Nowadays, timber constructions are dominated by two structural timber products: on the one hand by the beam-like unidirectionally build-up glued laminated timber (GLT) and on the other hand by the planar product cross laminated timber (CLT) made up of orthogonal layers of side-by-side arranged laminations. Both products are currently manufactured on their own specific production lines.
The basic idea of this research project is to additionally utilise current CLT production lines for manufacturing beam-like products build-up of unidirectionally or orthogonally arranged laminations, named as “flex_GLT” and “flex_CLT” products. This by splitting large panels of unidirectional or orthogonal single-layer panels each composed of laminations glued structurally on their narrow faces. Apart from increased flexibility in utilising current CLT production lines this approach enables in an economic appealing way also to increase the product portfolio by new products with somehow optimal mechanical and geometrical properties.
However, by separating the large panels into beams/columns of certain dimensions disrespecting any relative position to gaps within the panels, the width of the laminations of individual layers is reduced to an undefined extent. As a result of this cross-section reduction, the strength classification, which was carried out for the individual laminations referring locally to the respective full cross section dimension, usually becomes invalid. This also occurs when CLT is used as a "diaphragm-like" beam or column ("flex_ CLT"). As a consequence, the intended “flex_products” currently cannot be assigned to the current state-of-the-art nor represented by currently available models and thus are not covered by current regulations.
The project offers the opportunity for product diversification in existing CLT production lines. In particular, a deeper knowledge is gained on handling laminations with residual cross-sections and their influence on the mechanical properties of unidirectional and orthogonal products (“flex_GLT” and “flex_CLT” beams). Additionally, gain of knowledge, as expected from this product, in particular from stochastic-mechanical modelling, serves on one hand to describe the “flex_products”, generally to increase knowledge and possibilities to predict the influence of residual cross sections as well as on the other hand to generally increase the understanding and quantification of system effects as a result of serial, sub-parallel acting elements represented by rigid composites of laminations featuring full and residual cross sections. In-depth knowledge of this topic not only serves economic purposes as well as a solid decision basis, but also ensures an appropriate reliability of these products.