Search

Timber connection capacity, in case of beam-column joint connection provides significant impact on the wooden building structures. Strength and stiffness of timber connections using reinforcement technique of wooden building structures have not been studied intensively. This paper studies the use of nails and modified-washer to improve wood connection’s performance. The experimental tests were conducted in the laboratory by comparing the partial connection between test specimen timber without reinforcement (standard type) and the reinforcement (PRP type). The testing was conducted based on partial connection beam-column joint test using Universal Testing Machine’s with a modified holder. Wood studied includes Meranti (Shorea spp.) and Mersawa (Anisoptera spp.). PRP type connection was using nails and modified-washer strengthening, and standard type connection was using a classic washer. Parameters studied were strength and stiffness of the connection, reviewed both: proportional limit load and ultimate limit load conditions. Result obtained from this research indicates that the use of nails and modified-washer make a positive contribution to improving the performance of the beam- column timber joint connections, in terms of strength capacity (both of proportional limit and ultimate limit loads) and stiffness capacity (displacement ductility ratio). Meranti beam-column timber joint is more brittle than Mersawa beam column timber joint, it has an impact on the results. PRP-type of Mersawa timber connection produces a higher ductility than the standard type, while the PRP-type of Meranti timber connection produces a similar ductility to the standard type.

Batak Karo is one of the ethnic group that exists in North Sumatra. Wooden house of Batak Karo called with Siwaluh Jabu. This wooden house has a structure system of pillars on top of stone foundations. This type of foundation is able to improve the performance of the overall structure due to lateral style caused by the earthquake. This research was conducted to know the behaviour of the structure of a wooden Batak Karo home especially the restoration of wooden style joints by comparing the results of a laboratory test, numerical analysis and analysis with SAP2000. Experimental testing in the lab do the test objects as much as 3 pieces. Testing by giving a cyclic load with a capacity of 10 tons in each of the test object to damaged object. Then conduct an evaluation the behavior of the structure consist of failure modes and moment-rotational angle relationship. After the experimental test was completed, the analysis continued with validate test results with laboratory of numerical analysis. Then conducted an analysis of the power structure by using SAP2000 program to know the power of elements against the maximum tension. The analysis conducted on the overall structure of the system and the structure of mast above the foundation stone. The program was conducted with input data: the work load, etc. As the output from these programs is the element force, etc. The final results of this program are the weaknesses and advantages of structural system observed from wooden Batak Karo.

The goal of the work was to evaluate mechanical performance of full-scale timber beams containing scarf joint with a dowel. Work focused on standard testing using modular system to obtain effective stiffness and strength of the beams with and without the joint. The work further researched a contact zone between two timber parts of the joint – at the scarf face. This was carried out using non-destructive optical technique – digital image correlation (DIC) and newly developed algorithm. The joint was made of Norway spruce, dims. 6×0.2×0.24 m and was loaded by two modes: a) 3-point bending and b) 4-point bending. During the loading, a sequence of images was acquired for further investigation of contact zone using the proposed algorithm. The joint with scarf and dowel provided enough effective stiffness, ie. 73–93% for 3-point bending test and 71% for 4-point bending with respect to MOE measured on reference solid beams. Effective strength of the joint was also relatively high and in a range of 55% and 60% with respect to reference solid beams in both 3-point and 4-point bending tests. Contact length differed for loading modes. Mean contact length in symmetrical 4-point bending was about 40%, for asymmetrical 3-point bending test, it was approx. 20% on face closer to support and 44% on a face closer to loads.

The comprehensive experimental study examining the general load-displacement behavior, stress distributions and shear stress-shear-displacement behaviors in the connection area when wood structural elements are combined with adhesive or adhesive with mechanical anchorages have been found in very limited number of studies in the literature. Therefore, an experimental study was planned. In this study, the general load-displacement behavior of the timber connection regions which are connected by adhesive and mechanical anchorages together with adhesive, with varying lengths of 180, 240 and 350 mm are investigated experimentally. Besides, the effect of changing the number and location of mechanical anchorages used in the connection area on the general load-displacement behavior and shear stress-shear-displacement behavior was also investigated. Using the load-displacement graphs obtained as a result of the experimental study, a generalized material model is proposed for the shear stress-shear-displacement interfacial adhesion surface for wood-wood junction points. This material model, which is proposed for wood-wood connection points with mechanical anchors, is a model that can be useful and can be used in the analysis of structural systems containing such connections using finite element software. It is thought that the overall capacity and load-displacement behavior of structural systems containing such connection points can be calculated more realistically using the proposed interfacial material model.

The paper considers the stress–strain state of the timber-to-timber joint elements on inclined screwed-in rods. Experimental studies of timber-to-timber joints were performed for three types of connections: screws with anchorage details, screws, and threaded rods. The connections are established with the angle of deviation of the connecting element from the normal to the shear plane—45°.

This paper presents exploratory research on behavior of a lap scarf timber joint used in restoration of historical constructions in the Czech Republic. The joint with oblique faces and a dowel was tested in full-scale and was subjected to both three- and four-point bending where standard, optical and numerical techniques (FEA) were employed. The joint keeps 70–92% and 55–57% of the corresponding solid beam MOE and bearing capacity respectively. The FE analysis revealed the angle of the joint has the highest impact on its MOE. Paper demonstrates the advantages of coupling of full-field measurement technique and FEA in analysis of a timber joint, especially for model verification based on measured displacement of the structure.

This paper analyses the optimisation studies of a pre-stressed embedment-type timber joint system, the Kusabi–Nageshi (K–N) timber joint system, designed to be used for structures in seismic-prone countries. The K–N joint is composed of a triangular-sectioned beam and wedges in combination with bolts. Its resistive mechanism utilises the embedment strength of timber and the pre-stress in association with friction. In addition, elastic energy deposited in the bolt as storage fills the gap as it is deformed during the embedment. With the aim of optimising both mechanically and physically, several alterations were tested in terms of shape (taper angle) and of combining densified veneer wood (DVW) with the joint members. A cyclic loading test of the cross joints was made to examine their structural behaviour. The use of less tapered wedges showed higher stiffness and strength, but the beam beneath was undesirably embedded. Different combinations of reinforcement with densified veneer wood showed that the use of the wedges alone provided high optimisation, and an increase in bolt axial force. The successful test results observed in the alteration using the densified veneer wood are expressed using the ‘analytical K–N joint diagram', an analytical method modified from a conventional joint diagram used in mechanical engineering, which showed itself to be an applicable method to predict the trend of the altered K–N joint. The use of the new tapered angle and densified veneer wood for optimisation, and the performance predictions using the analytical K–N joint diagram, will need further precise investigations but their great benefits are potentially promising.

Many Javanese traditional timber structures have been destroyed by major earthquake. A lot of them tend to be dismantled due to a high cost of reconstruction and a demand for more reliable structures. In order to preserve this disappearing building as valuable and tangible culture, a deeper understanding on these traditional timber structures is necessary. Especially the restoring force of the traditional joints, which are the major earthquake-resisting elements has to be investigated. The static characteristic of these structural components has been investigated experimentally. A total of 12 full-scale specimens of 2 types made from glued Acacia-mangium were tested. The specimen simulated joint at middle part, which is a joint of column-tie beams interlocked each other. The horizontal cyclic load was applied on the specimen placed in pin joint frame from two mutually perpendicular directions. The cyclic loading protocol consists of 7 increasing target deformations from 1/200 radian to 1/15 radian, and finally until failure. As the test result, failures were caused by embedment, crack, and split in beams parallel to the load direction. All crack of beam started from corner of beam mortise and resulted in the split. From the curve of load and rotational relationship, occurrence of initial slip leaded to the larger deformation. It revealed the importance of joint tightness against future earthquake.

We, in this article, propose a manual calculation method for the skeleton curb of single bolted timber joint. The calculation method takes into account the edge distance, the end distance, and the slenderness ratio as the parameters. The validity of the proposed calculation method was confirmed by the experimental results, the edge distance of 1d, 2d, 4d, 6d, 7d, the end distance of 1d, 2.5d, 4d, 7d, 10d, the slenderness ratio of 0.625 d, 3.75d, 7.5d, 10d.

We, in this article, propose a manual strength calculation method of single bolted timber joint loaded parallel to the grain. The strength calculation method takes into account the edge distance, the end distance, and the slenderness ratio as the parameters. The validity of the proposed calculation method was confirmed by the experimental results, the edge distance of 1d, 2d, 4d, 6d, 7d, the end distance of 1d, 2.5d, 4d, 7d, 10d, the slenderness ratio of 0.625d, 3.75d, 7.5d, 10d.

Widely used for light frame structures or for heavy laminated wood structures, dowel-type fasteners are the most commonly used kind of connectors in timber construction. The purpose of this work is to develop a tool for the semi-rigid analysis and design of such joints. Firstly, interests and approaches described in literature for the semi-rigid modeling of timber plane frames are summarized. Secondly, for a better understanding of the problem, the main characteristics of wood used as a structural material are presented. Finally, a method for an efficient study of joints built with dowel-type fasteners is proposed and developed. This method consists of the introduction of a specific finite element called “Finite Semi-Rigid Element (FSRE)” between the ends of the jointed members. This joint element consists of two nodes, each with three degrees of freedom. These nodes will be tied with common beamelements during the FE analysis. The stiffness of the FSRE is computed from the geometry of the joints and embe...

We present a new and alternative proposition for the traditional Asian timber column-and-beam connection, using the Kusabi-Nageshi (K-N) joint system. The mechanical behaviour is complex and relies on the embedment strength of the timber, pre-stress, friction, and elastic energy storage. Using a systematic comparative analysis, the advantages of the K-N joint over more traditional joints can be made clear. The comparison of the hysteresis from cyclic loaded cross-joint tests with varied pre-stress clarifies the enhanced mechanical behaviour of the K-N joint system. © 2009 Elsevier Ltd. All rights reserved.

This paper presents a new paradigm that is possible to aid the traditional experimental analysis in timber joints research. Laboratory experiment has incurred a lot of cost and times to find optimize end distance of a timber joint. Particle swarm optimization (PSO) is applied and tested focusing on a single shear timber joints. The determination of fitness function is based on the findings from the previous datasets of the traditional laboratory experiments. The dataset includes the timber species of Kapur that emphasizes on 2D and 3.5D in diameter of end distance. Several PSO parameters were tested to find the maximum load carrying capacity of timber joint for different end distances. The findings show that PSO can give a feasible solution for a single shear strength timber joint performance. It demonstrates that the PSO has a potential to be used as a timber joint simulations that would be beneficial to timber joint researchers in predicting the load carrying capacity of a joint and contributes in reducing time and cost.

Tests investigating the fatigue performance of a bolted timber buttsplice connection containing wood splits are presented. Relationships of compressive axial load to joint slip at the bolt nut and of load to average and relative joint slip relationships are studied to explain the fatigue failure of this type of joint when cyclic loads are involved. None of the three joint slips alone was sufficient to indicate when a particular joint would fail; however, considering the interaction between the joint slip at the bolt nut and the relative joint slip between the bolt nut and head allowed a failure hypothesis to be established. The test results indicate that the fatigue resistance of the connection is more adversely affected when a split is located near the bolt hole on the bolt‐head side of the connection than when a post has no splits or has splits located near the bolt hole on the nut side of the connection.

The present study addresses the loading or deformation rate effect on the yield loads of nailed timber joints. Four different types of joints, which differed with respect to the thickness of the members and the angle of load to grain, were tested. The bearing strength of the wood and the bending strength of the nails were also tested in order to analytically verify the dynamic ultimate capacity of the joints. All tests were run with deformation rates from static loading values up to approximately 1 m/s (40 in./s). The pilot study results show that the strength of the nailed joints can be expressed in terms of the deformation rate. A logarithmic expression for the strength of the joints was obtained from regression analysis of approximately 200 results. The values obtained analytically agreed well with the experimental ones for the various joints tested.

This work presents the development of a three-dimensional lattice material model for wood and its application to timber joints including the potential strengthening benefit of second order effects. A lattice of discrete elements was used to capture the heterogeneity and fracture behaviour and the model results compared to tested Sitka spruce (Picea sitchensis) specimens. Despite the general applicability of lattice models to timber, they are computationally demanding, due to the nonlinear solution and large number of degrees of freedom required. Ways to reduce the computational costs are investigated.Timber joints fail due to plastic deformation of the steel fastener(s), embedment, or brittle fracture of the timber. Lattice models, contrary to other modelling approaches such as continuum finite elements, have the advantage to take into account brittle fracture, crack development and material heterogeneity by assigning certain strength and stiffness properties to individual elements. Furthermore, plastic hardening is considered to simulate timber embedment.The lattice is an arrangement of longitudinal, lateral and diagonal link elements with a tri-linear load-displacement relation. The lattice is used in areas with high stress gradients and normal continuum elements are used elsewhere. Heterogeneity was accounted for by creating an artificial growth ring structure and density profile upon which the mean strength and stiffness properties were adjusted.Solution algorithms, such as Newton-Raphson, encounter problems with discrete elements for which ’snap-back’ in the global load-displacement curves would occur. Thus, a specialised solution algorithm, developed by Jirasek and Bazant, was adopted to create a bespoke FE code in MATLAB that can handle the jagged behaviour of the load displacement response, and extended to account for plastic deformation.The model’s input parameters were calibrated by determining the elastic stiffness from literature values and adjusting the strength, post-yield and heterogeneity parameters of lattice elements to match the load-displacement from laboratory tests under various loading conditions.Although problems with the modified solution algorithm were encountered, results of the model show the potential of lattice models to be used as a tool to predict load-displacement curves and fracture patterns of timber specimens.

This paper proposes a numerical model capable of predicting the mechanical behaviour and the failure mechanism of typical wall-to-floor connections for Cross-Laminated Timber structures. Such systems are assembled with angle brackets and hold-downs, anchored to the wall and floor panels with profiled nails and bolts. The metal connector and the elements to which it is fastened are modelled using 3D solid bodies, while the steel-to-timber joints are simulated as non-linear hysteretic springs. Shear and tension tests are reproduced on two connection systems and results are compared to the test data obtained from similar configurations. Simulations lead to accurate predictions of the mechanical behaviour (i.e. elastic stiffness, maximum load-carrying capacity, and shape of the hysteresis cycles) and energy dissipation. Finally, the performance when lateral and axial loads are applied simultaneously is investigated. Analyses are carried out by varying the inclination of the load, with respect to the axis of the connector, between 0° and 90°. Results exhibit a quadratic interaction relationship between shear and tension loads, and prove that their coupled effect influences the stiffness and the maximum load-carrying capacity.

In the field of timber engineering, adhesive bonding remains a promising, though poorly developed, joining technique that may increase the structural stiffness and capacity of timber joints and structures. Selecting ductile adhesives may further allow to conceive ductile joints, which can compensate for the missing material ductility of timber. To demonstrate the potential of this approach, adhesively bonded double-lap timber joints were manufactured using a ductile acrylic adhesive and then subjected to axial tension and compression. The load–displacement responses were captured and compared to those of the same joints composed of a brittle epoxy adhesive. The effect of the different adhesives on the joint ductility has been studied and quantified.

In traditional Japanese timber structures, nuki-column joints are used as seismic elements. However, the elastic stiffness of their moment resistance performance is rather small. In this research, hardwoods were used for nuki in three ways to improve the performance of the joints. Moment resistance tests of the joints were conducted to evaluate their structural performance and clarify the differences depending on the wood species, the nuki cross sections, and reinforcing effects of hardwoods discussed. In some specifications, it was shown that using hardwoods for nuki improved the structural performance of the joints. A significant effect was observed on some characteristic values of the joints.

Self-Tapping Screws (STSs) are commonly used to realize many geometrical configurations for connections that are characterized by enhanced stiffness and load-carrying capacity. The analysis of STS joints and composite systems, however, usually requires designers to account for several aspects in their actual load transfer mechanisms, and most of them require refined calculation tools. In this paper, an extended Finite Element (FE) investigation is proposed for timber-to-timber slabs with STS joints, based on full 3D brick models inclusive of Cohesive Zone Modelling (CZM) techniques and damage constitutive laws for the materials in use. The final goal of the study takes advantage of the global and local performance assessment of a selection of STS joints, with careful consideration for their response under a conventional Push-Out (PO) test setup or a full-size bending configuration. As shown, major FE outcomes are discussed to elaborate a design procedure that can be developed on the base of correlation coefficients for maximum force and stiffness calculations in a given slab and loading condition. Major effects due to variable loading configurations are in fact explored at the screw level. Further, geometrically simplified spring-based FE models, that hardly capture the complex behaviour of the examined systems but are largely used in design practice, are presented in comparison to refined FE approaches and literature efforts. As shown, the variation of maximum force and stiffness parameters for STSs is emphasized in the paper for a selection of configurations, and fitting curves are proposed to estimate the STS performance along a given full-size slab, thus suggesting the feasibility and possible generalization of the procedure.

In this paper, a Finite-Element (FE) numerical investigation on timber-to-timber joints and composite beams with inclined self-tapping screws (STSs) is presented. Based on past experimental data and numerical literature efforts, full 3D solid FE models of selected geometrical and mechanical configurations of technical interest are implemented in ABAQUS software package and analysed under static loading conditions . The typical push-out samples include GL24h timber members with several types (WT-T-8.2, 190 mm and 220 mm their length), layouts (2 + 2, 4 + 4, 2 + 2 X-shaped) and inclination of screws (up to ±45°). For the full-scale beam samples in bending (8 m their span), composite systems consisting of GL24h timber beam, wooden plank, spruce floorboards and STSs are investigated. There, the STS joints take the form of two-rows or X-shaped connections, respectively (45° or 90° their inclination), including four screw types and different spacing. In both the push-out and full-scale cases, simple modelling approaches are taken from the ABAQUS library and adapted to the timber-to-timber structural system under investigation, so as to explore their structural performance in the elastic and post-damage phases, up to failure. A key role in the typical FE models is assigned to input material properties and mechanical contacts, including damage constitutive laws so as to reproduce possible local failure phenomena in the timber or steel components, as well as cohesive damage interactions for the joints. The presented FE models are calibrated in accordance with past research studies, and validated – for the examined structural typology – against experimental results available in literature. Comparative calculations are hence presented, based on the collected numerical, experimental and analytical estimations for the selected samples. As shown, the examined modelling approach can reasonably capture the expected performance of timber-to-timber joints and composite systems.

The employment of timber pegs in timber structure joints is a widespread technology in the field of timber frame building in the United States, where the Timber Frame Engineering Council has published a special Standard to supplement the National Design Specification for Wood Construction. The authors have been studying the possibility of supplementing the Eurocode 5 design formulas, thought for timber joints with metal connectors, with specifications needed for a reliable design when employing timber pegs. The field of application envisaged is that of restoring timber structures and results obtained until now are quite encouraging. In this step of the research, more attention has been paid to deformation process: fir and chestnut samples have been tested to determine their dowel-bearing behavior with steel and ash timber peg while double-shear plane joints made of the same wood species, and fastened with steel as well as timber pegs, have been analyzed.

The research deals with a 49.0 mm in diameter mechanical fastener to which load perpendicular to grain is applied. The experimental research was divided in two series: the first series was carried out with locally reinforced, and the second with non-reinforced timber specimens. The local reinforcement of timber elements with textile sheets between lamellas in a layer of adhesive was made in the production process. Furthermore, research on finite element models using Abaqus/CEA software package was carried out. UMAT subroutine and cohesive contact between surfaces were used for modelling complex timber mechanical properties and cracks opening. The research results have shown that glass fiber textile placed between lamellas in adhesive layer effectively increases the resistance and splitting capacity of timber joint. Analytical approach has been proposed for predicting the splitting capacity of the reinforced joint.

This paper investigates the mechanical and the hysteretic behaviour of steel-to-timber joints with annular-ringed shank nails in Cross-Laminated Timber (CLT). These fasteners are used to anchor typical metal connectors, such as hold-downs and angle brackets, to the CLT panels. The experimental programme presented in the paper was carried out at the Institute of Timber Engineering and Wood Technology, Graz University of Technology (Graz, Austria). Average and characteristic values of the experimental strength capacities are evaluated and compared to the analytical predictions determined according to current structural design codes and literature. Furthermore, to fulfil the requirements of the capacity-based design, the overstrength factor and the strength degradation factor are evaluated and conservative values are recommended.

The moment-rotation-behaviour of a post-tensioned beam–column timber joint has been analysed extensively with a series of static bending tests. The timber joint was loaded at the end of the beams in order to apply a moment to the connection. The tests were conducted with various forces in the tendon, from 300 kN up to 700 kN. The bending tests were performed with a controlled load level, so that no failure perpendicular to the grain in the column occurred. The maximal allowable vertical load to be applied was estimated using a simple spring model. A final bending test was conducted in order to study the failure mode of the post-tensioned timber joint. The vertical load on the beams was increased until the tendon elongation got so high that the test had to be aborted. The results of bending tests of the post-tensioned timber joint are presented herein. Attention will be given to the structural behaviour and to the influence of the applied post-tensioning force on the connection stiffness. The experimental results will be compared to the results obtained using a simplified analytical calculation model.

A theoretical model is presented to calculate the stress distribution around a pin-loaded hole in a timber joint and to predict brittle failure modes in bolted connections. The analytical solution uses the stress functions expressed in terms of complex parameters, and it can be considered an application of Lekhnitskii’s theory on stress distributions in anisotropic plates. The influence of the end distance and material properties on development of failure due to the splitting and shear-plug is shown for a dowel-type timber joint. Laboratory experiments on timber joints with 15.9-mm and 9.5-mm bolts loaded parallel to grain have shown good agreement with the model predictions.

Timber connection is one of the important aspects that need to be evaluated in construction and manufacturing. The end product produced from these sectors depends on the strength of the timber connection especially in building constructions. A lot of laboratory experiments to measure the strength of timber connection were done before proceeding with the transformation process of a product. However, these experiments require high cost and time-consuming. In addressing these issues, there is an alternative mean that can be applied to predict the strength of timber connection to overcome those problems. This paper addresses on the employment of particle swarm optimization (PSO) in a simulated timber connection for tensile test with and without glass fiber-reinforced polymer (GFRP). Data from laboratory experiment of tensile test of tropical timber were used. The PSO potentially can adapt the behavior of the timber and predict the maximum weight that can be supported by the timber connection. The findings are acceptable which obtained 99.39 % accuracy for GFRP joints and 95.34 % accuracy for non-GFRP joint. By using population size of 20, it has shown that PSO provides good results and has capability to predict the timber joint strength. Results show that by combining the glass fiber-reinforced polymer (GFRP) sheet, the timber joint gives better strength than timber joint without GFRP. Thus, the outcome of PSO application would encourage the engineer or related construction fields to predict the timber joint strength with various fiber-reinforced polymer or other composite material.

The moment-rotation-behaviour of a post-tensioned beam-column timber joint has been analysed extensively with a series of static bending tests. The timber joint was loaded at the end of the beams in order to apply a moment to the connection. The tests were conducted with various forces in the tendon, from 300 kN up to 700 kN. The bending tests were performed with a controlled load level, so that no failure perpendicular to the grain in the column occurred.

The multiple shear connection with slotted-in steel plates and dowel-type fasteners is a very efficient timber joint for large timber cross sections. It is used in practice, mainly due to its high capacity and its better performance under fire. However, when the number of inner plates is increased, instead of a ductile mechanism, brittle failure may govern its capacity. No standard deals explicitly with this kind of joint. A set of tests has been performed in order to study the brittle failure of this kind of connections. The test results are then compared with the available prediction models that study both ductile and brittle failure modes to assess their prediction accuracy. An improved model for the assessment of the brittle failure mode for the multiple shear connections with slotted-in steel plates and dowel-type fasteners is then proposed.

In the current European standards for design of timber structures, the issue of timber-to-timber joint type is addressed only to squared timber, which makes the pinpointing of the round timber bolted joints load carrying capacity near-unfeasible due to the insufficient support in the current standards. There have been made series of tests of round timber joints in different inclinations of the loading force and also the reference tests of squared timber joints to compare the behaviour of this type of joints. Mechanical behaviour of the round and the squared timber bolted joints was tested in the laboratory of the Faculty of Civil Engineering in Ostrava. This paper presents results of static tests in tension at an angle of 0 degrees, 90 degrees and 60 degrees to the grain of squared and round timber bolted joints. Load carrying capacity was determined according to the applicable standards and theories of fracture mechanics. The test results of laboratory tests were then compared with the results of theoretical calculations. Web of Science 39 61 56

Mortise-tenon joints for working chair construction fail under bending stresses. Dovetail joints could offer an alternative due to their resistance to bending. However, furniture joint strength depends on the design of the parts and appropriateness of the timber for the construction. Information on timber-joint design combination that would improve joint strength is lacking for most secondary timbers with prospects for joinery-making. This study assessed the bending strengths of two joint designs (dovetail and mortise-tenon) for leg-and-rail construction from Klainedoxa gabonensis (a secondary timber) and Entandrophragma cylindricum (popularly used for furniture). Dovetail joints were stronger than those of mortise-tenon. For both joints, the design with longer, wider and thicker tails and tenons [large-sized (Type LS)] was stronger than its counterpart [small-sized (Type SS)]. Joints manufactured from K. gabonensis were also stronger than those from E. cylindricum. Thus, K. gabonensis could be an...

In view of the development of heavy timber seismic resistant structures, in the context of modern seismic design approach based on the mechanical triad of strength, stiffness and ductility, the dissipative capabilities should be delegated to specific devices, considering that timber mechanical behavior is typically fragile. With reference to the structural type of Moment Resisting Frames (MRF), steel links located at the ends of the beams are very promising solutions. In this regards the paper focuses on a beam-column timber joint equipped with steel links for dissipative heavy timber seismic resistant MRF, inspired by a reference experimental campaign on timber beam-to column assemblages conducted at the University of Trento. A refined finite element numerical model of the joint is set-up through the Abaqus software (v. 6.14) and efficiently calibrated on the basis of the experimental evidences. A very good numerical simulation of monotonic tests carried out in Trento has been achieved. The FE model would be a powerful tool for carrying out parametrical analysis aiming at the characterization of the mechanical properties and the optimization of the system, for the application in seismic resistant timber MRF.

In the current European standards for the design of timber structures, the issue of timber-to-timber joint type is addressed only for squared timber, which makes the pinpointing of the round timber bolted joints carrying capacity near-unfeasible due to the insufficient support in the current standards. To compare the behavior of this type of connections have been made a series of tests of round timber joints in different inclinations tensile load to the grains but also the reference tests of squared timber joints. Mechanical behavior of round and squared timber bolted joints were tested in the laboratory of the Faculty of Civil Engineering in Ostrava. This paper presents results of static tests in tension at an angle of 0°, 90°, 60° to the grain of squared and round timber bolted joints.

© 2017 Elsevier Ltd Despite a large number of studies on estimating the effective bond length from the characteristics of the component materials, key parameters governing the effective bond length for FRP-to-timber joint have not been suggested by any of the current Codes and developed theories to date mostly cover FRP-to-concrete joints. Also, most theoretical bond strength models have been derived based on effective bond length. Therefore, to achieve a satisfactory bonded joint, the effectiveness of bond length is required to be accurately considered. This research study investigates 136 FRP-to-timber joints subjected to pull-out tests in order to determine the stress and strain distribution profiles along the interface and subsequently analyses the results to undertake direct measurement of the effective bond length. In addition, a modified test set up has been developed and is presented. A novel theoretical model has been established through regression analysis of bond length data and accordingly a new predictive model for effective bond length for FRP-to-timber joints has been developed. A comparative analysis between the results of the experimental pull-out tests results and those predicted from the analytical model indicates a satisfactory correlation is achieved between measured and predicted effective bond length, verifying the validity of the new model.

This paper presents an experimental program for testing glued-in rebar timber joints. Twenty five glulam specimens, each with a single glued-in rebar parallel to the grain were tested to evaluate the effects of anchorage length and glue-line thickness on pull-out strength and bond behaviour of glued-in rebar timber joints. Tests were conducted in pull-pull configuration. The test results showed that both the anchorage length and glue-line thickness had a significant influence on these two properties. Failure modes were characterized by pull out failure of the rebar, either alone or combined with the shear failure of timber along the glue line, longitudinal splitting of wood and bar yielding. For the same anchorage length, the average bond stress at both interfaces showed different variations (increasing by 11.6% at the bar/adhesive interface, and decreasing by 12% at the adhesive/timber interface) since the glue-line thickness increased from 2 mm to 6 mm. The load–slip relationship and initial stiffness of specimens were analysed in terms of anchorage length and glue-line thickness. An empirical bond–slip model for glued-in rebar timber joint was proposed by regression analysis based on the experimental data. It was observed that the proposed model fit the bond–slip relationship of glued in rebar timber joints with less than 15% deviation. Finally, the test results were compared with the design proposals reported in the literatures. It can be concluded that the prediction of Rossignon design proposal was more closely to the test results, and the Steiger design equation was unsafe, however, the Riberholt design equation was too conservative for the joint design.

A quite widespread methodology of restoration of ancient timber structures envisages the introduction of new timber elements, connected to the standing structure by a timber-to-timber joint. An efficient alternative to the most used jointing technologies, which employ metallic bolted plates, steel pins, or epoxy resin adhesives, could be the use of timber pegs, if reliable design formulas could be found in codes devoted to timber structures. The design rules currently available for pinned joints contemplate only steel connectors, involve mechanical characteristics of the dowel as well as of the timber elements constituting the joint and are based on Johansen’s theory. The present research has the target of verifying the applicability of this theoretical model, and of the derived design formulas, to the case of timber pegs. At this aim, an experimental research has been performed, devoting special attention to the description of timber peg behavior inside the double shear plane joint and of dowel-bearing strength of the base timber, when a timber peg substitutes the envisaged steel bolt. Obtained results were compared with theoretical ones, showing that the different nature of the material employed for the pins needs more specific evaluation of the mechanical properties to be inserted in design formulas. Moreover, as in the field of new building timber joints fastened by timber pegs are widely employed in prefabricated timber frame industry, contents of the design standard for those structures are also taken into account, especially with reference to the “effective shear” failure mode of the timber peg.

Timber connection is the most important part in timber structural building. In design, it depends on parameter criteria such as bolt diameter, bolt spacing, edge and end distance. End distance is one of design criteria that will influence mechanical timber joint such in single and double shear. This study focuses for a single fastener joint loaded in double shear with 12mm and 16mm bolt diameters having 30mm and 40mm end distance respectively. Double shear test was conducted on Balau timber species and the finding also focuses on the pattern failure modes with reference to European Yield Model (EYM) theory according to National Design Specification (NDS) 2005. It shows that the joint ability to withstand load decreased when the bolt diameter and end distance smaller and conversely with larger bolt diameter. The failure behavior for 12mm diameter tends to fail into category IIIs which described two plastic hinges formed with crushing of wood fibres in the side members. While, 16mm diameter bolt tends to fail under categories of mode Is which dowel bearing failure or crushing of the side members. Eventually, 12mm bolt diameter produces lower shear strength compared to 16mm bolt diameter.

A new type of moment resisting timber joint has been developed. The joint is made up of steel plates, bolts and cotters. The plates and the bolts are embedded with timber element of frame structure. By combining those elements with steel cotters, moment resisting joints can be constructed easily. Static loading tests of the joint have been performed, and results of the tests made it clear that the joint have rotational rigidity and strength required from constructing moment resisting joint. In this report, three kinds of racking tests were performed to simulate the moment-rotational angle. “A tests” were prototypes, and “B tests” and “C tests” had each kinds of joint. The simulation results of moment-rotational angle curves by three kinds of tests agree with the prototype tests results.