Irish Timber - Characterisation, Potential and Innovation

Abstract

In order to increase the utilisation of Irish timber in construction and novel engineered wood products, the mechanical and physical properties of the material must be established. For timber products used for structural applications, the fundamental properties are the modulus of elasticity, bending strength, density and dimensional stability as these define the structural grade of the material. In order to develop engineering design models for applications such as reinforced timber, knowledge of the nonlinear stress-strain behaviour in compression is also required. The paper presents the programme and results of an ongoing research project 'Innovation in Irish Timber Usage' which focuses on the characterisation of Sitka spruce as it is the most widely grown species in Ireland. In the past, a number of studies have been conducted to determine the properties of Irish-grown Sitka spruce. Nevertheless, due to the changes that have taken place in silvicultural practices since the publication of these studies, there is a need to determine how these properties have changed. This paper presents the data gathered from historical studies together with the results of an extensive test programme undertaken to characterise the properties of the present resource. Moreover, the paper examines the potential use of Irish grown Sitka spruce in novel timber products. Construction applications, such as fibre-reinforced polymer reinforced timber elements and connections, and cross-laminated timber are investigated.

Full text

ABSTRACT:
In order to increase the utilisation of Irish timber in construction and novel engineered wood products, the mechanical and
physical properties of the material must be established. For timber products used for structural applications, the fundamental
properties are the modulus of elasticity, bending strength, density and dimensional stability as these define the structural grade
of the material. In order to develop engineering design models for applications such as reinforced timber, knowledge of the
nonlinear stress-strain behaviour in compression is also required.
The paper presents the programme and results of an ongoing research project ‘Innovation in Irish Timber Usage’ which focuses
on the characterisation of Sitka spruce as it is the most widely grown species in Ireland. In the past, a number of studies have
been conducted to determine the properties of Irish-grown Sitka spruce. Nevertheless, due to the changes that have taken place
in silvicultural practices since the publication of these studies, there is a need to determine how these properties have changed.
This paper presents the data gathered from historical studies together with the results of an extensive test programme undertaken
to characterise the properties of the present resource.
Moreover, the paper examines the potential use of Irish grown Sitka spruce in novel timber products. Construction applications,
such as fibre-reinforced polymer reinforced timber elements and connections, and cross-laminated timber are investigated.
KEY WORDS: Sitka spruce, timber properties, reinforced timber, Cross-laminated timber
1 INTRODUCTION
Due to the increasing focus on the use of sustainable
construction materials to meet environmental targets related to
efficient energy use and emissions, a significant opportunity
exists for the Irish wood products sector. In 2012, the Irish
forestry and forest products sector generated €2.2 billion in
annual output, representing 1.3% GDP, and employed
approximately 12,000 people [1]. Moreover, there exists a
substantial potential to expand production. According to
COFORD [2] half of the forest estate is less than 25 years old
and further expansion of forest cover is planned by
policymakers. Forest products to a value of €303 million were
exported: including €73 million worth of sawn softwood and
€179 million worth of wood-based panels. In general, 89% of
the wood-based panels were exported [1]. The supply of
roundwood from Irish forests is projected to increase from
3903 million m3 in 2011 to 7110 million m3 in 2028. These
figures show the potential of Irish forests to provide increased
and sustainable supplies of wood products [3]. Increased sales
of existing products and the development of new markets at
home and abroad for new added-value wood products will
lead to job creation across the sector.
In order to increase the utilisation of Irish timber in
construction, the mechanical and physical properties of the
material must be established. For timber products used for
structural applications, the fundamental properties are the
bending modulus of elasticity (MOE), the modulus of rupture
(MOR), the density and the dimensional stability as these
define the structural grade of the material. In order to develop
engineering design models for reinforced timber, knowledge
of the nonlinear stress-strain behaviour in compression is also
required.
As part of the project ‘Innovation in Irish Timber Usage’,
funded by the Department of Agriculture, Food and Marine of
the Republic of Ireland under FIRM/RSF/COFORD scheme,
all of the available historical data on the properties of Irish
Sitka spruce, from published and unpublished sources, is
being collated. Moreover, testing of a large number of
samples is being carried out to establish the mechanical and
physical properties of the current resource. Furthermore, in
order to investigate the potential for new add-value timber
construction products, the two key research areas are
addressed, namely, Fibre-Reinforced Polymer (FRP)
reinforced timber and Cross-Laminated Timber (CLT).
2 CHARACTERISATION OF IRISH TIMBER
2.1 Introduction
The focus of this paper will be on timber from Sitka spruce as
it is the most widely grown species in Ireland. Irish-grown
Sitka spruce is characterised as a fast growing, low density
species due to the rapid growth condition in Ireland and short
rotation length. As a result of these growth conditions, the
most common structural grade achieved by Irish-grown Sitka
spruce is C16 grade.
In the past, a number of studies have been conducted on the
properties of Irish-grown Sitka spruce [4-16]. This species is
native to a narrow belt of the Pacific North West coast of
Irish Timber – Characterisation, Potential and Innovation
Annette Harte1, Daniel McPolin2 , Karol Sikora1, Caoimhe O’Neill2, Conan O’Ceallaigh1
1College of Engineering & Informatics, National University of Ireland, Galway, University Road, Galway, Ireland
2School of Planning, Architecture and Civil Engineering, Queen’s University Belfast, University Road, Belfast BT7 1NN, UK
email: annette.harte@nuigalway.ie, d.mcpolin@qub.ac.uk, karol.sikora@nuigalway.ie, coneill86@qub.ac.uk,
c.oceallaigh1@nuigalway.ie

North America, along Alaska in the north, down through
British Columbia, Washington and Oregon to California. Due
to similarities in climate between this region and Ireland, it
was first introduced to Ireland in 1831. The wide ranging site
types suited to growing Sitka spruce vary from very fertile
mineral to impoverished peaty soils [17].
A large study (the SIRT project) on Scottish Sitka spruce
was undertaken in Scotland in recent years [18]. This has
resulted in the publication of a report by the Forestry
Commission entitled ‘Wood properties and uses of Sitka
spruce in Britain’ [19]. This report is important for Ireland as
the growing conditions in Scotland are similar to those in
Ireland and the likelihood is that the physical and mechanical
properties of the timber produced in both countries will be
comparable.
In the following sections, properties of Irish Sitka spruce
from selected studies are presented.
2.2 Mechanical properties
Investigations and grading results carried out by sawmills
confirm that Irish Sitka spruce meets predominantly the
requirements of strength class of C16. Table 1 presents the
main strength requirements for C16 according to EN 338 [20]
Table 1. EN 338 [20] main characteristic values for C16.
Bending
strength
(fm,k)
Compressive
strength
parallel to
grain (fc,0,k)
Mean
modulus of
elasticity
parallel
(E0,mean)
Mean
density
(ρmean)
16 N/mm2
17 N/mm2
8 kN/mm2
370 kg/m3
Picardo [4] undertook a large-scale testing programme to
evaluate the influence of a number of classifying variables
such as yield class (mean of cubic metres of solid stem wood
added to an area of woodland per hectare per year
[m3/ha/yr]) , section size and forest on the strength and
stiffness of Irish Sitka spruce. From tests on 1487 planks, he
found that only section size had a practical influence on the
MOR.
Ní Dhubháin et al. [5] examined the influence of
compression wood on the bending MOE and MOR properties.
This study had a relatively small sample size of 100
specimens of single cross-sectional size. They found that
increased percentages of compression wood resulted in a
decrease in MOE but appeared to have no effect on MOR.
Picardo [6] conducted another large study involving the
machine grading of about 5000 pieces of timber into different
strength classes. This study found that the yields for C14 and
C16 were very high and the thickness has a significant impact
on the yield. He did not undertake destructive mechanical
tests.
Lucey et al. [7] investigated the utilisation of Irish grown
Sitka Spruce timber (from forests in County Galway) in I-
joists. It was reported that the stiffness of the I-joist has a high
correlation to the stiffness of both tension and compression
flanges. There was only a low level correlation between the
strength of the web material and the strength of I-joist.
Therefore, extensive testing programme was carried out on
specimens used for the flanges. The MOR of the flange
materials, presented in Table 2, was measured as described in
EN 408 [21]. The average MOR results ranged from 22.2
N/mm2 to 25.4 N/mm2 for all cross-sectional sizes. However,
the dimensions had an influence on the standard deviation of
and 5-percentile of the MOR, which was lower for the smaller
cross-sections.
Table 2. MOR parallel to grain results for square beams [7].
Specimen
type & size
No. of
specimens
Mean
MOR
[N/mm2]
S. D.
[N/mm2]
5-
percen.
[N/mm2]
compression
flanges:
44 x 44 mm2
31
22.2
4.6
13.5
tension
flanges:
44 x 44 mm2
31
22.3
3.9
15.5
compression
flanges:
65 x 65 mm2
11
24.8
2.0
21.9
tension
flanges:
65 x 65 mm2
11
24.4
4.0
18.1
compression
flanges:
65 x 65 mm2
10
25.5
2.1
22.9
tension
flanges:
65 x 65 mm2
10
25.4
2.8
20.9
The MOE parallel to grain was also measured in specimens
stressed in both tension and compression. The results differed
depending on cross-section size, and reached almost 8 MPa
for the bigger sizes and 7 MPa for the smaller ones. These
results for MOE testing are shown in Table 3.
Table 3. MOE parallel to grain results for square beams [7].
Specimen type &
size
No. of
specimens
Mean
MOE
[N/mm2]
S. D.
[N/mm2]
5-percen.
[N/mm2]
compression
flanges:
44 x 44 mm2
29
7027
1026
5148
tension
flanges:
44 x 44 mm2
29
7106
945
5610
compression
flanges:
65 x 65 mm2
11
7533
627
6770
tension
flanges:
65 x 65 mm2
11
7531
1319
5573
compression
flanges:
65 x 65 mm2
10
7997
606
7180
tension
flanges:
65 x 65 mm2
10
7999
885
6696
In addition to bending properties, Lucey et al. [7] examined
compression parallel to grain and tension strengths for various

sizes of samples using Irish Sitka spruce. The results of these
mechanical properties are summarised in: Table 4 –
compression strength parallel to grain and Table 5 – Tension
strength.
Table 4. Compressive strength parallel to grain results [7].
Specimen
size [mm
x mm x
mm]
No. of
specimens
Compressive
Strength
[N/mm2]
S. D.
[N/mm2]
5-
percen.
[N/mm2]
44 x 19 x
19
31
24.9
4.8
17.2
65 x 40 x
39
11
24.4
1.8
22.4
Table 5. Tensile strength parallel to grain results [7].
Specimen size
[mm x mm x
mm]
No. of
specime
ns
Mean
tensile
strength
[N/mm2]
S. D.
[N/mm2]
5-percen.
[N/mm2]
44 x 19 x 10
31
23.9
4.3
16.3
65 x 40 x 20
11
24.6
2.9
20.2
65 x 40 x 20
10
25.1
2.1
22.2
Raftery and Harte [8] undertook a comprehensive study in
order to assess the relationship between mechanical properties
and physical characteristics in the longitudinal direction on
clear and in-grade samples. Parameters, which were studied,
included density, knot area ratio, MOE and ultimate strength.
The results of this investigation might be essential in terms on
the future development, design and optimisation of engineered
wood products from Irish Sitka Spruce. It was concluded that
MOE was the most highly correlated parameter to the tensile
strength for both clear and in-grade specimens. Furthermore,
the knot area ratio had a considerable influence on the
strength of the timber both in compression and tension.
Density was more highly correlated to ultimate compressive
strength than ultimate tensile strength in clear wood
specimens. In addition, the authors reported that MOE in
tension had a poor correlation to the density of clear wood and
was also poorly correlated to the knot area ratio and the
density of in-grade specimens.
Moreover, testing of Irish timber has been undertaken in
Irish third level institutions as part of the research for MSc
and PhD theses. Not all of this data has been published in the
available literature. Nevertheless, some of these results are
shown in the following paragraphs.
The quality of Irish Sitka spruce was extensively
investigated by Evertsen [9] using destructive and non-
destructive methods. In order to determine the MOE and
MOR, static four point bending tests were carried out on over
200 planed planks of different sizes taken from woodlands of
yield classes 16 and 20. The moisture content of the samples
during test was generally at 15 ± 2%. The mean, maximum,
and minimum MOE and MOE results, including standard
deviation, for different yield classes are presented in Tables 6
and 7.
Table 6. MOE parallel to grain from destructive tests [9].
Yield
class
No. of
specimen
s
Mean
MOE
[N/mm2]
S. D.
[N/mm2]
Min.
[N/mm2]
Max.
[N/mm2]
16
64
8623
2757
1044
18424
20
116
9291
2511
3707
15772
16&20
180
9053
2601
1044
15772
Table 7. MOR parallel to grain from destructive tests [9].
Yield
class
No. of
speci
mens
Mean
MOR
[N/mm2]
S. D.
[N/mm2]
Min.
[N/mm2]
Max.
[N/mm2]
16
64
24.4
9.4
0.4
44.5
20
116
26.3
7.5
7.2
47.8
16&20
180
25.6
8.2
0.4
47.8
For the non-destructive determination of the mechanical
strength properties, an ultrasonic testing method was used by
Evertsen [9]. This technique was developed by Bucur [10,
11], who had found that the MOE for small clear specimens
had a high correlation with the ultrasound propagation speed
in increment core sized samples. 300 small clear specimens
were tested including 240 of yield class 16 and 60 of yield
class 20. The obtained average MOE values were 8639
N/mm2 and 7677 N/mm2 for the first and second batch,
respectively, and the average MOR values were 73.8 N/mm2
and 67.2 N/mm2, respectively.
Subsequently, tests results published by Patrick [12]
confirmed that Sitka spruce has a brittle mode of failure in
axial tension influenced by larger knot occurrence. The
characteristic in-grade strength of 14.4 N/mm2 was obtained
in comparison to mean in-grade strength of 27.1 N/mm2.
These values were approximately half of the characteristic and
mean strengths for clear timber, respectively. On the other
hand, the mean and characteristic compressive strengths
showed less variability reaching 30.6 N/mm2 and 21.0 N/mm2,
respectively, for in-grade samples. The value of MOE in
compression of 9125 N/mm2 was found.
For the purpose of the studies carried out by Bourke [13,
14] a substantial number of pieces were selected in order to
represent a typical forestry region and divided into three
batches. Bending MOE tests were carried out in accordance to
EN 408 [21] and the results are shown in Table 8.
Table 8. Mean MOE results [13,14].
Batch ID
No. of
specimens
Mean
MOE
[N/mm2]
S. D.
[N/mm2]
A
85
9367
1492
B
85
7475
1335
C
64
9036
-
In addition to these studies, Treacy et al. [15, 16] examined
the influence of density and microfibril angle on the bending
MOE and MOR of clear wood specimens from Sitka spruce of
four different provenances. This study was confined to small
clear samples and only 96 samples were subjected to bending
tests. A linear relationship, the same for all examined

provenances, was found between microfibril angle and
strength.
2.3 Physical properities
Evertsen [9] undertook an extensive testing programme to
determine the physical properties of Irish Sitka spruce.
Densities were examined by different testing procedures,
including oven drying, infra-density and microdensitometry
(optical density). The mean density (oven dry) of 273
specimens was 370 kg/m3 with standard deviation of 46.2
kg/m3. The average of basic density (wood dry mass over
wood fresh volume) of 480 samples was 366 kg/m3. X-ray
microdensitometry was used to determine the density of
specimens cut at different radial distances from the core.
Specimens were conditioned to a moisture content of 15 %,
prior to testing. These results for microdensitometry are
summarised in Table 9.
Table 9. Microdensitometry results [9].
Wood type
Mean
[kg/m3]
Max.
[kg/m3]
Min.
[kg/m3]
Juvenile wood
472
864
306
Adult wood
451
812
259
Yield class 16
462
838
283
Yield class 20
424
781
242
Other timber properties determined by Evertsen [9] include
values of twists and shrinkage. Mean values of twist and
shrinkage for samples of yield classes 16 and 20, are shown in
Tables 10 and 11, respectively.
Table 10. Twist results [9].
Yield
classes
Samples
no.
Mean twist
[mm/3m]
S. D.
[mm/3m]
16
80
6.38
4.81
20
159
7.17
4.49
16&20
239
6.90
4.60
Table 11. Dimensional shrinkage values [9].
Yield
class
No.
of
speci
mens
Length [%]
Width [%]
Depth [%]
Mean
S.D.
Mean
S.D
.
Mean
S.D.
16
78
0.055
0.037
2.17
0.76
1.88
0.62
20
157
0.041
0.030
1.52
0.75
1.37
0.52
16&20
235
0.045
0.033
1.73
0.81
1.54
0.60
Mean values of shrinkage for 960 specimens of yield class 20
were 4.21% with standard deviation of 0.94% for the
tangential direction and 2.15% with standard deviation of
0.69% for the radial direction.
Bourke [13, 14] investigated distortion in timber from fast-
grown Irish Sitka spruce, dried to 12% moisture content. The
results demonstrated that the dominant mode of distortion was
twist, which results in significant reduction of load bearing
capacity. It was found that almost all the planks were within
specification for both bow and crook, even for stricter limits
for special structural (SS) material. An analysis of the location
in the logs from which each board was sawn shows significant
variation with respect to radial position. A strong negative
correlation was demonstrated between distance from the pith
and the degree of twist that developed during drying.
Currently, as a part of the project ‘Innovation in Irish
Timber Usage’, the MOE and MOR are being determined
from flexural testing. Physical properties including moisture
content and density of each specimen are also being verified.
These tests are being carried out in order to establish the
variability in the mechanical properties including an
assessment of the in-board and between board variability in
the MOE, and to investigate the relationship between board
MOE, density and the timber origin.
3 POTENTIAL & INNOVATION
3.1 Introduction
The capacity of lower grade timber can be enhanced by its
utilisation in novel engineered wood products. The properties
of timber elements can be greatly improved through the
reinforcement by various materials. This strategy has been
successfully implemented within the construction industry and
has grown in recent years. The methodologies, with large
potential for Irish timber, are presented in the following
paragraphs.
3.2 FRP Reinforced Timber
Fibre reinforced polymer (FRP) is a composite consisting of
reinforcing fibres bound together in a polymer matrix. The
most common reinforcing fibre materials are glass, carbon and
aramid. These FRP materials are commonly used in the
aerospace, automotive and marine sectors due to their high
strength to weight ratio [22]. Timber has been reinforced
using FRP material in various configurations such as plates or
near surface mounted rods. Although FRP has been largely
used for retrofitting and repairing old timber structures there is
potential for the development of design codes to incorporate
the use of FRP material into new composite timber
engineering design.
Along with more commonly used FRP materials, increasing
focus on environmental issues has promoted the use of natural
fibres within FRP materials. Basalt fibre reinforced polymer
(BFRP) is a lesser known fibre which has the potential to rival
and surpass more commonly used fibres. BFRP is formed
similarly to many other reinforcing fibres. The basalt rock is
pre-treated and melted and the filaments are created as the
molten rock passes through hundreds of small orifices.
Lopresto et al. [23] compared basalt and glass fibre
reinforcement. The results showed a high tensile modulus,
compressive strength and bending strength for BFRP material.
The BFRP reinforcement also showed a 35 - 42 % higher
elastic modulus when compared to that of glass fibre
reinforced polymer (GFRP) reinforcement. This material
shows promising results both structurally when comparing
material properties and economically when looking at a cost
comparison with more expensive fibres such as carbon and
aramid fibres.
Many researchers have shown that the addition of FRP
reinforcement to solid timber beams results in an increase in
strength and stiffness [24, 25]. These enhancements are also
experienced in glued laminated beams. Glulam beams
reinforced with modest percentage reinforcement ratios (0.4

% - 2.9 %) of FRP material have been shown to demonstrate
superior strength, stiffness and ultimate moment capacity
when compared to glulam beams in their unreinforced state
[26, 27]. Hansson and Kristoffer [27], observed an increase in
bending stiffness of 85 % with a percentage reinforced area of
2 % using carbon fibre reinforced polymer (CFRP)
reinforcement plates. Raftery et al. [29], examined the effect
of GFRP rods on the structural properties of Irish-grown Sitka
spruce glued laminated beams. With a modest percentage
reinforcement of 1.4 %, a mean stiffness enhancement of 13.9
% and a mean improvement in the ultimate moment capacity
of 68 % was achieved when compared to beams in their
unreinforced state. Kelly [30] examined the effect of BFRP
rod reinforcement on low grade timber beams. The results
indicated an increase in bending stiffness of 12 %, with a
percentage reinforcement of 1.2 %, when compared to the
timber beams in their unreinforced state. These results show
great potential for such a low percentage reinforcement.
Much of the studies undertaken to date in the field of
reinforced timber have highlighted the positive effect of the
reinforcement on the short-term behaviour in bending. I. The
research being carried out as part of the project ‘Innovation in
Irish Timber Usage’ aims to determine the long-term
performance of such reinforced timber beams with respect to
load duration and variable climate and to develop appropriate
modification factors for design purposes.
3.3 Reinforced Timber joints
In timber engineering the critical elements in the design of a
structure are generally the joints. The most prevalent type of
joints found in timber structures are pinned joints. Moment
connections, however, are more versatile but these are less
common as they are perceived to be more expensive. Moment
connections can be achieved by using bolted plates, dowels
positioned in a circular arrangement or glued-in rods [31, 32].
Glued-in rod connections, as shown in Figure 1, can be
extremely efficient and possess many desirable attributes in
terms of manufacture, performance, aesthetics and cost
compared to the cumbersome conventional steel moment
connections that are often encountered in timber construction.
Not only do connections with glued-in rods look better than
conventional connections, they also have enhanced fire
protection as the rods which transfer moment are embedded
inside, and are therefore protected by, the timber.
Figure 1. Sketch of Glued-in Rod Connection
With regards to new-build construction, Gehri [33]
identified five areas where glued-in rods may be used for
connections: frame corner, beam-post connection, beam-beam
joint, supports and hinged joints.
Over the past two decades there have been many national
and international research projects commissioned on the use
of glued-in rods in timber joints e.g. GIROD, LICONS [34]
and Bainbridge and Mettem [35]. In spite of this, no universal
standard exists for their design. There had been an informative
annex in prBS ENV 1995-2 [36] which provided limited
coverage of the design of glued-in rods using steel bars
however this document was replaced by BS EN 1995-2:2004
[37] and no guidance is included in the current document. The
three main elements to be considered when designing glued-in
rod connections are: the timber, rod and adhesive. The most
significant challenge in the development of a standard design
method is the many varying approaches to defining these joint
properties as each of these elements can be expanded further,
thus making the definition of design rules more complicated.
The majority of research done in this area to date comprises
steel rods glued-in to glued laminated (glulam) elements with
lamellae of a high strength class timber. The investigation on
the use of locally sourced Irish Sitka Spruce is a part of the
project ‘Innovation in Irish Timber Usage’.
3.4 Cross-laminated timber (CLT)
Cross-laminated timber (CLT) is a prefabricated multi-layer
engineered wood product made of at least three orthogonally
bonded layers of timber. In order to increase rigidity and
stability, successive layers of boards are placed cross-wise to
form a solid timber panel, as show in Figure 2.
Figure 2. CLT panel schema [38].
Load-bearing CLT wall and floor panels are easily assembled
on site to form multi-storey buildings. This improves
construction and project delivery time, reduces costs, and
maximises efficiency on all levels [39-41]. In this project, the
feasibility of using Irish Sitka spruce to produce commercial
CLT panels is being investigated.
4 CONCLUSIONS
In the past, a number of studies has been conducted to
determine the properties of Irish-grown Sitka spruce.
Nevertheless, due to the changes in that have taken place in
silvicultural practices since the publication of these studies,
there is a need to determine how these properties have
changed.
Beam/Rafter
Rod(s) Glued-
in to Post
Grain direction

As a part of ‘Innovation in Irish Timber Usage’ ongoing
project testing of a large number of samples will be
undertaken to establish the properties of the current resource.
Comparative analysis will be undertaken with the data
produced for Scottish Sitka spruce in the SIRT project and
with historical data.
Other objectives of the project include determination of the
durability of reinforced timber beams with respect to load
duration and variable climate and to develop appropriate
strength modification factors.
The next aim of the research programme is to investigate
and develop a sustainable means of creating moment resistant
connections within timber frames using bonded-in FRP rods,
with a specific emphasis on the portal frame.
Moreover, the suitability of Irish-grown Sitka Spruce for the
manufacture of cross-laminated timber panels (CLT) is
investigated. This is vital in order to develop the necessary
engineering data to support the commercialisation of Irish-
made CLT.
ACKNOWLEDGMENTS
This work has been carried out as part of the project entitled
‘Innovation in Irish timber Usage’ (project ref. 11/C/207)
funded by the Department of Agriculture, Food and the
Marine of the Republic of Ireland under the
FIRM/RSF/COFORD scheme. The authors would also like to
thank ECC Ltd. (Earrai Coillte Chonnacht Teoranta) for
supplying the timber used in this project.
REFERENCES
[1] Irish Forestry and Forest Products Association (IFFPA), An overview of
the Irish forestry and forest products sector 2013, www.iffpa.ie, 2014.
[2] COFORD, Forecast report 2011, www.coford.ie, 2011.
[3] Phillips, H. (2011), All Ireland Roundwood Production Forecast 2011-
2028, Dublin.
[4] Picardo, V. (1987). Effects of yield class, tree section, forest and size on
strength of home grown Sitka spruce, Paper no CIB-W18A/20-6-2, CIB
W18 meeting, Dublin.
[5] Ni Dhubhain, A., Evertsen, J.A., and Gardiner, J. J. (1988), The
influence of compression wood on the strength properties of Sitka
spruce, Forest Products Journal 38(9)67-69.
[6] Picardo, V. (2000), Quantification of the yields of Irish grown Sitka
spruce in the new CEN stgrength classes, COFORD.
[7] Lucey, D. J., Mahony, R., and Kirk, D. (2001). The Design and
Performances of Thin Web Timber I-joists (Using Irish Timber and
Oriented Strand Board), Report, Dublin Institute of Technology.
[8] Raftery, G.M. and Harte, A.M, (2014). Material characterisation of
fast-grown plantation spruce, Structures and Buildings, DOI:
10.1680/stbu.12.00052.
[9] Evertsen, J. A. (1988), Determintion of wood quality in Sitka spruce
(Picea sitchensis (Bong.) Carr) by destructive and non-destructive
methods, PhD thesis, University College Dublin.
[10] Bucur, V. (1980), Resonance Wood Acoustical Properties Modified by
Long-Term Loading, Annales Des Sciences Forestieres, 37 (3), 249-64.
[11] Bucur, V. (1981), 'Wood Dynamical Young Modulus Determination on
Increment Core', Annales Des Sciences Forestieres, 38 (2), 283-98.
[12] Patrick, G. (2004), The structral performance of FRP reinforced glue
laminated beams made from homegrown Sitka Spruce, PhD thesis,
Queen's University Belfast.
[13] Bourke, M. (2007), Distortion Reduction Strategies for Irish Softwoods,
MSc thesis, University of Limerick.
[14] Bourke, M. (2008), Improving the stability of structural timber,
COFORD connects.
[15] Treacy M. (1999), The relationship between wood microstructure and
wood quality in four Irish grown sitka spruce (Picea sitchensis (Bong.)
Carr.) provenances. MSc thesis, University College Dublin.
[16] Treacy M., Evertsen, J., and Ní Dhubháin, A., (2000), A comparison of
mechanical and physical wood properties of a range of Sitka spruce
provenances, COFORD.
[17] Department of Agriculture, Food and the Marine, Sitka spruce (Picea
sitchensis (Bong.) Carr.),
www.agriculture.gov.ie/media/migration/forestry/publications/SitkaSpr
uce_low.pdf.
[18] Moore, J., Lyon, A., Ridley-Ellis, D., and Gardiner, B. (2008).
Properties of UK-grown Sitka spruce: Extent and sources of variation,
Proceedings of the 10th World Conference on Timber Engineering,
Miyazaki.
[19] Moore, J. (2011). Wood properties and uses of Sitka spruce in Britain,
Forestry Commission Research Report, Forestry Commission,
Edinburgh.
[20] EN 338:2009 Structural timber – Strength classes, CEN.
[21] EN 408:2010+A1:2012 Timber structures – Structural timber and glued
laminated timber – Determination of some physical and mechanical
properties, CEN.
[22] Zaman, A., Gutub, S. A., and Wafa, M. A. (2013), A review on FRP
composites applications and durability concerns in the construction
sector, Journal of Reinforced Plastics and Composites, 32 (24), 1966-
88.
[23] Lopresto, V., Leone, C., and De Iorio, I. (2011), Mechanical
characterisation of basalt fibre reinforced plastic, Composites Part B:
Engineering, 42 (4), 717-23.
[24] Kliger, R. I. and André, A. (2013), Enhanced timber properties with
FRP composites, Cost Action FP1004 - Innovative Timber Composites-
Improving wood with other materials, pp. 11.
[25] Plevris, N. and Triantafillou, T. (1992), FRP
‐
Reinforced Wood as
Structural Material, Journal of Materials in Civil Engineering, 4 (3),
300-17.
[26] Raftery, G. M. and Harte, A. M. (2011), Low-grade glued laminated
timber reinforced with FRP plate, Composites Part B: Engineering, 42
(4), 724-35.
[27] Gilfillan, J. R., Gilbert, S.G., and Russell, D.P. (2001b), Enhancement of
the structural performance of glue laminated, homegrown Sitka spruce,
using carbonfibre-reinforced polymer, Structural Engineer, 79 (8), 23-
28.
[28] Hansson, S. and Kristoffer, K. (2007), Moisture-related creep of
reinforced timber, Chalmers University of Technology, Goteborg,
Sweden.
[29] Raftery, G., Whelan, C., and Harte, A. (2012), Bonded in GFRP rods
For the repair of Glud Laminated Timber, World Conference of Timber
Engineering, Auckland 2012, 16-19 July, Auckland, New Zealand.
[30] Kelly, F. (2012), Basalt FRP rods for strengthening and repair of glued
laminated timber, MSc thesis National University of Ireland, Glaway.
[31] Ozelton, E.C and Baird, J.A. (2006). Timber Designers’ Manual, Third
Edition, Blackwell Publishing, Oxford UK.
[32] Porteous, J.;Kermani,A.; 2007, Structural Timber Design to Eurocode
5, Blackwell Publishing, Oxford UK.
[33] Gehri, E. (2010), High Performing Jointing Technique Using Glued-in
Rods [online] Available at
http://www.ewpa.com/Archive/2010/june/Paper_095.pdf
[34] Broughton, J.G. and Hutchinson, A.R. (2004). LICONS Task 2-Sub tast
2.2, Oxford Brookes University
[35] Bainbridge, R.J. and Mettem, C.J. (1998). A Review of Moment-
Resistant Structural Timber Connection. Proceedings of the ICE -
Structures and Buildings 128(4), 323–331.
[36] prEN 1995-2: Design of timber structures, Part 2: Bridges. Final Project
Team draft. Stage 34, CEN.
[37] EN 1995-2:2004 Eurocode 5. Design of timber structures. Bridges,
CEN.
[38] Rimetz, B. (2011). Future of Wood Update / X Marks the Opportunity,
ProSales, http://www.prosalesmagazine.com/products/lumber/x-marks-
the-opportunity_o.
[39] Handbook 1. Timber structures (2008). Leonardo da Vinci Pilot Project.
[40] Crespell, P., and Gagnon, S., (2010). Cross Laminated Timber: a
Premier, FPInnovations
[41] Yeh, B., Gagnon, S., Williamson, T., Pirvu, C., Lum, C., and
Kretschmann, D. (2012). Wood Design Focus, 22(2)13-21.