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Effect of Porosity on the Wind Loads on a Hyperbolic Paraboloid Canopy Roof



Author(s)

Yasushi Uematsu, Yukari Miyamoto and Eri Gavansky

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DOI:10.17265/1934-7359/2015.06.009

A discussion is made of the wind force coefficients for designing the main wind force resisting systems of H.P. (Hyperbolic-Paraboid)-shaped porous canopy roofs on the basis of a wind tunnel experiment. Roof models with a number of small circular holes were made of nylon resin using laser lithography. The porosity was changed from 0 (solid) to 0.4. Besides the porosity, the geometric parameters of the models were the rise to span ratio and slope of the roof. The overall aerodynamic forces and moments acting on a model were measured by a six-component force balance in a turbulent boundary layer. The results indicate that the porosity significantly reduces the wind loads. The design wind force coefficients for porous canopy roofs can be provided by those for solid roofs with the same configuration multiplied by a reduction factor. The proposed wind force coefficients are verified by a comparison of the load effect predicted by the proposed wind force coefficients with the maximum load effect obtained from dynamic analyses using the time history of wind force and moment coefficients. The axial forces induced in the columns supporting the roof are regarded as the load effect for discussing the design wind loads.

Canopy roof, hyperbolic paraboloid, porosity, wind tunnel experiment, main wind force resisting system, wind force coefficient, codification.