Name: Gerhard Fink - ETH Zurich, Switzerland
STSM Topic : Risk based analysis of partly failed or damaged timber constructions
Host Institute: Jochen Kohler - NTNU Trondheim, Norway
Duration: 1 month
Outcomes: RILEM conference on "Risk Based Investigations of Partly Failed or Damaged Timber Constructions"
Abstract: In the last decade a significant amount of failures has been detected on timber constructions. Fortunately the majority of those constructions show only partly failure; e.g. one failed structural member whereas the remaining structural members are apparently unaffected but could be also damaged due to the additional loading caused by load redistribution. In such cases the corresponding engineer has to made a decision for the repair alternatives. Possible alternatives could be:
(a) exchange of the failed member,
(b) reinforcement of the all members
(c) complete renovation of the entire construction.
To find the optimal decision it is essential to estimate the actual material properties of existing structural components with a sufficient accuracy. The main purpose of the STSM was the development of a framework to estimate the material properties of the remaining, not-failed structural components. It is demonstrated how different kind of information, such as the resistance of the failed member(s) or the results of destructive and non-destructive measurements can be considered for estimating the material properties. In order to illustrate the application of the developed framework a case study is conducted. Thereby a risk analysis is made for a partly damaged timber-hall located in Zurich.

Name: Natalie Quinn - University College London
STSM Topic : Analysis and strengthening of Peruvian mortice and tenon connections
Host Institute: Thierry Descamps - University of Mons, Belgium.
Duration: 1 month
Download: STSM report
Outcomes: SHATIS 2013 Conference with publication in Advanced Materials Research - Volume 778 and to be published in "International of Architectural Heritage"

Abstract: The coast of Peru is one of the most seismically active regions in the world. It also has a large number of important historic residential buildings built after the arrival of the Spanish in Peru in the mid-16th century. These buildings are particularly susceptible to earthquakes and little research has been carried out to analyse their behaviour or determine how best to protect them. Work is currently being carried out at UCL to investigate the global behaviour of these buildings during an earthquake by means of finite element analysis, in order to assess their vulnerability and recommend suitable retrofitting measures. The ground floor of these buildings is usually adobe, with the upper storeys in quincha, a traditional construction technique consisting of a timber frame with cane and mud infill, covered with a layer of lime plaster. Despite a large number of these buildings still being in existence, no consistent study has been conducted to characterise this typology and understand the mechanical behaviour of the quincha.

Name: Jose-Ramon Aira - Universidad Politecnica de Madrid
STSM Topic : Analysis by FEM of stress distribution in traditional timber joints
Host Institute: Thierry Descamps - University of Mons, Belgium.
Duration: 2 months
Outcomes: Wood Science and Technology - Under reviewing (April 2013)

Abstract: In this study the stress distribution and stress concentration factor (SCF) of a generic notched wood piece and ASTM D 143:94 notched shear block specimen are analyzed. A 2D plane stress finite element model with linear elastic behaviour was assumed for the bulk material and it was considered a predefined potential crack path and cohesive behaviour of the crack surfaces. Wood was considered as an orthotropic material with transversal isotropy. In the notched wood pieces, the shear stress distribution along the shear plane and the SCF when varying the ratio l/t (length of the heel/depth of the notch) was obtained. The shear stress distribution is not uniform in any situation getting closer to a slightly triangular shape. The shear stress concentration increases when l/t is greater and for l/t > 8 the failure occurs due to crack progressing. The SCF can be approximated fairly well to the natural logarithm of l/t. In the ASTM D 143:94 notched shear block specimen, the shear stress distribution remains a constant value only in the central part of the shear plane and the SCF is 2,41.

Name: Tomasz Nowak - University of Technology, Poland
STSM Topic : Diagnosis of timber structures using nondestructive techniques.
Host Institute: Robert Kliger - Chalmers University of Technology, Goteborg, Sweden.
Duration: 2 weeks
Download: STSM report
Outcomes: "In situ assessment of the timber floor structure of the Skansen Lejonet fortification, Sweden" published in "Construction and Building Materials"

Abstract: The most effective way of assessing the condition of the material in a structure are destructive tests, but in most cases it is impossible to take samples from the members of an existing structure. In order to nondestructively obtain both qualitative results (the extent of possible degradation, structural discontinuities, etc.) and quantitative results (density, strength, the modulus of elasticity) it is necessary to carry out nondestructive tests combined with  destructive tests on samples taken from the structural members. Through the correlation of nondestructive test results and strength test results comprehensive data for static-strength analyses of timber structures can be obtained. Guidelines for the design of reinforcements for historic timber structures can be developed by properly interpreting the data. None of the existing nondestructive methods for assessing the condition of the members of timber structures is capable of assessing the strength characteristics of wood unequivocally. Even the X-ray method, quite precisely measuring wood density, is incapable of this because of such structural characteristics of the material as inclusions and the slope and nonuniform pattern of grain, which significantly affect (the least in the case of compression) the strength parameters of wood. Further research is needed to improve both the NDT techniques and the interpretation of the obtained results.

Name: Carina Fonseca Ferreira - University College London
STSM Topic : Seismic assessment of historical vaulted timber structures
Host Institute: Jose Fernandez-Cabo - Universidad Politechnica de Madrid, Spain
Duration: 3 weeks
Outcomes: WG1 Meeting, Trento, September 2013: "Analysis of nailed joints in historic vaulted timber structures" and SHATIS 2013 Conference with publication in  Advanced Materials Research - Volume 778

Abstract: The present STSM sought the refinement and calibration of the numerical model of a historic timber vault by modelling the structural response of traditional nailed joints. These joints are connecting together the several planks that make the arches. The STSM was hosted by the Universidad Politécnica de Madrid (UPM) and took place from the 22nd of October to the 11th of November, 2012. Before the STSM, UPM performed static tests on a traditional planked timber arch and tested single nailed joints under bending and shear. A numerical model of UPM’s arch was developed within the STSM in order to numerically reproduce the experimental results. For this purpose, the parameters used to characterise the springs which simulate the nailed joints of the arches, and the material properties of the timber were adjusted. The historic timber vault was then modelled by using the same approach applied to the modelling of UPM’s arch and the input parameters previously calibrated. The principal outcome of the STSM is a numerical model of a representative historic timber vault that simulates in a realistic way the global deformation of the structure and the relative displacements of the planks of the arches.

Name: Alexey Vorobyev - Uppsala University, Sweden
STSM Topic : Mechanics of wood deformation at multiscale levels
Host Institute: Olivier Arnould - University of Montpellier, France
Duration: 1 month
Download: STSM report
Outcomes: Participation to the 5th Asia Pacific Congress on Computational Mechanic, Singapore, December 2013. Article in progess. 

Abstract: Classical characterization methods for anisotropic materials usually need the machining of several samples along different directions. Wood is considered to be an orthotropic material. This means that material constants, within the linear elasticity, in the three principal directions are different and thus needs 9 independent measurements at least. However, due to the strong variability within a single tree, the consistence of the corresponding constants is not ensured if different samples are used. The reduction of the number of samples used for the determination of all the elastic constants is then a crucial point for wood, especially if it is an archeological material. Resonant ultrasound spectroscopy could offer a good alternative because the determination of the entire specimen elastic constants can be obtained from only one sample thanks to noncontact measurements of its resonant frequencies. Conventional quasi-static measurements on samples, with in situ image correlation technique, do not give all necessary orthotropic elastic properties, or not by using a single sample, but can be more accurate and are done at low frequency, more relevant to the loading time of the beam in the Vasa warship. During the STSM, tests were performed on Vasa archeological oak (impregnated with PEG) along with a recent oak with different densities, spanning the entire range evenly (sampling), found in the structural elements. The aim of the STSM is to compare results obtained by the RUS technique and static compression test to identify all the elastic constants with a high degree of confidence and better understand the effect of PEG impregnation on the elastic properties.

Name: Teresa Artola - Basque Country University, Spain
STSM Topic : Development of a decision support toll for timber reinforcement selection.
Host Institute: Annette Harte - National University of Ireland, Galway, Ireland
Duration: 1 month
Download: STSM report
Outcomes: Participation to W1-T1 Meeting at UCL, London (February 2014) and  WG2 Meeting in Antalya, Turkey (May 2014).

Abstract: Research related to structural timber reinforcements commonly results in new methods, new materials or innovative methods of application. The findings of the research are generally disseminated in the form of publications (scientific books, journal papers or articles), seminars or conference proceedings. Therefore, although this work is of great value, there is an elongated timeline to utilisation due to traditional dissemination being employed. The mentioned aspects show us that the designer has to be supported in the decision making. Basic relationships for construction parts and a sufficient number of design possibilities have to be laid down in a suitable database. Knowledge based systems have to assist the user in all planning tasks with the objective to improve and facilitate the complex design of reinforcement for timber roofs. As a result, errors are minimized and time and cost can be reduced. The purpose of my STMS at the College of Engineering and Informatics of the National University of Ireland in Galway is working on preliminary studies to develop a decision support IT tool for choosing an appropriate reinforcement method with consideration of cultural heritage aspects.
The NUI has provided the collaboration of a 2nd year MSc student in IT with a degree in Architectural Technology, and together we processed all the information and decide the best way to organize all the data.

Name: Ivan Giongo - University of Trento, Italy
STSM Topic : Seismic Assessment of Reinforced and Unreinforced Timber Floor Diaphragms.
Host Institute: Jason Ingham, University of Auckland, New Zeeland
Duration: 1,5 month
Download: STSM report
Outcomes: Participation to WG Meeting in Biel.

Abstract: The poor earthquake-performance of unreinforced masonry (URM) buildings has been widely recognized for decades: the recent Christchurch earthquake in New Zealand (22 February 2011) that severely damaged the city’s unreinforced masonry (URM) buildings and killed more than 150 people, demonstrated once more the vulnerability of URM buildings during seismic events (Fig. 2). In those cases the floor diaphragms were almost always comprised of comparatively light timber floor diaphragms, which have routinely demonstrated a significant influence on the seismic performance of the complete masonry structure due to their flexible nature and often inadequate connection to the masonry perimeter walls. The accurate prediction of diaphragm in-plane strength and stiffness is therefore a crucial component within the framework of masonry building seismic assessment.
The need to increase the in-plane stiffness has induced, in the past, some strengthening solutions which recent earthquakes have demonstrated to be inadequate or, in some cases, even unfavourable. As a matter of fact, the substitution of timber floors with concrete ones, the insertion of a concrete curb “inside” the thickness of the masonry walls, could imply, respectively, a significant self weight increase and a weakening of the existing masonry walls.

Name: Robert Jockwer, Switzerland
STSM Topic : Fracture mechanics model to account for the impact of wood characteristics on the growth of cracks in glulam beams.
Host Institute: Prof. Erik Serrano, Lund University, Division of Structural Mechanics, Lund, Sweden
Duration: 1 week
Outcomes: Abstract send to ICASP12 conference, Vancouver, Canada.

Abstract: Fracture of timber when subjected to excessive shear and tensile stresses perpendicular to the grain is one of the most relevant failure mechanisms due to the wood’s low strength and its brittle failure behaviour. Careful design of regions exposed to shear and tensile stresses perpendicular to the grain is required in order to reach the level of structural safety as asked by design codes. With regard to cracking it is important to prevent excessive crack growth and separation of the cracked parts. According to current procedures the fracture energy of wood is determined on small clear specimens. However, for the prediction of the structural behaviour of full scale glulam members the influence of wood characteristics, like e.g. knots, grain deviations and cracks has to be accounted for. In this STSM different FE models have been used in order to simulate the impact of grain deviations and knots on the fracture of timber. The effective fracture energy during fracture can be expressed by a knot factor along the predefined crack path in an analytical model. The variation of the load-carrying capacitydepends on the distribution characteristics of this knot factor.

Name: Karel Šobra, Czech Republic.
STSM Topic : Experimental evaluation of dovetail joints.
Host Institute: Prof. Jorge M. Branco, Department of Civil Engineering, School of Engineering, University of Minho, Guimaraes - Portugal 
Duration: 3 months
Download: STSM report
Outcomes: Paper presented at CLB – MCS 2014, Guimaraes, March 2014. Abstract sent to Nano and Macro Mechanics 2014, Czech Technical University in Prague, September 2014 and to SHATIS conference in September 2015, Poland . Two journal papers will be prepared and submitted during 2014. 

Abstract: An experimental campaign was defined within a STSM of COST action FP1101. This experimental work performed in the University of Minho, Portugal, was divided into two parts: the behaviour of different species under compression was evaluated in the first one, while in the second one, smaller models of dovetail joint were tested.
Compression tests were performed according to EN408 and ASTM D143 – 14 on specimens made of
Scots pine (Pinus sylvestris), Silver fir (Abies alba), Maritime pine (Pinus pinaster) and chestnut (Castanea sativa). Both types of specimens were tested in compression perpendicular to the grain and angled under angle of 45 degree to the grain. Moreover, compression parallel to the grain was evaluated through according EN408. Obtained results were evaluated and compared with theoretical behaviour of wood. A total amount of 120 specimens were tested in this first part of the work.
Experimental tests of scaled models of the dovetail joint in the scale ratio 1:2 were made in the second part of the project. Overall 17 specimens made from Scots pine (Pinus sylvestris) and Maritime pine (Pinus pinaster) were tested to monotonic compression and tension. Then test simulating positive and negative bending moment were made as well as cyclic tension / compression and cycling bending tests. Cycling tests were made according to EN 12512. Data obtained from the test were compared with theoretical model.

Name:  Izabela Burawska, Poland.
STSM Topic : Local reinforcement of timber with D-shape CFRP elements.
Host Institute: Robert Widmann, EMPA Switzerland 
Duration: 1 month
Download: STSM report
Outcomes:  SMAR 2015 Conference, Antalya, Turkey

Abstract: Wood is a natural material, additionally loaded with structural defects. Knots are the defects that most reduce the structural strength of timber, and the longitudinal tensile strength is most affected followed by modulus of rupture, compression strength parallel to the grain and modulus of elasticity.
The negative influence of knots is important both in existing structures (especially historical) as well as in new ones, at the stage of material preparation. Because of noticeable limited access to high quality raw material, it is crucial to look for other possibilities.
The aim of the project was to investigate the possibility of compensation the knot influence through the introduction of reinforcement material, in aspect of elastic properties and bending strength. D-shape reinforcement made of CFRP tape was proposed. The tape was introduced into the wooden cross section into the previously prepared slots. The bond between wood and CFRP was made using two-component epoxy adhesive.
Samples were tested in four point bending according to the EN-408:2012 standard. At the first stage of the project non-weakened samples were tested to determine their elastic properties. Then the bores simulating knots were drilled and samples were tested to determine again the mechanical behaviour in the elastic range. The last and crucial stage was to test reinforced, weakened with a bore samples and determine the reinforcement efficiency. The D-shape reinforcement has bring significant gain of MOE and MOR in comparison to unreinforced, weakened with a bore sample. The typical failure mode was started by tension perpendicular to the grain as well as by shear in the wood-CFRP contact zone.
The designed strengthening technique is purposeful in structural applications. However, there is a need of further investigations leading to optimization of reinforcement technique by modelling.

Name: Caoimhe O’Neill, Northern Ireland, UK
STSM Topic : Durability of Bonded-in BFRP Rods in Irish Timbers.
Host Institute: Dr Annette Harte - National University of Ireland Galway (NUIG), Ireland
Duration: 2,5 weeks
Download: STSM report
Outcomes: Abstracts submitted to the IStructE Young Researchers’ Conference 2015 (Under review - Dec 2014) and “Mechanical behaviour of wood and wood composites” Symposium in conjunction with M2D’2015 (Under review - Dec 2014)  

Abstract: Ongoing research in Queen’s University Belfast (QUB) is investigating the use of Basalt Fibre Reinforced Polymer (BFRP) rods bonded-in to locally sourced Irish Sitka Spruce. The pull-out capacity of the bonded-in BFRP rods at varying embedded lengths has been assessed in QUB as well as the use of BFRP to reinforce timber beams. To further complete our knowledge about the behaviour of this material combination the durability of such needed to be researched.
Nine specimens underwent accelerated aging and subsequent pull-out testing. In the majority of specimens it was observed that some delamination had occurred by debonding of the epoxy and the BFRP bar rather than the clean pull-out failure which had accounted for approximately two thirds of failures in the specimens tested at ambient temperature. To further investigate aging effects on these bonded-in rods, a further nine bonded-in rod specimens are being subjected to a moisture cycling regime in the variable climate chamber at NUIG for the next 6 months. After this time, the specimens will be tested to failure and the pull-out capacity compared with that of specimens tested at ambient temperature to give more information on the impact of aging on of bonded-in BFRP rods in Irish timber. This will allow a better assessment of their suitability for applications such as reinforcement and repair.
During the STSM some characterisation tests were also carried out on Irish grown Sitka Spruce (Picea sitchensis), including the estimation of properties from results of a non-destructive test method using a Timber Grader MTG.  The properties obtained from such tests can be added to a database of properties gathered from across the country which will then be used for the design and modelling of bonded-in rod connections, reinforcement of this timber and more.

Name: Jan Siem, NTNU, Norway
STSM Topic : Carpentry Joints.
Host Institute: A.J.M. Andre Jorissen Technische Universiteit Eindhoven Eindhoven, Netherlands
Duration: 9 days
Download: STSM report
Outcomes: Paper to be submitted to SHATIS 2015, Wroclaw, Poland

Abstract: The objective of the STSM was to produce an overview of all accessible information on design rules for carpenter joints available in EC5, in national NCCI documents and in previous National codes of the countries who have participated in the development of EC5. This information should then be discussed mainly based on assumed and observed failure modes.
As a first step we asked a lot of the experts in Europe if they could send us information on earlier and existing design rules for their country on carpentry joints. The answer from these experts resulted in copies of parts of 9 standards in addition to Eurocode 5. We also received a lot of articles within the subject from the same experts. Literature search completed the document quantity with both articles and textbooks.  The work started with making an overview of the most commonly described carpentry joints in the reviewed literature. We limited the work to joints carrying loads in plane structures. Then we focused on yield and failure criteria used in the standards to describe the strength of the joints. The last subject was the design rules for the geometry of joints.  

Name: Anna Sandak, Trees and Timber Institute/national Research Council (IVALSA/CNR), Italy 
STSM Topic : Hyperspectral imaging of weathered wood samples.
Host Institute: Prof. Ingunn Burud, Norwegian University of Life Sciences, Akershus.
Duration: 7 days
Download: STSM report
Outcomes: Paper to be submitted to  NIR2015 conference, Foz do Iguassu, Brazil.

Example of PCA analysis performed on not weathered (a) and sample after 28 days of weathering (b).

Wood has been traditionally used for various kinds of load-bearing structures, as well as for complementary constructive components, such as cladding and decking. Wooden elements can undergo to alteration during their service life that can be caused by mechanical, environmental or biological agents. Surfaces are the most vulnerable parts of the structures, since these are the most exposed to altering factors, such as ageing, weathering or decay. Weathering is the general term used to define the slow degradation of materials exposed to the weather condition. The rate of weathering varies within timber species, function of product, technical/design solution, finishing technology applied but most of all on the specific local conditions. In general, the process of wood weathering leads to a slow breaking down of surface fibers, their removal, and in consequence to a roughening of the surface and reduction of the glossiness. The formation of discontinuities on the wooden surface can cause penetration of the wood-decaying biological agents into the material structure and influencing mechanical performances of the loadbearing members. The other significantly changing parameter is colour, which changes rapidly when exposed to weathering. It is mostly caused by photodegradation of lignin and wood extractives in middle lamella.
The goal of this research is to investigate the kinetic of the degradation rate of wooden samples exposed for the short term weathering conditions. It is expected that using hyperspectral imaging technique for detection of colour alteration, changes to chemical composition and detection of decay at the early stage may provide new understanding for the weathering process. The experimental samples used for evaluation were weathered in 15 locations in Europe for a period of 1 month.

Name: Charline Lefevre, University of Mons, Department of Structural Mechanics, Belgium
STSM Topic : Large diameter single dowel joint: Finite element modeling of reinforced joints
Host Institute: Prof. Roberto Crocetti, NLund University, Sweden..
Duration: 2 months
Download: STSM report
Outcomes: Poster presented at COST FP1101 Final Conference

Joints for timber structures may be quite complex and expensive what sometimes makes timber structures uncompetitive compared to other materials. Moreover, the bearing capacity of a timber structure is often limited by its connections and those last ones may be responsible for collapse of failures in timber structures. This STSM investigates a large diameter single dowel connection reinforced by a steel plate glued on a rubber layer. It aims to gain knowledge about this reinforced connection by using a finite element method with the software ABAQUS and by calibrating the model with test results.
The analyses performed with ABAQUS indicates that the steel plate is prone to buckling behavior. Its shape, its thickness, its dimensions or the rubber stiffness are all parameters that may influence the critical load of the plate. The mechanical properties of the steel used for the plate are also fundamental for the load bearing capacity of the joint. Furthermore, the findings concludes that the load-bearing capacity is greatly affected for load directions that are not parallel to the grain. 

Name: Anna Serafini, University of Strathclyde, Glasgow, UK
STSM Topic : Early Assessment of 17/18C Timber Roof Structures in Scotland
Host Institute: Mariapaola Riggio, University of Trento, Trento, Italy.
Duration: 2 weeks
Download: STSM report
Outcomes: Poster presented at COST FP1101 Final Conference

The biggest difficulty in approaching conservation of timber structures is their assessment, due to the organic nature of the material and to its variable properties. Professionals are often unable to say with certainty if a timber roof structure is safe or not, even because the available testing and modelling methods are expensive and time consuming. For this reason, they often over-consolidate them or even worse, substitute them with “safer” materials, such  as steel or concrete. A  template/database for the assessment of historic timber roof structures has been developed d uring this STSM with a twofold purpose: help professionals during their inspections in recording and organizing all the information needed; create a tool that can help analyse the data from several inspections allowing to associate typical damages to each structural typology. The template helps understanding what part of the structure is affected by the damage (the whole roof,  one truss, one element or only once connection), and what is the damage status (active, non-active, etc) and role (primary, secondary). It also helps distinguishing between the damage effects and the damage causes: this is very important as interventions often address effects rather than causes, not solving the problem. A lot of work has been done on terminology, to allow for this tool to be used in any European country, and drawings and sketches have been added as legends to avoid the misinterpretation of specific terms. 

Name: Fotis Kondis, National Technical University of Athens, Greece.
STSM Topic : Assessemnt and diagnosis of an ancient collar truss by means of visual grading and non-destructive tests.
Host Institute: Prof. Jorge M. Branco, Department of Civil Engineering, School of Engineering, University of Minho, Guimaraes - Portugal.
Duration: 1 month
Download: STSM report
Outcomes: Poster presented at COST FP1101 Final Conference.

The main objective of the present work is to evidence the importance of the inspection and diagnosis phase on the assessment of existing timber structures through visual grading and non-destructive testing (NDT) of its elements, especially for old structures with historical importance. To that aim, a collar truss was inspected and assessed. This truss was part of an ancient roof with over than one hundred years old that was decommissioned and then reassembled in laboratory conditions in the University of Minho (Portugal). Another timber truss was then tested on full scale at laboratory conditions until failure.

Name: Caoimhe O’Neill, Northern Ireland, UK
STSM Topic : Durability of Bonded-in BFRP Rods in Irish Timbers - Phase 2.
Host Institute: Dr Annette Harte - National University of Ireland Galway (NUIG), Ireland
Duration: 1 week
Download: STSM report
Outcomes: Poster presented at COST FP1101 Final Conference 

Abstract: In Phase One of this STSM accelerated ageing by vacuum-pressure soaking was used to simulate the deteriorative effects of long term moisture ingress on a bonded-in rod connection. This vacuumpressure regime is an extreme form of moisture cycling giving a worst case scenario representation. This second phase explores an alternative method of aging by cycling relative humidity which represents a more realistic exposure condition for structures designed for service classes 1 and 2. Following a review of literature by both institutions in Phase 1, a cycling regime mimicking a typical Northern European annual relative humidity cycle was agreed upon with specimens being cycled through a minimum 65% RH and an upper limit of 90% RH at a constant temperature of 20 degree Celcius. Phase 2 involved the testing of these specimens and the capacities of these aged specimens are presented in this report. The durability performance of the bonded-in rods at both moderate and severe exposure conditions can be assessed to give a fuller picture of the impact of aging on bonded-in BFRP rods in Irish timber. This allows a better assessment of their suitability for applications such as reinforcement and repair.

Name: Jakub Sandak,CNR-IVALSA, Italy.
STSM Topic : Development of the in-field sensor for estimation of fracture toughness and shear stress
Host Institute: Prof. Kazimierz Orlowski, Gdansk University of Technology, Poland
Duration: 1 week
Outcomes: Poster presented at COST FP1101 Final Conference 

Abstract: The goal of this STSM is to develop a novel system capable to determine selected wood properties; fracture toughness and shear stress. It could be considered as an alternative approach for assessing timber structures, supporting decision of the expert in field. The measurement methodology ases on the theoretical work developed collectively by host and applicant. The  overall summary of the theory has been recently published and was also submitted as a Polish patent. The next step of this development is to implement the numerical procedures and to develop a prototype device.