| Summary |
Design wind force coefficients for porous canopy roofs have been investigated based on a series of wind tunnel experiments. Three types of roof geometries, i.e. gable, troughed and mono-sloped roofs were tested. The roof models were made of 0.5 mm thick perforated duralumin plates, the porosity of which was changed from 0 (solid) to 36 %. Overall aerodynamic force and moment coefficients were measured in a turbulent boundary layer with a six-component force balance for various wind directions. The results indicate that the wind loads on canopy roofs generally decrease with an increase in porosity, or a decrease in pressure loss coefficient of the roof. Assuming that the roof is rigid and supported by the four corner columns with no walls, the axial forces induced in the columns are regarded as the most important load effect for discussing the design wind loads. Two loading patterns causing the maximum tension and compression in the columns are considered. Based on a combination of the lift and moment coefficients, the design wind force coefficients on the windward and leeward halves of the roof are presented for the two loading patterns as a function of the roof pitch and porosity for each roof geometry. The effect of porosity is taken into account as a reduction factor of the wind loads. |