Search

This study proposed a novel type of self-centering (SC) timber beam–column connection utilizing shape memory alloy (SMA) bars and investigated its cyclic behavior through experimental and numerical studies. In this SC connection, anchor bars consisting of SMA bars, steel bars, and couplers were utilized to connect the beam and column and achieve SC and energy dissipation capabilities. The configuration of the SC timber beam–column connection and material properties of the SMA bars were first introduced. The cyclic behavior of the SC timber beam–column connection was systematically investigated through experimental and numerical studies. A series of cyclic loading tests were conducted on the SC timber beam–column connection to evaluate its stiffness, SC, and energy dissipation capabilities, and the effect of multiearthquake loading. A detailed finite element model of the timber connection was also built and validated using the experimental results. Results indicated that the timber connection could exhibit a desirable flag-shaped hysteretic behavior, indicating favorable SC and moderate energy dissipation capabilities. The connection remained functional without any repair work after experiencing two consecutive cyclic loads up to 4% drift ratios, demonstrating its potential to withstand multiple seismic events. [ABSTRACT FROM AUTHOR]

In this study, alder, spruce, and beech woods were used for homogeneous symmetric, inhomogeneous symmetric (combined) and inhomogeneous non-symmetric glued laminated timber (glulam) beams glued with resorcinol phenol formaldehyde (RPF) adhesive. The aim of this paper is to determine and compare the modulus of elasticity of glulam beams using three methods, i.e., analytical calculation, numerical model (FEM) and experimental testing. As an additional characteristic, the bending strength (MOR) of the beams was determined during experimental testing. Analytical calculation was used to calculate the modulus of elasticity (MOE) of glued laminated timber based on the knowledge of the modulus of elasticity of solid wood and to estimate the location of the neutral axis during bending. According to calculations, for symmetrical combinations, the deviation from the real neutral axis does not exceed 5%. In the case of the modulus of elasticity, the deviation is an average of 4.1% from that of the actual measured beams. The numerical model includes finite element modelling, where the deflection of the modelled beams can be calculated with a deviation of up to 10%. The last method was experimental testing of glued beams using four-point bending, in which, among homogeneous beams, beech glulam beams achieved the highest MOE and MOR, while alder glulam beams achieved the lowest. The combination of wood species resulted in an increase in both MOE and MOR compared to homogeneous spruce and alder beams. [ABSTRACT FROM AUTHOR]

These elements are innovative and of interest to many researchers for the reinforcement of wooden elements. For the reinforced beam elements, the effect of the reinforcement factor, FRP and steel elastic modulus or FRP and steel arrangement of the reinforcement on the performance of the flexural elements was determined, followed by reading the load-displacement diagram of the reinforced beam elements. The finite element model was then developed and verified with the experimental results, which was mainly related to the fact that the general theory took into account the typical tensile failure mode, which can be used to predict the flexural strength of reinforced timber beams. From the tests, it was determined that reinforced timber beam elements had relatively ductile flexural strengths up to brittle tension for unreinforced elements. As for the reinforcements of FRP, the highest increase in load-bearing capacity was for carbon mats at 52.47%, with a reinforcement grade of 0.43%, while the lowest was for glass mats at 16.62% with a reinforcement grade of 0.22%. Basalt bars achieved the highest stiffness, followed by glass mats. Taking into account all the reinforcements used, the highest stiffness was demonstrated by the tests of the effectiveness of the reinforcement using 3 mm thick steel plates. For this configuration with a reinforcement percentage of 10%, this increase in load capacity was 79.48% and stiffness was 31.08%. The difference between the experimental and numerical results was within 3.62–27.36%, respectively. [ABSTRACT FROM AUTHOR]

Laboratory research of wood–CFRP (carbon fiber reinforced polymer) structural elements, especially beams, is a scientific issue undertaken by many scientists. Research is often complemented with numerical analysis with the use of complex finite element method (FEM) models. Modern FEM software offers models that can reproduce such properties and phenomena as orthotropy and plasticity of wood and CFRP, delamination and mechanical behavior of adhesive layers, and damage of a strengthened element. The author of the paper reproduces numerical laboratory research of a four-point bending test of a glulam beam strengthened with CFRP tape. The main goal of the numerical research is an analysis of how the complexity of the FEM model influences the results of calculations, especially stress, deflection, and bearing capacity of the glulam beam. In some cases, a simpler model can be satisfactory, especially for a structural engineer, who takes into account serviceability limit states (permissible deflection of a structural member) and assumes that stress should not exceed the yield stress of timber. [ABSTRACT FROM AUTHOR]

Timber is one of the fundamental materials of human civilization, it is very useful and ecologically acceptable in its natural environment, and it fits very well with modern trends in green construction. The paper presents innovative hollow glued laminated (GL) timber elements intended for log-house construction. Due to the lack of data on the behavior of the hollow timber section in compression perpendicular to the grain, the paper presented involves testing the compression strength of elliptical hollow cross-section glue-laminated timber specimens made of softwood and hardwood, as well as full cross-section glue-laminated softwood timber specimens. The experimental research was carried out on a total of 120 specimens. With the maximal reduction of 26% compared to the full cross-section, regardless of the type of wood and direction of load, the compression strength perpendicular to the grain of hollow specimens decreases by about 55% compared to the full cross-section, with the coefficient kc,90 equal to 1.0. For load actions at the edge and the middle of the element, kc,90 factors were obtained with a value closer to those obtained for full cross-section, which indicates the same phenomenology, regardless of cross-sectional weakening. At the same time, the factors in the stronger axis are lower by about 10%, and in the weaker axis by about 30% compared to those prescribed by the Eurocode. Experimental research was confirmed by FEM analysis. Comparative finite element analysis was performed in order to provide recommendations for future research and, consequently, to determine the optimal cross-section form of the hollow GL timber element. By removing the holes in the central part of the cross-section, the stress is reduced. The distance of the holes from the edges defines the local cracking. Finally, if the holes are present only in the central part of the element, the behavior of the element is more favorable. [ABSTRACT FROM AUTHOR]

The use of a double-skin façade (DSF) is a quite new approach in the building renovation process, complementing conventional renovation strategies. A double-skin façade is an envelope wall construction that consists of two transparent surfaces separated by a cavity and can essentially improve the thermal and acoustic resistance of the building envelope. The main double-skin wall components are usually composed of a hardened external single glazing pane and a double or triple thermal insulating internal glass pane, which are connected to the frame structure. Recently, many studies have analysed the thermal and acoustic performance of DSF elements, but almost none in terms of structural behaviour, especially in terms of determining the racking resistance of such wall elements. Moreover, with a view to reduce the global warming potential, an eco-friendly timber frame instead of a commonly used steel, aluminium or plastic frame is studied in this analysis. However, structurally combining timber and glass to develop an appropriate load-bearing structural element is a very complex process involving a combination of two materials with different material properties, where the type of bonding can be selected as a crucial parameter affecting the racking resistance range. Since the costs of experiments performed on such full-scale DSF elements are very high and such experiments are time-consuming, it is crucial to develop special mathematical models for analysing the influence of the most important parameters. Therefore, the main goal of this paper is to develop the finite element mathematical model of the studied DSF structural elements with a highly ecological solution by using a timber frame. In the second step, the developed model is further implemented in the numerical analysis of racking stiffness and followed by a comprehensive parametric numerical study on different parameters influencing the horizontal load-bearing capacity of such DSF timber elements. The obtained results indicate that the new approach of the developed load-bearing prefabricated timber DSF elements can essentially improve racking resistance and stiffness compared with the widely studied timber-glass single-skin wall elements and can thus be fully recommended especially in the structural renovation process of old buildings. [ABSTRACT FROM AUTHOR]

Glued-laminated timber (GLT) is an efficient and renewable material with potential to enhance sustainability in construction, but its potential has been partly hindered by relatively large uncertainty related to its strength. Previous research indicate that by linking information from the grading process to the GLT fabrication more reliable GLT beams could be made. To this end, this paper represents a finite element based modelling approach combining a continuum damage model with sequentially linear analysis that is suitable for simulation of the bending stiffness and strength of GLT beams. The model has been implemented in Matlab and can be easily integrated into different parametric simulation workflows. Based on validation against 36 experimentally tested GLT beams, the model can predict bending stiffness with high accuracy and provides reasonably accurate predictions for bending strength. The model is also capable of producing qualitatively realistic fracture patterns of GLT beams. The mesh-size study suggests that the best agreement for bending strength with test data is obtained with a sparse mesh, which is discussed in detail. The model is considered suitable for follow-up studies involving the optimization of GLT beam layups. • A novel simulation approach for glued-laminated timber beams is presented. • The model has been validated against experimental data with good agreement. • The model can also qualitatively predict post-peak fracture behaviour. • Mesh-size effects are evaluated and suggestions based on findings are given. [ABSTRACT FROM AUTHOR]

Experimental out-of-plane, four-points bending tests were performed on two series of three-layered Cross Laminated Timber (CLT) panels made of Calabrian Beech and Calabrian Beech and Corsican Pine respectively. The predominant failure mechanism was rolling shear alongthe innerlayer and the glue line. A linear elastic model of a three-layered, CLT panel was developed to describe the stress distribution in CLT slabs in bending, with a focus on their load-bearing performance before the propagation of cracks. In the analytical model, each timber layer was defined as an Euler-Bernoulli beam. The two glue lines were modeled using extensional springs, infinitely rigid in the direction perpendicular to the beam's axis, and with a defined stiffness in the tangential direction. The outer layers are assumed axially flexible whilethe innerone is regarded as axially rigid. The results of the proposed model were thus compared and validated with the experimental evidence and with additional FE numerical predictions given by 3D numerical simulations carried out in Abaqus. [ABSTRACT FROM AUTHOR]

• Parametric analysis conducted on seven variables with verified finite element model. • Current codes over-estimate the effective flange width of mass timber composites. • Web spacing and shear connection had greatest impact on effective flange width. • Flange thickness and web width also influenced effective flange width. • Flanges' modulus of elasticity did not significantly impact effective flange width. Mass timber composites (MTCs), where the webs are typically spaced 750–2000 mm apart, have shown potential in overcoming span limitations of conventional flat slab mass timber floors. However, fundamental research investigating the non-linear stress distribution (i.e., shear lag) in the flanges is required. While this behaviour has been simplified in design for other materials using the concept of an effective flange width (EFW), no guidance exists in international design codes for mass timber composites. In the current study, a parametric analysis was conducted on a mass timber I-beam under positive bending where the effects of web spacing, beam configuration (edge or interior placement), shear connection stiffness, concentrated versus uniform loading, web depth, web width, flange thickness, and flange modulus of elasticity on the EFW, were investigated. The reference section in the finite element model consisted of a glued-laminated timber (GLT) panel for the flanges, a glulam beam web, and a fully composite glued connection between elements. The results have shown that existing design code provisions, even those meant for light-frame wood members, over-estimate the EFW of GLT-glulam I-beams. The web spacing, shear connection stiffness, loading type, flange thickness, and web width were observed to be the most influential parameters on the EFW of GLT-glulam MTCs. Between the upper and lower boundaries of connection stiffness, a sharp increase in the EFW was observed below the point of full composite action due to the section beginning to behave as three separate elements. Although, the decrease in composite action resulted in an overall decrease in the bending stiffness of the section. For GLT-glulam MTCs, the modulus of elasticity (MOE) of the GLT flange was not observed to significantly affect the EFW for high degree of composite action configurations. A small increase in the EFW was observed when the degree of composite action was relatively low. Ultimately, the development of equations for quantifying the EFW of MTCs is key to their increased adoption but requires the expansion of the current study to include other mass timber elements, as well as experimental data investigating the most significant parameters identified herein. [ABSTRACT FROM AUTHOR]

Highlights • Pull-pull tests on the glulam joints with glued-in single rod were conducted. • A finite element model considering bond-slip location function was established to investigate the bond behaviour of the glulam and the glued-in rod. • The numerical results considering bond-slip location function show better agreement with the experimental results compared to that without considering bond-slip location function. • The proposed calculation model can be able to predict the joint withdrawal stiffness effectively. Abstract It was frequently reported that the bond-slip relationships at different locations along the bonded length are different, which can be illustrated as bond-slip location effect. In order to reveal the influence of this effect on the bond behaviour between glue laminated timber (glulam) and glued-in rod, a 3D finite element model considering bond-slip location function is developed for the glulam joints with glued-in rod in this paper. Moreover, an experimental program conducted on the glulam joints with glued-in rod is also presented. The numerical and experimental results are compared and discussed in terms of withdrawal capacity, typical failure modes, load-slip behaviour, strain development of glued-in rod and the interface shear stress distribution. It is indicated that the non-linear spring elements can be used to simulate the bond behaviour between the glulam and the glued-in rod effectively. The numerical results obtained considering the bond-slip location function are generally in better agreement with the experimental results compared to that obtained neglecting the bond-slip location function. Finally, the withdrawal stiffness of the glued-in rod glulam joints is evaluated by a theoretical approach based on the Volkersen theory. The withdrawal stiffness calculated by the proposed model shows good agreement with the experimental results, which confirms that the calculation model is effective for predicting the withdrawal stiffness of the glulam joints with glued-in rod. [ABSTRACT FROM AUTHOR]

Hexagonal glue-laminated timber with large cross-sections, made from small diameter logs, was studied. Effects of relative humidity variations on the moisture-induced stresses were investigated to evaluate how the prediction model compared to a real outcome. The test samples were exposed to an environment with relative humidity variations from 80% to 30%. The moisture content inside the samples was measured via X-ray computed tomography scanning. A moisture transport and a hygromechanical finite element simulation model was used for the prediction of moisture content and resulting stress distribution. The results from both the test and simulation showed that the moisture content in the edge angles of the samples dropped rapidly due to a large moisture diffusion rate. The moisture gradient was generated via a different moisture transfer rate at the inner and external parts of the samples. The maximum stress perpendicular to the grain in the simulation was 8 MPa and was located at the surface near the corners. This stress peak caused cracking according to the model, which was also seen in the test samples. The results for the measured moisture content agreed with the simulated results and this indicated that the moisture transfer model was adequate for simulation. [ABSTRACT FROM AUTHOR]

The present paper focuses on the analysis of tensile stresses perpendicular to the grain in both standard and non-standard simply supported beams made of glued laminated timber. The beams are analysed using two methodology approaches: a code design verification method and a finite element method (FEM) in terms of the linear theory of elasticity with plane stress assumption. The analysis is performed for various material parameters both isotropic and orthotropic, proving that both methodologies lead to consistent results in the case of standard glulam beams and therefore the FEM can be used in the case of non-standard structures, which are not included in Eurocode 5. [ABSTRACT FROM AUTHOR]

This paper presents an experimental campaign conducted on the glue laminated timber (glulam) joints with epoxy bonded-in GFRP rod aiming to investigate the bond-slip mechanism between glulam and GFRP rod. The tests were conducted in pull-pull configuration. To measure the axial strains of GFRP rods during testing, strain gauges were internally installed in the GFRP rods in advance of bonding. The test results were summarized and discussed in terms of typical failure modes, load-slip behavior, distributions of GFRP rod strain, bond stress and relative slip. The local bond stress-slip relationships at different locations along the bonded length were obtained based on the obtained bond stress and relative slip distributions. It was founded that the local bond stress-slip relationships at different locations differ from each other. The local bond stress-slip curves near the loaded end are generally stiffer than those close to the anchorage end, which indicates that it might not be reasonable to do finite element modelling using an unified bond-slip law. The local bond-slip stiffness distributed nonuniformly along the bonded length confirming the differences among the local bond-slip relationships at different locations again. Finally, the analytical models were used to predict the bond-slip behaviour of the specimens. The results showed that the analytical models can predict the bond-slip behaviour between the glulam and the GFRP rod effectively. This study expanded the data base of the timber joints with glued-in rod and provided some references for the structural analysis and design of the glued-in FRP timber joints. [ABSTRACT FROM AUTHOR]

The bending behavior of T-section beams composed of a glulam web and an upper cross-laminated timber flange was studied. The influence of two fundamental factors on the bending strength and stiffness was considered: the wood species used for the webs and pretensioning with unbonded tendons. Sixteen specimens with a 9 m span were tested until failure: eight of them were nontensioned (4 Picea abies webs and 4 Quercus robur webs) and the other eight were pretensioned using threaded bars with 20 mm diameter anchored in plates fixed at the ends of the specimens (4 Picea abies webs and 4 Quercus robur webs). Pretensioning with unbonded tendons showed a clear improvement in the load capacity of the specimens with Picea abies webs, while the difference was not significant for the specimens with Quercus robur webs. Considering deflection, pretensioning gave the advantage of an initial precamber but also generated slight variations in the stiffness as a result of increasing the portion of the section that was in compression. The variation in the stiffness depended on the relation between the compressive and tensile moduli of elasticity parallel to the grain, and its influence on the deflection was analyzed using a finite element method. [ABSTRACT FROM AUTHOR]

In order to achieve larger spans of timber arch bridges, glulam massive timber sections must be spliced on-site by moment resisting and rotationally stiff joints. In this paper, a novel timber splice connection utilizing long threaded rods and grout-filled couplers is presented. Flexural characteristics of the splice joint were investigated by full-scale experimental tests and 3D finite element models. An analytical model is proposed for determining the moment capacity and the rotational stiffness of the splice connection. The experimentally measured efficiency of the splice connection with regard to moment capacity and rotational stiffness was 69% and 66%, respectively. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of bending behaviour of glued laminated timber (glulam) beams reinforced with carbon fibre reinforced polymer (CFRP) plates, based on finite element numerical modelling. Nonlinear 3-dimensional model was developed and validated by experimental tests carried out on unreinforced beams and beams reinforced with two different reinforcement arrangements. Suitable constitutive relationships for each material were utilised in the model, as well as anisotropic plasticity theory for timber in compression. Adhesive bond between CFRP plate and timber was modelled as a perfect connection. Beam failure in the model was defined by maximum stress criterion. The predicted behaviour of beams has shown good agreement with the experimental results in relation to load-deflection relationship, ultimate load, elastic stiffness and strain profile distribution. The non-linear behaviour of reinforced beams before failure was also achieved in the numerical analysis, confirming the finite element model to be accurate past the linear-elastic range. Experimentally tested reinforced beams usually failed in tensile zone after compressive plasticization of top lamination, which was also simulated in the numerical model. The results proved that the load carrying capacity, stiffness and ductility of glulam beams were successfully increased by addition of CFRP plate at tension side of the section. [ABSTRACT FROM AUTHOR]

Finite element models were, in the first time, developed to simulate the pre-stressing behaviour of Glulam beams with insertion of compressed wood blocks, which were further used to simulate the structural behaviour of the pre-stressed beams subjected to subsequent destructive bending. Here, both the Glulam and compressed wood were modelled as orthotropic elasto-viscoplastic materials. The moisture-dependent, including spring back, swelling of the compressed wood block and the creep of the Glulam were considered in the modelling. The models developed were validated against the corresponding experimental results, with reasonably good correlation in terms of the free swelling, the precamber, initial stress state of the Glulam beams reinforced and load-deflection relationships. With validated models, further studies were then undertaken to investigate effects of the thickness, depth and spacing of compressed wood blocks on the precamber, initial bending stiffness and ultimate load carrying capacity of the beams pre-stressed. The results indicate that there are significant enhancements on the precamber (up to 1/288 of the deflection/span ratio), the initial bending stiffness (up to 23.8%) and the ultimate load carrying capacity (up to 10.4%). [ABSTRACT FROM AUTHOR]

• Beech and Corsican Pine short chain supply hardwood was used to realize glulam beams. • Bending and shear test were performed. • Hybrid Beech-Corsican Pine glulam beams show high flexural mechanical performances. • Hypotheses have been formulated to extend the validity of the formulations of EN 14,080 also to homogeneous hardwood products. • Finite Elements analyses were carried out to compare C24 Spuce glulam beams with tested beams. This paper describes the results of an experimental investigation on novel homogeneous and hybrid beech-Corsican pine glue-laminated timber (glulam) beams made of short supply chain timber boards and melamine-based adhesive. The aim is to carry out the mechanical characterization of these glulam beams both in the homogeneous and in the hybrid configuration by four-point bending tests with different span to depth ratios of the specimens in order to differentiate bending and shear tests. The experimental results were fitted analytically as well as by means of Finite Element (FE) numerical simulations. Moreover, the stiffness of these novel beams is further evaluated, with respect to a comparison with a commercial product made of GL24h glulam. The experimental and numerical analysis point out the goodness of hardwood for the manufacturing of glulam beams, even in hybrid configuration in which the inner layers are made of low graded timber boards, with a great opportunity to optimize the raw material. [ABSTRACT FROM AUTHOR]

This paper examines the embedment behaviour of single-dowel connections in Scandinavian Spruce Glulam by means of experimental and numerical investigations. First, the experimental results of a series of single-dowel tests on samples of different geometry and grain directions are presented. The evolution of local strain concentrations around the fastener at increasing levels of bearing deformation, is reported in detail by means of non-contact field strain measurements and its implications are discussed. Detailed Finite Element simulations are also carried out and subsequently employed to highlight the main features of the response of doweled connections in glulam. A foundation model, initially developed for Douglas-fir ( Pseudotsuga menziesii ) timber, is upgraded and adapted for Scandinavian Spruce Glulam ( Picea abies ) elements subjected to loads acting perpendicular and parallel to the grain direction. The proposed model is based on the definition of equivalent material parameters for the crushing region around the dowel hole. To this end, relationships for the estimation of material characteristics as a function of the crushing volume are suggested. The validity and accuracy of the proposed modified foundation models are examined against the experimental results. It is shown the improved foundation model is able to simulate the embedment stiffness, capacity and inelastic behaviour of single-dowel connections on glulam with reasonable accuracy for strains of up to 8%, and can therefore be used for design and assessment purposes. [ABSTRACT FROM AUTHOR]

This paper presents a finite element modeling method for a certain type of nailed joint between glulam beams. The joint in question is a traditional arrangement of a horizontal beam and a vertical pillar but here there is also a nailed steel plate inserted on the two sides in order to strengthen the joint. Experimental results and a comparisons of simulated and experimental results are made. The model includes the elastic and plastic orthotropic behaviour of wood and the elastic and plastic behaviour of nails. The nail joint between the steel plate and the wood is modelled as an elastic-plastic surface to surface connection with elastic-plastic properties. Also the reinforcing effect of nails in the nail-affected volume of wood is taken into consideration by raising rolling shear yield limit in the affected wood volume. The comparisons show that the model works well and give results that are comparable to experimental results. [ABSTRACT FROM AUTHOR]

This paper presents the formulae and finite element analysis models for predicting the Modulus of Elastic (MOE) and Modulus of Rupture (MOR) of Cathay poplar finger-jointed glulam. The formula of the MOE predicts the MOE of Cathay poplar glulam glued with one-component polyurethane precisely. Three formulae are used to predict the MOR, and Equation (12) predicts the MOR of Cathay poplar glulam precisely. The finite element analysis simulation results of both the MOE and MOR are similar to the experimental results. The predicted results of the finite element analysis are shown to be more accurate than those of the formulae, because the finite element analysis considers the glue layers, but the formulae do not. Three types of typical failure modes due to bending were summarized. The bending properties of Cathay poplar glulam were compared to those of Douglas fir glulam. The results show that Cathay poplar glulam has a lower stiffness, but a marginally higher strength. One-component polyurethane adhesive is shown to be more effective than resorcinol formaldehyde resin adhesive for Cathay poplar glulam. This study shows that Cathay poplar has the potential to be a glulam material in China. [ABSTRACT FROM AUTHOR]

Wood, as a naturally grown material, is affected by growth inhomogeneities like branches. Especially in solid timber or glulam beams, knots lead to a decrease in stiffness and strength. In this contribution, approaches to model knots and the grain course in an FE-simulation are presented. Based on these methods, the influence of knots is evaluated by structural analyses. For validation, the numerical results are compared to experimental data. Since knots often initiate damage in structural timber parts, a failure criterion is applied in the area of the knots. [ABSTRACT FROM AUTHOR]

• A fully-bolted joint for light steel-natural timber composite beam and column is proposed to meet the requirements of low-rise residential buildings in villages and towns. • The seismic performance of composite beam-column joints is studied by a series of cyclic tests. • The finite element model is proposed to provide a reference for similar types of composite structures. • The component-based model is proposed to calculate the initial rotational stiffness and ultimate capacity for practical applications. Current timber structures or steel-timber composite structures are made of thick steel and glued laminated timber (glulam) with beams and columns connected by high-strength bolts used in high-rise and large-span structures. However, there is no high strength requirement for low-rise buildings in villages and towns. The composite action of thin-walled steel and fast-growing timber is selected to constitute the structural members together, which are connected using plain bolts for a structural system suitable for residential houses in villages and towns. Thin-walled steel can be used to minimize the initial defects and material variability of fast-growing timber. To meet the requirements of the light steel-fast-growing timber composite structural system, a fully bolted joint is designed in this paper. The quasi-static tests of seven joints are carried out to analyze their seismic performance. The results show that the seismic performance of joints can meet the requirements of low-rise residential buildings in villages and towns. The finite element simulation of the test specimens is also carried out, and the modeling approach is described in detail to analyze similar structures further. Finally, the component-based expression was used to propose a simplified spring model to calculate the joints' initial rotational stiffness and ultimate capacity and compared with the experimental results for practical applications. [ABSTRACT FROM AUTHOR]

The analysis of connections between elements of glued laminated pressed bamboo guadua (Guadua angustifolia Kunth) for a housing project is presented in this article. The analysis was carried out in four stages: design, load test, numerical simulation and finite element modeling. Design connection was developed using the allowable stresses method. In load test, displacements were measured in order to identify the behavior of connections for different load increments. Numerical simulation was performed in the software ETABS® with the loads used in the load test in order to determine the displacements at points experimentally instrumented in the test; each stage of load of test was simulated. Finally, the finite element modeling was performed in the software ANSYS®. Differences between the experimental results and those obtained with the simulations were found, which could be result of the differences between real conditions of the load test and design considerations as behavior completely rigid or pinned of connections. [ABSTRACT FROM AUTHOR]

With the development of wooden structures and buildings, there is a need to research physical and numerical tests of wood-based structures. The presented research is focused on construction and computational approaches for new types of joints to use in wooden structures, particularly glued lamella elements made of wood and wood-based composites. This article focuses on improving the frame connection of a wooden post and a beam with the use of fasteners to ensure better load-bearing capacity and stiffness of the structure. In common practice, bolts or a combination of bolts and pins are used for this type of connection. The aim is to replace these commonly used fasteners with modern ones, namely full thread screws. The aim is also to shorten and simplify the assembly time in order to improve the load-bearing capacity and rigidity of this type of frame connection. Two variations of the experimental test were tested in this research. The first contained bolts and pins as connecting means and the second contained the connecting means of a full threaded screw. Each experiment contained a total of two tests. For a detailed study of the problem, we used a 2D or 3D computational model that models individual components, including fasteners. [ABSTRACT FROM AUTHOR]

This study investigates timber connections with flexible polyurethane adhesives, which prove to have the potential for timber-adhesive composite structures without mechanical connections for seismic regions. Results of conducted cyclic double lap-shear adhesive timber joints tests were compared with available experimental results on timber connections with standard mechanical dowel-type fasteners and with results of numerical finite element analysis. The study found that the shear strength, elastic stiffness and strength degradation capacity of the flexible adhesive connections were significantly higher compared to mechanical fasteners commonly used in seismic-resistant timber connections. The latter, however, manifested larger ultimate displacements but also yielded at lower displacements. [ABSTRACT FROM AUTHOR]

This work is focused on a creep formulation in bending for timber beams, of glue laminated (glulam) type, which is suited to be implemented in both geometrical and material non-linear finite element method (FEM) models. It studies the performance of timber beams by accounting the deformation under increments of time and stress in the long term. The proposed creep formulation uses a power-law function expressing the creep strain by means of one coefficient and two exponents. This function needs a fewer number of material coefficients than a classical mathematical analysis of non-linear viscoelasticity, so design applications, such as FEM codes, may more simply describe the deformations in the long term. The formulation has been developed for cantilever beams made of glulam timber using experimental tests in bending and accounting the relations between strains, and both time and tension progresses. Also, the timber creep law has been numerically tested by FEM code runs, with large displacements and large strains assumptions, and further compared with a Navier analytical model. The scatters between experimental and analytical values, and FEM numerical values have reached a standard deviation of 4.06 and of 7.66%, respectively. The acceptable agreement in the comparison between experimental, analytical, and FEM numerical results have demonstrated the capability of the creep formulation to model the behavior in bending of a glulam timber. Also, the proposed creep model has shown an interesting ability to be employed in a FEM code to analyze a timber beam in bending, along time and load evolutions. [ABSTRACT FROM AUTHOR]