Over 5 million m 3 of engineered wood products (EWPs) are produced in the EU annually and the market is rising. However, EWPs have a high degree of petrochemical use in their manufacturing. In addition, throughout the life span of these EWP products from manufacture to disposal, they emit formaldehyde and other volatile organic compounds (VOCs), which makes recycling very difficult. In this paper, preliminary experimental work on Adhesive Free Engineered Wood Products (AFEWPs) is presented, which covers (1) manufacture of compressed wood (CW) dowels, (2) fabrication of adhesive free laminated beams and connections, (3) structural testing of AFEWPs. Also, the finite element models are being developed to assist designing of AFEWPs in terms of size of compressed wood dowel and dowel patterns in order to maximise their stiffness and load carrying capacities.
To support the transition to a bio-based society, it is preferable to substitute metallic fasteners and adhesives in timber construction with an eco-friendly alternative. Recent studies have identified compressed wood dowels and plates as a possible substitute for metallic fasteners in contemporary and mainstream applications. In this study, a spliced beam-beam connection system using compressed wood dowels and slotted-in compressed wood plates was examined under four-point bending. The study has considered specimens with compressed wood dowels of 10 mm diameter and compressed wood plates of 10 mm thickness. The load carrying capacity of connections using compressed wood dowels and plates were compared to connections utilising steel dowels and plates of equivalent capacity. Typical failure modes, moment resistance and rotational stiffness of both connection systems are evaluated on the basis of the experimental results. Tests have demonstrated similar failure modes when comparing steel-timber and compressed wood-timber connection systems. The mean failure load for the compressed wood-timber connection system is only 20.3% less than that achieved for the steel-timber connection system. The mean rotational stiffness of the compressed wood-timber connection system is 18.55% less than that achieved for the steel-timber connection system. These preliminary results demonstrate the potential for the use of compressed wood elements in the manufacture of timber connections.
The widespread use of energy-intensive metallic connectors and synthetic adhesives in modern timber construction has negative implications for the end-of-life disposal or re-use of the structural timber components. Therefore, it is favourable to substitute metallic connectors and synthetic adhesives with bio-based alternatives such as wood-based connectors. Recent studies have shown that densified or compressed wood (CW) with superior mechanical properties could be suitable for the manufacture of wood-based connectors in the form of CW dowels and CW plates. This study experimentally examines the moment-rotation behaviour of semi-rigid type timber-CW beam-beam connections under pure bending. The study also assesses the suitability of current design rules to predict the moment capacity of timber-CW connections. The comparative study has shown that the moment capacity of the timber-CW connection can be conservatively predicted from the characteristic load-carrying capacity of the connections calculated using the EC 5 strength equations.
The use of timber in construction in medium–high rise construction has increased in recent years largely due to the significant innovation in engineered wood products and connection technology coupled with a desire to utilise more environmentally sustainable construction materials. While engineered wood products offer a low-carbon solution to the construction industry, the widespread use of adhesive and metallic fasteners often limits the recyclability of the structural components at the end of life of the structure and it may be beneficial to reduce this where possible.
To establish the possibility of an all-wood connection solution, this preliminary study examines a series of beam-column connections designs to evaluate the relative performance of the different designs, which are connected with modified or compressed wood (CW) connectors. The connection designs are formed between glued-laminated beam and column members in the first instance and later examined when connecting dowel-laminated timber (DLT) members.
The results show that significant moment capacity and rotational stiffness can be achieved for connections solely connected using CW fasteners. Furthermore, the all-wood solution utilising CW fasteners to connect DLT members has also demonstrated significant moment capacity and rotational stiffness capacity without the use of adhesive and metallic components.