Stability and Strength Behavior of Thin-Walled Roof-Panel-Purlin System under Wind Loading

The objective of this paper is to examine the stability and strength behavior of trapezoidal thin walled steel roof panel-purlin systems under the action of realistic spatial wind loading. The current practice of applying uniform static pressure to test the effect of wind loading on thin walled metal roof panels fails to capture the realistic representation of wind effects. The trapezoidal roof panel-purlin system is examined for wind loading by adopting pressure coefficient readings from wind tunnel tests conducted at the University of Western Ontario for a low-rise building. Computational fluid dynamics model is developed and validated, with simulations used to generate more refined spatially-varying wind loading. Finite element analysis is undertaken to carry out the stability analysis of the roof model where buckling loads and modes are compared with results from uniform uplift pressure tests. A comparative study is conducted for examining the stability and strength of Z-section purlins due to cross-sectional distortion induced by wind-uplift under current design assumptions and realistic wind loading. In addition, parametric studies examining the stability of the thin-walled roof panel-purlin system for imperfection sensitivity and impact on distortional buckling due to the wind-uplift direction and associated fastener pull-out are conducted. The collapse behavior of the panel-purlin system to moment gradient in members due to spatial and directional variation of wind loading are examined. The results from this research lay the foundation for a more accurate design approach that considers the stability of thin-walled structures under spatial and transient wind loading.

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