scholarly journals Strength Properties of Structural Glulam Elements from Pine (Pinus sylvestris L.) Timber Reinforced in the Tensile Zone with Steel and Basalt Rods

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2574
Author(s):  
Radosław Mirski ◽  
Marcin Kuliński ◽  
Dorota Dziurka ◽  
Marta Thomas ◽  
Ryszard Antonowicz
Keyword(s):  
Pinus Sylvestris ◽  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Strength Properties ◽  
Lower Strength ◽  
Industrial Practice ◽  
Potential Applicability ◽  
Tensile Zone

The study analyzed potential applicability for asymmetric reinforcement of glulam beams using materials with a higher modulus of elasticity. Reinforcement elements included smooth and ribbed steel rods as well as basalt rods. These rods were placed only in the tensile zone, assuming that they will not only impart increased rigidity but first of all will reduce the scatter of bending strength values. What is significant, tests were conducted on timber with defects, as it is most commonly used in industrial practice. Analyses showed that this provides an increase in rigidity close to the assumed level. A significant increase in strength was observed. The manufactured beams reinforced with steel and basalt rods were characterized by mean bending strength amounting to 54 and 47 N/mm2, respectively. However, no significant improvement was found in the scatter of the observed variable. Beams reinforced with steel exhibit a 20% higher strength than unreinforced beams. The lower strength of beams reinforced with basalt bars may be related to the lower modulus of elasticity of the basalt itself.

Strength Properties of Chestnut Structural Timber with Wane

2013 ◽  
Vol 778 ◽  
pp. 377-384 ◽  
Author(s):  
Michele Brunetti ◽  
Michela Nocetti ◽  
Paolo Burato
Keyword(s):  
Cross Section ◽  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Rectangular Cross Section ◽  
Ring Width ◽  
Physical And Mechanical Properties ◽  
Strength Properties ◽  
Mean Value ◽  
National Standards ◽  
Timber Element

Grading of timber for structural purposes allows material with similar physical and mechanical properties to be grouped together. The groups are defined by specific strength values and indicate the basic working stresses and stiffnesses to be used for structural design purposes. In particular, visual strength grading bases the assignment of each timber element to a grade on the characteristics that are visually measurable (i.e. knots, slope of grain, annual ring width). Very similar principles are implemented for the in situ assessment of timber structures, as recommended for example by the Italian standard UNI 11119, that specifies the procedures for the diagnosis of timber members. Currently, however, European standards and most of the national standards on strength grading refer to timber elements with rectangular cross section, while in existing buildings, members with irregular cross section are extremely common. Thus, 10 different provenances (5 from Italy and 5 from France) of chestnut timber were sampled. More than 600 structural elements with wane were visually examined in laboratory and all the characteristics were collected. Bending tests were then performed on each timber element until failure, and bending strength, as well as modulus of elasticity and density, were determined. Here, the limitations for the main strength-reducing characteristics and the characteristic values (fifth percentile for bending strength and density and the mean value for modulus of elasticity) of chestnut timber with wane are presented.

Mechanical properties of Ficus vallis-choudae (Delile), a lesser utilized species in Nigeria

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 6550-6560
Author(s):  
Lawrence Aguda ◽  
Babatunde Ajayi ◽  
Sylvester Areghan ◽  
Yetunde Olayiwola ◽  
Aina Kehinde ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Moisture Content ◽  
Modulus Of Elasticity ◽  
Bending Strength ◽  
High Strength ◽  
Strength Properties ◽  
Modulus Of Rupture ◽  
Impact Bending ◽  
Timber Market

Declining availability of the prime economic species in the Nigerian timber market has led to the introduction of Lesser-Used Species (LUS) as alternatives. Their acceptability demands information on the technical properties of their wood. The aim of this study was to investigate the mechanical properties of Ficus vallis-choudae to determine its potential for timber. Three mature Ficus vallis-choudae trees were selected and harvested from a free forest area in Ibadan, Oyo State, Nigeria. Samples were collected from the base (10%), middle (50%), and top (90%) along the sampling heights of each tree, which was further partitioned into innerwood, centrewood, and outerwood across the sampling radial position. Investigations were carried out to determine the age, density, moisture content, impact strength, modulus of elasticity, modulus of rupture, compressive strength parallel-to-grain, and shear strength parallel-to-grain. The mean impact bending strength, modulus of rupture, modulus of elasticity, maximum shear strength parallel-to-grain, and maximum compression strength parallel-to-grain for Ficus vallis-choudae at 12% moisture content were 20.4 N/mm2, 85.8 N/mm2, 709 N/mm2, 10.7 N/mm2, and 33.6 N/mm2, respectively. The study found the species to be dense with high strength properties in comparison with well-known timbers used for constructional purposes.

scholarly journals The Usefulness of Pine Timber (Pinus sylvestris L.) for the Production of Structural Elements. Part II: Strength Properties of Glued Laminated Timber

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4029
Author(s):  
Radosław Mirski ◽  
Dorota Dziurka ◽  
Monika Chuda-Kowalska ◽  
Jakub Kawalerczyk ◽  
Marcin Kuliński ◽  
...  
Keyword(s):  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Strength Properties ◽  
Bending Test ◽  
Structural Elements ◽  
Pine Wood ◽  
Glued Laminated Timber ◽  
The Individual ◽  
Horizontal Arrangement

The paper assessed the feasibility of manufacturing glued structural elements made of pine wood after grading it mechanically in a horizontal arrangement. It was assumed that the pine wood was not free of defects and that the outer lamellas would also be visually inspected. This would result in only rejecting items with large, rotten knots. Beams of the assumed grades GL32c, GL28c and GL24c were made of the examined pine wood. Our study indicated that the expected modulus of elasticity in bending was largely maintained by the designed beam models but that their strength was connected with the quality of the respective lamellas, rather than with their modulus of elasticity. On average, the bending strength of the beams was 44.6 MPa. The cause of their destruction was the individual technical quality of a given item of timber, which was loosely related to its modulus of elasticity, assessed in a bending test. Although the modulus of elasticity of the manufactured beam types differed quite significantly (11.45–14.08 kN/mm2), the bending strength for all types was similar. Significant differences occurred only during a more detailed analysis because lower classes were characterized by a greater variation of the bending strength. In this case, beams with a strength of 24 MPa to 50 MPa appeared.

Mechanical Grading of Structural Larch Dimension Lumber

2012 ◽  
Vol 517 ◽  
pp. 683-688 ◽  
Author(s):  
Wan Li Lou ◽  
Hai Qing Ren ◽  
Zhao Hui Wang ◽  
Xiu Qin Luo
Keyword(s):  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Strength Properties ◽  
Modulus Of Rupture ◽  
Bending Test ◽  
Total Production ◽  
Good Relationship ◽  
Dimension Lumber ◽  
Structural Applications ◽  
Viable Approach

Larch dimension lumber bending strength properties from full-size bending test were used to establish preliminary grade boundary settings for mechanical grading of lumber by modulus of elasticity. Simulated production using the grade boundary settings were evaluated for modulus of rupture, ultimate tensile strength, and ultimate compressive strength. The results showed a good relationship between modulus of rupture and modulus of elasticity, and the observed relationships between strengths properties were consistent with that assumed for the standard grades. Through mechanical grading, larch dimension lumber could be sort grades: M14, M30 and M40. Assuming the visual requirements are met, the M30 and M40 grades account for more than 80% of the total production. Mechanical grading of larch appears to be a viable approach for grading Chinese large for structural applications.

scholarly journals Strength Properties of Structural Glulam Manufactured from Pine (Pinus sylvestris L.) Side Boards

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7312
Author(s):  
Radosław Mirski ◽  
Dorota Dziurka ◽  
Marcin Kuliński ◽  
Adrian Trociński ◽  
Jakub Kawalerczyk ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Pinus Sylvestris ◽  
Bending Strength ◽  
Strength Properties ◽  
Structural Timber ◽  
The Difference

The aim of this study was to assess the static bending strength of pine glulam manufactured when obtaining the main yield, i.e., structural timber or timber to be used in the production of structural glulam. Analyses were conducted on pine timber harvested from three different locations in Poland. Two beam variants were manufactured, differing in the timber arrangement, horizontal vs. vertical. It was shown that the static bending strength of beams manufactured in the vertical timber arrangement variant is slightly higher than that of beams produced from horizontally arranged layers, with the latter beams characterised by a smaller confidence interval for this strength. Moreover, it was found that the difference in the value of the 5th percentile for both beam types is slight and both beam types are considered to exhibit a high bending strength of over 40 N/mm2.

scholarly journals Influence of Scots Pine (Pinus sylvestris L.) Veneers Quality on Selected Properties of Layered Composite for Flooring Materials

Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1017
Author(s):  
Izabela Burawska-Kupniewska ◽  
Paweł Mycka ◽  
Piotr Beer
Keyword(s):  
Mechanical Properties ◽  
Pinus Sylvestris ◽  
Scots Pine ◽  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Deformation Modulus ◽  
Physical And Mechanical Properties ◽  
Production Costs ◽  
Base Layer ◽  
Class A

The article concerns the quality issues in wood industry, and especially the advisability of removing defects from veneers. The research purpose of the study was to analyse the influence of the layered structure of plywood base layer made of low-quality wood on selected mechanical properties of floor composites. The utilitarian purpose is to analyse the possibility of producing floors from low-quality materials reducing waste. Four quality classes of Scots pine veneers (Pinus sylvestris L.) were taken into account: A, B, C, D, from the highest class-A without defects to the lowest class-D characterized by a lot of knots (including broken and falling out ones) and cracks. The base layer of the floors was made of these wood quality classes. The value of the modulus of elasticity in elastic deformation, modulus of elasticity in the dynamic and fatigue tests, stiffness and static bending strength were investigated. The test results showed that, as expected, the samples made of class A had the highest values of the measured parameters (static bending strength, static and dynamic modulus of elasticity, and stiffness). However, the values of the tested parameters for the remaining classes B, C, and D did not significantly differ. It was concluded from the research that the change of the plywood base layer conditions regarding the quality of veneers does not significantly affect the physical and mechanical properties of composites. Hence, it is possible to use wood of lower quality classes for production without verification of which class they belong to, which will significantly reduce the production costs.

scholarly journals Density, hardness and strength properties of densified fir and aspen woods pretreated with water repellents

Holzforschung ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Hüseyin Pelit ◽  
Fatih Emiroglu
Keyword(s):  
Compression Ratio ◽  
Bending Strength ◽  
Linseed Oil ◽  
Vacuum Treatment ◽  
Strength Properties ◽  
Aspen Wood ◽  
Positive Effect ◽  
Water Repellents ◽  
Impregnated Wood ◽  
Compression Temperature

AbstractIn this study, the effect of thermo-mechanical densification on the density, hardness, compression strength, bending strength (MOR), and modulus of elasticity (MOE) of fir and aspen wood pretreated with water repellents was analyzed. Wood specimens were impregnated with paraffin, linseed oil and styrene after pre-vacuum treatment. Then, the impregnated wood specimens were densified with compression ratios of 20 and 40%, and at 120, 150 and 180 °C. The results indicated that the density, hardness and strength properties of the all densified specimens (untreated and impregnated) increased depending on the compression ratio and temperature. For all tested properties, higher increases were obtained in the paraffin and styrene pretreated specimens compared to untreated samples. However, the increase rates in linseed oil pretreated specimens were generally lower than untreated specimens. Regarding water repellents the most successful results in all tested properties were determined in styrene pretreated specimens. The density, hardness and strength properties of all specimens increased with the increase in compression ratio. On the other hand, the increase in the compression temperature negatively affects the properties of untreated and linseed oil pretreated specimens, while having a generally positive effect on the properties of paraffin pretreated specimens. However, all tested properties of styrene pretreated specimens have increased significantly due to the increase in compression temperature. The increasing strength properties of wood as a result of densification have increased much more with paraffin and especially styrene pretreatment. These combinations can be considered as an important potential for applications that require more hardness and strength.

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