Evaluation of the Out-of-Plane Shear Properties of Cross-Laminated Timber

Jianhui Zhou,Zhijun Liang,Zhiqiang Wang,Xiaoyan Cao,Yin Yang

doi:10.32604/jrm.2019.07558

Abstract

The out-of-plane shear properties of cross-laminated timber (CLT) substantially influence the overall mechanical properties of CLT. Various testing methods and theories related to these properties have recently been developed. The effects of the number of layers (three and five layers) and testing method (short-span three- and four-point bending tests) on the out-of-plane shear properties of CLT were evaluated. The out-of-plane shear strength values were calculated based on different theories for comparison. The failure mode in the short-span four-point bending (FPB) method was mainly the rolling shear (RS) failure in the cross layers, indicating that the FPB method was appropriate to evaluate the RS strength of CLT. The out-of-plane shear capacity obtained using the three-point bending (TPB) method was higher than that tested by the FPB method. The testing methods significantly influenced the out-of-plane shear capacity of the three-layer specimens but not that of the five-layer specimens. With an increase in the number of layers, the out-of-plane shear strength of the specimens decreased by 24%. A linear correlation was found among the shear strength values obtained from different theories.

Highlights

Cross-laminated timber (CLT) is a prefabricated solid engineered wood product made from solid sawn pieces of lumber for roof, floor, and wall applications [1]
The rolling shear failure first appeared in the cross layers and some further extended to the glue lines between layers, with the specimens being mainly in a brittle state
Most CLT specimens, for five-layer specimens tested by the four-point bending (FPB) method, failed in rolling shear (RS)

Summary

Introduction

Cross-laminated timber (CLT) is a prefabricated solid engineered wood product made from solid sawn pieces of lumber for roof, floor, and wall applications [1]. A normal CLT panel has layers oriented perpendicular to one another, whereas CLT in special configurations has consecutive layers placed in the same direction, resulting in a double layer (e.g., double longitudinal layers at the outer faces and additional double layers at the core of the panel) for specific structural capacities [2]. These configuration characteristics improve the physical and mechanical properties of CLT.

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