joint frames, composite steel and concrete ceilings, truss girders and bracings. This document includes design, internal force enumertion and structural assessment, including joints. Dlubal RFEM 5 structural analysis and design software has been utilized in the process. Drawings of the structure are enclosed.
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Lloyd, Emma. "The development of novel post-tensioned glulam timber composites". Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.707817.
Testo completoAbstract (sommario):
Improvements in the structural performance of glulam timber beams by the inclusion of reinforcing materials can improve both the service performance and ultimate capacity. In recent years research focusing on the addition of fibre reinforced polymers to strengthen members has yielded positive results. However, the FRP material is still a relatively expensive material and its full potential has not been realised in the combination with structural timber. The primary aim of this research is to evaluate the feasibility of strengthening timber beams by the addition of a post-tensioned basalt fibre reinforced polymer rod. This will be achieved through the experimental testing of a combination of unreinforced and post-tensioned GL28 timber beams, with both unbonded and bonded Basalt Fibre Reinforced Polymer (BFRP) rods being utilized as the post-tensioning tendon. It is intended that experimental and analytical research will begin to assess the viability of using this timber composite in construction scenarios.
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Palliyaguru, Nishantha Sepala. "Alternative structural design strategies for bridge decks in low traffic volume roads". Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/61092/1/Nishantha_Palliyaguru_Thesis.pdf.
Testo completoAbstract (sommario):
This research is part of a major project with a stimulus that rose from the need to manage a large number of ageing bridges in low traffic volume roads (LTVR) in Australia. The project investigated, designed and consequently constructed, involved replacing an ageing super-structure of a 10m span bridge with a disused Flat-bed Rail Wagon (FRW). This research, therefore, is developed on the premises that the FRW can be adopted as the main structural system for the bridges in LTVR network. The main focus of this research is to present two alternate deck wearing systems (DWS) as part of the design of the FRW as road bridge deck conforming to AS5100 (2004).
The bare FRW structural components were first examined for their adequacy (ultimate and serviceability) in resisting the critical loads specified in AS5100(2004). Two options of DWSs were evaluated and their effects on the FRW examined. The first option involved usage of timber DWS; the idea of this option was to use all the primary and secondary members of the FRW in load sharing and to provide additional members where weaknesses in the original members arose. The second option involved usage of reinforced concrete DWS with only the primary members of the FRW sharing the AS5100 (2004) loading. This option inherently minimised the risk associated with any uncertainty of the secondary members to their structural adequacy.
This thesis reports the design phases of both options with conclusions of the selection of the ideal option for better structural performance, ease of construction and cost. The comparison carried out here focuses on the distribution of the traffic load by the FRW as a superstructure. Advantages and disadvantages highlighting cost comparisons and ease of constructability of the two systems are also included.
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Podešť, Jakub. "Ocelová konstrukce vícepodlažní budovy". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392272.
Testo completoAbstract (sommario):
This diploma thesis deals with the design of a steel structure of a multi-storey building in the locality of Opava. The proposal is developed in two variant solutions. Variant 1 has ground plan dimensions of 37,5 m x 37,5 m and a height of 47 m. The variant 2 has ground plan dimensions of 45 m x 45 m and a height of 49,5 m. The modular size of the fields is 7,5 m x 7,5 m. The main supporting structure is made steel columns and beams, ceiling construction with composite steel and concrete joinst and roofing of arched laminated timber. The stability of the structure is ensured by vertical and roof bracings.
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Rininger, Zachary Scott. "The utilizaton of small diameter timbers in pultruded long strand composites". Online access for everyone, 2008. http://www.dissertations.wsu.edu/Thesis/Summer2008/Z_Rininger_072108.pdf.
Testo completo
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Manthey, Manuel. "Comportement des poutres mixtes bois-béton sous sollicitations accidentelles". Thesis, Rennes, INSA, 2015. http://www.theses.fr/2015ISAR0034.
Testo completoAbstract (sommario):
Les planchers mixtes bois - béton sont une solution pertinente en construction neuve comme en réhabilitation. Ce travail de recherche s'inscrit dans une volonté de favoriser l'essor de la construction mixte bois - béton en France. Il vise une meilleure connaissance des phénomènes affectant le comportement mécanique ou thermomécanique de la connexion bois - béton. En comparaison de procédés constructifs traditionnels, relativement peu de recherches ont été menées concernant le comportement d'un système de connexion mixte sous conditions accidentelles de séisme et d'incendie. Ces deux points sont ici abordés via une approche expérimentale puis numérique. Dans ce contexte, plusieurs campagnes expérimentales ont été réalisées.24 essais Push Out ont été réalisés à température ambiante sur le système de connexion mixte bois-béton par tirefonds métalliques SBB. 12 essais Push Out ont suivi un chargement cyclique alterné et 12 autres ont suivi un chargement statique monotone. Les essais ont montré un comportement ductile de la connexion et une bonne résistance mécanique du système. Les essais sous chargement cyclique ont assuré de la capacité du système à dissiper de l’énergie et de quantifier la perte de résistance de la connexion sous chargement alterné. Des modèles descriptifs ont été adaptés afin de mettre en équation les courbes force-déplacement expérimentales.Afin d’étudier plus précisément les phénomènes locaux intervenant entre le bois et le connecteur, une campagne d’essais complémentaires a été menée. Elle consiste en 16 essais d’arrachement du connecteur mis en place dans du lamellé-collé et 3 séries de 16 essais en enfoncement de différentes parties du connecteur (filet, partie lisse) dans du bois lamellé-collé. La connaissance du comportement de la connexion pour ces phénomènes locaux a permis d’alimenter plusieurs modèles prédictifs (numériques et analytiques) du comportement au cisaillement de la connexion. Ces derniers présentent une bonne corrélation avec les essais Push-Out réalisés précédemment.Afin d’apprécier le comportement sous incendie des planchers mixtes bois-béton, des essais sous feu ISO 834 ont été menés. La base de données sur les essais sous incendie des planchers mixtes SBB est composée d’un essai sur plancher mixte chargé (dimensions 5.35m x 3.5m) et d’une série d’essais au cisaillement sur trois configurations différentes de connexion mixte bois-béton. Ces derniers essais fortement instrumentés en thermocouples ont permis de valider les modèles thermiques numériques également développés dans ce travail. Les modèles thermiques et thermomécaniques couplés réalisés sous Abaqus© ont permis de confirmer l’échauffement limité des connecteurs bois-béton en situation d’incendie ainsi que de quantifier les dégradations de rigidité et de résistance de ces derniers. Ainsi le comportement mixte des planchers mixtes bois-béton peut être assuré en situation d’incendie sous réserves de sections suffisantesTimber - concrete composite structures are competitive technical solutions for new building construction as well as in refurbishment. This work aims at promoting timber - concrete construction in France thanks to a better knowledge of mechanical and thermo-mechanical behavior of the fasteners. Regarding more traditional buildings systems, few researches were lead about seismic and fire design of timber concrete structures. Particular emphasis is put on those two points in this study through experimental, analytical and numerical approaches. As a matter of fact, several experimental campaigns were lead. 24 Push Out tests have been carried out at ambient temperature on the SBB timber-concrete composite system. The test program involved 12 Push Out tests under cyclic loading and 12 Push Out tests under monotonic loading. Experimental results brought to light the good mechanical performances as well as the large ductility reserve of SBB timber-concrete connection system. The cyclic tests have revealed the system ability to dissipate energy and allowed quantifying the loss of rigidity and resistance of the system. Descriptive models (Foschi, Dolan, Richard) have been adapted to reproduce to the experimental load-slip curves.In order to get further insight into the local phenomenon taking place between timber and the SBB connector, a second test program was devised. The tests involved 16 Pull Out tests (connector from timber) and 3 series of 16 embedment tests og various parts of the connector in glue laminated timber. Thanks to these experimental results, a better understanding of the SBB behavior has been reached. Predictive models are provided for numerical and analytical modeling of timber - concrete fasteners. Those models show good agreement with the Push Out tests introduced in previous part.In order to assess the fire behavior of timber - concrete composite floor system with the SBB connection system, fire tests were conducted according to ISO 834 standard. Fire results database with SBB timber - concrete connection includes a full-scale fire floor test (floor dimensions are 5.35m x 3.5m) and several fire Push Out tests based on three different timber - concrete composite beam sections. Fire Push Out tests were heavily instrumented with thermocouples in order to allow the validation of thermal models developed in this thesis.Thermal and thermomechanical coupled simulations were conducted with finite element software Abaqus©. These models demonstrate the good performances of timber-concrete composite structures subjected to fire. Heating of the elements and loss in shear resistance and stiffness of the connection system were quantified. Furthermore fire design rules are proposed for timber - concrete structures. Fire behavior analysis pointed out that thermal dilatation of concrete must be considered in fire design of timber-concrete composite structures
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FRANCO, LUCA. "Numerical modelling strategies and design methods for timber structures". Doctoral thesis, Università IUAV di Venezia, 2020. http://hdl.handle.net/11578/283196.
Testo completoAbstract (sommario):
Over the last years timber constructions are gaining back a primary role in the building industry after decades in which they were almost abandoned in favor of concrete and steel structures. A sign of this change is the appearance in the last years in many Italian universities of courses dedicated to the design of timber structures. One of the main reasons behind this success must be sought in the development of new engineered timber materials, such as glued-laminated and cross-lam timber, that allowed to wooden structures to reach structural potentialities that until some decades ago were prerogative of concrete or steel building materials. Tests recently carried out on full-scale buildings have also proven the excellent capabilities of these new timber technologies in providing reliable and highly-performant multi-storey building able to withstand high seismic intensities.
Since the employment of timber to build multi-storey buildings in seismic-prone areas is quite recent, many aspects relating the understanding of their structural behavior and their correct design are still to be sought, as demonstrated by the lack of provisions in current building codes and standards and the still ongoing great amount of research activity on seismic behavior of timber structures.
Modern timber technologies also allow to cover very large spans with long glued-laminated timber beams, satisfying the need of large open spaces and architectural flexibility required by modern building design approaches. These bulky big-size elements anyway result quite expensive in production, transportation and installation phases undermining the economic competitiveness of timber structures. To cope with this problem, the prototype of an innovative timber-steel composite beam consisting of sub-elements assembled on-site to create longer members has been ideated at KTH Royal Institute of Technology of Stockholm in Sweden.
One of the objectives of this thesis is therefore to provide an advance in the state of knowledge of timber building technology adopted for seismic-prone areas, focusing in particular on both numerical modelling strategies and design methods for cross-laminated timber buildings, illustrated respectively in the first and second part of the thesis. The other goal is the development of an analytical tool for the enhancement and the investigation of the structural performances of the innovative composite beam ideated at KTH Royal Institute of Technology, and it will be exposed in the third and last part of the thesis.
43
Béreyziat, Antoine. "Étude du comportement thermomécanique de poutres mixtes acier-bois en situation d’incendie". Thesis, Ecully, Ecole centrale de Lyon, 2022. http://www.theses.fr/2022ECDL0005.
Testo completoAbstract (sommario):
La mixité acier-bois présente un fort potentiel de développement : les composants en bois et en acier peuvent se renforcer mutuellement ; le bois, par son caractère isolant, peut être utilisé pour protéger l'acier du feu ; l'acier apporte son caractère incombustible. Cette forme de mixité est pourtant peu répandue malgré le récent essor du bois dans la construction de bâtiments multiétagés, à cause du manque de références scientifiques et techniques sur le sujet. On propose alors d'étudier des poutres mixtes pour lesquelles l'acier et le bois sont associés de manière à obtenir des performances les meilleures possibles, en situations normale et d'incendie. On décrit d'abord le comportement des matériaux acier et bois, à froid et en situation d'incendie. Une description de la combustion du bois est proposée pour mieux comprendre ce qui sous-tend l'évolution de ses propriétés avec la température. Un intérêt particulier est porté sur les transferts hydriques qui se produisent dans le bois lorsqu'il brûle. On examine ensuite la question de la mixité acier-bois à travers un aperçu global. Puis on passe en revue les travaux portant sur un certain type de configuration, qui consiste à insérer des poutres en bois entre les semelles d'un profilé en I laminé à chaud, tout en faisant en sorte que ce profilé soit protégé du feu par le bois. La description du comportement élastique à froid des poutres étudiées est réalisée par l'utilisation de la méthode gamma. La réalisation d'essais de flexion sur des poutres mixtes et leurs constituants permet de confirmer ce modèle analytique, mais un effet composite non-anticipé est observé dès lors que l'acier commence à se plastifier. Un gain de résistance significatif est alors permis par l'association du bois et de l'acier. On parvient à simuler ce comportement en augmentant la limite d'élasticité de l'acier modélisé par rapport à la valeur mesurée, ainsi que la résistance du bois en traction longitudinale. Des essais thermiques sur des éprouvettes acier-bois non chargées sont ensuite réalisés. On confirme à cette occasion que la mesure correcte des températures dans le bois nécessite d'orienter les thermocouples parallèlement aux isothermes. De nombreuses configurations sont comparées, ce qui permet d'appréhender finement l'efficacité de la protection au feu des profilés métalliques apportée par le bois. Les transferts de masse qui se produisent dans le bois se révèlent avoir un effet sensible sur la température des profilés métalliques protégés. La comparaison des températures mesurées et simulées permet de mettre en évidence l'importance de l'étanchéité des joints d'assemblage pendant l'exposition au feu. La combustion du bois et la température de l'acier sont observées après la fin de l'exposition au feu, on oppose alors le comportement des configurations creuses à celui des configurations pleines. Finalement, des essais au feu sur des poutres chargées mécaniquement montrent qu'un profilé protégé par une épaisseur de bois de 45 mm peut résister au feu pendant 81 min. On met en évidence un effet du chargement sur la température du profilé métallique par l'intermédiaire d'une ouverture des joints d'assemblage. La simulation numérique montre que le bois contribue à la résistance au feu de la poutre mixte non seulement en protégeant thermiquement l'acier, mais également en reprenant une partie des charges. Ces travaux montrent l'efficacité des poutres mixtes acier-bois, en situation normale et sous incendie, et contribuent à la compréhension de leur comportement. Ils permettent de formuler des propositions d'amélioration et d'identifier de nouvelles problématiques ouvrant des perspectives pour l'étude et l'utilisation de ces poutres mixtesTimber-steel hybridization has great potential, because steel and timber component can reinforce each other, timber can be used to protect steel from fire, and the non-combustibility of steel can be used in an advantageous way. However, this form of hybridization is not widespread despite recent developments in the use of timber for multi-story buildings. Therefore, it is proposed to study composite beams made from timber and steel combined in such a way that the best possible performances are achieved, in normal and fire situations. Firstly, behavior of steel and timber is described in normal and fire situations. A description of wood combustion is proposed to better understand what underlies the temperature dependence of its properties. A focus is made on the mass transfer that occur into timber as it burns. Then, the timber-steel hybridization is addressed through an overview. Afterward, a literature review is made on a specific configuration type, which is assembled by inserting timber beams between the flanges of a hot-rolled “I” profile, while ensuring that this profile is protected from fire by timber. The description of the elastic behavior of studied beams in normal situation is achieved using the gamma method. Bending tests on hybrid beams and their components corroborate this analytical model, but an unexpected composite behavior is observed when steel yielding begins. Thus, a significant strength gain results from the combination of timber and steel. We manage to simulate this behavior by increasing the yield point of the modeled steel compared to the measured value, as well as the tensile strength of timber. Then, fire tests on unloaded specimens are performed. On this occasion, we confirm that correct temperature measurements into timber require orienting thermocouples parallel to isotherms. Many configurations are compared, which allows to understand in detail the effectiveness of the fire protection provided by wood to steel profiles. Mass transfers that occur into timber appear to have a significant effect on temperatures measured on protected steel profiles. The comparison of measured and simulated temperatures allows to highlight the importance of tightness of assembly joints during exposure to fire. Wood combustion and steel temperatures are observed after the end of the fire exposure, and the behavior of hollow configurations is contrasted with that of the timber filled configurations. Finally, fire tests on mechanically loaded beams show that a steel profile protected using 45 mm thick timber components can resist fire for 81 min. Thus, R60 is exceeded with relatively thin protection. Results show that the loading has an impact on steel temperatures, because of an opening of the assembly joints. Numerical simulations show that timber gives fire resistance of the composite beam both thermally and mechanically, by protecting the steel profile, but also by relieving its load. This work shows the effectiveness of steel-timber composite beams, in normal and fire situations, and contributes to the understanding of their behavior. However, proposals for improvement and new challenges are formulated, opening prospects for the study and use of these composite beams
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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/.
Testo completoAbstract (sommario):
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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El, Ladki Inaya, e Leylafer Gümüs. "LIVSCYKELKOSTNAD (LCC) : En jämförelse mellan en tvärspänd plattbro i limträ och en samverkansbro". Thesis, KTH, Byggvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231823.
Testo completoAbstract (sommario):
This essay is a bachelor thesis written for the Degree Program in Constructional Engineering and Design at The Royal Institute of Technology (KTH). This thesis was an assignment given by WSP Sweden and their bridge and water department. The purpose of this report is to conduct an examination on the Life Cycle Cost (LCC) on a prestressed glulam deck bridge and a composite bridge in the early stages of the design phase. This report illuminates the factors that are most crucial in a LCC-calculation for the selected overpasses, and provides an overview regarding which overpass is most efficient from an economic standpoint. The LCC has been calculated based on an 80-year lifespan for the prestressed glulam deck bridge and a 120-year lifespan for the composite bridge. The cost of investment, operating, maintaining and finally the demolition cost was all considered as well. The bridge works that were examined are real life projects in an early stage of the design phase with plans to be built. In the results, the LCC-analysis shows a clear difference in life cycle costs between the prestressed glulam deck bridge and the composite bridge and show that the cost of investment is the most decisive cost during the bridges’ lifespans. The LCC-calculations show that the total life cycle cost for a prestressed glulam deck bridge is higher than the composite bridges’ total life cycle cost.
46
Kavaliauskas, Saulius. "Kompozitinių medinių-betoninių sijų tarpsluoksnio įžambinės medsraigtinės jungties elgsena". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20100317_151214-02629.
Testo completoAbstract (sommario):
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.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.
47
Stuckey, Harold Troy. "Ecological Enhancement of Timber Growth: Applying Compost to Loblolly Pine Plantations". Thesis, University of North Texas, 1999. https://digital.library.unt.edu/ark:/67531/metadc2265/.
Testo completoAbstract (sommario):
This study explored the application of compost onto a small loblolly pine tree forest in northeast Texas. Its purpose was to determine if the application of various amounts of compost would provide for accelerated rates of growth for the trees. Soil parameters were also monitored. A total of 270 trees were planted and studied in a northeast Texas forest ecosystem. Compost rates of 5, 25, and 50 tons per acre with either soil or compost backfill were utilized and compared to a control without compost. Nonparametric and parametric ANOVA and Chi-Square tests were utilized. The results indicated that greater application rates retained greater moisture and higher pH levels in the soil. Compost applications also yielded a greater survival rate as well as larger tree height and diameter when compared to the control. The 25 ton/acre application backfilled in native soil achieved the greatest average in height and diameter when compared to the averages for the control plot. Greater growth differences for the 25S application can be attributed to additional nutrients coupled with a stable pH consistent with native soil acidity.
48
Čierny, Juraj. "Obchodní dům". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265530.
Testo completoAbstract (sommario):
The aim of this diploma thesis is a design of the multy-storey steel structure with a wooden dome structure of the shopping centre in city of Banská Bystrica, Slovakia. Minimum build-up area is 2 000m2. Minimum number of storeys is set at 2. Steel structure is composed as a frame construction with composite steel-concrete ceilings. Building has 2 storeys at all. Wooden structure of dome is composed by glue laminated curved beams. The structural design and analysis is performed by software SCIA Engineer 15.
49
Vondráček, Vít. "Nosná konstrukce atypického rodinného domu ve Vrchlabí". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240297.
Testo completoAbstract (sommario):
The subject of master’s thesis is design and assessment of steel load-bearing construction of atypical family house in Vrchlabí. Structure is designed as multi-storey steel structure, cooperating with stiff concrete core. The design was considered in four different options which combines possibility of using steel, steel and timber with different way of stiffness for whole structure. There is also composite steel-concrete alternative floor trimmer for selected option. Design and assessment was conducted in accordance with the applicable standards and by using software Scia Engineer.
50
Chan, Kathleen Joyce. "Investigation of Processing Conditions and Viscoelastic Properties on Frictional Sliding Behavior of Unidirectional Carbon Fiber Epoxy Prepreg". Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/86444.
Testo completoAbstract (sommario):
The quality of continuous fiber reinforced polymer matrix composite parts and structures depends strongly on the friction during the composite forming process. The two major types of friction that cause deformations during this process are ply-ply friction and tool-ply friction. One of the challenges in the composite forming process is the occurrence of wrinkling and shape distortion of the fabric caused by the surface differences between the forming tool and surface of the laminate. Frictional measurements of composites can vary widely depending on processing parameters, measurement technique, and instruments used.
In this study, a commercial rheometer was used to evaluate tool-ply friction of unidirectional carbon fiber epoxy prepreg at various contact pressures, temperatures and sliding velocities. Viscoelastic properties such as the complex viscosity (η*), storage modulus (G'), loss modulus (G"), and loss factor (tan δ) were used to determine the critical transition events (such as gelation) during cure. An understanding of changes in viscoelastic properties as a function of time, temperature, and cure provides insight for establishing a suitable processing range for compression forming of prepreg systems.
Surface imaging results were coupled with rheological results to qualitatively examine the effects of processing parameters on prepreg distortions. Changes in gap height over the measurement interval qualitatively describe the changes in contact area and contact mechanisms between the tool-ply surfaces. The results indicate that friction behavior of the prepreg system is a contribution of adhesive and frictional forces, where increase in viscosity, reduction in gap height, and cure of the sample correlate to higher friction values.Master of Science
The quality of composite parts and structures depends strongly on the friction present during the composite forming process. One of the major challenges in the forming process is the occurrence of wrinkling and shape distortions of the fabric caused by the surface differences between the forming tool and material. The presence of these defects can compromise the final material property and lead to failure when in use. Frictional measurements of composites can vary widely depending on processing parameters, measurement technique, and instruments used. The extent of interaction between the tool and surface of the material depends on the tooling height, and by extension, contact area, which cannot easily be monitored with traditional test designs. A commercial rheometer was used in this study to evaluate tool-ply friction of unidirectional carbon fiber epoxy prepreg at various contact pressures, temperatures, and sliding velocities. Gap height and torque were monitored to provide information on the frictional dependence of processing parameters. In addition, surface-imaging results were coupled with rheological results to examine the relationship between friction and fiber distortions. The understanding of changes in material property with respect to the tooling process is the key to optimizing the composite forming process.