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Author ORCID Identifier

https://orcid.org/0000-0003-2388-6863

Document Type

Campus-Only Access for Five (5) Years

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Environmental Conservation

Year Degree Awarded

2019

Month Degree Awarded

September

First Advisor

Peggi L. Clouston

Second Advisor

Alexander C. Schreyer

Third Advisor

Sanjay R. Arwade

Subject Categories

Structural Engineering

Abstract

Cross-laminated timber (CLT), is a new generation of engineered wood product initially established in Europe, is utilized in residential and non-residential applications in several countries. CLT is new to the north of the United States, but Europeans have used CLT more than 25 years as an eco-friendly construction product in many construction sectors. Also many spectacular low, mid and even high-rise building constructed around the world using CLT products. CLT panels can be used in wall, roof and floor system. Using CLT specifically in a floor system is a growing trend that has proven structural benefits greater than traditional light frame wood joisted floors.

One of the problems associated with the CLT floors is that considerable shear deformation may occur in a plane perpendicular to the grain direction due to low rolling shear stiffness especially in the low span-to-depth ratio floor panels. This vulnerability is more problematic for CLT using locally low-valued eastern species. To address this challenge, this dissertation investigates the mechanical properties improvement of CLT floor system by optimizing the orientation and configuration of lamstocks in CLT panel.

For this purpose, firstly, a regular CLT panel with three and five layers for variety orientation was analyzed using classical lamination theory to determine the effective engineering constant of laminates. Then, the two-plate shear test was performed according to ASTM D-2718 for determination of shear properties of lumbers for fiber orientations of 0°, 30°, 45°,60°, and 90° with respect to the load direction. Next, sixteen three layers of angled CLT specimens with the mid-layer orientation of 30°, 45°, 60°, and 90° and twelve four layers asymmetric panel with the fiber orientation of 30°, and 45° were fabricated from Eastern Hemlock species. To measure the deformation and shear strength of the panels, the three-point bending test was used according to ASTM D198. To determine the shear stress distribution, estimate the deformation of panels, and investigate the coupling effect of the asymmetric panels under the three-point bending test, further numerical Finite Element (FE) analysis in the elastic range was conducted using ABAQUS software. The results of the experimental test were compared with the finite element modeling as well as shear analogy method. Based on the results, there was a general tendency for both bending properties and rolling shear capacities to increase by changing the fiber orientation of the mid-layer from 90° to 30°.

DOI

https://doi.org/10.7275/236f-rp42

Available for download on Tuesday, September 01, 2020

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