Effects of Grain Pattern on the Rolling Shear Properties of Wood in Cross-Laminated Timber

Guofang Wu,Haiqing Ren,Yong Zhong

doi:10.3390/f12060668

Guofang Wu, Haiqing Ren + Show 1 more

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https://doi.org/10.3390/f12060668

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Abstract

Rolling shear modulus and strength are the key factors affecting the mechanical performance of some wood products such as cross-laminated timber (CLT). As reported, rolling shear property strongly depends on the sawing pattern such as the aspect ratio and grain direction (grain mode). However, the mechanism behind this phenomenon has not yet been clarified. In this work, the rolling shear modulus and strength of spruce-pine-fir (SPF) with different grain modes and aspect ratios were experimentally investigated. In addition, a theoretical investigation was carried out to reveal the mechanism behind this phenomenon. The results exhibited that the rolling shear moduli of 0° and 90° grain-mode wood were the same. This value can be called the pure rolling shear modulus. Rolling shear modulus of wood with angles other than 0° and 90° can be calculated from the pure rolling shear modulus and grain angle. Therefore, this modulus can be called the apparent rolling shear modulus. Thus, using 0° and 90° grain-mode specimens to determine the pure rolling shear modulus and strength of wood is recommended.

Highlights

Cross-laminated timber (CLT) is an innovative engineered wood product which consists of several layers of boards stacked crosswise and glued together [1]
The transverse laminations, which are oriented perpendicular to the major strength direction of CLT, work in rolling shear when subjected to the out-of-plane load
Considering that the rolling shear strength and modulus of wood are rather low, CLT members usually fracture due to cracks initiating from the transverse laminations [3]

Summary

Introduction

Cross-laminated timber (CLT) is an innovative engineered wood product which consists of several layers of boards stacked crosswise and glued together [1]. CLT has gained its popularity in residential and nonresidential constructions in recent years due to its advantages of high material utilization rate, good dimensional stability, outstanding thermal insulation properties, and effective fire resistance [2]. The transverse laminations, which are oriented perpendicular to the major strength direction of CLT, work in rolling shear when subjected to the out-of-plane load. Considering that the rolling shear strength and modulus of wood are rather low, CLT members usually fracture due to cracks initiating from the transverse laminations [3]. Rolling shear modulus and strength are considered the key factors affecting the mechanical performance of CLT

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