Doctor of Philosophy
Civil and Environmental Engineering
The integrity of the roof system is essential for ensuring the safety of inhabitants and preventing excessive damage to light-frame wood structures. The uplift capacity of fastened roof panels has been investigated using experimental tests and numerical models, where monotonic uniform static pressures are often applied to the roof panel models. The verification is needed for the adequacy of using static uniformly distributed pressure representing the wind load. Moreover, the uncertainty of nail withdrawal behaviour has not been included in existing numerical models, and the effect due to construction errors has not been addressed rationally.
A nonlinear Finite Element model is developed in this study to incorporate the nail withdrawal uncertainty in terms of maximum withdrawal force, initial stiffness, proportional limit, and the displacement at maximum force of the nail withdrawal behaviour. This model is used to investigate the statistical characteristics of the panel uplift capacity. The effect of spatial varying wind load is discussed by using the pressure coefficient obtained from wind tunnel model test at the Boundary Layer Wind Tunnel at the University of Western Ontario.
Furthermore, the impact of construction error is investigated, in terms of missing nail effects, with first-hand survey information. The detailed survey was carried out at the IRLBH (The Insurance Research Lab for Better Homes) facility to inspect the quality of construction, specifically for the statistical information of missing nails on roof panels. Finally, the evaluated statistical characterization of panel uplift capacity is used for the reliability analysis of a typical panel considering or ignoring the missing nail effects.
Both code specified pressure-gust coefficient from NBCC (2005) and the peak pressure coefficients obtained from wind tunnel test are used. Results suggested that the nonlinear pushover analysis using the proposed nonlinear Finite Element model is adequate for estimating the panel uplift capacity. A more stringent fastening schedule with a spacing of 150 mm for the edges and intermediate supports is suggested for the construction of light frame wood houses.
He, Weixian, "Numerical Assessment of Roof Panel Uplift Capacity under Wind Load" (2010). Electronic Thesis and Dissertation Repository. 19.