Cross-laminated timber (CLT) is a rapidly evolving building product, particularly well-suited to load- bearing applications in construction, with outstanding strength and stiffness properties. Thanks to its high strength-to-weight ratio, environmental compatibility, CO2 storage capacity, aesthetic appeal and mechanical properties, CLT has become the preferred choice for medium- to large-scale timber construction projects. This is due to the growing demand in the construction industry for sustainable, high-performance building materials in the construction industry and the increasing acceptance of cross-laminated timber (CLT) as a viable alternative to traditional building materials such as concrete and steel. As CLT becomes increasingly important in construction, it is essential to investigate and understand its performance at the limit state of load-bearing capacity. Despite many years of R&D work on CLT, civil engineers today still face the challenge of properly verifying stress interactions and concentrations in CLT elements at the ultimate limit state (ULS), which is therefore considered an open research question.
In particular, the interactions between transverse stresses and shear stresses can lead to critical failure mechanisms in CLT that are hardly covered by the current state of the art and knowledge. Existing ULS verification formats often consider these stresses separately from each other, which can potentially result in conservative or uncertain design outcomes. This knowledge gap motivates the development of advanced ULS verification methods that consider the interactions between the different types of stress, thus ensuring a more accurate and reliable design process for CLT structures under combined stresses.
The inevitable interactions between the different types of stress are crucial for the performance of CLT in various structural applications. For example, CLT elements used in ceilings, walls and roofs experience different combinations of stresses depending on their orientation and the type of loads acting on them. This research project focuses on the advanced verification of the ultimate limit state of CLT structures under combined stresses. The focus is on the interaction between stresses perpendicular to the fibre and shear stresses. The project will integrate theoretical modelling, computational simulations and experimental tests to investigate the stress distribution, the stress interaction and the onset of failure in CLT elements under combined stresses. Additionally, the study will examine how material properties, geometric configurations and loading scenarios affect the types of failure that occur. Models for stress interaction will be developed and interaction diagrams or equations for ULS verification will be proposed. Furthermore, the effects of local stress concentration in CLT elements will be investigated in order to incorporate the impact of openings in CLT beams, walls and floor elements into the verification process.
By the end of the project, the research will improve the understanding of stress interactions in CLT structural components, formulate cross-validated prediction models that take the layered orthotropic nature of CLT into account, develop an advanced ULS verification framework that considers stress interactions, and propose practical recommendations for incorporating the results into design standards and corresponding guidelines.
Funding programme Collective Research
Collective Research | General Programmes
The funding of cooperative research projects (sector projects) in Collective Research supports pre-competitive research projects which do not include any directly exploitable product and process or service developments.
Collective Research stands for cooperative research projects for whose results are made available to the industry and is open to all topics.