The potential use of beech (Fagus sylvatica Linnaeus) sawn timber for structures has been investi... more The potential use of beech (Fagus sylvatica Linnaeus) sawn timber for structures has been investigated. Beech stands in transition from coppice to high forest after thinning interventions have been sampled from different Italian sources. A sample of 160 beams of two different cross sections was extracted and tested, according to the normalized procedures for the characterization of wood for structures. The specimens were visually graded considering the strength relevant defects, according to the Italian standard. To determine the mechanical properties of the timber (namely strength and stiffness), four-point bending tests were performed and the main characteristic values were derived. The results of the study reveal that knot ratio was the principal defect that influenced both resistance and yields. The potential strength class D30 was achieved with the resulting characteristic values, although, due to the small number of samples tested, the reached class could not be formally assigned. To improve the effectiveness of the grading rule in the Italian standard, some modifications and a new grade were proposed for the beech sawn timber. Finally the D40 strength class could be theoretically reached, but with reduced yields.
Poor-quality Corsican pine (Pinus nigra subsp. laricio (Poir.) Maire) and Douglas fir (Pseudotsug... more Poor-quality Corsican pine (Pinus nigra subsp. laricio (Poir.) Maire) and Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) wood samples were heat treated with the aim of testing the improvement of wood quality that could increase their economic value. Wood properties were measured to assess quality in treated and non-treated materials, including density, hardness, anti-swelling efficiency (ASE), modulus of elasticity (MOE), modulus of rupture (MOR), and compression strength. The results showed higher dimensional stability in heattreated wood, yet mechanical performance in compression and bending strength were only marginally affected by loss of density. Despite having a relatively low density after heat treatment, Corsican pine sapwood has potential in manufacturing higher-value products. In contrast, heat treatment applied to Douglas fir wood did not appear economically viable; insufficient differences were detected between the naturally desirable characteristics of this species and heat-treated samples.
Riassunto: Il lavoro presenta il quadro aggiornato dell'evoluzione normativa in atto nel settore ... more Riassunto: Il lavoro presenta il quadro aggiornato dell'evoluzione normativa in atto nel settore del legno strutturale, con particolare riferimento alla travatura di castagno che in Italia trova ampio spazio negli impieghi di carpenteria. In questo ambito vengono evidenziate le peculiarità degli assortimenti in legno massiccio, i risultati finora acquisiti a seguito di una serie di iniziative di supporto all'adeguamento normativo finalizzato alla loro marcatura CE e le prospettive che si delineano per gli operatori del comparto. Parole chiave: Norme Tecniche per le Costruzioni, classificazione del legname, classi di resistenza, travi, Uso Fiume
ABSTRACT An innovation of the traditional timber truss is proposed, designed, built and tested. I... more ABSTRACT An innovation of the traditional timber truss is proposed, designed, built and tested. It is an original joining system to connect the top-chord and the tie–beam. The joint studied enables prolonging the rafter over the linkage with the tie, so as to form overhanging eaves. The behaviour of the connection under loads was analysed either by considerations relating to the possible limit states and by means of Finite Elements Analysis (FEA). In accordance with the design which was theoretically analysed, a prototype was made and it was subjected to loading tests that gave positive results.
This paper describes the -Deformometric Kit‖ (DK), which is both a methodological approach and an... more This paper describes the -Deformometric Kit‖ (DK), which is both a methodological approach and an equipment conceived, designed and made at DEISTAF (University of Florence). The DK's main purpose is to carry out measurements and monitoring of the deformation dynamics of wooden objects. The monitoring can take place in virtually any environment, for any desired duration (minutes, hours, weeks, years, and so on). The measurement can be carried out mainly, but not exclusively, in connection with fluctuations of ambient temperature and relative humidity. The DK provides a reliable and accurate record (a first step towards understanding) of the behaviour of original panel paintings placed in their usual exhibition location, enabling curatorial staff and researchers to (a) obtain information about the behaviour of individual supports, in order to evaluate the impact of climate on their conservation state, help to make decisions for future restoration interventions; and (b) provide reference data for calibrating and validating numeric models. It can also provide data on the deformation of a panel while it is handled and transported, enabling an evaluation of stresses to which it is subjected during this operation. The device consists of two displacement transducers, which are fixed (in a low-impact, reversible way) to the back face of the panel, perpendicular to the grain, at different distances from the panel's surface. The two transducers not only measure the in-plane shrinkage/swelling of the panel, but since they are located at different distances, their measurements can also be combined with simple geometrical calculations to indicate the amount of distortion (cupping) which the panel undergoes. This paper explains the geometrical principles on which the DK is based, as well as its construction. Some examples of the data which have been obtained during actual monitoring by the DK are also included.
International Journal of Adhesion and Adhesives, 2014
The use of adhesive joints with bonded-in steel rods or plates is of great interest nowadays for ... more The use of adhesive joints with bonded-in steel rods or plates is of great interest nowadays for both new large timber structures design and timber strengthening. Bonded-in joints offer some advantages: high stiffness, high strength, ductile behaviour in some cases, easiness of factory production and possibility of in situ realization. Their use in Service Class 1 and 2 is possible but not in Service Class 3, due to the extreme conditions. While the effect of the environmental conditions on the wood is well known, their effect on epoxy glue and on the mechanical properties of full scale timber joints requires ad hoc tests. In order to verify the effects of extreme environmental conditions, on the durability of the epoxy resin and on the mechanical behaviour of full scale ordinary joints, different epoxy specimens and timber joints were exposed to various conditions and ageing cycles: immersion in water (demineralized and swimming pool water), high and low temperature treatments cycles, treatments at different temperature and RH. Epoxy specimens showed transformation only in the case of immersion in swimming pool water. Full scale timber joints showed a shear strength variation due only to the moisture content variation between 12-24%. Joints submerged in water showed a strength reduction higher than the one expected for the reached moisture content, demonstrating that extreme conditions affect not only the timber strength, but also the performance of the full joints.
Interest in both the time effect on the timber mechanical properties and the reuse of old solid t... more Interest in both the time effect on the timber mechanical properties and the reuse of old solid timbers has prompted many research works since the 1970s, mainly focusing on evaluating bending strength (MOR) and stiffness (MOE). However, only few studies have investigated the effect of aging on shear modulus (G). In this work, transverse vibration test is used to calculate G and MOE of over 80 old timber beams. The MOE/G ratio and the relationship between G and different timber features are investigated. The main outcome of the research confirms that the MOE/G ratio is around 20, close to the value reported in literature for new solid timber. No relationship exists between G and MOE (r 2 =0.07) or between G and other timber features. When density and knots are used as predictors in a multiple regression model, the G prediction improves (r 2 =0.22). This work confirms that G is not affected by the age of timber.
This paper describes the "Deformometric Kit" (DK), which is both a methodological approach and an... more This paper describes the "Deformometric Kit" (DK), which is both a methodological approach and an equipment conceived, designed and made at DEISTAF (University of Florence). The DK's main purpose is to carry out measurements and monitoring of the deformation dynamics of wooden objects. The monitoring can take place in virtually any environment, for any desired duration (minutes, hours, weeks, years, and so on). The measurement can be carried out mainly, but not exclusively, in connection with fluctuations of ambient temperature and relative humidity. The DK provides a reliable and accurate record (a first step towards understanding) of the behaviour of original panel paintings placed in their usual exhibition location, enabling curatorial staff and researchers to (a) obtain information about the behaviour of individual supports, in order to evaluate the impact of climate on their conservation state, help to make decisions for future restoration interventions; and (b) provide reference data for calibrating and validating numeric models. It can also provide data on the deformation of a panel while it is handled and transported, enabling an evaluation of stresses to which it is subjected during this operation. The device consists of two displacement transducers, which are fixed (in a low-impact, reversible way) to the back face of the panel, perpendicular to the grain, at different distances from the panel's surface. The two transducers not only measure the in-plane shrinkage/swelling of the panel, but since they are located at different distances, their measurements can also be combined with simple geometrical calculations to indicate the amount of distortion (cupping) which the panel undergoes. This paper explains the geometrical principles on which the DK is based, as well as its construction. Some examples of the data which have been obtained during actual monitoring by the DK are also included.
International Journal of Adhesion and Adhesives, 2014
The use of adhesive joints with bonded-in steel rods or plates is of great interest nowadays for ... more The use of adhesive joints with bonded-in steel rods or plates is of great interest nowadays for both new large timber structures design and timber strengthening. Bonded-in joints offer some advantages: high stiffness, high strength, ductile behaviour in some cases, easiness of factory production and possibility of in situ realization. Their use in Service Class 1 and 2 is possible but not in Service Class 3, due to the extreme conditions. While the effect of the environmental conditions on the wood is well known, their effect on epoxy glue and on the mechanical properties of full scale timber joints requires ad hoc tests. In order to verify the effects of extreme environmental conditions, on the durability of the epoxy resin and on the mechanical behaviour of full scale ordinary joints, different epoxy specimens and timber joints were exposed to various conditions and ageing cycles: immersion in water (demineralized and swimming pool water), high and low temperature treatments cycles, treatments at different temperature and RH. Epoxy specimens showed transformation only in the case of immersion in swimming pool water. Full scale timber joints showed a shear strength variation due only to the moisture content variation between 12-24%. Joints submerged in water showed a strength reduction higher than the one expected for the reached moisture content, demonstrating that extreme conditions affect not only the timber strength, but also the performance of the full joints.
Riassunto: Il lavoro presenta il quadro aggiornato dell'evoluzione normativa in atto nel settore ... more Riassunto: Il lavoro presenta il quadro aggiornato dell'evoluzione normativa in atto nel settore del legno strutturale, con particolare riferimento alla travatura di castagno che in Italia trova ampio spazio negli impieghi di carpenteria. In questo ambito vengono evidenziate le peculiarità degli assortimenti in legno massiccio, i risultati finora acquisiti a seguito di una serie di iniziative di supporto all'adeguamento normativo finalizzato alla loro marcatura CE e le prospettive che si delineano per gli operatori del comparto.
The potential use of beech (Fagus sylvatica Linnaeus) sawn timber for structures has been investi... more The potential use of beech (Fagus sylvatica Linnaeus) sawn timber for structures has been investigated. Beech stands in transition from coppice to high forest after thinning interventions have been sampled from different Italian sources. A sample of 160 beams of two different cross sections was extracted and tested, according to the normalized procedures for the characterization of wood for structures. The specimens were visually graded considering the strength relevant defects, according to the Italian standard. To determine the mechanical properties of the timber (namely strength and stiffness), four-point bending tests were performed and the main characteristic values were derived. The results of the study reveal that knot ratio was the principal defect that influenced both resistance and yields. The potential strength class D30 was achieved with the resulting characteristic values, although, due to the small number of samples tested, the reached class could not be formally assigned. To improve the effectiveness of the grading rule in the Italian standard, some modifications and a new grade were proposed for the beech sawn timber. Finally the D40 strength class could be theoretically reached, but with reduced yields.
Poor-quality Corsican pine (Pinus nigra subsp. laricio (Poir.) Maire) and Douglas fir (Pseudotsug... more Poor-quality Corsican pine (Pinus nigra subsp. laricio (Poir.) Maire) and Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) wood samples were heat treated with the aim of testing the improvement of wood quality that could increase their economic value. Wood properties were measured to assess quality in treated and non-treated materials, including density, hardness, anti-swelling efficiency (ASE), modulus of elasticity (MOE), modulus of rupture (MOR), and compression strength. The results showed higher dimensional stability in heattreated wood, yet mechanical performance in compression and bending strength were only marginally affected by loss of density. Despite having a relatively low density after heat treatment, Corsican pine sapwood has potential in manufacturing higher-value products. In contrast, heat treatment applied to Douglas fir wood did not appear economically viable; insufficient differences were detected between the naturally desirable characteristics of this species and heat-treated samples.
Riassunto: Il lavoro presenta il quadro aggiornato dell'evoluzione normativa in atto nel settore ... more Riassunto: Il lavoro presenta il quadro aggiornato dell'evoluzione normativa in atto nel settore del legno strutturale, con particolare riferimento alla travatura di castagno che in Italia trova ampio spazio negli impieghi di carpenteria. In questo ambito vengono evidenziate le peculiarità degli assortimenti in legno massiccio, i risultati finora acquisiti a seguito di una serie di iniziative di supporto all'adeguamento normativo finalizzato alla loro marcatura CE e le prospettive che si delineano per gli operatori del comparto. Parole chiave: Norme Tecniche per le Costruzioni, classificazione del legname, classi di resistenza, travi, Uso Fiume
ABSTRACT An innovation of the traditional timber truss is proposed, designed, built and tested. I... more ABSTRACT An innovation of the traditional timber truss is proposed, designed, built and tested. It is an original joining system to connect the top-chord and the tie–beam. The joint studied enables prolonging the rafter over the linkage with the tie, so as to form overhanging eaves. The behaviour of the connection under loads was analysed either by considerations relating to the possible limit states and by means of Finite Elements Analysis (FEA). In accordance with the design which was theoretically analysed, a prototype was made and it was subjected to loading tests that gave positive results.
This paper describes the -Deformometric Kit‖ (DK), which is both a methodological approach and an... more This paper describes the -Deformometric Kit‖ (DK), which is both a methodological approach and an equipment conceived, designed and made at DEISTAF (University of Florence). The DK's main purpose is to carry out measurements and monitoring of the deformation dynamics of wooden objects. The monitoring can take place in virtually any environment, for any desired duration (minutes, hours, weeks, years, and so on). The measurement can be carried out mainly, but not exclusively, in connection with fluctuations of ambient temperature and relative humidity. The DK provides a reliable and accurate record (a first step towards understanding) of the behaviour of original panel paintings placed in their usual exhibition location, enabling curatorial staff and researchers to (a) obtain information about the behaviour of individual supports, in order to evaluate the impact of climate on their conservation state, help to make decisions for future restoration interventions; and (b) provide reference data for calibrating and validating numeric models. It can also provide data on the deformation of a panel while it is handled and transported, enabling an evaluation of stresses to which it is subjected during this operation. The device consists of two displacement transducers, which are fixed (in a low-impact, reversible way) to the back face of the panel, perpendicular to the grain, at different distances from the panel's surface. The two transducers not only measure the in-plane shrinkage/swelling of the panel, but since they are located at different distances, their measurements can also be combined with simple geometrical calculations to indicate the amount of distortion (cupping) which the panel undergoes. This paper explains the geometrical principles on which the DK is based, as well as its construction. Some examples of the data which have been obtained during actual monitoring by the DK are also included.
International Journal of Adhesion and Adhesives, 2014
The use of adhesive joints with bonded-in steel rods or plates is of great interest nowadays for ... more The use of adhesive joints with bonded-in steel rods or plates is of great interest nowadays for both new large timber structures design and timber strengthening. Bonded-in joints offer some advantages: high stiffness, high strength, ductile behaviour in some cases, easiness of factory production and possibility of in situ realization. Their use in Service Class 1 and 2 is possible but not in Service Class 3, due to the extreme conditions. While the effect of the environmental conditions on the wood is well known, their effect on epoxy glue and on the mechanical properties of full scale timber joints requires ad hoc tests. In order to verify the effects of extreme environmental conditions, on the durability of the epoxy resin and on the mechanical behaviour of full scale ordinary joints, different epoxy specimens and timber joints were exposed to various conditions and ageing cycles: immersion in water (demineralized and swimming pool water), high and low temperature treatments cycles, treatments at different temperature and RH. Epoxy specimens showed transformation only in the case of immersion in swimming pool water. Full scale timber joints showed a shear strength variation due only to the moisture content variation between 12-24%. Joints submerged in water showed a strength reduction higher than the one expected for the reached moisture content, demonstrating that extreme conditions affect not only the timber strength, but also the performance of the full joints.
Interest in both the time effect on the timber mechanical properties and the reuse of old solid t... more Interest in both the time effect on the timber mechanical properties and the reuse of old solid timbers has prompted many research works since the 1970s, mainly focusing on evaluating bending strength (MOR) and stiffness (MOE). However, only few studies have investigated the effect of aging on shear modulus (G). In this work, transverse vibration test is used to calculate G and MOE of over 80 old timber beams. The MOE/G ratio and the relationship between G and different timber features are investigated. The main outcome of the research confirms that the MOE/G ratio is around 20, close to the value reported in literature for new solid timber. No relationship exists between G and MOE (r 2 =0.07) or between G and other timber features. When density and knots are used as predictors in a multiple regression model, the G prediction improves (r 2 =0.22). This work confirms that G is not affected by the age of timber.
This paper describes the "Deformometric Kit" (DK), which is both a methodological approach and an... more This paper describes the "Deformometric Kit" (DK), which is both a methodological approach and an equipment conceived, designed and made at DEISTAF (University of Florence). The DK's main purpose is to carry out measurements and monitoring of the deformation dynamics of wooden objects. The monitoring can take place in virtually any environment, for any desired duration (minutes, hours, weeks, years, and so on). The measurement can be carried out mainly, but not exclusively, in connection with fluctuations of ambient temperature and relative humidity. The DK provides a reliable and accurate record (a first step towards understanding) of the behaviour of original panel paintings placed in their usual exhibition location, enabling curatorial staff and researchers to (a) obtain information about the behaviour of individual supports, in order to evaluate the impact of climate on their conservation state, help to make decisions for future restoration interventions; and (b) provide reference data for calibrating and validating numeric models. It can also provide data on the deformation of a panel while it is handled and transported, enabling an evaluation of stresses to which it is subjected during this operation. The device consists of two displacement transducers, which are fixed (in a low-impact, reversible way) to the back face of the panel, perpendicular to the grain, at different distances from the panel's surface. The two transducers not only measure the in-plane shrinkage/swelling of the panel, but since they are located at different distances, their measurements can also be combined with simple geometrical calculations to indicate the amount of distortion (cupping) which the panel undergoes. This paper explains the geometrical principles on which the DK is based, as well as its construction. Some examples of the data which have been obtained during actual monitoring by the DK are also included.
International Journal of Adhesion and Adhesives, 2014
The use of adhesive joints with bonded-in steel rods or plates is of great interest nowadays for ... more The use of adhesive joints with bonded-in steel rods or plates is of great interest nowadays for both new large timber structures design and timber strengthening. Bonded-in joints offer some advantages: high stiffness, high strength, ductile behaviour in some cases, easiness of factory production and possibility of in situ realization. Their use in Service Class 1 and 2 is possible but not in Service Class 3, due to the extreme conditions. While the effect of the environmental conditions on the wood is well known, their effect on epoxy glue and on the mechanical properties of full scale timber joints requires ad hoc tests. In order to verify the effects of extreme environmental conditions, on the durability of the epoxy resin and on the mechanical behaviour of full scale ordinary joints, different epoxy specimens and timber joints were exposed to various conditions and ageing cycles: immersion in water (demineralized and swimming pool water), high and low temperature treatments cycles, treatments at different temperature and RH. Epoxy specimens showed transformation only in the case of immersion in swimming pool water. Full scale timber joints showed a shear strength variation due only to the moisture content variation between 12-24%. Joints submerged in water showed a strength reduction higher than the one expected for the reached moisture content, demonstrating that extreme conditions affect not only the timber strength, but also the performance of the full joints.
Riassunto: Il lavoro presenta il quadro aggiornato dell'evoluzione normativa in atto nel settore ... more Riassunto: Il lavoro presenta il quadro aggiornato dell'evoluzione normativa in atto nel settore del legno strutturale, con particolare riferimento alla travatura di castagno che in Italia trova ampio spazio negli impieghi di carpenteria. In questo ambito vengono evidenziate le peculiarità degli assortimenti in legno massiccio, i risultati finora acquisiti a seguito di una serie di iniziative di supporto all'adeguamento normativo finalizzato alla loro marcatura CE e le prospettive che si delineano per gli operatori del comparto.
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