Determination of wind loads on porous sunshade roof cover sheets using conversion factor

Porous sunshade roof cover sheets installed on building roofs are new structures for mitigating heat absorption. Thus, there have been few studies on wind flow and its effects on wind-permeable structures, and there is no provision for these structures in the major international wind load standards and codes. Unlike wind loading on building roofs, wind loading on porous sunshade roof cover sheets is a combination of wind pressures on both the upper and lower surfaces, which complicates the calculation of wind loading. From the viewpoint of structural design, we need a simple method for determining wind loading on these structures. Wind tunnel tests have been carried out for various wind angles, three porosities (ratio between area of orifices and area of sheet), and five gaps between sheet and roof, and results have been analyzed. As a result, the author proposes a simple formula for calculating wind loading on porous sunshade roof cover sheets from wind loadings on normal building roofs available from wind loading codes and standards. The calculated results based on this formula and the Japanese wind loading standard (AIJ-RFLB (2015))[4] are compared with those of wind tunnel tests. There is a good similarity between them.