An Inelastic Theoretical Model regarding the Load-Carrying Capacity of PSL Bending Component

Baolu Sheng,Aiping Zhou,Dong He,Yuling Bian,Musa Adamu

doi:10.1155/2021/6677450

Abstract

Parallel strand lumber (PSL) is an attractive structural wood composite which may have prospective use in building constructions. Conducting nonlinear analysis for the bending of PSL beams is a critical step in the determination of ultimate strength and deflection of them, which is an essential requirement of the building design philosophy based on probability of ultimate state. For the purposes of this article, an inelastic theoretical model regarding the load-carrying capacity of the PSL bending component has been developed. Based on the uniaxial loading tests, the stress-strain behaviors of PSL composite in the grain direction were measured. 4-point bending experiments were also performed in this study to investigate the failure mechanism of the PSL components. The results show that the tensile stress-strain relationship of PSL materials in the grain direction remains linear until breaking, while the compressive stress-strain relationship exhibits nonlinear characteristics once the compressive stress exceeds the proportional limit, which can be expressed by a quadratic polynomial. The failure mode of the PSL beam can be summarized that the fibres in the top of the broken section were buckling and those in the bottom of the section were broken when failure occurred. Significant nonlinear behavior was exhibited based on the load-deflection curves of the PSL beams. To predict the nonlinear bending performance of the PSL beams, a theoretical model that could consider the nonlinear stress-strain relations of PSL and predict the damage modes of the PSL beams was developed. Well agreements can be observed between the results of calculations and experiments.

Highlights

Parallel strand lumber (PSL) is a wood-based composite material with outstanding mechanical properties for construction
PSL is a wood-based composite material with outstanding mechanical properties for construction. It is fabricated by gluing raw wood strands together along the grain direction under high pressure and microwave heat, which are often a by-product during the plywood manufacturing process [1]
As a matter of fact, PSL is a natural oriented fiber-reinforced composite. e approach of strength theory and mechanical model proposed by classical theories to analyze the behaviors of the component made of homogeneous or isotropic materials cannot be suitable to conduct the inelastic analysis for PSL structural members

Summary

Introduction

PSL is a wood-based composite material with outstanding mechanical properties for construction. Considerable researchers have found that almost all engineered wood composites or raw wood materials, including PSL, have strong nonlinear characteristics in the stress-strain relationship under compression parallel to grain [4,5,6]. It is commonly accepted that the stress-strain relationship of raw wood materials in the grain direction is linear for tensile stress and nonlinear for compressive stress. E theoretical model, of which the nonlinearity of stress-strain relationships was considered, to predict the deflection, stress and strain, and ultimate bearing capacity of wood-based composite structural components in the strength limit state, is not available up to now.

Analytical Model

Test Validation

Conclusions