Preserving wooden buildings for longer



Dr. Serena Gambarelli from the Materials Testing Institute at the University of Stuttgart wants to understand and model the hygro-thermo-mechanical properties of wood, and has been included in the Baden-Württemberg Foundation’s Elite Program for postdocs.

Wood isn’t only used in a variety of engineering projects, it’s also used in objects of cultural interest such as sculptures and paintings. If the complex organic material is exposed to unsuitable environmental conditions such as changes in humidity and temperature or mechanical influences, this can lead to damage and impair its durability. Dr. Serena Gambarelli at the Materials Testing Institute at the University of Stuttgart wants to understand and model the complex hygro-thermo-mechanical behavior of wood in order to preserve structures, historical buildings and artifacts. As a part of the Elite Program for postdocs run by the Baden-Württemberg Foundation, she was eligible for funding for her project.

Dr. Gambarelli is carrying out research into the computational mechanics of various building materials and building methods. The focus is on the development of reliable digital tools for analyzing the most important processes of deterioration in heterogeneous materials, such as for example concrete, natural stone, masonry or wood, which are caused by a variety of different stresses and interactions. In order to better understand the influence of material heterogeneity on the behavior of the material at the macro level, modeling is also used at the smaller meso scale.

Using a concrete model as an example

In order to gain a better understanding of the complex hygro-thermo-mechanical properties of wood, Gambarelli draws on a 3D hygro-thermo-mechanical model which was originally designed for concrete as part of a preliminary study carried out by the Institute of Construction Materials at the University of Stuttgart. She is now developing this further to make it possible to investigate the damage induced in wood by mechanical and environmental impacts. The model currently being proposed consists of a mechanical and a non-mechanical part (transport of warmth and moisture). This is being formulated within the framework of continuum mechanics, taking the basic principles of irreversible thermodynamics into consideration.

As a way of reducing the equations (discretization), standard-finite elements (FE) with two coordinate systems are used, the global and the local. The global coordinate system defines the direction of the growth rings in the tree trunk, whereas the FE discretization on the other hand is carried out in the local coordinate system. Unlike the majority of mesoscale models, the proposed model automatically recognizes the position of the individual rings in the FE network for any given ring width. The mechanical part of the model is based on the "microplane" model, a model designed to analyze damage and fractures in concrete which has been converted to use with wood. First of all the directional dependency of the properties of wood (anisotropy) is taken into consideration, then secondly the high longitudinal strength of the wood (fiber direction). Add to that the function of the ring width, which takes into account the fact that young wood is not as stiff as old wood.

Protection against aggressive environmental conditions

The non-mechanical part of the model takes into consideration the transport of warmth and moisture by anisotropic material, meaning material whose physical, mechanical and chemical properties are directionally dependent. The transport through solid wood fibers as well as through pores also has a part to play.

Further findings are gained about the hygro-thermo-mechanical properties of wood based on an objective, physical-based mathematical model. This should be used effectively when investigating damage to both new and existing wooden structures. Furthermore, rules can be formulated by means of extensive parameter studies, and relatively simple macro models for wood can then be proposed based on the developed meso model. This means that the lifespan of wooden structures which are exposed to aggressive environmental conditions should increase over the long term.

Share this page

" alt="<p> <span >If you click on this link a connection to Facebook will be established:<br/> </span> <a href=’#’ target=’_blank’ >Share this page on Facebook Regard our privacy notice.

" If you click on this link a connection to Twitter will be established: Share this page on Twitter Regard our privacy notice.

" alt="<p> <span >If you click on this link a connection to Twitter will be established:<br/> </span> <a href=’#’ target=’_blank’ >Share this page on Twitter Regard our privacy notice.

" If you click on this link a connection to LinkedIn will be established: Share this page on LinkedIn Regard our privacy notice.

" alt="<p> <span >If you click on this link a connection to LinkedIn will be established:<br/> </span> <a href=’#’ target=’_blank’ >Share this page on LinkedIn Regard our privacy notice.

" If you click on this link a connection to Xing will be established: Share this page on Xing Regard our privacy notice.

" alt="<p> <span >If you click on this link a connection to Xing will be established:<br/> </span> <a href=’#’ target=’_blank’ >Share this page on Xing Regard our privacy notice.

Share this page on E-Mail Regard our privacy notice.

" alt="<p> <span ><br/> </span> <a href=’#’ target=’_self’ >Share this page on E-Mail Regard our privacy notice.


This site uses cookies and analysis tools to improve the usability of the site. More information. |