Type of Document Dissertation Author Lang, Elemer M. URN etd-10202005-102826 Title Modeling the behavior of wood-based composite sheathing under hygrothermal load Degree PhD Department Wood Science and Forest Products Advisory Committee
Advisor Name Title Dolan, James Daniel Committee Chair Ifju, Geza Committee Member Kamke, Frederick A. Committee Member Woeste, Frank E. Committee Member Keywords
- Composite construction.
- Wooden-frame houses Thermal properties.
Date of Defense 1993-10-15 Availability restricted Abstract
In light-frame residential construction wood-based composite panels used externally or internally are exposed to relative humidity and/or temperature changes. The subsequent moisture content change of the panels will result in two types of deformations as follows: 1. elastic deformation of the panel due to the constraint, 2. warpage of the panel due to the unbalanced expansion of the layers. Such deformations can cause unacceptable serviceability problems in light-frame wood construction.
A model was developed to predict quantitatively the global deflection of wood-based composite panels exposed to relative humidity changes. The model was based on the constitutive relationship of the Classical Lamination Theory and the thermal stress analogy in composites. As an alternative solution, the applicability of the eccentrically loaded column formula was evaluated.
The developed models were experimentally validated for OSB and plywood sheathing. Test variables included the panel type, exposure (symmetric and non-symmetric MC gradient) and specimen configuration (single span, multiple span). The comparison of measured and predicted deflections are presented. The important elastic and hygroscopic material properties were acquired through testing. Statistical analyses of test results are discussed.
The uncertainty analysis was used to make statistical inference comparing the means of measured deflection to the uncertainty interval of predictions. Good agreement between predicted and measured deflections was found for single span test structures. Also, for double span structures the models predicted the experimental response fairly veil. Uncertainties in Me measurements made the prediction less reliable when symmetric moisture content gradient developed during the exposure. Due to its lower variability in material properties, the response of OSB sheathing to moisture content changes is more predictable.
Filename Size Approximate Download Time (Hours:Minutes:Seconds)
28.8 Modem 56K Modem ISDN (64 Kb) ISDN (128 Kb) Higher-speed Access LD5655.V856_1993.L366.pdf 14.38 Mb 01:06:33 00:34:13 00:29:57 00:14:58 00:01:16next to an author's name indicates that all files or directories associated with their ETD are accessible from the Virginia Tech campus network only.
If you have questions or technical problems, please Contact DLA.