A review of factors influencing rolling shear in CLT and test methodology

Rolling shear (RS) is one of the key design parameters that influence the out-of-plane bending stiffness of cross-laminated timber (CLT) panels and thus affects the design and performance of CLT floor and wall systems. Various experimental methods are currently used to determine the RS capacity of CLT panels and feedstock. Some methods have been adapted to measure RS properties of clear wood such as Iosipescu, Arcan, and single cube apparatus, but there is no specific standard test method to accurately determine the RS stiffness or strength of CLT feedstock. This article presents a comprehensive review of potential RS test methods and highlights the importance of considering RS in CLT design. Test methods were thoroughly reviewed, and critically evaluated for their relative advantages and shortcomings. It was shown that sample preparation, testing procedure, and post-processing of results can significantly affect experimental outcomes, especially the RS modulus. It is recommended that in addition to current recommendations in CEN - EN 408, Timber Structures – Structural Timber and Glued Laminated Timber – Determination of Some Physical and Mechanical Properties, further specifications should be outlined in regards to plate material and type, glue type, and, more importantly, the relative location of reference points used for deformation measurement to ensure consistent and reliable comparison of RS characteristics reported by researchers. An equation was derived, and is presented, that ensures the vertical load passes through the centroid of the inclined specimen to avoid eccentricity in the specimen and moment transfer at the base of the plates. The effect of various factors on RS properties have been reviewed. Copyright © 2021 by ASTM International