Projects / Programmes
Modelling pyrolysis to determine the decomposition of wood in natural fire
| Code |
Science |
Field |
Subfield |
| 2.01.03 |
Engineering sciences and technologies |
Civil engineering |
Constructions in civil engineering |
| Code |
Science |
Field |
| T220 |
Technological sciences |
Civil engineering, hydraulic engineering, offshore technology, soil mechanics |
| Code |
Science |
Field |
| 2.01 |
Engineering and Technology |
Civil engineering |
Pyrolysis of wood, charring of wood, natural fire, hygro-thermal-pyroylsis model
Researchers (1)
| no. |
Code |
Name and surname |
Research area |
Role |
Period |
No. of publicationsNo. of publications |
| 1. |
34368 |
PhD Robert Pečenko |
Mechanics |
Head |
2017 - 2019 |
73 |
Organisations (1)
Abstract
The use of timber structures in modern times is rapidly increasing. Concerns for sustainable, ecological, low energy and affordable construction are some of many benefits that speak in favour of timber. In accordance with the Construction act (ZGO-1), to use timber buildings, proof of fire safety is required. However, current prescriptive rules to determine fire safety represent an obstacle for the engineer, since they allow the design of timber buildings only up to four storeys according to Slovenian technical guideline and up to eight storeys according to the most of Europeans guidelines. It is possible to design higher building based on the computational models, which unfortunately at this moment are not precise enough, so that additional measures based on the prescriptive rules are needed to achieve the desired fire safety. However, using mixed approach is not optimal and occasionally also unsafe. Therefore, to design higher structures, a performance based approach is needed, where the influence of natural fire and advanced computational models has to be accounted for. To determine fire safety of timber structures in natural fire, it is necessary to know physical and chemical phenomena that have an influence on the behaviour of timber structures in natural fire. Two processes are dominant. First is heat and moisture transfer, which governs the distribution of temperatures in timber. Second is pyrolysis of wood associated with charring and reduction of mechanical properties of wood at elevated temperatures. The pyrolysis describes the decomposition of the basic chemical constituents of wood (cellulose, hemicellulose, lignin), where the fire growth rate plays a decisive role, because the decomposition of each constituent depends not only on the temperature increase in wood but also on how fast this increase is. Based on the decomposition of constituents, it is possible to determine deterioration and degree of charring of individual wood fibres for a random fire. This is also the main objective of the proposed project, i.e. development of a new advanced mathematical and numerical model that will couple heat and moisture transfer together with the wood pyrolysis and will be suitable for a random fire load, which will present a step towards a performance based design. New hygro-thermal-pyrolysis model will allow predicting the decomposition of wood fibres, which will be the basis to determine the response and fire safety of timber structures exposed to natural fire. The proposed model will be formed on a precise physical and chemical description of the problem, allowing the design of more secure and economical timber structures. At the same time, new model will represent an innovation in this field. Based on the new knowledge it will be possible to influence on the development of broader scientific community in this field. The results of the proposed project can also help to improve existing standards and refine engineering methods to be applicable also for calculating fire safety of timber structures in natural fires. Further on, beneficial outcomes of the proposed project can also be more targeted experimental investigations, the upgrade of technical guideline and many others. In addition, based on the new model the restriction regarding constructing multi-storey timber structures () 4 storeys) will be indirectly abolished, which may potentially result in larger number of such buildings. This can lead to substantial economic boost for the construction and entire forest-wood industry. Moreover, by constructing multi-storey timber buildings it is possible to solve the housing issues in Slovenia. Finally, increased wood production means lower environmental impact and reduced global warming.
From the foregoing, it is evident that the results of the proposed project have an immense influence on the development of the scientific field, economy, social infrastructure, as well as on the preservation of natural and cultural heritage.
Significance for science
The main product of the proposed project is the development of coupled hygro-thermal-pyrolysis model that will be suitable to model timber structures in natural fire, which is also the basic principle of the performance-based design. The new developed model will represent a novelty in this field and, thus, contribute to a better understanding of physical and chemical processes occurring in timber exposed to natural fire. Currently, the main issue in Slovenia and globally, is still the behaviour of timber structures in natural fire, meaning that with the newly acquired knowledge it will be possible to have an impact on the development of science in this field.
The new model will predict the damage of wood fibres in natural fire. Based on that a new reduction coefficient for timber strength can be determined that will be appropriate for random fire load. These coefficients are currently limited to the use of standard fires. The new coefficients will be available not only to the scientific but also for the broader engineering community, which will enable the design of safer and optimized timber structures.
The main objective currently in Europe is to improve the existing design methods to determine fire resistance of timber structures given in Eurocode 5 [1] by taking into account natural fire exposure. So far, this has been the main disadvantage of this design code. Therefore, the proposed postdoctoral project is topical and very promising in realizing the European strategic goals. Possible improvements of the current Eurocode are:
Determination of char front temperature and charring rate as a function of fire growth rate.
Upgrading existing simplified methods to determine the fire resistance, so that they are eligible for natural fires
Identification of new coefficients for reducing the strength and stiffness of wood
Project plan is also to perform the sensitivity analysis of the hygro-thermal-pyrolysis model, where key material parameters that affect the model behaviour will be identified. Based on that it will be possible to design more targeted experimental research in order to measure these key material properties of wood. In this context, new numerical model may in the future present a support for an advanced experimental research.
Project results can potentially have an influence on the development of new guidelines for the design of multi-storey timber structures in cases of fire, since current regulations allows only construction up to 4 floors. One of the possibilities is an upgrade of technical guideline TSG-01-2010.
Current research outcomes will be regularly presented in various congresses, workshops and meetings through the COST Action FP1404. Therefore, immediate feedback of the wider European research community in this field will be acquired, which may result in important findings that may have a direct impact on the broad scientific environment.
Significance for the country
The most valuable contribution of the project is that the new developed hygro-thermal-pyrolysis model will allow planning and designing safer and more economical timber structures exposed to fire. Consequently, this means fewer human casualties and less damage in fire. Therefore, the foreseen project results will be of utmost importance in terms of demographic and socio-economic development.
The proposed project objective is also a more optimized design and determination of fire safety of multi-storey timber buildings () 4 storeys) in Slovenia. The possibility to optimally design multi-storey timber structures () 4 storeys) could potentially lead to the increased construction of these facilities, and, thereby to increased wood consumption in Slovenia (annually there is 2 million m3 of wood available). This will generate a need for logging and manufacturing timber structural elements, such as solid wood, glued laminated timber, cross laminated panels and others, which will have a direct positive impact on the economic activity of the entire forest-wood chain in Slovenia. In turn, the potential to create new jobs will emerge, especially in rural areas, which are economically the weakest. The increased activity of the forest-wood chain goes also hand in hand with the action plan to increase the competitiveness of the forest-wood chain in Slovenia accepted in 2012.
A big issue in Slovenia is unresolved housing problems. In the last decade, housing construction has been more or less stationary, although the demand is still rising. Constructing multi-storey timber buildings () 4 storeys) could contribute to resolving the housing issue, since the construction of timber structures is fast and low-cost. Furthermore, timber creates a favourable living environment due to its thermal end hygroscopic features, meaning that living in timber buildings has a positive effect on the psycho-physical well-being of an individual. Taking all these advantages into account, it is evident that the proposed project is of great importance in terms of improving social infrastructure as well as human health.
The importance of increased wood production is not seen only in the economic growth and social infrastructure improvement, but also as concerns all of us and our future generations. Wood is natural, organic, and the only renewable building material. Thus, it enables a sustainable supply, which is today particularly valuable, especially in terms of sustainable building and living and environmental protection. To process wood, little energy is consumed, in addition, the energy for processing is drawn from own wood residues. As a results, word processing and production have small environmental impact. Further on, wood as building material has a very low carbon footprint, and has as such an important role in the reduction of global warming. From this point of view the proposed project is of vital importance also in preservation of natural and cultural heritage.
Most important scientific results
Interim report,
final report
Most important socioeconomically and culturally relevant results
Interim report,
final report
