The effects of densification on rolling shear performance of southern yellow pine cross-laminated timber

Pradhan, S.C.; Entsminger, Edward D.; Mohammadabadi, Mostafa; Ragon, Kevin; Nkeuwa, William Nguegang

doi:10.1016/j.conbuildmat.2023.132024

Cited by 3 publications

(11 citation statements)

References 30 publications

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“…In contrast, a higher value of rolling shear was observed (Li et al 2020) when OSB was used as mid-layer orienting in both parallel and perpendicular directions. Pradhan et al (2023) studied the effect of densification on rolling shear strength using the modified planar shear test. The study showed an increase in rolling shear strength by a factor of two when the lumber pieces were densified by 50% CR (compression ratio).…”

Section: Introductionmentioning

confidence: 99%

Influence of densification on structural performance and failure mode of cross-laminated timber under bending load

Pradhan,

Mohammadabadi,

Entsminger

et al. 2024

BioRes

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The effect of densification of the laminas was studied relative to the shear performance of cross-laminated timber (CLT) specimens submitted to the bending test. The three-layered CLT panels were fabricated using loblolly pine (Pinus taeda L.). A compression ratio (CR) of 50% was used to densify the lumber using the thermomechanical densification technique. The process included plasticizing the lumbers by soaking them in boiling water for 10 minutes and then hot-pressing to the target thickness at 140 °C. Four groups were made, i.e., a control sample with all three layers non-densified, only mid-layer densified, all layers densified, and all layers planed to the same thickness of densified layers. Specimens were tested in short-span bending with a span-to-depth ratio of eight. For specimens having densified mid-layer, the failure mode changed from rolling shear to tensile failure of the outer layer, and the maximum shear stress was increased by 34%. Densification of the mid-layer at CR of 16% was sufficient to change the failure mode from rolling shear in mid-layer to tensile in outer layer. In the case of all-layer-densified specimens, the maximum rolling shear strength was increased by 129% compared to the control.

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Section: Introductionmentioning

confidence: 99%

Influence of densification on structural performance and failure mode of cross-laminated timber under bending load

Pradhan,

Mohammadabadi,

Entsminger

et al. 2024

BioRes

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“…For this purpose, it is necessary to evaluate the initial shear strength of non-densified virgin lumber in order to calculate the necessary increment required to achieve the minimum required shear strength for a specific span length-to-depth ratio to endure the maximum developed shear stress. To evaluate the compression ratio of densification, the linear relationship between the increase in shear strength and the compression ratio of loblolly pine, shown in Figure 3, reported by Pradhan et al [10] has been utilized. For this purpose, it is necessary to evaluate the initial shear strength of non-densified virgin lumber in order to calculate the necessary increment required to achieve the minimum required shear strength for a specific span length-to-depth ratio to endure the maximum developed shear stress.…”

Section: Required Densification To Meet Mrssmentioning

confidence: 99%

“…As all the samples failed in rolling shear as shown in Figure 4, the rolling shear strength of the sample was equal to the maximum shear stress developed in CLT. To evaluate the compression ratio of densification, the linear relationship between the increase in shear strength and the compression ratio of loblolly pine, shown in Figure 3, reported by Pradhan et al [10] has been utilized. For this purpose, it is necessary to evaluate the initial shear strength of non-densified virgin lumber in order to calculate the necessary increment required to achieve the minimum required shear strength for a specific span length-to-depth ratio to endure the maximum developed shear stress.…”

Section: Shear Strength Assessment Of Non-densified Lumbermentioning

confidence: 99%

“…This understanding is essential for advancing CLT design methodologies and achieving enhanced structural performance. The mechanical properties of wood, specifically rolling shear characteristics, are susceptible to various influencing factors, such as the sawing pattern [6], aspect ratio [5,[7][8][9][10][11][12][13], wood species [5,14,15], density [5,13,16], and the overall condition of the board [3,17]. Researchers have pursued improving CLT performance by utilizing the relationship between rolling shear and these influencing factors.…”

Section: Introductionmentioning

confidence: 99%

“…Through the densification process, a higher density can be achieved, resulting in improved mechanical strength [29][30][31][32][33][34][35][36]. Pradhan et al [10] used thermomechanical densification at varying compression ratios and reported a linear relationship between the percentage increase in rolling shear strength and the compression ratio. The study also reported that at a 50% compression ratio, the rolling shear strength of the lumber increased by double with respect to non-densified lumber.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Optimizing Lumber Densification for Mitigating Rolling Shear Failure in Cross-Laminated Timber (CLT)

Pradhan,

Mohammadabadi,

Seale

et al. 2024

Construction Materials

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Rolling shear in cross-laminated timber (CLT) has been identified as the governing factor influencing design value. Likewise, densification has been found to be an effective method of enhancing the rolling shear strength of lumber and in turn, CLT. In this study, utilizing knowledge of material properties, optimization of the compression ratio for densification has been presented. Three-layered CLT beams made from non-densified lumber, grade #1 loblolly pine (Pinus taeda L.), were subjected to a bending load at a span-to-depth ratio of eight and had a rolling shear failure at the mid-layer with a shear strength of 3 MPa. Assuming the same modulus of rupture (MOR) for both lumber and CLT made from the same species and grade, the MOR of lumber was used to calculate the minimum required shear strength (MRSS) of the transverse mid-layer to change the failure mode of the CLT beam from rolling shear to tensile failure. Using the relationship between the compression ratio and the increase in rolling shear strength, the optimized compression ratio for densification was calculated. This procedure resulted in a compression ratio of 16.67% for densification of the mid-layer to avoid rolling shear in the case of CLT beams with a span-to-depth ratio of eight. To verify this process, CLT beams with mid-layers densified at 16.67% were fabricated and submitted to a bending test. Rolling shear failure was mitigated and densified CLT beams failed in tension with a MOR similar to that of lumber, 47.45 MPa. Likewise, rolling shear strength was observed to increase by 48% for CLT that had a densified mid-layer at 16.67%.

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Influence of Densification on Structural Performance and Failure Mode of Clt Under Bending Load

Pradhan,

Mohammadabadi,

Entsminger

et al. 2023

Preprint

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The effects of densification on rolling shear performance of southern yellow pine cross-laminated timber

Cited by 3 publications

References 30 publications

Influence of densification on structural performance and failure mode of cross-laminated timber under bending load

Influence of densification on structural performance and failure mode of cross-laminated timber under bending load

Optimizing Lumber Densification for Mitigating Rolling Shear Failure in Cross-Laminated Timber (CLT)

Influence of Densification on Structural Performance and Failure Mode of Clt Under Bending Load

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