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The modulus of elasticity (MOE), bending strength (MOR) and density of 45 150 × 200 × 5400 mm3 Salzmann pine timber pieces from an existing eighteenth century structure were obtained by testing and also estimated by non-destructive testing. Density was estimated by means of the drilling technique and the MOE and MOR by recording the longitudinal natural frequency of vibration. Four methods for defining the dimensions of the nominal cross-section were applied to establish which was most adequate to address the high variability in the cross-sections along the length. MOE and MOR linear regression results showed r2 = 59–68% using dynamic MOE, relative edge knot diameter and slope of grain as independent variables. The nominal cross-section defined as the mean cross-section area along the length proved to be the most effective for estimating mechanical properties, followed by the nominal cross-section defined as the average measurements of the piece taken at the middle part or central third along its length. The longitudinal vibration method enables the acquisition of superior predictive models compared to time-of-flight measurement-based methods. [ABSTRACT FROM AUTHOR]

The article offers information on industrial archaeology, a relatively new branch of archaeology that studies sites, methods, and machinery used in industrial processes. Topics include the definition of industrial heritage, which encompasses movable and immovable assets and sociability systems associated with industrial activities from the Industrial Revolution to the late 20th century.

The use of wood in construction requires knowledge of the mechanical properties and the particularities that wood presents in comparison with other materials used for structural purposes such as steel, concrete, brick, or stone. The introduction mentions the environmental advantages that justify the use of wood today. The orthotropy of wood is one of the differentiating characteristics that must be taken into account when studying its behaviour. The determination of the properties of wood is then addressed from a historical perspective and the differentiation is made between the properties of small clear wood (defect-free timber) and structural timber. The timber grading systems (visual and mechanical grading) and the non-destructive techniques that currently prevail are explained. Finally, the factors that influence the mechanical properties, such as duration of the load, moisture content, quality, temperature, and the effect of size are explained. The objective of this work is to provide an overview of the current knowledge on the mechanical properties of wood, based mainly on published articles and European and North American standards, including historical references to the beginnings and current trends in this field. [ABSTRACT FROM AUTHOR]

Nondestructive testing (NDT) includes several highly efficient techniques for the estimation of the physical and mechanical properties of structural timber. However, NDT results are affected by several factors [moisture content (MC), temperature, specimen dimensions, sensor positioning and grain angle, timber-sensor coupling, etc.], of which wood MC is the most important. Scientific research on MC influence in NDT measurements started in the 19th century, and 2018 was the first year that a MC adjustment for NDT measurements was published in a European standard (EN14081-2). Although MC influence on NDT has been studied for more than 170 years, MC adjustment factor research is important nowadays because it is widely used in the industry. Currently, NDT device manufacturers develop their own MC adjustment factors adapted to their equipment and species. This paper presents an exhaustive review of MC adjustments for different types of NDT equipment, as proposed by several authors from the 19th century to date, and a discussion of factors affecting MC adjustments. [ABSTRACT FROM AUTHOR]

Key message: Mechanical properties of small-diameter round timber from hardwood thinnings of common alder (Alnus glutinosa(L.) Gaertn.), European ash (Fraxinus excelsiorL.), European birch (Betula pendulaRoth. andBetula pubescensEhrh.), and sycamore (Acer pseudoplatanusL.) can be evaluated by non-destructive testing on either standing trees or green logs without wood density determination. Velocity differences between acoustic and resonance methods are influenced by tree species and age. Tree diameter improves the estimation of bending strength but not of stiffness. Context: There is a need for a reliable, fast, and inexpensive evaluation method to better sort hardwood thinnings according to mechanical properties for use in potential added-value applications. Aims: The estimation by non-destructive testing of mechanical properties of round small-diameter timber of four hardwood species (common alder, European ash, European birch, and sycamore). Methods: Acoustic velocity was measured in 38 standing trees and resonance velocity was recorded in green logs from these trees. The logs were then dried and tested in bending. Estimation models to predict mechanical properties from non-destructive testing measurements were developed. Results: Large differences between velocities from acoustic and resonance techniques were found. Models based on both non-destructive testing velocities together with a species factor are well correlated with bending modulus of elasticity while models including tree diameter are moderately well correlated with bending strength. Inclusion of density in the models does not improve the estimation. Conclusion: Models based on acoustic measurements on standing trees or resonance on green logs together with tree species and diameter provide reliable estimates of mechanical properties of round timber from hardwood thinnings. This methodology can be easily used for pre-sorting material in the forest. [ABSTRACT FROM AUTHOR]

Nondestructive testing (NDT) includes several highly efficient techniques for the estimation of the physical and mechanical properties of structural timber. Apart from visual grading, scientific research using Nondestructive testing on timber has been used in Spain since the 1990s. Nondestructive testing can be used for two different purposes: timber grading and the assessment of existing timber structures. The most common devices used in Spain are portable ones based on ultrasound, stress waves, vibration and probing techniques. Many statistical linear models for estimating the mechanical properties of new sawn timber and timber from existing structures have been proposed. Furthermore, several factors that affect Nondestructive testing measurements have been studied (moisture content, temperature, specimen dimensions, sensors position-grain angle, among others) and adjustment factors have also been proposed. Species have been characterized for visual grading standards from the 1980s to date. The large number of research works using different species, devices and procedures shows the need of homogenization and standardization of Nondestructive testing use. This paper presents a review of research works using Nondestructive testing on timber in Spain, in order to add to knowledge, elucidate the concepts to unify Nondestructive testing used and promote research group collaboration in the near future. [ABSTRACT FROM AUTHOR]

Time-of-flight (ToF) measurements were conducted on twelve 76×226-mm2 in cross-section, 4.52-m long specimens of Norway spruce timber pieces from a dismantled 19th-century building in Barcelona (Catalonia, Spain). Two commercially available acoustic devices were used: the USLab ultrasound device with conical 22 and 45 kHz sensors and the MicroSecond Timer (MST) stress wave device with spike sensors. ToF were obtained for the full-length (4.52 m) specimens in an end-to-end arrangement and for lengths of 0.5, 1, 1.5, 2, 3 and 4 m on the same surface and on opposite surfaces. The differences between the velocities obtained from end-to-end and semi-direct measurements were less than 4.5%. Apparent velocity dependence on length was observed in short-distance measurements. This could be corrected by determining a time lag (tL) from a linear regression between the ToF and the distance. Estimation of the modulus of elasticity (MOE) from the dynamic MOE (MOEdyn) is acceptable (r2=0.45–0.69) depending on the measurement procedure, and the best results for in situ timber are obtained in edge surface velocity. Although modulus of rupture (MOR) estimation from MOEdyn improves slightly when knottiness is included, it has low predictive capacity. [ABSTRACT FROM AUTHOR]

Density estimation by non-destructive or semi-destructive methods is applied mainly on softwood species. The instruments are expensive, the methods are complicated and the determination coefficients are low. In the present study, the simple core hollow drilling approach is revisited. Data of 600 cores or cylindrical specimens from 300 pieces of 10 different softwood and hardwood species were evaluated in the density range from 350 to 975 kg m−3. The data were obtained from complete pieces and from the cores from core drilling, while the difference between the two data sets is 1.7%. At higher densities, the differences are greater. A model was proposed concerning the piece density estimation with a determination coefficient of 0.98. It is concluded that core drill is a cheap and reliable method for density estimation and the data are equally reliable for radial (R) or tangential (T) probing. The cylindrical cores obtained are suitable for moisture content (MC) and species determination. [ABSTRACT FROM AUTHOR]

Needle penetration resistance (NPR), screw withdrawal resistance (SWR), core drilling (CD) and drilling chips extraction (DCE) are nondestructive and semi-destructive techniques used to estimate density in timber structures. In most of the previous studies, these techniques were tested in clear sawn timber and clear specimens. The goal of the present paper is to study the relationship between density and these techniques by means of five different devices in whole pieces of timber from built-in engineering structures, which are from 12 4.5-m long structural timber joists of Norway spruce from a 19th century building in Barcelona (Catalonia, Spain). Although determination coefficients (R2) for density estimation models were lower than those from clear timber, the results obtained confirmed that these four techniques are suitable for in-situ density estimation of woods in buildings. The best results were obtained by CD (the bigger the bit, the higher the correlation), followed by DCE, and SWR. The worst correlation was found for NPR devices, but the results could be probably improved with more measurements. [ABSTRACT FROM AUTHOR]

Needle penetration resistance (NPR) and screw withdrawal resistance (SWR) are widely used techniques for density estimation of woods integrated in timber structures. The moisture content (MC) influences these measurements and correction coefficients are needed to ensure the accuracy of results. The goal of the present paper was to scrutinize the relation between NPR and SWR measurements and MC in case of radiata pine, Scots pine, Salzmann pine, and maritime pine usually used in wood constructions, from which 25 specimens from each species were probed. The specimen's MC ranged from 65.1 to 8.3%. Results show that NPR depth has a positive linear relationship with MC while the SWR force a negative one below the fiber saturation point (FSP). Above the FSP, the MC influence is less pronounced and less regular. MC correction factors of measurements below the FSP are proposed for the species studied. [ABSTRACT FROM AUTHOR]

Non-destructive techniques (NDTs) are well suited for rapid estimation of timber properties, but NDT results are affected by several factors, the most important of which is the moisture content (MC) of wood. Much of the research in this context was limited to ultrasound measurement of a few wood species, mainly to Norway spruce. The present paper investigates the MC influence on the NDT results obtained by instruments based on ultrasound (two devices), impact stress waves (one device) and longitudinal vibrations (two devices). A hundred large cross-section specimens of four timber species were tested, namely: radiata pine, Scots pine, Salzmann pine and maritime pine. The influence of MC on velocity was found to be stronger below the fiber saturation point (FSP) than above FSP. MC adjustment factors below FSP are proposed for these wood species. [ABSTRACT FROM AUTHOR]

The mechanical properties of timber can be estimated from wave propagation velocity by measuring wave time-of-flight (ToF). However, a time-lag complicates the measurements, which produces an apparent velocity dependency on length and this species and instrument dependent property is also influenced by knottiness. This research is dealing with time-lag determination by different sensor positioning in situ ToF measurements. ToF longitudinal measurements were conducted on 120 90 mm × 140 mm specimens of the coniferous species radiata pine, Scots pine, laricio pine and maritime pine. The following commercially available acoustic devices were used: Sylvatest Duo, USLab, and Microsecond Timer. The sensors were arranged for the measurement types "end-to-end", "on the same surface" and "on opposite surfaces". ToF data were obtained from the full-length (4 m) specimens and then from the same specimens shortened to 3 m, 2 m and 1 m in length. The in situ procedures of ToF are applicable for a reliable length determination independently from the time-lag (tL) and velocity. The differences observed by end-to-end measurements, with respect to velocity, are below 4.4%. A velocity correction factor can be deduced for each instrument, which is independent of species. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to define the reference conditions and to propose modification factors to standardize the variables recorded by different nondestructive techniques. This practice will make it possible to generate consistent practical data while developing a procedure for the standardization of timber structure assessment. The nondestructive variables analyzed are: time of flight, natural frequency, pullout resistance, penetration depth and drill resistance. The factors which affect these variables are: moisture content, temperature, size/length and positioning of sensors and angle to the grain. Reference conditions are defined and equations and modifications factors are proposed to help in the evaluation of existing timber structures and decision making. [ABSTRACT FROM AUTHOR]