Bamboo/Wood Composites and Structures Shear and Normal Strain Distributions in Multilayer Composite Laminated Panels under Out-of-Plane Bending

Jan Niederwestberg,Dongsheng Huang,Ying Hei Chui,Jianhui Zhou,Hui Yao

doi:10.1155/2021/6637853

Abstract

Innovative mass timber panels, known as composite laminated panels (CLP), have been developed using lumber and laminated strand lumber (LSL) laminates. In this study, strain distributions of various 5-layer CLP and cross-laminated timber (CLT) were investigated by experimental and two modelling methods. Seven (7) different panel types were tested in third-point bending and short-span shear tests. During the tests, the digital imaging correlation (DIC) technique was used to measure the normal and shear strain in areas of interest. Evaluated component properties were used to determine strain distributions based on the shear analogy method and finite element (FE) modelling. The calculated theoretical strain distributions were compared with the DIC test results to evaluate the validity of strain distributions predicted by the analytical model (shear analogy) and numerical model (FE analysis). In addition, the influence of the test setup on the shear strain distribution was investigated. Results showed that the DIC strain distributions agreed well with the ones calculated by the shear analogy method and FE analysis. Both theoretical methods agree well with the test results in terms of strain distribution shape and magnitude. While the shear analogy method shows limitations when it comes to local strain close to the supports or gaps, the FE analysis reflects these strain shifts well. The findings support that the shear analogy is generally applicable for the stress and strain determination of CLP and CLT for structural design, while an FE analysis can be beneficial when it comes to the evaluation of localized stresses and strains. Due to the influence of compression at a support, the shear strain distribution near the support location is not symmetric. This is confirmed by the FE method.

Highlights

Cross laminated timber (CLT) and other mass timber panels like glue, nail, or dowel-laminated timber have become increasingly popular in the last decades. e increase in popularity can be a tribute to their large dimensions and cross sections, which allow for high levels of prefabrication and fast construction
E following graphs show colour contour plots from the digital imaging correlation (DIC) and FE evaluations, as well as strain diagrams presenting data evaluated based on DIC, shear analogy (SA) method, and finite element (FE) analysis. e locations of the strain evaluations in the DIC and FE contour plots tests are indicated by black dashed lines. e associated strain distributions were evaluated based on a chosen reference line within the software
It should be noted that the legends associated with the DIC colour contour plots are based in the full contour plot areas. e FE strain distributions were measured at the outer surface of the models. e colours within the DIC and FE contour plots might not match, and the plots are presented in order to show the strain distributions over the sections

Summary

Introduction

Cross laminated timber (CLT) and other mass timber panels like glue-, nail-, or dowel-laminated timber have become increasingly popular in the last decades. e increase in popularity can be a tribute to their large dimensions and cross sections, which allow for high levels of prefabrication and fast construction. Cross laminated timber (CLT) and other mass timber panels like glue-, nail-, or dowel-laminated timber have become increasingly popular in the last decades. E increase in popularity can be a tribute to their large dimensions and cross sections, which allow for high levels of prefabrication and fast construction. Due to the parallel members, these panel types behave like beam elements in out-of-plane loading situations and can be considered as one-way elements. CLT panels are made from the commonly orthogonally arrangement of layers consisting of graded sawn lumber pieces that are glued to each other. E orthogonal arrangement of the layers lets CLT panels behave more like plates under out-of-plane loading, where loads can be transferred in both panel directions. The orthogonal arrangement of the layers leads to layers with radial-tangential cross section, which provide low shear modulus and strength.

Methods

Results

Conclusion