Experimental investigation on the influence of lamination aspect ratios on rolling shear strength of cross-laminated timber

Cross-laminated timber (CLT) as one novel engineered massive wood is prone to the rolling shear failure, due to its configuration characteristics of orthogonal orientation of adjacent layers. For comprehending its rolling shear behavior and clarifying the influence of the lamination aspect ratios on the rolling shear strength, pseudo-static monotonic rolling shear tests were conducted on the CLT specimens with aspect ratios ranging from 2.54 to 9.40, based on a modified planar shear test method. Their rolling shear strength or rolling shear resisting capacity was calculated with respect to the influence of the aspect ratios. The damage modes of the rolling shear specimens were analyzed considering the influence of their lamination width. The effect of the lamination width and that of the lamination thickness on the rolling shear strength were investigated, respectively. Besides, in the case of different aspect ratios, the strength modification factor defined as the ratio between the design rolling shear strength to the design parallel-to-grain shear strength of the outermost laminations was provided, which can facilitate the estimation of the rolling shear strength. Considering the influence of the aspect ratios, both the regression equations of the strength modification factor and the predictive equations of the rolling shear strength were proposed. It is found that a highly positive linear correlation exists between the rolling shear resisting capacity and the aspect ratio. The damage modes of the CLT rolling shear specimens depend on their lamination width; besides, when the lamination width increases from 184 to 235 mm, little improvement can be identified for the rolling shear resisting capacity. Meanwhile, larger thickness of the CLT transverse laminations can result in less CLT rolling shear strength. Overall, the proposed equations are capable of predicting the rolling shear strength of CLT fabricated with the SPF lumber. The study can contribute to the comprehension on the CLT rolling shear behaviors and provide reference values for mitigating the possibilities of CLT rolling shear damages in engineering design.

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Opracowanie rekordu ze środków MEiN, umowa nr SONP/SP/546092/2022 w ramach programu "Społeczna odpowiedzialność nauki" - moduł: Popularyzacja nauki i promocja sportu (2022-2023)