Seismic Design of Timber Buildings: Highlighted Challenges and Future Trends

Use of timber as a construction material has entered a period of renaissance since the development of high-performance engineered wood products, enabling larger and taller buildings to be built. In addition, due to substantial contribution of the building sector to global energy use, greenhouse gas emissions and waste production, sustainable solutions are needed, for which timber has shown a great potential as a sustainable, resilient and renewable building alternative, not only for single family homes but also for mid-rise and high-rise buildings. Both recent technological developments in timber engineering and exponentially increased use of engineered wood products and wood composites reflect in deficiency of current timber codes and standards. This paper presents an overview of some of the current challenges and emerging trends in the field of seismic design of timber buildings. Currently existing building codes and the development of new generation of European building codes are presented. Ongoing studies on a variety topics within seismic timber engineering are presented, including tall timber and hybrid buildings, composites with timber and seismic retrofitting with timber. Crucial challenges, key research needs and opportunities are addressed and critically discussed.

Bending Strength Analysis of Durian and Coconut Timber Laminated Beam

Durian timber grows well in the Gunungpati area, although its use is still limited to the needs of light construction. Lamination (glulam) is a combination of one or more kinds of materials and the materials are made into relatively thin layers glued together to form a larger dimension. Timber engineering experiment was conducted by creating a laminated beam made of Durian and coconut timber, with a composition of coconut - Durian – coconut. The purpose of this study was to determine the bending strength of a composition of coconut – durian – coconut laminated beam in strengthening the weak side of the durian timber. Coconut timber was used to reinforce durian timber because the weight of coconut timber is relatively larger compared to Durian timber. Durian laminated beam with coconut timber reinforcement on the top and bottom can be used as an alternative material to improve the bending strength durian timber. Lamination technology was able to increase the bending strength of Durian timber with laminated beams by 12.6% from the average bending strength of 36.68 MPa durian timber, laminated beams into bending strength of 41.30 MPa.

Performance of glued-in-rod connections in cross-laminated timber

The widespread availability of Cross-laminated timber (CLT) provides opportunities to extend the use of wood beyond traditional low-rise residential construction. Glued-in rods (GiR) are an interesting technical solution for numerous structural applications in timber engineering. Although GiR connections have the potential to be used in combination with CLT, research on this application is scarce. In this thesis, an experimental investigation on the performance of GiR in CLT is presented. Two different 5-ply CLT panel thicknesses (139 and 175 mm), two steel rod diameters (d = 12.7 and 19.1 mm) and five different anchorage lengths (la = 6d, 10d, 12d, 14d and 18d) were considered in single and multiple rod connections. A total of 260 specimens were fabricated and subsequently tested under uni-axial quasi-static monotonic tension. The results were assessed in terms of load-carrying capacity, stiffness and failure modes and demonstrated that GiR in CLT offer an alternative high capacity timber connection.

Modelling the viscoelastic mechanosorptive behaviour of Norway spruce under long-term compression perpendicular to the grain

The effects of variation in humidity coupled with long-term loading give rise to dimensional changes and creep effects in wooden elements. Many wooden products such as cross-laminated timber (CLT) plates as well as many common structural details used in timber engineering are vulnerable to variations in moisture content (MC) as well as to creep effects. This paper addresses the long-term effects in the material modelling of timber by the finite element method (FEM), also considering the viscoelastic and mechanosorptive effects in wood. The model was calibrated using both relaxation tests and creep tests. The results from both long-term compression perpendicular- to-grain tests (relaxation and creep) performed on glulam (GL30c) from Norway spruce (Picea abies) with moisture control are presented in this paper. The material model considers the effect of loading and moisture changes. For realistic comparison, the pith location of each lamella was specified in the numerical analyses. Ultimately, a comparison between the numerical results and the experimental results has been provided, exhibiting an overall good estimation of timber response.

Towards efficiency in constructive timber engineering - design and optimization of timber trusses

<p>Currently, laminated timber is widely used. The gluing allows for higher part length and involves an advantageous behavior regarding deformations due to shrinkage and lead to better, more regular mechanical properties. The drawback is a low material utilization factor. Starting from a tree trunk, only 25-30 % are part of the final product. Thus, the high-quality product has to be used as efficient as possible.</p><p>At moment mostly, plate girders made of laminated timber are used as a result of the efficient industrialized manufacturing process. If in comparison a truss system is used, a similar load bearing capacity and stiffness can be achieved with much less material effort. The aim of the authors is to industrialize the design and manufacturing process of timber truss systems to be able to compete with the common plate girder systems. The complete process starting from the design, static optimization, work preparation to production process will be cumulated in a continuous digital approach. The paper describes the research approach and experiments about the digital production (by use of a robot arm) and load bearing behavior of different wood- wood connections as first development step. In addition, the design of 1:1 load tests at different timber trusses as well as comparable plate girders is presented.</p>