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.

With the growing emphasis on sustainability, awareness of the environmental impacts and negative potential inherent in current business systems has increased. The circular economy (CE) represents an innovative approach that transforms the traditional linear economy into a restorative system, focussing on extending the life cycle of materials through continuous circulation. The Circular B project aims to develop an international framework that considers multiple facets of the CE, including material and asset management and the use of components in the built environment throughout the entire life cycle of the value chain. The primary objective of the CE is to eliminate waste and pollution (e.g., carbon reduction) and strengthen the resilience of the value chain. However, the current implementation of circular strategies has not yet been found to be effective, with several challenges that cause adverse impacts. This study focuses on investigating and analyzing these challenges, particularly in the cultural and societal domains, using both qualitative and quantitative approaches. The scope of the questionnaire was to identify (1) awareness and understanding, (2) cultural attitude, (3) barriers to adoption, (4) incentives and motivations, (5) participation and engagement, and (6) education and training. A questionnaire was distributed to 270 respondents, with anonymous responses collected. The survey included eight questions specifically designed to address cultural and societal challenges. The survey was conducted with participants from various sectors, including academia, local authorities, industry professionals, consultants, and others collected from all over the world, ensuring diverse perspectives. The main weaknesses found based on this survey are related to (1) budget constraints due to high costs of reintegrating in the loop of materials or components due to the complexity of circular processes, (2) applicability on the market remains still limited, (3) the importance of planning and design in the initial phases, (4) the importance of establishing a comprehensive network to enhance collaboration among stakeholders, and (5) inadequate policies. The insights gained from this study will help stakeholders, such as constructors, maintainers, engineers, designers, and consultants, across various organizations in the value chain to develop practical solutions to mitigate these challenges and improve the overall business system.

Due to the growing need to preserve our planet and reduce carbon emissions during construction, the use of the only carbon-absorbing material, timber, is increasingly being imposed. In addition to the requirement of reducing emissions, there is a necessity for the shortest possible construction time and the minimum use of construction machinery, which has led to the development of prefabricated construction systems. This paper deals with the innovative, hollow, glue-laminated timber elements which are intended for modular construction. Comparing this new system with existing modular systems, the main features and behavior of the constitutive elements, i.e., the hollow, glue-laminated timber elements, are presented. Experimental and numerical analysis of the mechanical performance of the timber elements was carried out and a comparative analysis of the behavior of two different types of hollow timber elements was conducted. The finite element method was used to predict the behavior of this innovative structural system. The results are compared with the analytical procedure to provide a background for the development of standardized methods for the design of timber structures.

The TCC concept has been studied and developed over the past decades. The variety of solutions shows the meaningfulness and functionality of this system, as well as the continuous work of scientists over time. To benefit from these advantages, the composite needs to provide sufficient stiffness to meet the serviceability criteria and load capacity to resist loading at every stage of the building life. An example of connector types and load slip curves according to EN 1995 is given. This paper discusses possible limitations related to residential areas, and additionally, the possible solutions that EN 1995 does not discuss in the case of resonant response (f₁ < 8 Hz). The theoretical studies were accompanied by numerical analyses considering certain simplifications suitable for practical use.

Fire safety greatly contributes to feeling safe, and it is a key parameter for the selection of building materials. The combustibility of timber is one of the main reasons to have the strict restriction on timber for use as a building material, especially for multistory buildings. Therefore, the main prerequisite for the use of timber in buildings is to ensure adequate fire resistance, using passive and active fire protection measures. This article contains the results of mechanical and fire experimental tests of both normal and innovative hollow glued laminated timber beams. A total of 10 timber beams were tested at ambient temperature, and 3 timber beams in fire conditions, which differed in cross-section type but also in the applied fire protection. The first beam was a normal GL beam without fire protection, the second a hollow beam covered by intumescent paint, while the third was also hollow, additionally protected by mineral wool infill inside the holes. The load-carrying capacity of the hollow beam in ambient conditions was estimated at 65% of the load-carrying capacity of a normal GL beam. Fire tests indicated that hollow timber beams with both intumescent paint and mineral wool infill failed at a similar time as a normal GL beam without fire protection. One-dimensional β₀ and notional charring rates β_n were obtained. Time to the protective material failure was 17 min. The main cause of failure of hollow beams was the appearance of delamination due to the reduction of the lamella bonding surface.