Wood-Based Beams

The effect of MC on the mechanical properties of wood has been a widely studied topic in the last decades [7,22–28]. Generally, most of the wood mechanical properties decreased with increasing MC, while the changing trend of σL within the wide MC ranges was different. The properties of the cell wall components in relation to the longitudinal elasticity of the wood. Wood Sci.

The effect of moisture content and temperature on the mechanical properties of wood: An analysis of immediate effects. Wood Fiber Sci. Modeling moisture-related mechanical properties of wood Part II: Calculation of properties of a wood model and comparison with experimental data. Sci.

Figure 1. Moisture contents of poplar (a) and Chinese ﬁr (b) at a series of relative humidity.

Bending Stiffness, Load-Bearing Capacity and Flexural Rigidity of Slender Hybrid

Wood-Based Beams

Introduction
Materials and Methods
Results
Discussion
Conclusions

The type D test pieces did not meet the aesthetic requirement of non-visibility of the reinforcements. The largest standard deviation of the midspan deflection was observed for the type A beams, in the case of both series. The Type C samples had a carrying capacity 33% greater than that of the Type A reference samples (Figure 9).

The highest load-bearing capacity was found for hybrid beams of type C. 32] described the positive influence of knots in wood on resistance to shear loads.

Figure 1. An example of window elements with a height of 5.8 m.

Nondestructive Characterization of Dry Heat-Treated Fir (Abies Alba Mill.) Timber in View of Possible

With the intensity of the heat treatment, the total color differenceΔE* was significantly increased (ANOVA,p. The ultrasound velocity was significantly improved in the longitudinal (vLL) and radial direction (vRR) of the heat-treated structural wood, up to a treatment temperature of 210◦4C, however, the latter also caused a reduction of 210◦4C. ies insignificantly (ANOVA,p= 0.15), in the modulus of elasticity in the tangential direction of the wood (ET) by increasing the intensity of the thermal process (Table 2).

The latter finding indicates the possible presence and increase of structural inhomogeneity in the heat-treated wood, which is also enhanced by increasing the heat-treatment temperature. However, wood density was a common decision criterion for strength rating of the heat-treated wood.

Figure 1. (a) The experimental setup for determination of velocity of ultrasound in longitudinal- (v LL ), radial- (v RR ) and tangential (v TT ) wood direction; (b) principle of the analysis of ﬂexural vibration response of structural timber specimens.

Eﬀect of Selected Factors on the Bending Deﬂection at the Limit of Proportionality and at the Modulus of

Results and Discussion

Tables 2 and 3 show the average value and the coefficients of variation for the deflection at the limit of proportionality (YE) and the deflection at the modulus of rupture (YP) in the laminated aspen and beech materials reinforced with a non-wood component (glass and carbon fiber) glued with PUR Ace. Table 3 shows the deflection properties (YEandYP) of the laminated beech materials that were reinforced with non-wood components. In the case of deflection at the modulus of rupture, the highest values (20.01 mm) were measured on the 18 mm thick test specimens glued with PVAc adhesive and reinforced with glass fibers.

40], who presented results of the deflection of beech slats bonded with PUR and PVAc adhesives. Table 4 shows the results of the statistical evaluation of the effect of the test sample of aspen and beech on the deflection at the limit of proportionality and deflection at the breaking modulus of the laminated materials with a non-wood component on the top and bottom. These results clearly showed that the type of test sample had a significant effect on the deflection at the limit of proportionality and on the deflection at the modulus of fracture.

From Figure 3 and Table 4, it was clear that it was more beneficial to apply the reinforcement material at the bottom of the laminated aspen material for the deflection at the limit of proportionality. Statistical evaluation of the effect of type of specimens on the deflection at the limit of proportionality and deflection at the modulus of rupture. Figure 5 graphically depicts a comparison of the factors that were focused on the deflection at the modulus of rupture in the aspen wood.

The dependencies were similar to the deflection at the limit of proportionality, as seen in Table 4. As in all the previous cases, higher deflection at the modulus of rupture was achieved in the reinforced laminated beech materials by gluing the reinforcement material to the underside relative to the loading direction (Figure 6). With glass fibers, the deflection at the modulus of rupture increased by approximately 20% compared to carbon fibers.

Table 2. Mean Values of the Deﬂection at the Limit of Proportionality and the Deﬂection at the Modulus of Rupture, and Coeﬃcient of Variance of the Aspen Wood.

Conclusions

Methods for determining plastic work in bending and the influence of selected factors on its value. Composition. New composite material based on winter rapeseed and its elasticity properties as a function of selected factors. Composition. The plasticity of the composite material based on winter rape as a function of the selected factor. Composition.

Bending forces at the limit of proportionality and maximum-Technological innovations for better performance in wood processing companies. Structural Evaluation and Design Procedure for Timber Beams Repaired and Retrofitted with FRP Laminates and Honeycomb Sandwich Panels.Compos. Sandoz, J.L. Industrial ultrasonic sanding for multi-glued laminated wood; Études & Constructions Bois, Concept Bois Technologie: Paris, France, 2009.

In Proceedings of the Final Conference of COST Action E53: The Future of Quality Control for Wood & Wood Products, Edinburgh, Scotland, 4–7 May 2010. EN 310. Wood based panels: determination of modulus of elasticity in bending and of flexural strength; European Committee for Standardization: Brussels, Belgium, 1993. Determination of moisture content for physical and mechanical tests; International Organization for Standardization: Geneva, Switzerland, 2014.

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

Laminated Veneer Lumber with Non-Wood

Components and the Eﬀects of Selected Factors on Its Bendability

In the next step, the bendability of the tested material was assessed based on the minimum bending radius (RminBandRminC) and the bending coefficient (KbendBandKbendC). Comparison of the effects of individual factors using Duncan's test on the coefficient of pliability (KbendC) for aspen and NWC on soil. Comparison of the effects of individual factors using the Duncan test on the coefficient of bending (KbendC) for esp and NWC superimposed.

Comparison of the effects of individual factors using Duncan's test of the degree of bending (KbendC) for beech and NWC on the bottom. Comparison of the effects of individual factors using Duncan's test of the bending capacity (KbendC) for beech and NWC on top. Comparison of the effects of individual factors using Duncan's test on the bending coefficient (KbendB) of asp and NWC on the bottom.

Comparison of the effects of individual factors using Duncan's test on the bending coefficient (KbendB) for aspen and NWC at the top. Comparison of the effects of individual factors using Duncan's test on the bending coefficient (KbendB) for beech and NWC in the bottom. Comparison of the effects of individual factors using Duncan's test on the bending coefficient (KbendB) for beech and NWC on top.

In the samples with a carbon fiber non-wood component, the effect of the glue used was also significant. The largest KBendingB values in the asp lamellas were achieved in samples with a non-wood component on the bottom of the laminated material. The lowest KbuigB values were also found in the samples with a carbon fiber non-wood component placed on top of the material.

Inﬂuence of Natural and Artiﬁcial Weathering on the Colour Change of Different Wood and

Wood-Based Materials

Material and Methods

The color of the specimens was measured every 100 hours for a total duration of 500 hours of artificial weathering. Figure 1 shows the visual appearance of the model house and the plotted color values (L*, a* and b*) versus exposure time for Norway spruce (PA) only. The values for ΣΔE (see equation (2)) showed that the course of color changes was quite similar for all exposure directions.

Norway spruce (PA), wax-treated Norway spruce (PA-NW), and European larch (LD) were light-colored materials, so the development of the darkly pigmented blue stain fungi was the most noticeable. Blue color assessment of the facade and covering elements of the model house was carried out periodically (Table 2). In the next part of the study, we decided to simulate weathering in the laboratory.

After the first exposure of the samples to the fungal spore suspension, only three of the twelve materials developed surface stains. In general (but with some exceptions), the samples showed a decrease in Δa* values throughout the experiment. However, the most important objective of the relevant research was to show how the in-service test related to the laboratory test.

The purpose of the relevant work was to determine the correlations between the in-service test and the laboratory test. Determination of the protective effectiveness of a preservative treatment against blue stain in wood in service. Testing and classification of resistance to biological agents of wood and wood-based materials.

Figure 1. Exposure sites on the wooden model house unit in October 2017, after four years of weathering

Surface Changes of Selected Hardwoods Due to Weather Conditions

Growth is caused by uneven surface erosion in late and early wood with thin-walled cells and lower density [30]. During weathering, we assume that the gradual decomposition of lignin and changes in the hemicellulose complex are manifested by pronounced color changes and increased surface roughness of the wood surface. This study follows and extends the findings of the previously published study of Oberhofnerová et al.

The color of the wood surface was measured using a spectrophotometer CM-600d (Konica Minolta, Osaka, Japan). The following figures (Figures 2-6) show the 3D microstructure of the surface of all examined wood samples after 2 years of weathering obtained by confocal laser scanning microscopy. Visual evaluation of samples was performed using confocal laser scanning microscopy of the wood sample surface before and during exposure (Figure 7).

These results indicate that the structure of the lignin polymer and the hemicelluloses was significantly degraded. At the end of the two-year exposure, the a* and b* values stabilized at a level corresponding to the gray color. Reduced absorption on that band is interpreted as lignin decay combined with the formation of new carbonyl groups, indicating photoinduced oxidation of the wood surface.

The decrease in lightness L* indicated a gradual darkening of the samples, decreasing a* and b* values showed a more pronounced shift to the gray color. Testing and classifying the durability against biological agents of wood and wood-based materials; European Committee for Standardization: Brussels, Belgium, 2016. The impact of UV radiation on the change of color and composition of the surface of basswood treated with a CO2 laser.J.