Strength grading of timber in the UK and Ireland in 2021

Ridley-Ellis, Daniel; Gil-Moreno, David; Harte, Annette M.

doi:10.1080/20426445.2022.2050549

Cited by 7 publications

(4 citation statements)

References 5 publications

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“…In fact, the results are comparable to data reported for PSMN from the UK [15], and data collected within the GradeWood project by BRE (unpublished). The two genera produce higher timber quality than Sitka spruce [7,16] and the GDPs are comparable enough between themselves producing yields above 80% for the strength class C18 investigated in this paper as shown in Table 3. The optimum grading for the entire population was C20, that is, the one that results from using the values of the destructive tests instead of those based on the IP.…”

Section: Gpds Of Ungraded Timbermentioning

confidence: 66%

“…Table 4 also shows settings for the combination C18/batten14. Batten14 is a user-defined strength class with characteristic values of: fk = 14 N/mm 2 ; E0,mean = 7.5 kN/mm 2 and ρk = 330 kg/m 3 [7]. The peculiarity of this grade is that fk is the same as in C14, but E0,mean and ρk are higher.…”

Section: Calculation Of Settingsmentioning

confidence: 99%

“…In Great Britain, larch is the third largest timber species, and Douglas fir is the fifth [5]. In 2018 and 2020, as part of the WoodProps programme at the University of Galway, machine grading settings were developed for Douglas fir [6], PSMN, and larch (WLAD: European larch (Larix decidua), hybrid larch (Larix x eurolepis) and Japanese larch (Larix kaempferi)), separately [7], for the grading area formed by Ireland and the United Kingdom (UK). Douglas fir and larch produce higher timber quality than British spruce and it would be desirable to have more material available on the market.…”

Section: Introduction 456mentioning

confidence: 99%

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Considerations for Grading Species Combinations. The Example of Douglas Fir With Larch in Ireland and Uk

Gil-Moreno

Ridley-Ellis

Harte

2023

World Conference on Timber Engineering (WCTE 2023)

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This paper examines the grading of Douglas fir (Pseudotsuga menziesii) and larch (Larix spp.) as a strength grading species combination for the growth area formed by Ireland and the UK. The two genera produce higher timber quality than Sitka spruce (Picea sitchensis), the main commercial timber species in the two countries. Developing this species combination may increase the volume of timber available for the market, making these species more commercially attractive to sawmills, particularly if there are common settings that can be used for either species whether mixed in production or not. Simultaneously, the paper examines the challenges of mixed species grading within the framework of the European standard EN14081 for machine control grading, as the requirements for combining species are not clearly defined. More than 1600 pieces are used for this study. The results found that the ranges of modulus of elasticity, strength and density of both species are similar, but special considerations are required to ensure the safe grading of the timber.

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Section: Gpds Of Ungraded Timbermentioning

confidence: 66%

Section: Calculation Of Settingsmentioning

confidence: 99%

Section: Introduction 456mentioning

confidence: 99%

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Considerations for Grading Species Combinations. The Example of Douglas Fir With Larch in Ireland and Uk

Gil-Moreno

Ridley-Ellis

Harte

2023

World Conference on Timber Engineering (WCTE 2023)

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“…This timber grade is commonly used in Ireland and the UK for roof trusses. TR26 grade timber has characterisitic and mean densities of and 370 kg/m 3 and 444 kg/m 3 , respectively [24]. The moisture content of the timber boards at the time of recovery was estimated using a hand-held moisture meter to be between 18% and 23%.…”

Section: Recovered Timber Samplesmentioning

confidence: 99%

Embedment Strength of Recovered Spruce and Oak

Chúláin,

Gil-Moreno,

Llana

et al. 2023

World Conference on Timber Engineering (WCTE 2023)

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The circular use of construction materials is an essential step in the drive to reduce the environmental impact of the construction sector. One of the factors that currently limits the ability to reuse timber recovered from demolition in structural applications is the lack of data relating to its structural performance, which would allow for the certification of its characteristics and the development of design guidelines.This paper presents a study on the embedment performance of recovered timber by determining the embedment strength of spruce and oak specimens recovered from demolition sites in Ireland and Slovenia. Tests were carried out in the parallel and in the perpendicular to the grain directions using three different dowel diameters. The results were comparable with mean values reported in the literature and with the empirical Eurocode 5 predictions. Based on these findings, it can be concluded that the embedment performance of the recovered spruce and oak is equivalent to that of new timber. Further studies on recovered timber of different origin, species, ages and history of use are needed to confirm these findings.

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Timber tensile strength in mixed stands of European beech (Fagus sylvatica L.)

Rais¹,

Kovryga²,

Pretzsch

et al. 2022

Wood Sci Technol

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The conversion to climate-stable, resilient and productive forests has resulted in an increasing share of mixed stands. Different growth conditions and silvicultural treatments lead to an increased scatter in strength compared to what is expected from monoculture experience. The study (i) quantified the magnitude of variation in strength of European beech timber from stands of different composition and (ii) showed the impact of grading on the characteristic strength value of timber coming from those stands. Strength grading models and machine settings for hardwood tensile classes on over 900 European beech (Fagus sylvatica L.) boards were derived. One model used only the dynamic modulus of elasticity (Edyn), and a more complex model used a knot value in addition. Afterwards, 407 boards from pure beech stands as well as mixed stands of beech with Douglas fir (Pseudotsuga menziesii (Mirb.) Franco), Norway spruce (Picea abies (L.) Karst.), sessile oak (Quercus petraea (Matt.) Liebl.), and Scots pine (Pinus sylvestris L.) were graded and analyzed for their material properties from tension tests parallel to grain. Although a variance components analysis attributed only 4.2% of the variation to mixture, the ungraded timber showed significant strength differences between the pure and the beech-pine stands (65.2 versus 46.6 MPa). The yield of the material graded to the highest class in a class combination was higher in pure beech stands. The required characteristic strength values were mostly met for boards from the pure stands; while boards from the beech-pine mixed stands hardly ever reached the required values. To reduce strength variation and guarantee reliable timber products, strength grading should consider the various growth situations in forests when sampling material for the derivation of settings.

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Strength grading of timber in the UK and Ireland in 2021

Cited by 7 publications

References 5 publications

Considerations for Grading Species Combinations. The Example of Douglas Fir With Larch in Ireland and Uk

Considerations for Grading Species Combinations. The Example of Douglas Fir With Larch in Ireland and Uk

Embedment Strength of Recovered Spruce and Oak

Timber tensile strength in mixed stands of European beech (Fagus sylvatica L.)

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