Mechanical behaviour of sugar maple in cantilever bending under constant and variable relative humidity conditions

Segovia, Franz; Blanchet, Pierre; Laghdir, Aziz; Cloutier, Alain

doi:10.1179/2042645312y.0000000024

Cited by 14 publications

(5 citation statements)

References 16 publications

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“…This parameter is vital for analyzing the relaxation response over time of a beam inside an interconnected structure, such as cross-arms. This parameter is also called the irrecoverable creep strain, which accounts for the relaxation coefficient of the viscoelastic property [ 55 ]. Figure 11 depicts the viscoelastic properties of the current and braced PGFRPC cross-arms in accordance with location along the main members.…”

Section: Resultsmentioning

confidence: 99%

Utilization of Bracing Arms as Additional Reinforcement in Pultruded Glass Fiber-Reinforced Polymer Composite Cross-Arms: Creep Experimental and Numerical Analyses

et al. 2021

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The application of pultruded glass fiber-reinforced polymer composites (PGFRPCs) as a replacement for conventional wooden cross-arms in transmission towers is relatively new. Although numerous studies have conducted creep tests on coupon-scale PGFRPC cross-arms, none had performed creep analyses on full-scale PGFRPC cross-arms under actual working load conditions. Thus, this work proposed to study the influence of an additional bracing system on the creep responses of PGFRPC cross-arms in a 132 kV transmission tower. The creep behaviors and responses of the main members in current and braced PGFRPC cross-arm designs were compared and evaluated in a transmission tower under actual working conditions. These PGFRPC cross-arms were subjected to actual working loads mimicking the actual weight of electrical cables and insulators for a duration of 1000 h. The cross-arms were installed on a custom test rig in an open area to simulate the actual environment of tropical climate conditions. Further creep analysis was performed by using Findley and Burger models on the basis of experimental data to link instantaneous and extended (transient and viscoelastic) creep strains. The addition of braced arms to the structure reduced the total strain of a cross-arm’s main member beams and improved elastic and viscous moduli. The addition of bracing arms improved the structural integrity and stiffness of the cross-arm structure. The findings of this study suggested that the use of a bracing system in cross-arm structures could prolong the structures’ service life and subsequently reduce maintenance effort and cost for long-term applications in transmission towers.

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Section: Resultsmentioning

confidence: 99%

Utilization of Bracing Arms as Additional Reinforcement in Pultruded Glass Fiber-Reinforced Polymer Composite Cross-Arms: Creep Experimental and Numerical Analyses

et al. 2021

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“…In this study, another parameter was being evaluated, η k , which represented the relaxation coefficient for the viscoelastic property. Moreover, the viscoelastic parameter, also known as irrecoverable creep strain, demonstrated the relaxation response over time [23]. Figure 12 displays the viscoelastic properties for both cross-arms (braced and existing cross-arms), showing relatively the same values of viscoelastic modulus.…”

Section: Burger Modelmentioning

confidence: 96%

Influence of Additional Bracing Arms as Reinforcement Members in Wooden Timber Cross-Arms on Their Long-Term Creep Responses and Properties

et al. 2021

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Previously, numerous creep studies on wood materials have been conducted in various coupon-scale tests. None had conducted research on creep properties of full-scale wooden cross-arms under actual environment and working load conditions. Hence, this research established findings on effect of braced arms on the creep behaviors of Virgin Balau (Shorea dipterocarpaceae) wood timber cross-arm in 132 kV latticed tower. In this research, creep properties of the main members of both current and braced wooden cross-arm designs were evaluated under actual working load conditions at 1000 h. The wooden cross-arm was assembled on a custom-made creep test rig at an outdoor area to simulate its long-term mechanical behaviours under actual environment of tropical climate conditions. Further creep numerical analyses were also performed by using Findley and Burger models in order to elaborate the transient creep, elastic and viscoelastic moduli of both wooden cross-arm configurations. The findings display that the reinforcement of braced arms in cross-arm structure significantly reduced its creep strain. The inclusion of bracing system in cross-arm structure enhanced transient creep and stress independent material exponent of the wooden structure. The addition of braced arms also improved elastic and viscoelastic moduli of wooden cross-arm structure. Thus, the outcomes suggested that the installation of bracing system in wooden cross-arm could extend the structure’s service life. Subsequently, this effort would ease maintenance and reduce cost for long-term applications in transmission towers.

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“…This regression of ε s can be explained by the densification phenomenon that appears during the different loading cycles (Kutnar et al 2015, Blomberg andPersson 2004). Indeed, just as in the drying process, the cell wall is compacted and the mass of the ligneous substance in a given volume increases during the different loading cycles (Kutnar et al 2015, Segovia et al 2013. This has the consequence of stiffening the specimens and thus reducing the strain in the following cycles.…”

Section: Impact Of Loading Combined With Variations In Moisture Contementioning

confidence: 98%

Comparative studies of three tropical wood species under compressive cyclic loading and moisture content changes

Edzang

Nziengui

Ango³

et al. 2020

Wood Material Science & Engineering

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The objective of the present study is to perform an experimental comparative cyclic compressive loading test on three tropical species (Aucoumea Klaineana Pierre, Milicia Excelsa and Pterocarpus Soyauxii), at different internal moisture content stages. 150 samples of these three species, dimensioned according to standard NF EN 408 were tested. The specimens were loaded into the static compressive test until they collapsed in order to obtain the mechanical characteristics of each species in terms of: (i) the modulus of elasticity, (ii) the maximal strength and (iii) the stress at the yield point. The specimens are submitted five times to loading-unloading-reloading in cyclic compressive at different internal moisture contents. The applied force was taken at 10% of the maximum rupture force of Okoume species and kept constant at each cycle. The results show a stiffening of the three types of specimens with the loading cycles. The stiffening is faster from the densest species to the least dense species, respectively. In addition, the phenomenon of densification, that occurs during the five loading-unloading cycles, is done with constancy of compressive strength in the three species studied.

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Mechanical behaviour of sugar maple in cantilever bending under constant and variable relative humidity conditions

Cited by 14 publications

References 16 publications

Utilization of Bracing Arms as Additional Reinforcement in Pultruded Glass Fiber-Reinforced Polymer Composite Cross-Arms: Creep Experimental and Numerical Analyses

Utilization of Bracing Arms as Additional Reinforcement in Pultruded Glass Fiber-Reinforced Polymer Composite Cross-Arms: Creep Experimental and Numerical Analyses

Influence of Additional Bracing Arms as Reinforcement Members in Wooden Timber Cross-Arms on Their Long-Term Creep Responses and Properties

Comparative studies of three tropical wood species under compressive cyclic loading and moisture content changes

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