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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.

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 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.