In the last two decades, the use of wood as a structural material in construction has experienced exponential growth all around the world. In some countries, structural timber is usually used in roofs, walkways and singlefamily homes, limiting its use in big buildings which tend to have additional complexity, with a large floor volume or even a considerable height (up to 20-25 floors).
In this last application, the structural typology based on surface elements (walls and slabs) predominates globally, using panels of cross-laminated wood or CLT. Regarding the structural design of this type of buildings, two great challenges appear compared to the calculation of conventional buildings: the modelling/verification of the linear elements and panels as structural elements and the modelling/design of the joints between panels.
One of the main characteristics of CLT panels is their orthotropy (both sectional and at the material level),
which adds complexity to structural modelling in nonspecific commercial calculation software, since a preprocess is required to transform the characteristics of the panel. to the characteristics of the finite element (different for each software).
Regarding its verification, again a specific formulation is required, not included in the usual software, which requires an external post-processing by the user to transform the forces of the finite element into stresses and demand/capacity ratios.
In relation to the joints between panels, the situation is analogous. It is possible to model them in conventional software with additional effort, while external postprocessing is required to allow the joints to be dimensioned.
Regarding the first point, there are several programs aimed at sectional calculation and design of isolated
elements of timber. The use of these programs is very useful in the design of small-scale buildings and in the pre-dimensioning of elements. Among the commercial calculation software, there is a range of alternatives for the design of both linear and planar timber elements, however, not always the demands from the project are satisfied because of the available manufacturers of each region or the latest technical
approvals or codes.
Furthermore, these software does not resolve all aspects of the design, since the results in joints between panels are limited to the mere obtaining of forces, also requiring external post-processing. Lastly, they do not have the versatility and power of other more advanced commercial software that allow for more complex applications to be carried out.
Scope
The post-processing tools developed are intended to be used as a plug-in or additional module of different commercial finite element software for the design of timber buildings. The novelty of this solution can be analysed from several points of view.
First of all, it allows the design of technologically advanced timber products (CLT panels), which are currently the spearhead of an industry that is committed to sustainability in the construction sector, reducing the carbon footprint.
Secondly, the development of these tools was born after detecting a gap between the possibilities of the existing commercial software and the new products available in the construction sector. In other words, structural engineering consultants are increasingly required to design advanced wooden structures, and to date there is no complete tool that allows their design (as there is for conventional materials such as
concrete and steel).
Lastly, the existence of software that allows the integral design of wooden structures in an automatic and
optimized way facilitates the design of more complex buildings, such as high-rise buildings (up to 20-25 floors), which are very expensive to calculate with the currently existing software. One of the main challenges of this project is to create a versatile post-processing tool that can be used in conventional structural calculation software, for which an input data package or “input” has to be established that
can be easily adapted to the different programs.
Another challenge is to create a friendly interface that can be used by any technician without programming or program code knowledge. If the proposed objectives are met, the tool would allow
an integral design of wooden building structures, overcoming the limitations of existing commercial
software.
Finally, the existence of this tool would simplify and optimize the calculation of these structures, which would undoubtedly promote the use of wood in the construction sector.
Glued-laminated Timber
Results for linear elements:
Cross-laminated Timber
CLT Joints
Results for screwed connections between CLT panels:
Timber Interactive Modelling and Post-Processing Software (TIMPS) is a design tool compatible with many of the commercial software for the purpose of the analysis, design and optimization of big timber structures based on the latest codes and technical approvals.