Creep behaviour of thin cross-laminated timber under short-term loading

dc.contributor.advisorGong, Meng
dc.contributor.authorChen, Meizhen
dc.description.abstractCross-laminated timber (CLT) has been developed and used in building applications, such as walls, roofs, and floors, which are subjected to long-term loading in the perpendicular-to-grain direction. Thus, the creep performance of CLT is critical in the design and construction of a building using CLT panels. The creep behaviour of a material, component, connection, or system is defined as the deformation increases with time under constant load. This thesis report examined the creep of CLT using the thin specimens. Two loading levels (60% and 30% of proportional limit (PL), or 93kg and 25kg), two relative humidities (30% and 65%), and two panel directions (major and minor). A total of four groups of thin CLT specimens were fabricated, and each group had six specimens (three for major and three for minor), producing a total of 24 specimens. The third-point static bending tests were performed to determine the load levels for creep tests. A constant load was applied on each specimen, and the flexural deflection was recorded in the course of loading. It was found that 1) In third-point bending test, the PLs of thin CLT specimens in the major and minor directions were 3,000N and 800N, respectively. The average MOE[subscript app] and MOR[subscript app] of the specimens in the major direction were 8,510 MPa and 46.64 MPa, respectively, and the average MOE[subscript app] and MOR[subscript app] in the minor direction were 809 MPa and 9.48 MPa, respectively; 2) With increasing load level up from 30% to 60% PL, the minor strength direction specimens deflected 81.04% than that of 30% PL. And for major strength direction specimen, the deflection increased 32.07%; 3) With decreasing the RH, the deflection of CLT specimens showed a slower increment. At the load level of 60% PL, the deflection of creep specimens in the minor direction showed a difference of about 2 mm after 7 days. However, at the load level of 30% PL, RH showed little impact on creep. 4) CLT in the major direction exhibited a superior load-bearing capacity than those in the minor direction. At the load level of 30% PL, the maximum deflection in the minor direction was about 1.8 times larger than that in the major one, and at the load level of 60% PL, the deflection in the minor direction was approximately 2.5 times larger than that in the major one. 5) The Burger model could well describe the 7-day creep of thin CLT specimens with a high r-square value around 0.9135 tested in this study. It could be recommended to investigate the long-term creep behaviour of full-size CLT members by taking cyclic humidity and edge-bonding into account for at least one to three months. Keywords: Creep, cross-laminated timber, modelling, panel direction, relative creep, relative humidity, load level
dc.description.copyright© Meizhen Chen, 2021
dc.description.noteA Report Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Forestry Engineering in the Graduate Academic Unit of Forestry and Environmental Management
dc.format.extentxiv, 124 pages
dc.publisherUniversity of New Brunswick
dc.subject.disciplineForestry and Environmental Management
dc.titleCreep behaviour of thin cross-laminated timber under short-term loading
dc.typemaster thesis and Environmental Management of Forest Engineering of New Brunswick
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