To see the other types of publications on this topic, follow the link: Timber connections.
Dissertations / Theses on the topic 'Timber connections'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Timber connections.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Krepper, Martin, and Anders Reutermo. "Calculation program for timber connections." Thesis, Linköpings universitet, Kommunikations- och transportsystem, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-131977.
Full text
2
Yeboah, David. "Rigid connections in structural timber assemblies." Thesis, Queen's University Belfast, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.580103.
Full textAbstract:
Bonded-in rod joints have several advantages over the conventional type of joints in terms of performance, cost and aesthetics. The use of basalt fibre reinforced polymer (BFRP) rods would result in lower weight of the joint and improved resistance to corrosion but there appears to be little or no investigation on the use of these rods in the bonded-in rod technique. The aim of this research was to examine the behaviour of bonded-in BFRP and steel rods and to propose design models to enhance current knowledge in bonded-in rod technology. The mechanical properties of the timber members were characterised so as to predict the behaviour of donor and spliced beams for the proposed stressed model. Pull-out tests of the rods were conducted to investigate some factors that affect joint capacity and based of the results bonded-in rod timber beams were fabricated and tested for ultimate capacity and flexural stiffness. An analytical model based on the interfacial tress-strain interaction of the BFRP rods with the adhesive layer and the timber members was developed to predict pull-out capacity of the samples. Average shear strength from steel pull-out tests was also used to propose a design equation for pull-out capacity of steel samples. In both the BFRP and steel samples, good agreement with the tests results was observed. A trapezoidal timber compressive stress model was developed to predict ultimate moment capacities of steel and BFRP timber beams. Good agreement was found between the theoretical and bonded-in steel rod beams whereas results form bonded-in BFRP rod beams were lower due to tensile splitting. Bonded-in steel beams recorded higher stiffness than the theoretical stiffness, whereas there was strong agreement between the theoretical predictions and BFRP beam tests. Thus, the presented models may serve as a useful reference for future design of bonded- in rod joints.
3
Mmari, Winston. "Modeling of nailed timber connection : Displacement path dependency in sheathing-to-framing connections." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-66956.
Full textAbstract:
Connections in wood have been investigated and advanced ever since the ground-breaking work of Johansen in the early nineteenth century. Nevertheless, not much investigation has been undertaken on the existence of load-displacement path dependency in a sheathing-to-framing connection. Herein, a sheathing-to-framing connection is investigated in relation to displacement path dependency. This work uses 3D Finite Element beam-on-foundation models of an Oriented Strand Board (OSB/2) sheathing nailed to a C24 wood framing, to study possible strategies to numerically simulate the displacement path dependency. The models are used to study if non-linear elastic or elastic-plastic embedment properties of an annular-ringed shank nail in the wood-based materials bring about the path dependency using Connector elements in combination with different material models in the FE software Abaqus. Numerical results are compared with corresponding experimental test results of the connection together with the Eurocode 5 approach. The outcome of the numerical study both; confirms the existence of displacement path dependency and shows that this property in the connection can be described by plasticity properties in nail, sheathing material and the wood framing.
4
Harvey, Kim. "Improved timber connections using bonded-in GFRP rods." Thesis, University of Bath, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425878.
Full text
5
Thomson, Andrew. "The structural performance of non-metallic timber connections." Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.544513.
Full textAbstract:
Reducing the amount of metal used within a timber structure has many advantages, particularly when dealing with connections. Fire resistance and durability are commonly cited benefits. In addition the use of alternative connector materials minimises thermal bridging and can also provide a lighter weight structural solution. Existing contemporary forms of non-metallic timber connections are commonly provided through the use of adhesives. However, these connections are reliant on a need for careful offsite, prefabricated construction. Traditional green oak carpentry connections provide a mechanically fastened non-metallic solution. However, carpentry connections are not widely compatible with contemporary architectural design or with the use of modern engineered timber products such as glulam. Building upon research completed at the University of Bath, the aim of this thesis was to develop a mechanical, non-metallic connection system suitable for contemporary applications. Specific objectives were to investigate the structural performance of a defined connection system and to develop analysis methods to facilitate design. A review of the literature demonstrated a lack of uptake and use of mechanical non-metallic connections. Guidance for the design of mechanical fasteners reflects the lack of innovation and research into the use of non-metallic materials. Following an initial experimental investigation of non-metallic materials, an experimental testing programme was completed to investigate the use of glass fibre reinforced plastic (GFRP) dowels in conjunction with densified veneer wood (DVW) plates. The findings of the experimental study demonstrate that the use of these materials can provide a robust connection system for contemporary applications. The results of the experimental work provide guidance on dowel spacing requirements, connection response to load and connection failure modes. The failure modes of the proposed connection system were shown to be unique to the materials used and specific strength analysis methods have been developed to predict connection yield and ultimate strength. A method for predicting initial connection stiffness was also developed through the use of a beam on elastic foundation model.
6
Oh, Jiyoon. "Timber moment connections using glued-in steel rods." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57566.
Full textAbstract:
The experimental study completed in this thesis focused on timber-steel hybrid moment connections using d=12.7mm diameter mild steel threaded rods glued into Douglas-Fir glulam with polyurethane based adhesive. Two phases of experiments were conducted: the first to determine the minimum design parameter values that result in a ductile tensile failure of the glued-in steel rod, instead of a brittle timber or pull-out failure; and the second, to determine a relationship between the different design parameters and the moment capacity of the connection.
The work established that the moment connection fails in a ductile manner due to rod yielding and plasticizing, when the shear force induced into the system was less than 25% of the maximum axial capacity of the steel rods. Then, ductile failure occurred even when the edge distances of the steel rods were below the recommendation of a minimum 2.5d to prevent splitting of the wood. Rod pull-out failure was prevented by having a glued-in embedment length of the rods equal to or greater than 15d. In addition, ductility and equivalent viscous damping ratio were found to decrease as the moment capacity of the connection increased.
The theoretical yield moment was calculated based on the assumption that the compression and tension members are timber and steel, respectively, and by applying the concept that plane-sections remain plane and the traditional elastic transform theory. The experimentally determined yield moments were established to be a close match. The results of the research provide guidance to practicing engineers to design moment connections with glued-in steel rods.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
7
Madhoushi, Mehrab. "Fatigue of glued-in pultruded connections for structural timber." Thesis, University of Bath, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269838.
Full text
8
Karagiannis, Vasileios. "Behaviour of hybrid timber-steel beam-to-column connections." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/59187.
Full textAbstract:
This thesis studies the behaviour of hybrid systems consisting of tubular steel columns and laminated glulam timber beams. The research includes experimental investigations at the material and structural system levels as well as several numerical and assessments. Firstly, an extensive experimental programme is conducted on the determination of the material properties of the glulam. This involve compressive, tensile, shear and bending material tests. In addition, one-dowel connection tests are carried out to examine the interaction between the steel fastener and the timber volume around the fastener hole with the aid of Digital Image Correlation (DIC) techniques. Subsequently, detailed three-dimensional detailed models are constructed and their results are compared with the experimental tests. To account for the material damage, the foundation zone approach was used. This model was shown to be able to correctly simulate the crushing response of wood in the embedding region. The implementation of this region into the model allows an accurate simulation of the damage accumulation process. To this end, new relationships were formulated as part of this thesis, that can be used to estimate the material characterisation as a function of the crushing volume. The proposed model allows for a relatively low dependence on the radius of the foundation volume adopted making it applicable to a wider range of varying geometrical configurations. The validity and accuracy of the proposed modified foundation models were examined against the experimental force-displacement curves, and good agreement was found between the experimental response and the numerical simulations The second experimental programme is concerned with the performance of timber beam-steel column assemblages. Two timber beam-to-steel column alternatives are examined: a) top and seat angle connection and b) slotted-in T-stub connection with bolts. The configuration of the connections and their set-up are presented, followed by detailed results in the form of figures and tables as well as observations from the tests. The main behavioural patterns are identified and key response characteristics such as stiffness, capacity and failure mechanisms are discussed. Detailed finite element models were created to simulate the experimental timber beam-to-steel column connection tests. The models included advance features such as contact phenomena, bolt pretension and orthotropic material definitions. The foundation zone approach developed in this thesis was implemented. The results of the models were validated against the experimental results and good agreement was found. Additionally, component-based models were also formulated for the prediction of the flexural response of the connection types tested. These expressions were developed to estimate the stiffness, capacity and ultimate loads of the connections and the results were validated against the experimental and numerical findings. The component models proposed were able to predict the response of the connection accurately including those cases where screws and bottom-wedge angles were involved. In the concluding part of the thesis, the developed finite element models are employed in a parametric assessment in order to highlight the influence of key geometric and material considerations. The dearth of information on timber-steel hybrid connection of this type, design methodologies must be developed to offer a preliminary assessment on the prediction and evaluation of the key characteristics and hence the results are also compared with simplified analytical expressions. Finally, the last section of the thesis summarised all the findings and numerous possible future research are identified.
9
Brandon, Daniel. "Fire and structural performance of non-metallic timber connections." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665417.
Full textAbstract:
Recent studies showed the need for timber connections with high fire performance. Connections of members in timber structures commonly comprise steel connectors, such as dowels, screws, nails and toothed plates. However, multiple studies have shown that the presence of exposed metal in timber connections leads to a poor performance under fire conditions. Replacing metallic fasteners with non-metallic fasteners potentially enhances the fire performance of timber connections. Previous studies showed that Glass Fibre Reinforced Polymer (GFRP) dowels can be a viable replacement for steel dowels and that Densified Veneer Wood functions well as a flitch plate material. However, as the resin matrix of GFRP dowels is viscoelastic, connection creep, which is not studied before, can be of concern. Also no research has been carried out on the fire performance of these connections. Therefore, a study of the creep behaviour and the fire performance of non-metallic timber connections comprising GFRP dowels and a Densified Veneer Wood flitch plate was performed, as is discussed in this thesis. Predictive models were proposed to determine the connection slip and load bearing capacity at ambient and elevated temperatures and in a fire. The material properties and heat transfer properties required for these models were determined experimentally and predictions of these models were experimentally validated. Furthermore, an adjustment of the predictive model of connection slip at ambient temperature allowed approximating the creep of the connection. The material properties, required for the creep model, were determined experimentally and predictions of the model were compared to results of longterm connection tests. The study confirmed that timber members jointed with non-metallic connectors have a significantly improved fire performance to timber joints using metallic connections. Models developed and proposed to predict fire performance gave accurate predictions of time to failure. It was concluded that non-metallic connections showed more creep per load per connector, than metallic connections. However, the ratio between initial deflection and creep (relative creep) and the ratio between load level and creep were shown to be similar for metallic and non-metallic connections.
10
Abdulrahman, Nasser A. H. "Load transfer mechanism in punched metal plate timber connections." Thesis, Edinburgh Napier University, 2002. http://researchrepository.napier.ac.uk/Output/6193.
Full textAbstract:
The load capacity of the punched metal plate timber joints is established, in general, by empirical means as a result of destructive testing in accordance with relevant national standards. The basis of tests is tensile or compressive loading applied parallel and perpendicular to the grain of the timber. In general, the design-analyses of trusses are based on the assumption that joints behave as pins due to the concentration of fasteners in a small area limiting the moment arm. A number of testing methods and apparatus were developed to determine the behaviour of the punched metal plate timber joints under different types of loading (tension,compression and moment). A combined programme of experimental and analytical work was carried out to evaluate the semi-rigid characteristics of the punched metal plate timber joints with respect to the level of translation and rotational rigidity under short term loading. The effects of different parameters such as load and deformation rates, number and length of bites, thickness of the plates and the orientation of the plates and timber grains were considered. The load-displacement and moment-rotation characteristics were studied and empirical models were developed to simulate displacements up to failure loads. The study results show that the strength and stiffness of the joints can be expressed in terms of connector parameters. Increasing deformation rate, number of bites, length of bites, thickness of the plates and decreasing plate and grain orientations would increase the strength and stiffness of the joints. Also, the results show that the punched metal plate connections can possess a considerable moment capacity. A statistical technique was used to classify the level of importance of parameters such as number of bites, length of bites and grain direction on the performance of the punched metal plate timber joints. All the specimens were tested under both tension and compression loads up to failure. From the tests and analysis carried out it was found that the grain direction had significant effect on the performance of the joints under tensile loading and the effectiveness of the grain direction was less when joints were subjected to compressive loading. There was a strong indication that the effect of the number of bites was dominant when joints were subjected to compressive loading. A design flowchart for punched metal plate timber joints is provided incorporating the research findings into a design/analysis process.
11
Habite, Tadios Sisay. "Moisture-induced crack development in timber beams : a parametric study performed on dowelled timber connections." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-68610.
Full textAbstract:
A problem has been observed by many researchers regarding the cracks caused mainly by moisture variation in timber structures. However, this effect has been neglected over the past decades. In addition, many design codes do not have a room for a realistic formulation of the moisture diffusion and its effect in causing internal stress, deformation, and cracks. Moreover, if this effect occurs in connection areas, usually the weakest structural section, it has and also had shown a devastating effect on the service life of many wooden structures. In the current work, a Fickian moisture diffusion model is implemented by use of finite element simulation with the help of the commercial software ABAQUS for a dowelled beam column connection. The results of such moisture diffusion were used to analyse the stress situation inside the timber section. Moreover, an extended finite element method was applied in ABAQUS to investigate how moisture induced crack develops into the timber section. Furthermore, a parametric study was performed by using Python scripting to investigate the effect of dowel spacing (horizontal and vertical) and critical energy release rate on the development of the moisture-induced crack. The results obtained revealed that for the same material property when the dowel spacing increases (either horizontal or vertical) the crack length increases significantly. Likewise, the crack length increases when the critical energy release rate requirement of the timber is decreasing.
12
Deng, James X. "Strength of Epoxy Bonded Steel Connections in Glue Laminated Timber." University of Canterbury. Civil Engineering, 1997. http://hdl.handle.net/10092/8262.
Full textAbstract:
In New Zealand, there has been little use of epoxy bonded steel connections in the timber construction industry due to the lack of knowledge and experiences about the performance. A research was carried out both experimentally and theoretically to study the epoxy bonded steel connections in glue laminated timber. This research provides a better understanding of the mechanical and physical properties of such connections in tension, subjected to short and long duration load, with variables of embedment length, bar diameter, edge distance, hole diameter, moisture content, steel bar type and epoxy type.
In the study, five different failure modes were identified. A theoretical three dimensional model was established using a finite element method. The characteristics of the connection, the three dimensional stress distributions and the effect of the variables in the connections were studied using this model. The study shows that there is a strong correlation between the failure modes and the stress concentrations. It is possible to optimise the design of the connections by developing a better geometry.
The study also shows that the connections can be used safely in timber structures provided the moisture content of wood does not exceeding 22%.
Empirical equations were developed to predict the axial capacity of the connection in tension or compression.
13
Gerard, Robert Buonomo. "Fire Resistance of Connections in Pre-Stressed Heavy Timber Structures." Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2010. http://hdl.handle.net/10092/4337.
Full textAbstract:
Construction with composite materials has become increasingly popular in contemporary structural design for multi-storey residential, commercial, and industrial buildings. As a composite structure, pre-stressed heavy timber buildings offer sustainable, environmentally-friendly advantages over competing construction technologies utilising structural steel and concrete components. Research at the University of Canterbury is continually investigating the performance and behaviour of this composite heavy timber construction assembly. The following research report provides a fire resistance analysis for pre-stressed heavy timber structures that includes:
• A comprehensive literature review detailing the fire resistance for pre-stressed heavy timber structural components and typical connections; and
• A four-phase series of experiments with epoxy grouted steel threaded rods and proprietary mechanical fasteners to determine the fire resistance properties of steel to wood connections.
Laboratory experimentation includes cold testing to determine connection performance at ambient temperature, oven testing to evaluate heating effects on steel to wood connections, cooled testing to determine the residual strength of connections in minor fires and, finally, furnace testing to generate fire resistance design and analysis equations to be utilised for steel to wood connections.
Recommendations for the fire performance of connections in pre-stressed heavy timber structures are included in the report.
14
Jin, Hui, and Hao Wu. "Finite Element Modelling of Fracture in dowel-type timber connections." Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-34783.
Full textAbstract:
Dowel-type steel to timber connections are commonly used in timber structure. The load carrying capacity and the stress distribution within the connection area are complicated and the failure behavior of a connection depends on many parameters. The main purpose of this thesis was to verify, using the data obtained from previous experiments, the conventional design method of European Code 5(EC5) (hand calculation) for dowel type joints subjected to pure bending moment and other alternative design methods based on the finite element method (FEM) including the use of the mean stress approach and the extended finite element method (XFEM). Finite element models were created in the software ABAQUS. The models were then used to predict the load bearing capacity and compare this to the experimental results. In addition parametric studies were performed with modifications of material properties and other parameters. The closest prediction in relation to the test results was obtained using XFEM where the predicted capacity was 3.82% larger than the experimental result. An extension of the mean stress method going from a 2D-formulation to a 3D-formulation was verified as well. A general conclusion drawn from this work is that the numerical modelling approaches used should also be suitable for application to complex connections and situations involving other loading situations than pure tension.
15
Debarbouille, Quentin. "Consequences of using Eurocode 5 for design of steel-timber connections." Thesis, Linnéuniversitetet, Institutionen för teknik, TEK, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-12499.
Full textAbstract:
Timber construction has increased in popularity in different countries in Europe thanks to a new material apparition and environmental stakes. In order to construct a timber structure we use different types of connections. The design of connections is complex since it is influenced by many different factors. However, the connection is the weak part of the structure and has high risk of collapse. Therefore the connection often determines the capacity of the structure.In 1975 the commission of the European Community decided to harmonize of technicalities and rules of design in the field of construction. The aim is to increase the competition between companies and simplify the trade of products and services within the European Union. The regulation for timber structures is Eurocode 5 (EC5).This study investigates how the EC5 can influence the design of a connection with a single shear plane for a steel-timber connection with nails or screws. This study is based on the comparison between the connection properties obtained using the EC5 and those recommended in a brochure from one of the large glulam manufacturers in Sweden based on the Swedish regulations.The outcome is that the new regulation has a strong impact on the design of the steel plates. The requirement in minimum spacing imposes a specific dimension and position of the fasteners. Moreover, the capacity of the connection is influenced by the distance between the fasteners parallel to the grain, which determines the effective number of fasteners involved in the connection.
16
Werner, Åström Petter. "Experimental study on innovative connections for large span structural timber trusses." Thesis, KTH, Byggnadsmaterial, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-256507.
Full textAbstract:
Large span timber trusses are usually built with glulam. One problem with large span glulam trusses is that the connections needed to transfer the load between truss members are often complex and expensive. Another issue is transportation. Building large span trusses out of structural timber instead, could be a way of simplifying the connections and at the same time increase the degree of on-site construction and thereby solving the transportation problem.In this study, a total of 18 laboratory tests were performed with the purpose of investigating the tensile strength and the load slip behavior of different connection designs for large span structural timber trusses. Six different test groups corresponding to six different connection designs were tested. The materials used include members made of C24 timber and gusset plates made of birch plywood, aluminum, and steel. Screws were used as fasteners for five test groups and adhesive was used for one group. The influence of different reinforcement techniques including reinforcement screws and added aluminum sheets was studied.The results showed a ductile failure behavior for all test groups except for the group where adhesive was used. However, a decrease of ductility was observed for groups were aluminum sheets were used on the outsides of the mid placed plywood gusset plate. A 12-17 % increase in capacity was observed due to the presence of aluminum sheets. The reinforcement screws had no significant effect on the capacity. However, the presence of reinforcement screws did lead to a reduction in scatter both regarding capacity and stiffness.
17
Gikonyo, Joan, and Pierre Modig. "Parameterized and Adaptive Modelling of Mechanical Connections in Timber Frame Structures." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-77189.
Full textAbstract:
This study investigates the global stiffness of a timer frame structure under wind loading using the finite element method by creating parameterized script files. Of key interest was the accuracy of the global stiffness determined from an adaptive 3D beam model in comparison to a 2D beam model and, the stiffness of a 3D beam model when subjected to different types of bracing in the presence of internal bracing provided by a lift shaft structure. Investigation of contact forces on the surfaces between the fastener and the timber at the connection was carried out and a design check for the specified bolts shear capacity done with respect to Eurocode 5. A 3D adaptive connection was created for a 2D frame model and the stiffness of the structure was studied. A comparison of the maximum displacement of the structure in the x direction, under the same wind loading, spring stiffness and boundary conditions, with a 2D beam structure without the adaptive connection initially showed a difference in the displacement. This implied that the rotational stiffness in the beam model was greater than that of the adaptive connection created. Therefore after altering the rotational stiffness of the beam model to achieve similar displacement as in the adaptive model, the rotational stiffness of the created connection was found to be 33.4 · 106Nm. The study also determined the contact forces generated at the surfaces between the fasteners and the timber using the finite element method to integrate over the surfaces and calculate the forces. The results were generated using the History Output in the step module. The only disadvantage of acquiring the contact forces was that, the contact surface simulation caused larger run times for the model to complete the time step. For the adaptive model it took 18 hours to complete each step. Further investigation into the stiffness of a 3D frame structure was conducted. The model of the 3D structure was created by a parameterized script which makes it easy to change input variables such as number of internal walls, geometry in x-z-plane, number of storeys, cross-sectional dimensions, material properties number of diagonals and location of diagonals. A variety of models with different conditions was analyzed. This showed that stiffness has a major impact on the magnitude of reaction forces and displacements.
18
Fang, Demi L. "Timber joinery in modern construction: Mechanical behavior of wood-wood connections." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127868.
Full textAbstract:
Thesis: S.M. in Building Technology, Massachusetts Institute of Technology, Department of Architecture, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (pages [107]-112).
Timber joinery is a method of geometrically interlocking timber elements prevalent in historic cultures around the world, including North America, Europe, and East Asia. The use of joinery as structural connections faded with the development of metallic screws and nails. Two recent developments offer the opportunity to revive this historic timber connection type: 1) the increasing desire to reduce embodied carbon in buildings by replacing more components with timber as a low-carbon structural material, and 2) recent digital fabrication capabilities which enable the precise milling of complex geometries as an alternative to the time- and labor-intensive handiwork required previously. How can joinery connections be designed in modern structural joints? Can we quantify the sustainability advantage of using these all-timber joints in lieu of the modern convention of metallic fasteners? This thesis addresses both questions as applied to the Japanese Nuki joinery type, though the workflows may be applied to any joinery geometry. First, the rotational stiffness of the Nuki joint is characterized and cross-verified using multiple methods. Second, the embodied carbon of a gravity frame using Nuki joints is compared to that of a gravity frame using conventional metallic fasteners. The use of Nuki joints not only eliminates the use of steel and aluminum but also provides rotational stiffnesses that enable smaller beam sections to be used. It is shown that gravity frames designed with Nuki joints could reduce embodied carbon by over 70% compared to gravity frames designed using conventional beam hanger connections. The findings make a case for all-timber joinery connections to be implemented as a sustainable alternative to conventional metallic connections used in modern timber construction.
by Demi L. Fang.
S.M. in Building Technology
S.M.inBuildingTechnology Massachusetts Institute of Technology, Department of Architecture
19
Schneider, Johannes. "Conventional and novel timber steel hybrid connections: testing, performance and assessment." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54140.
Full textAbstract:
The combination of timber and steel for residential hybrid buildings is an unconventional approach to date. The challenge of a hybrid structure is the link between the individual materials. The focus of this research is the connection between steel frame and the infill wall.
Over 100 conventional bracket-type connections with various combinations of bracket and fasteners with cross-laminated timber were tested, investigated and assessed for damage under seismic loading protocols for a hybrid application. An energy-based formulation according to Krätzig was applied to calculate the development of the damage index, and the resulting index was validated with visual observation.
Six of the connections were modeled in OpenSees. For the modeling, a CUREE-10 parameter model was chosen to reproduce the test curves. The load-displacement results from both test and model were analyzed; the first method according to ASTM standards, where the envelope curve of the hysteretic results are considered and plotted in an equivalent energy elastic-plastic curve (EEEP). The second analyzing method used, was Krätzig’s damage accumulation model. Throughout all six combinations and both loading directions (parallel- and perpendicular-to-the-grain) a major difference was found in the analyzing methods. The EEEP curve roughly approximates the performance but with the damage accumulation method showed that analysis of the subsequent cycles is required to better reflect the empirical performance of the connections. To avoid the extensive destruction of a bracket type connection after completion of seismic loadings, a new approach was chosen. It was found that a tube connection can obtain comparably similar strength results as a conventional bracket connection. The computed mechanical properties of bracket-type and tube-type connections were compared and evaluated. The new tube connection showed great potential for future timber-steel hybrid structures and their connecting challenge. A total of 27 connection assemblies were tested under quasi-static monotonic and reversed cyclic loads. The tube connections showed two major differences when compared to traditional bracket connections: i) the completely linear elastic behaviour at the beginning, and ii) the continued load increase after yielding. Both phenomena are founded in the geometry of that connector effectively making the novel connector a very promising alternative.Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate
20
Viau, Christian. "Investigation and Optimization of Connections in Timber Assemblies Subjected to Blast Loading." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40405.
Full textAbstract:
The majority of research on high strain-rate effects in timber structures has been limited to the study of the load-bearing members in isolation. Limited work has been conducted on timber connections and full-scale timber assemblies under blast loading, and these have generally been constrained to qualitative observations. In North America, the increasing prevalence of mid- and high-rise timber structures makes them susceptible to blast effects. In addition, questions remain on how to design and optimize these timber assemblies, including the connections, against blast loads, due in part to the limitations on comprehensive design provisions.
The effects of far-field blast explosions were simulated using the University of Ottawa shock tube. A total of fifty-eight dynamic tests were conducted on connection-level and full-scale specimens. The research program aimed to investigate the behaviour of heavy-timber connections when subjected to simulated blast loads. The experimental results showed that connections with a main failure mechanism consisting of wood crushing experienced significant increases in dynamic peak load when compared to the static peak load. In contrast, connections where steel yielding and rupturing occurred experienced no statistically significant increase in dynamic peak load. Full-scale glulam specimens with bolted connections designed to yield via wood crushing and bolt bending performed better than those with overdesigned connections. Bolted connections which failed in splitting led to premature failure of the glulam assembly. Reinforcement with self-tapping screws allowed these bolted joints to fail in a combination of bolt yielding and wood crushing, and provided more ductility when compared to unreinforced specimens. Specially designed energy-absorbing connections significantly increased the energy dissipation capabilities of the timber assemblies. The basis of these connections was to allow for connection yielding while delaying failure of the wood member. This was achieved via elastoplastic connection behaviour, which effectively limited the load imparted onto the wood member. Based on the experimental results, limitations in the current Canadian blast provisions were highlighted and discussed. A two-degree-of-freedom blast analysis software was developed and validated using full-scale and connection-level experimental results and was found to adequately capture the system response with reasonable accuracy. Sensitivity analyses regarding the applicability of using single-degree-of-freedom analysis were presented and discussed.
21
Gutshall, Scott T. "Monotonic and cyclic short-term performance of nailed and bolted timber connections." Thesis, Virginia Polytechnic Institute and State University, 1994. http://hdl.handle.net/10919/50106.
Full textAbstract:
This paper presents the results of testing to determine the appropriateness of the seismic load duration factor and to investigate the possible effect of previous load history from cyclic loading on connection reserve capacity and ductility. The single shear nail and bolt connection types tested represent common connection geometries used in wood construction in the United States. The results of two methods of fully reversing cyclic loading of connections are presented.
The first method was a load-controlled test with the applied cyclic loads acting at specified percentages above current nominal design values. The sets of specimens were then ramped to failure and the results were compared to a monotonic control set of specimens to determine if any reduction in connection capacity or ductility had occurred as a result of the cyclic loading. From the load-controlled cyclic testing, it was found that previous cyclic loading at load levels as high as twice current nominal design loads did not adversely affect connection capacity.
The second cyclic loading method was a displacement-controlled test that involved successive phases at increasing displacement levels. Each phase consisted of a peak displacement, followed by a series of three decay cycles, then by a series of three cycles at the original peak displacement, the third of which is used to determine the stabilized system. The process is repeated at increasing incremental levels of displacement. The phased displacement stabilized load-displacement curve was fit to an equivalent energy elastic-plastic system for determination of connection parameters. Results from the two cyclic test methods, and from monotonic testing, indicate that the current load duration factor for wind and seismic loading is justified.Master of Science
incomplete_metadata
22
van, Beerschoten Wouter Adrian. "Structural Performance of Post-tensioned Timber Frames under Gravity Loading." Thesis, University of Canterbury. Department of Civil and Natural Resources engineering, 2013. http://hdl.handle.net/10092/8735.
Full textAbstract:
A new structural system for multi-storey timber buildings has been developed over the last seven years at the University of Canterbury. The system incorporates large timber structural frames, whereby semi-rigid beam-column connections are created using post-tensioning steel tendons. This system can create large open floor plans required for office and commercial buildings.
Several material properties of the engineered timber used were determined based on small-scale experimental testing. Full-scale testing of beams, connections and frames resulted in a more comprehensive understanding of the behaviour of such systems. Numerical, analytical and framework models also led to the development of design equations and procedures which were validated with the acquired experimental data.
23
Johnsson, Helena. "Plug shear failure in nailed timber connections : avoiding brittle and promoting ductile failures /." Luleå : Univ, 2004. http://epubl.luth.se/1402-1544/2004/03.
Full text
24
Richardson, Benjamin Lee. "Examination of the Lateral Resistance of Cross-Laminated Timber in Panel-Panel Connections." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/56969.
Full textAbstract:
Cross-Laminated Timber (CLT) combines layers of dimension lumber in alternating grain direction to form a mass timber panel that can be used to create entire wall, floor and roof elements. The viability of CLT as an element to resist lateral forces from racking has been of great interest (Dujic et al. 2004, Blass and Fellmoser 2004, and Moosbrugger et al. 2006). However, most research to date has been conducted on full-scale wall panels connected with proprietary fasteners according to European Test Methods. Little research has focused on non-proprietary connections, including nails, bolts and lag screws. The behavior of CLT full-scale wall panels is dependent upon the individual connection properties including the panel-panel connections between adjoining CLT panels within the wall.
The purpose of this research is to evaluate the behavior of three small-scale CLT connection configurations using non-proprietary fasteners. Three different connections -LVL surface spline with lag screws, half-lap joint with lag screws, and butt joint with a steel plate fastened with nails - were tested in both monotonic and cyclic tests. In all, 30 connection tests were conducted, with 15 monotonic test and 15 cyclic tests. Connection strength, stiffness, and ductility were recorded for each connection. Experimental values were compared to National Design Specification for Wood Construction, or NDS (AWC 2012) predictions for connection strength.
Nailed steel plate connections yielded much greater loads and behaved in a more ductile manner than did the lag screwed connections. The surface spline and half-lap connections often failed in a catastrophic manner usually due to splitting of the spline and fastener failure. Experimental results were generally lower than predicted by the yield models for the surface spline and steel plate connections. The half-lap connection resulted in higher experimental results than predicted. A discussion of the connection strength for materials with a non-homogeneous grain direction is also included.Master of Science
25
González, Barillas Enrique. "Performance of timber connections with single and multiple glued-in threaded steel rods." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54217.
Full textAbstract:
The experimental research conducted within this thesis project focused on joints composed of softwood glulam members and mild steel glued-in threaded rods. In a first phase, the influence of the embedment length and the rod diameter using three different adhesives was studied to establish performance benchmarks. In the second phase, the investigation focused on the influence of manufacturing defects on the capacity of timber joints with glued-in steel rods. For this purpose, timber joints were manufactured with two different types of defects likely to be encountered during their manufacturing on-site: i) rods placed at an angle to the drill hole instead of being in the joint axis, and ii) rod placed at the edge of the drill hole instead of fully centred. Finally, in the third phase, joints with multiple rods (two, three and four rods) were manufactured and tested. The adhesive type and rod diameter were kept constant and the embedment length and the spacing between rods were varied during this phase. In all phases of this experimental campaign, specimens were tested under uniaxial quasi-static tension loading. The results showed that, for single glued-in rod joints using mild steel threaded rods, a ductile-type of failure can be consistently attained if the embedment length of the rod is long enough (>10d). Furthermore, the results for specimens with bonding defects considered in this study had no significant negative impact on the capacity of the joints if compared to the results obtained in the first experimental phase. Finally, a spacing between rods greater than four times the rod diameter demonstrated to be sufficient to facilitate a ductile steel yielding failure as long as the joints were manufactured with sufficient embedment length (>10d). The results from this study can contribute towards better understanding of the influence that the parameters under investigation have on the performance on timber joints with glued-in rods, as well as to translate this information to promote the development of more studies on further applications such as moment resisting connections.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
26
Merlo, García Ramón. "Glass-fibre reinforcement on steel to timber connections. : A parametric study through FEM modelling on double-shear single-dowelled connections." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-66848.
Full textAbstract:
In a context where timber is gaining popularity as a building material and glass-fibre reinforced composites (GFRC) are becoming more accessible in a wide variety of formats, it is considered appropriate to reconsider the combination of these two materials. Additionally, given the increasing use of laminated timber elements where stiffness and strength are better controlled, attention is drawn back to the connection between elements. For these reasons, it is considered of interest to study reinforcing possibilities for connections within timber structures. This work consists in a parametric study of a single-dowelled connection between a timber part and a slotted-in steel plate, reinforced wirh GFRC plates glued into the timber slot at both sides of the steel plate. The study was carried out through simulations in ABAAUS Finite Element Analysis software considering the effect of specimen's geometry and the fibre distribution within the GFRC. Results show the increase of stiffness for the different configurations and give an insight of what can be expected from such type of reinforcements.
27
Xu, Shengmin, and Peiwei Tan. "Glued timber connections : Experimental and numerical study of tension behavior under various influencing parameters." Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-45371.
Full textAbstract:
Glued connections are relatively new in structural timber engineering. They are expected to show high connection stiffness as well as a high connection strength compared to mechanical connections e.g. dowel‐type connections.The main aim of this thesis is to characterize the behavior of glued timber connections under pure tension by conducting experiments as well as numerical simulations. Hereby the influence of different parameters is studied such as the geometry (bond-line length and thickness) and the material properties (e.g. adhesives of highly diverse stiffness). Additionally, reference tests on a dowel-type connection are made. The purpose is to see the differences between dowelled and glued connections and to see if there are some advantages in using glued timber connections (the base geometry was chosen acc. to Eurocode 5).Finite element models were created in the software ABAQUS. The models were used to predict the connection stiffness and compare this to the experimental results. In addition, parametric studies were performed on e.g. overlapping lengths. The comparison between experiments and simulations showed good agreement.It was found that glued connections with the adhesives SikaPower-4720 and SikaFast-5215 NT (an epoxy and an acrylate, respectively) had higher stiffness than the dowel connections, whereas connections with the silicone adhesive SikaSil SG-500 had a lower stiffness. A general conclusion drawn from this work is that the glued timber connections simulated in this project should also be suitable for application to complex connections and situations involving other loading situations than pure tension.
28
Reshke, R. G. "Bolted timber connections loaded perpendicular-to-grain, influence of joint configuration parameters on strength." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0005/MQ44856.pdf.
Full text
29
Ronstad, David, and Niklas Ek. "Study of glue-laminated timber connections with high fire resistance using expanded steel tubes." Thesis, Luleå tekniska universitet, Byggkonstruktion och brand, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-70788.
Full textAbstract:
A key factor regarding fire safety of timber buildings is the performance of connections between the structural elements, since this determines the load-carrying capacity of the structure. Traditional timber connections do generally perform poorly in a fire compared to surrounding parts since the joints often consist of exposed metal parts and cavities which locally decreases the fire resistance. This weakness does often lead to the appliance of gypsum which removes the aesthetic appearance of timber. Through an innovative timber connection design, the hope is that the failings at elevated temperature are changed from the connection itself to surrounding parts thus increasing the fire resistance to the limits of the connected components. Two types of glue-laminated timber connections have been built and tested at RISE facilities in Borås with the purpose to determine if these could withstand fire exposure for 90 minutes under load. The connections are assembled by expanding hollow steel tubes that clinches the members together and at the same time makes the steel tube yield against the inside of the pre-drilled hole. Pre-stresses are created in the connection during this process that avoids an initial slip if the connection is loaded, which is one of the reasons that this type of connections is suitable in earthquake-prone areas. The joint design results in a significantly increased rotational stiffness, moment capacity and embedded energy of the joint in comparison with conventional timber connections. One of the connections is designed to withstand moment forces. The specimen is built as a beam to beam connection that is subjected to a four-point bending test at both ambient and elevated temperature. The connection withstood 39.5 kNm in ambient temperature and failed after 87 minutes and 6 seconds of fire exposure under load. However, failure in elevated temperature did not occur within the connection, and visual inspection after the test indicated that the steel tubes still were in excellent condition. The connection is therefore expected to have been able to withstand 90 minutes of fire exposure. The other connection is designed to withstand shear-forces and is built as a column to beam connection that is tested at both room temperature and elevated temperature. The connection endured a maximum shear-force of 181.4 kN in ambient temperature, approximately 30 kN higher than previously performed test with identical setup, and failed after 113 minutes of fire exposure under load. The failure in elevated temperature did however not occur inside the connection. The testing is limited to unprotected connections consisting of glue-laminated timber which are tested in accordance with ISO 834.En nyckelfaktor för brandsäkerheten i träbyggnader är prestandan hos förbanden mellan konstruktionselementen eftersom dessa bestämmer konstruktionens lastbärande kapacitet. Traditionella träförband har i allmänhet dåligt brandmotstånd i förhållande till omgivande delar, detta eftersom förbanden ofta består av exponerade metalldelar och kaviteter som lokalt försvagar brandmotståndet. Dessa svagheter motverkas ofta genom att montera gips vilket negativt påverkar träets estetiska utseende. Genom en innovativ konstruktion av träförband är hoppet att den svaga punkten vid förhöjd temperatur flyttas från själva anslutningen till omgivande delar, vilket ökar konstruktionens brandmotstånd genom att brandmotståndet då begränsas av prestandan hos de anslutna komponenterna. Två typer av limträförband har byggts och testats vid RISE-anläggningen i Borås med syfte att bestämma om dessa under belastning skulle kunna stå emot brandexponering under 90 minuter. Förbanden monteras genom att expandera ihåliga stålrör som klämmer samman elementen och samtidigt deformeras mot insidan av det förborrade hålet. Förspänningar skapas i förbandet under denna process som förhindrar en primär förskjutning om förbandet är lastat, vilket är en av anledningarna till att denna typ av anslutningar är lämpliga i jordbävningsbenägna områden. Denna konstruktion resulterar i en betydligt ökad rotationsstyvhet, momentkapacitet och inbäddad energi i jämförelse med konventionella träförband. En av anslutningarna är konstruerad för att motstå momentkrafter. Provkroppen är byggd som en balk-balkanslutning som utsätts för ett fyrapunkts böjningstest vid både rumstemperatur och förhöjd temperatur. Anslutningen klarade 39.5 kNm vid rumstemperatur och fallerade efter 87 minuter och 6 sekunder av belastning i förhöjda temperaturer. Brottet i förhöjd temperatur inträffade emellertid inte i anslutningen och den visuella inspektionen som utfördes efter testet indikerade att stålrören fortfarande var i utmärkt skick. Anslutningen bedöms därför ha kunnat motstå 90 minuters brandexponering. Det andra förbandet är konstruerat för att motstå tvärkrafter och är byggt som en pelare-balkanslutning som testas vid både rumstemperatur och förhöjd temperatur. Anslutningen klarade en maximal skjuvkraft på 181.4 kN vid rumstemperatur, cirka 30 kN högre än tidigare utfört test med identisk uppställning, och fallerade efter 113 minuters belastning i förhöjd temperatur. Brottet i förhöjd temperatur inträffade emellertid inte i själva anslutningen. Testerna är begränsade till oskyddade förband bestående av limträ som under brandpåverkan testas enligt ISO 834.
30
Vessby, Johan. "Shear walls for multi-storey timber buildings." Licentiate thesis, Växjö University, School of Technology and Design, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-2420.
Full textAbstract:
Wind loads acting on wooden building structures need to be dealt with adequately in order to ensure that neither the serviceability limit state nor the ultimate limit state is exceeded. For the structural designer of tall buildings, avoiding the possibly serious consequences of heavy wind loading while taking account at the same time of the effects of gravitation can be a real challenge. Wind loads are usually no major problem for low buildings, such as one- to two-storey timber structures involving ordinary walls made by nailing or screwing sheets of various types to the frame, but when taller structures are designed and built, serious problems may arise.
Since wind speed and thus wind pressure increases with height above the ground and the shear forces transmitted by the walls increase accordingly, storey by storey, considerable efforts can be needed to handle the strong horizontal shear forces that are exerted on the bottom floor in particular. The strong uplift forces that can develop on the wind side of a structure are yet another matter that can be critical. Accordingly, a structure needs to be anchored to the substrate or to the ground by connections that are properly designed. Since the calculated uplift forces depend very much upon the models employed, the choice of models and simplifications in the analysis that are undertaken also need to be considered carefully.
The present licentiate thesis addresses questions of how wind loads acting on multi-storey timber buildings can be best dealt with and calculated for in the structural design of such buildings. The conventional use of sheathing either nailed or screwed to a timber framework is considered, together with other methods of stabilizing timber structures. Alternative ways of using solid timber elements for stabilization are also of special interest.
The finite element method was employed in simulating the structural behaviour of stabilizing units. A study was carried out of walls in which sheathing was nailed onto a timber frame. Different structural levels were involved, extending from modelling the performance of a single fastener and of the connection of the sheathing to frame, to the use of models of this sort for studying the overall structural behaviour of wall elements that possess a stabilizing function. The results of models used for simulating different load cases for walls agreed reasonably well with experimental test results. The structural properties of the fasteners binding the sheathing to the frame, as well as of the connections between the members of the frame were shown to have a strong effect on the simulated behaviour of shear wall units.
Regarding solid wall panels, it was concluded that walls with a high level of both stiffness and strength can be produced by use of such panels, and also that the connections between the solid wall panels can be designed in such a way that the shear forces involved are effectively transmitted from one panel to the next.
31
Tannert, Thomas. "Structural performance of rounded dovetail connections." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/694.
Full textAbstract:
The structural performance of Rounded Dovetail Connections (RDC) has been studied experimentally and numerically to provide information needed for connection structural design.
RDC are mainly used to transfer vertical shear forces, but test results show that they can carry considerable load in tension and bending. Geometric parameters, such as dovetail flange angle and dovetail height are shown to significantly effect affect the structural performance of RDC. Results show that it is impractical to determine a set of empirical equations to describe the structural performance of RDC based on basic wood material properties. RDC manufactured and tested with low and constant moisture content outperformed those evaluated under other climatic conditions, and test results demonstrate that RDC should be produced at low machine speed and with minimal a gap between the connecting members. RDC in laminated strand lumber have higher capacity and fail under larger deformations compared to RDC in western hemlock.
A three-dimensional finite element method model is presented and validated with experimental tests. Good agreement is achieved between the load deformation response predicted by the model and the experimentally observed load deformation response. Therefore the model is deemed suitable for estimating the stresses needed to develop failure criteria. A failure criterion for the analysis of RDC is presented taking into account size effect in the strength of wood. Based on the experimental and numerical studies, a design equation for RDC is presented that provides the engineering community with a new design tool. Finally, self tapping screws as reinforcement have been studied and are shown to significantly improve the structural performance of RDC under vertical shear loading.
32
Zhu, Hong. "Experimental investigations of residual and fatigue capacities of timber connections with glued-in FRP rods." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50164.
Full textAbstract:
Well-designed and executed glued-in rod connections can provide excellent structural performance in terms of strength, stiffness, and efficiency in load transfer. The pull-out residual and fatigue capacity of timber connections with glued-in Glass Fibre Reinforced Polymer (GFRP) rods bonded by Polyurethane adhesive (PUR) have been studied extensively. Previous research conducted at the University of British Columbia in Vancouver (UBC) investigated the impact of anchorage length and rod diameter on the performance of glued-in GFRP rods glulam joints. Each of the test specimens consisted of two glued-in rod connections, with one rod inserted in each end-grain face. One side joint failed brittle but the other side joint survived under quasi static tensile test. The first rod connection to fail could be called the broken side or first side and the unbroken rod could be called the surviving side or second side. However, universal agreement on the design of glued-in rod connections has not yet been reached.The experimental work for this thesis was performed in the Timber and Material Laboratories at UBC. In the pull-out tension test, which is a follow-up test to previous study regarding the geometric characters of the glued-in GFRP rods joints, the short term tensile capacities of the surviving sides of symmetrical glued-in rod test specimens were determined. A total of 25 test series were tested with 5 replicates each where the anchorage length and the rod diameter were the same. The surviving side capacities were not always higher than the first sides, possibly explained by damage caused through the previous quasi static tensile tests. Subsequently, the average capacities from each series based two sides data were compared to the calculated predictions from different design approaches and it was shown that the German Design Code could best predict the capacity of symmetrical glued-in-rod connections.The fatigue tests were conducted based on the novel “PYHBAL” loading protocol which involves two single step tests and one load increase test. Compared to conventional fatigue tests, the “PHYBAL” method can provide fast and economic fatigue estimation. The fatigue capacity of the glued-in GFRP rod joints was approximately 65% of short-term capacity.Forestry, Faculty of
Graduate
33
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.
Full textAbstract:
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.
34
Vessby, Johan. "Analysis of shear wallsfor multi-storey timber buildings." Doctoral thesis, Linnéuniversitetet, Institutionen för teknik, TEK, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-11489.
Full textAbstract:
This doctoral thesis addresses questions of how wind loads acting on multistoreytimber buildings can be dealt with by structural design of such buildings.The conventional use of sheathing either nailed or screwed to a timberframework is considered, together with other stabilizing structures such ascross-laminated timber panels.The finite element method was employed in simulating the structuralbehaviour of stabilizing wall units. A series of studies was carried out of walls inwhich the sheathing was nailed to a timber frame. Different structural levelswere studied starting with modelling the performance of single sheathing-toframingconnections, to the use of models for studying the overall structuralbehaviour of walls. The results of calculations using models for simulation ofwalls subjected to different loading agree reasonably well with experimentalresults. The structural properties of the connections between the sheathing andthe frame, as well as of the connections between the members of the frame,were shown to have a substantial effect on the simulated behaviour of shearwall units. Both these types of connections were studied and described inappended papers.Regarding cross-laminated timber wall panels, it was concluded that walls witha high level of both stiffness and strength can be produced by the use of suchpanels, and also that the connections between the solid wall panels can bedesigned in such a way that the shear forces involved are transmitted from onepanel to the next in an efficient manner.Other topics in the thesis include the properties of connections between shearwalls and the rest of the building. Typically high tension forces occur at specificpoints in a timber structure. These forces need to be transmitted downwards inthe structure, ultimately connecting them to the substrate. A lap-joint that maybe used for this purpose has been studied using generalized Volkersen theory.Finally the maximum capacity of a conventional rail to substrate connection hasbeen examined using linear and nonlinear fracture mechanics.
35
Gustafsson, Johan, and Jakob Myhrberg. "Expansion Joints in timber bridges : Mechanical behavior under external loading." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-105321.
Full textAbstract:
To design a bridge, different typologies of construction materials can be used. All materials have in common that deformations occur due to different events, such as externalloading, temperature- and moisture variations. To allow these kinds of deformations,Expansion Joints (EJs) are used in the structure. In timber bridges, these joints haveturned out to be a complex construction detail, due to problems related to their strengthand moisture capacity. The purpose of this thesis is to overview design codes and tostudy the mechanical behavior of Nosing EJs in a roadway timber bridge under externalloading. The aim is to identify critical actions and provide an alternative design of thestudied EJ. The aim is also to create a Finite Element (FE) model of the EJs and carryout calculations according to the design codes. To achieve this, literature studies, designcalculations and FE-simulations were performed. It turned out that there were lack ofearlier studies within this field. Therefore, studies which treats EJs in bridges with othermaterial than timber were considered. The results from the simulations indicated thatthe steel components in EJs are the most exposed parts in the detail. It also turned outthat an eventual failure can transferred away from the screws to the parts consideredmore favorable in the EJ.
36
Albright, Dustin Graham. "The Effects of Bolt Spacing on the Performance of Single-Shear Timber Connections Under Reverse-Cyclic Loading." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/34324.
Full textAbstract:
Much previous experimentation related to wood structures has employed monotonic loading to replicate static situations. However, instances of natural hazards have raised interest in the response of structural connections to dynamic loads. This increased interest led the Consortium of Universities for Research in Earthquake Engineering (CUREE) to develop a testing protocol for reverse-cyclic loading, which involves cycling loads through zero in order to test specimens in both tension and compression. With the CUREE testing protocol in place, recent research has been devoted to understanding the effects of reverse-cyclic loading on multiple-fastener connections.
Experimentation by Heine (2001), Anderson (2002), Billings (2004) and others contributed to a better understanding of bolted connection behavior under reverse-cyclic loading. However, some questions remained. Billings was unable to consistently produce yield modes III and IV, meaning that her suggested bolt spacing of seven times the bolt diameter (7D) could not be applied to connections subject to these yield modes without further testing. In addition, the work of Anderson and Billings raised questions regarding the proper measurement of bending yield strength in bolts and the relationship between the bending yield strength and the tensile yield strength. These topics are each addressed by this project and thesis report.
Results of the connection testing presented in this report can be used in conjunction with the work of Anderson and Billings to critically evaluate the 4D between-bolt spacing recommended by the National Design Specification (NDS) for Wood Construction (AF&PA, 2001). Results of the bolt testing provide a supplement to the search for a reliable method for the measurement of bending yield strength in bolts.Master of Science
37
Cote, Dominic. "Effect of Realistic Boundary Conditions on the Behaviour of Cross-Laminated Timber Elements Subjected to Simulated Blast Loads." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36993.
Full textAbstract:
Cross-laminated timber (CLT) is an emerging engineered wood product in North America. Past research effort to establish the behaviour of CLT under extreme loading conditions has focussed CLT slabs with idealized simply-supported boundary conditions. Connections between the wall and the floor systems above and below are critical to fully describing the overall behaviour of CLT structures when subjected to blast loads. The current study investigates the effects of “realistic” boundary conditions on the behaviour of cross-laminated timber walls when subjected to simulated out-of-plane blast loads.
The methodology followed in the current research consists of experimental and analytical components. The experimental component was conducted in the Blast Research Laboratory at the University of Ottawa, where shock waves were applied to the specimens. Configurations with seismic detailing were considered, in order to evaluate whether existing structures that have adequate capacities to resist high seismic loads would also be capable of resisting a blast load with reasonable damage. In addition, typical connections used in construction to resist gravity and lateral loads, as well as connections designed specifically to resist a given blast load were investigated.
The results indicate that the detailing of the connections appears to significantly affect the behaviour of the CLT slab. Typical detailing for platform construction where long screws connect the floor slab to the wall in end grain performed poorly and experienced brittle failure through splitting in the perpendicular to grain direction in the CLT. Bearing type connections generally behaved well and yielding in the fasteners and/or angles brackets meant that a significant portion of the energy was dissipated there reducing the energy imparted on the CLT slab significantly. Hence less displacement and thereby damage was observed in the slab. The study also concluded that using simplified tools such as single-degree-of-freedom (SDOF) models together with current available material models for CLT is not sufficient to adequately describe the behaviour and estimate the damage. More testing and development of models with higher fidelity are required in order to develop robust tools for the design of CLT element subjected to blast loading.
38
Knudson, Caleb Jesse. "Investigation into the effects of variable row spacing in bolted timber connections subjected to reverse cyclic loading." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Thesis/Fall2006/c_knudson_110906.pdf.
Full text
39
Bezzi, Stefano. "Ductility of cross-laminated timber buildings, influence of low-cycle fatigue strength and development of an innovative connection." Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/258010.
Full textAbstract:
This thesis is mainly focused on the seismic behaviour of cross laminated timber (CLT) buildings. The document can be subdivided into three main sections closely related to each other.
In the first part, after a short introduction on the state of the art on timber buildings regarding the constructive and legislative issues, the behaviour of CLT buildings is presented. The research is focused on the study on single shear-walls, on the multi-storey single-walls and on the behaviour of the whole buildings. The analyses are performed in order to assess the ductility level achievable by a CLT building as a result of different choices for the ductility of the connections at the foundation level. In order to estimate the ductility level, a large number of non-linear analyses were performed. This was possible thanks to a Matlab code, specifically developed, which allowed to reduce the computational burden. The results are used to evaluate a reliable set of behaviour factors to be applied in the seismic design of CLT buildings.
In the second part of thesis, the low-cyclic fatigue strengths for different typologies of dissipative timber connections are presented. The low-cyclic fatigue strength represents a key-parameter in the assessment of the seismic behaviour of timber connections. In fact, high values of ductility associated with low values of strength degradation ensure a remarkable and reliable energy dissipation without a significant loss of strength. Despite the current version of chapter 8 of Eurocode 8 requires specific values of seismic demand for timber connections in terms of low-cyclic fatigue strength, no specific provision is reported to this regard in the European Standard for the cycling testing of timber connections and assemblage in seismic design (EN 12512). In This Standard the ductility capacity and the impairment of strength are calculated as separate mechanical parameters. For this reason, a proposal of revision of European Standard EN12512 is presented and discussed.
The third and last part of the thesis describes an innovative connection for CLT buildings. This innovative connection was originally developed in order to absorb both traction and shear actions. Furthermore, a good performance has been obtained in terms of low-cyclic fatigue strength and ductility, with the aim of conceiving a connection able of satisfy the requirements of the current seismic European Standard. The design of this new connection was an iterative process, starting from some simplified numerical models. After some improvements, it was possible to obtain the expected performance levels. The strength and rigidity of the designed connection were initially obtained through numerical analysis, and then compared with the results of physical tests carried out in the Materials and Structures Testing Laboratory (MSTL), that is a part of the Department of Civil, Environmental and Mechanical Engineering (DICAM) of the University of Trento.
40
Billings, Mary Anna. "Investigation of the Effects of Spacing between Bolts in a Row in a Single-Shear Timber Connection Subjected to Reverse Cyclic Loading." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/35757.
Full textAbstract:
This thesis presents the results of testing to determine if spacing between bolts in a multiple-bolt, single-shear connection subjected to natural hazard loading affects seven strength and serviceability parameters: maximum load, failure load, E.E.P. yield load, 5% offset load, elastic stiffness, E.E.P. energy, and ductility ratio. This research also determines if a statistical difference exists between previously published research for 4D spacing as compared to results produced by this research for five alternate spacings: 8D, 7D, 6D, 5D, and 3D. Finally, this research determines which of the spacings examined: 8D, 7D, 6D, 5D, 3D; produced the most optimal results for each examined strength and serviceability parameter where optimization is based on economy and performance.
Three connection configurations with five different spacings between bolts were subjected to reverse cyclic loading for a total of one hundred and fifty tests. The reverse cyclic protocol was based on recommendations by the Consortium of Universities for Research in Earthquake Engineering (CUREE) for testing woodframe structures. The same connection configurations were also subjected to monotonic loading for an additional forty-five tests.
Results of this research can be used to evaluate the current design recommendation presented in the National Design Specification (NDS) for Wood Construction (AF&PA, 2001) of spacing bolts at four times the bolt diameter (4D) to determine if a different spacing should be recommended for natural hazard loading conditions.
Master of Science
41
Mahjoub, Musaab. "FE modeling of glulam beams with mechanical slotted-in steel plate connections." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-105430.
Full textAbstract:
The mechanical behavior of timber beams with a slotted-in steel plate is studied by creating anumerical model that can simulate the global bending behavior and the load carrying capacity aswell as the nonlinear plastic fastener force distribution. Experimental results from Material TestingInstitute (MPA), University of Stuttgart were compared with simulation results done at LinnaeusUniversity. The modeling of the timber beams and the mechanical connections is performed withshell, beam, and nonlinear connector elements. Three models were created, where the first modelwas a single-dowel double shear joint model to study the ability to use structural elements in themodeling of the test beams. It was used to simulate some of the basic failure modes in Eurocode5 (EC5). The second model was a beam model used to simulate the bending of a jointed timberbeam with a slotted-in steel plate, where only two connector elements are used to model the jointbehavior of each dowel group. It can be used to study the global deflection and the load carryingcapacity of the timber beams. The third model was a combined beam-shell model where the beamelements are used for the timber parts outside the connection area and the fasteners, while the shellelements are used for the slotted-in steel plate and the timber parts within the connection area.It uses two nonlinear connectors to connect each dowel to the wood and pure coupling to connectthe dowels to the slotted-in steel plate. This model can simulate same things as model two andalso the development of the elasto-plastic shear force distribution in all the dowels. All the modelswere created using parameterized Python scripts, which makes it possible to easily change differentinput parameters.Most of the modeling results show good agreement with both experimental results and with calculated load carrying capacity results for individual dowels according to EC5. The use of thesestructural elements (beam, shell, and connector elements) was found to result in much less computational time compared to the use of solid elements.
42
Reynolds, Thomas Peter Shillito. "Dynamic behaviour of dowel-type connections under in-service vibration." Thesis, University of Bath, 2013. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608327.
Full textAbstract:
This study investigated the vibration serviceability of timber structures with dowel-type connections. It addressed the use of such connections in cutting-edge timber structures such as multi-storey buildings and long-span bridges, in which the light weight and flexibility of the structure make it possible that vibration induced by dynamic forces such as wind or footfall may cause discomfort to occupants or users of the structure, or otherwise impair its intended use. The nature of the oscillating force imposed on connections by this form of vibration was defined based on literature review and the use of established mathematical models. This allowed the appropriate cyclic load to be applied in experimental work on the most basic component of a dowel-type connection: a steel dowel embedding into a block of timber. A model for the stiffness of the timber in embedment under this cyclic load was developed based on an elastic stress function, which could then be used as the basis of a model for a complete connector. Nonlinear and time-dependent behaviour was also observed in embedment, and a simple rheological model incorporating elastic, viscoelastic and plastic elements was fitted to the measured response to cyclic load. Observations of the embedment response of the timber were then used to explain features of the behaviour of complete single- and multiple-dowel connections under cyclic load representative of in-service vibration. Complete portal frames and cantilever beams were tested under cyclic load, and a design method was derived for predicting the stiffness of such structures, using analytical equations based on the model for embedment behaviour. In each cyclic load test the energy dissipation in the specimen, which contributes to the damping in a complete structure, was measured. The analytical model was used to predict frictional energy dissipation in embedment, which was shown to make a significant contribution to damping in single-dowel connections. Based on the experimental results and analysis, several defining aspects of the dynamic response of the complete structures, such as a reduction of natural frequency with increased amplitude of applied load, were related to the observed and modelled embedment behaviour of the connections.
43
Alcântara, Segundinho Pedro Gutemberg de [UNESP]. "Análise teórico-experimental de um tabuleiro misto madeira-concreto composto por vigas circulares." Universidade Estadual Paulista (UNESP), 2005. http://hdl.handle.net/11449/91482.
Full textAbstract:
Made available in DSpace on 2014-06-11T19:25:21Z (GMT). No. of bitstreams: 0
Previous issue date: 2005-02-14Bitstream added on 2014-06-13T19:12:02Z : No. of bitstreams: 1
alcantarasegundinho_pg_me_ilha.pdf: 4485630 bytes, checksum: 0e58733013f71fa0d93bb68c2fdabebb (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O estudo em estruturas mistas é dedicado ao emprego do material madeira-concreto em estruturas de pontes, mais precisamente no seu tabuleiro. No entanto, a aplicação desse material no Brasil não está regulamentada por normas que permitam ao engenheiro civil fazer sua aplicação nas estruturas correntes. Com a proposta de viabilizar o uso desse material madeira-concreto esse estudo vem contribuir com um melhor entendimento do comportamento físico da ligação entre os materiais madeira e concreto. O estudo dessa ligação foi realizado quantificando o módulo de deslizamento em corpos-de-prova do tipo push-out, vigas T e tabuleiro de madeira-concreto. Os resultados experimentais do módulo de deslizamento obtidos por esses três tipos de ensaios foram comparados com os resultados obtidos teoricamente pelo Eurocode 5 (1993). Também, no seguinte estudo foi feito uma simulação numérica do tabuleiro de madeira-concreto usando um programa para análise estrutural baseado no Método dos Elementos Finitos (MEF). Na conclusão dessa pesquisa verificou-se que o comportamento estrutural desse material misto pode-ser calculado usando o Eurocode 5 (1993) e o Método dos Elementos Finitos (MEF).
The study of mixed structures is dedicated to the use of timber-concrete material in bridges' structures, more precisely in its tray. However, the application of this material in Brazil is not regulated by standards that allow the civil engineer to make its application in the current structures. With the proposal to make possible the use of this timber-concrete material this study contributes to understand better the physical behavior of the linking between wood and concrete. The study of this connection was carried through quantifying the slip's module in specimens of push-out type, T beams and timber-concrete's tray. The experimental results of the slip's module from these three kinds of tests had been compared with the results obtained theoretically for Eurocode 5 (1993). Also, in the following study it was made a mathematical simulation of the wood-concrete's tray using a numerical analysis' program based on the Finite Elements' Method (MEF). In the conclusion of this research it was verified that the structural behavior of this mixed material can to be calculated using Eurocode 5 (1993) and the Method of the Finite Elements (MEF).
44
Baena, Juliano Silveira. "Comparação dos critérios de dimensionamento de ligações por pinos metálicos (parafusos) em estruturas de madeira." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-21122015-105438/.
Full textAbstract:
Um dos tipos de ligação mais comum em estruturas de madeira é aquele feito por meio de parafusos solicitados transversalmente (pino metálico). A revisão da ABNT NBR:7190 de 1997, que introduziu os conceitos do Método dos Estados Limites, apresentou alteração nos critérios de dimensionamento dessas ligações, levando a resultados diferentes em relação à norma anterior, de 1982, de acordo com o meio técnico-científico. Nesse contexto, o objetivo deste trabalho foi realizar uma comparação dos critérios de dimensionamento das normas ABNT NBR:7190, versões 1997 e 1982, com as normas EUROCODE 5: 2004, LRFD: 1996, AS: 1994, que possuem grande tradição na utilização de estruturas de madeira. Após a realização da comparação teórica entre os critérios, foi realizada experimentação em modelos de ligação, para a situação com maior divergência. Para pequenas relações entre a espessura da peça de madeira e o diâmetro do pino, os resultados obtidos na comparação teórica indicaram que os valores de resistência calculados pela ABNT NBR7190: 1997 são inferiores aos calculados pelas outras normas, enquanto que, para valores elevados dessa relação e com madeira de maior resistência, os valores obtidos pela norma brasileira podem ser superiores.Bolts laterally loaded (metal dowel-type) are the most commonly used connectors in timber structures. The review of the NBR: 7190 1997 standard that introduced the concepts of the states limit method showed changes in design criteria of bolts, reaching different results compared to the previous standard, 1982, according to the scientific technician staff. In this context, the aim of this study was to compare the design criteria of NBR standards: 7190, versions 1997 and 1982, and standards of other countries with great tradition in the use of timber structures. After the theoretical comparison of the criteria, an experimental evaluation in connections was done considering the case with greater divergence. For small relationships between the thickness of the timber member and the bolt diameter, theoretical results indicated that the strength values calculated by ABNT NBR7190: 1997 are lower than those calculated by other standards, while for high values of this relationship and wood of higher strength classes, the values obtained by Brazilian standards may be higher.
45
Aslankaya, Güzide. "Influence of joints on the seismic response of traditional timber frames in Turkey." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/668866.
Full textAbstract:
Timber frame structures which constitute an important cultural heritage of many countries, are well known as efficient seismic resistant structures worldwide and are worth to be preserved. Himis is one common traditional Turkish timber system, which consists of a simple timber frame filled with masonry (such as bricks, adobes or stones with mortar), and a masonry ground floor, built on continuous stone foundations. These buildings are usually located in seismic areas.This thesis aims to make a review of the structural performance of Himis timber system under seismic loading, with specific emphasis on joints and following strenghening of joints with CFRP (Carbon fiber reinforced polymer). Due to the seismic demands these timber structures mostly depend on connections, so that the joints have to be evaluated accurately in terms of translational and rotational stiffness and moment resistance. Subsequently, a series of experimental tests on two different types of timber joints (lap joint and mortise-tenon) which are common in Turkish timber structures have been carried out under monotonic and cyclic bending loading. The numerical analysis, FEM (the finite element method) has been performed in order to the calibrate the results from experiments. Finally, a numerical analysis considering semi-rigid joints in traditional timber connections has been performed globally.Las estructuras de madera constituyen un importante patrimonio cultural en muchos países y son conocidas como tipologías estructurales eficientes des del punto de vista sísmico por su resistencia y ductilidad. Himis es uno de los sistemas de madera tradicional más conocidos en Turquía, consistente en marcos en forma de retícula de madera simple, relleno de mampostería en su interior (ladrillos, adobe, o piedras con mortero) en plantas piso, mientras que la planta baja es totalmente de mampostería sobre de una cimentación contínua de piedra. Esta tesis tiene como principal objetivo el de realizar una evaluación de la eficiencia estructural del sistema Himis sometido a cargas sísmicas, mediante la evaluación de la respuesta de las uniones más típicas de madera y su contribución al conjunto. Esta tesis se complementa con un análisis experimental y numérico de la contribución que aporta el refuerzo de dichas uniones mediante fibras de polímeros reforzados CFRP (polímeros reforzados con fibras de carbono). La respuesta de estas estructuras frente a sismo se debe, en parte, a la rigidez y ductilidad de las uniones entre barras de madera, por lo que éstas requieren de una especial atención en términos de rigidez traslacional y rotacional. La investigación lleva a cabo una campaña experimental, cubriendo dos tipologías básicas de uniones tradicionales entre barras de madera en Turquía (junta por solape y de espiga) bajo flexión monotónica y también cíclica. Paralelamente, se evalúan dichas uniones mediante un análisis FEM debidamente calibrado con los resultados de los ensayos experimentales, que permite reproducir el comportamiento global de estas estructuras a partir del grado de rigidez de las uniones con o sin refuerzo.
46
Huang, Qibin, and Anitha Joy. "Compression perpendicular to the grain of Cross-Laminated Timber : Influence of support conditions of CLT on compressive strength and stiffness." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-77339.
Full textAbstract:
Cross-Laminated Timber (CLT) has recently become a popular construction material for building timber structures. One advantage of CLT is, that it can be used as floor, beam and wall element. As the arrangements of layers in CLT is in perpendicular direction to each other, it exhibits remarkable strength properties in both in-plane directions. However, the low stiffness and strength properties in compression perpendicular to the grain hinder application of CLT in high rising building, since forces are usually transferred from the wall elements through floor elements perpendicular to the grain. Thus, the aim of this thesis is to get a thorough understanding of the mechanical properties of such connections for different setups, including wood-wood connections, connections with acoustic layers and connections with screws. In addition, the wall was place at different positions on the CLT-floor element. Mechanical tests and numerical simulations, by means of finite element modelling (FEM) were carried out. CLT floor elements, consisting of 5-layers, were loaded by 3-layered CLT wall elements. Displacement and deformation were continuously measured by Potentiometers/LVDTs and an optical measurement system, respectively. Based on the experimental results compressive strength, slip curve and stiffness of the CLT connections were evaluated. Subsequently, results from FE-modelling were compared with experimental findings, which show a good agreement in elastic stiffness. Experimental results exhibited a pronounced influence of the wall position and connection setup on strength and stiffness. Central position of the wall showed higher mechanical properties than edge position. Highest strength and stiffness were found for screwed connections, where the wood-wood connections showed similar results. Connections with acoustic layers exhibited the lowest mechanical properties.
47
Gomes, Orlando Ferreira. "Estudo das ligações cavilhadas impregnadas com resinas estirênicas empregadas em estruturas de madeira." Universidade de São Paulo, 1996. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-02042018-102638/.
Full textAbstract:
O trabalho tem por finalidade o estudo teórico e experimental de ligações em estruturas de madeira com cavilhas de madeira de seção cilíndrica impregnadas com resinas estirênicas. A impregnação da madeira tem como objetivos: diminuir o processo de degradação, retardação ao fogo, melhorar a estabilidade dimensional e aumentar as propriedades de resistência e elasticidade da madeira. Foram determinados experimentalmente as características de resistência e elasticidade do material e posteriormente realizados ensaios de ligações padronizados com solicitação paralela e normal às fibras. Os resultados dos ensaios mostram aumento na resistência de compressão normal até 292% e aumento de 80% no limite de proporcionalidade da ligação. A madeira utilizada para a impregnação foi o Pinus de reflorestamento.The aim of this work is a theorytical and experimental studies of joints in timber structures with wooden dowels of circular cross section impregnated with styrenic resins. The objetives of wood impregnation are to decrease the deterioration process, to promote fire retardation, to improve dimensional stability and mainly increase the compression strength and stiffiness of wood. The strength and stiffness properties of the material are determined. Standard joints tests are carried out in compression both parallel and perpendicular to grains. The test results increases of compression perpendicular strength up to 292% and the up to 80% proportional limit joint. The wood used for impregnation was Pinus from reforestation sites.
48
Alcântara, Segundinho Pedro Gutemberg de. "Análise teórico-experimental de um tabuleiro misto madeira-concreto composto por vigas circulares /." Ilha Solteira : [s.n.], 2005. http://hdl.handle.net/11449/91482.
Full textAbstract:
Orientador: José Antônio MatthiesenBanca: Renato Bertolino Junior
Banca: Antonio Alves Dias
Resumo: O estudo em estruturas mistas é dedicado ao emprego do material madeira-concreto em estruturas de pontes, mais precisamente no seu tabuleiro. No entanto, a aplicação desse material no Brasil não está regulamentada por normas que permitam ao engenheiro civil fazer sua aplicação nas estruturas correntes. Com a proposta de viabilizar o uso desse material madeira-concreto esse estudo vem contribuir com um melhor entendimento do comportamento físico da ligação entre os materiais madeira e concreto. O estudo dessa ligação foi realizado quantificando o módulo de deslizamento em corpos-de-prova do tipo "push-out", vigas T e tabuleiro de madeira-concreto. Os resultados experimentais do módulo de deslizamento obtidos por esses três tipos de ensaios foram comparados com os resultados obtidos teoricamente pelo Eurocode 5 (1993). Também, no seguinte estudo foi feito uma simulação numérica do tabuleiro de madeira-concreto usando um programa para análise estrutural baseado no Método dos Elementos Finitos (MEF). Na conclusão dessa pesquisa verificou-se que o comportamento estrutural desse material misto pode-ser calculado usando o Eurocode 5 (1993) e o Método dos Elementos Finitos (MEF).
Abstract: The study of mixed structures is dedicated to the use of timber-concrete material in bridges' structures, more precisely in its tray. However, the application of this material in Brazil is not regulated by standards that allow the civil engineer to make its application in the current structures. With the proposal to make possible the use of this timber-concrete material this study contributes to understand better the physical behavior of the linking between wood and concrete. The study of this connection was carried through quantifying the slip's module in specimens of "push-out" type, T beams and timber-concrete's tray. The experimental results of the slip's module from these three kinds of tests had been compared with the results obtained theoretically for Eurocode 5 (1993). Also, in the following study it was made a mathematical simulation of the wood-concrete's tray using a numerical analysis' program based on the Finite Elements' Method (MEF). In the conclusion of this research it was verified that the structural behavior of this mixed material can to be calculated using Eurocode 5 (1993) and the Method of the Finite Elements (MEF).
Mestre
49
Holmberg, Kristian, and Jacob Svensson. "Anslutningar för sammansättning av flera moduler i KL-trä till ett bostadshus." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-76556.
Full textAbstract:
De moduler som tillverkas i dagsläget baseras vanligtvis på traditionellträregelstomme. Det finns dock en möjlighet att istället tillverka moduler i KL-trä.Arbetets mål är att dimensionera infästningar för vertikal och horisontell lastverkanoch utforma infästningarna så att ett rationellt montage av KL-trämoduler möjliggörs.Infästningar som avses dimensioneras är från modul till grund samt från modul tillmodul. Litteraturstudie, platsbesök och intervju ligger till grund för val avinfästningsmetod. Förslaget resulterar i förband med stålplåt och dymlingar,skråskruvning samt förband med laskteknik. I framtida projekt med moduler i KL-träkan detta arbete ligga till grund för infästningsmetoder.The modules currently manufactured are usually based on traditional wood frameconstruction. On the other hand, it is possible to manufacture modules in CLTinstead. The goal of the work is to design connections subjected to vertical andhorizontal load and design the connections so that a rational assembly of CLTmodulesis possible. Connections intended to be designed are from module tofoundation and from module to module. Literature survey, site visits and interviewsform the basis of the choice of attachment method. The proposal results in joints withsteel sheet and dowels, bevel screw, and single surface spline. In future projects withmodules in CLT, this work can be used as a basis for connection methods.
50
Shields, Lance David. "Investigation of Through-Tenon Keys on the Tensile Strength of Mortise and Tenon Joints." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/33971.
Full textAbstract:
A timber frame is a structural building system composed of heavy timber members connected using carpentry-style joinery that may include metal fasteners. A common variant of mortise-and-tenon joints are keyed (or wedged) through-tenon joints. No research on the behavior of wedged joints in timber frames is available. This research provides design knowledge of keyed through-tenon joints from experimental observations and comparisons between mathematical models and experimental measurement. Evaluation of through-tenon keyed mortise and tenon joints was performed by measuring tensile load and stiffness of white oak (Quercus alba) and Douglas-fir (Pseudotsuga menziesii) joints with four- and 11-inch tenons with one and two keys and comparing these results to mathematical models developed from the National Design Specification of Wood Construction (NDS), General Dowel Equations for Calculating Lateral Connection Values (TR-12), and engineering mechanics. Variables included joint species (white oak or Douglas-fir), protruding tenon length (four or 11 inches), and number of keys (one or two). Joints were tested to ultimate load, then model input specimens were cut from tested joints and additional key stock to generate inputs for joint load predictions that were compared to experimental joint load results for validation. Forty joints were tested with white oak keys and six of these joints were retested with ipe (Tabebuia) keys.
Joints with four-inch tenons behaved in a brittle manner with tenon failures. Most joints with 11-inch tenons behaved in a ductile manner with key bending and crushing failures. Joint load and stiffness was similar between white oak and Douglas-fir joints. Joints with 11-inch tenons had greater load and stiffness than with four-inch tenons. Joints with two keys had greater load and stiffness than joints with one key, after normalizing joint load and stiffness responses on key width. Joints retested with ipe keys had greater load than joints originally tested with white oak keys.
Tenon relish (row tear-out) failure was predicted for all joints with four-inch tenons. Horizontal key shearing was predicted for all joints with 11-inch tenons. Ratios of predicted ultimate joint load divided by experimental ultimate joints load (calculated/tested) or C/T ratios were used to validate the models chosen for load prediction. C/T ratios showed that ultimate load model predictions over predicted joint load which was due to occurrence of unpredicted tenon failures and simultaneously occurring key failures where models predicted key failures independently. Design safety factors (DSFs) were developed by dividing experimental ultimate joint load by governing allowable (design) load predictions. C/T ratios and DSFs were most similar between white oak and Douglas-fir joints and most different between joints with one and two keys. Alternative design values (ADVs) were developed for comparison to design load predictions. Comparisons between ADVs and DSFs showed that model predictions were most conservative for joints fastened with denser keys than joint members.Master of Science