Wind Pressure On Flat Roof

The external wind pressure on the structure w e corresponds to the pressure effect on the exterior surface of the roof.

Wind pressure on flat roof.

Once the wind speed has been calculated the user can provide additional information regarding the building such as building height type and cladding to get the wind pressure wind load based on asce 7 10 as 1170 and en 1991 provisions. It provides the wind load calculations on uplift leeward windward and roof forces of a building. 6a the roof is flat and out of all the incident wind angle the maximum pressure coefficient is found to be as 0 4 which is less than the maximum pressure coefficient of 0 9 by wind tunnel experimental study and the maximum pressure coefficient of 0 98 by cfd simulation study on flat roof without opening as described by roy et al. The unit for wind pressure is pounds per square foot psf.

Wind pressure is given by the equation p 0 00256 x v 2 where v is the speed of the wind in miles per hour mph. In order for a structure to be sound and secure the foundation roof and walls must be strong and wind resistant. The paper examines the use of ultimate strength design safety provisions in wind uplift design of roof assemblies in. The use of wind pressure tables included in the monograph which allow the selection of wind pressure values without detailed calculations and converting them to fm global wind uplift ratings is explained.

For example using asce 7 10 for a 30 tall flat roof building in a 115 mph wind zone you may calculate a positive wind pressure of around 11 psf. For example if the wind speed is 70 mph the wind pressure is 0 00256 x 70 2 12 5 psf. As it accelerates around the side of the building and over the roof it creates a reduced or negative pressure in its trail. These are typically higher than what you would calculate using the pressure coefficients.

When wind strikes a building it is deflected to generate a positive pressure on the windward face. 2012a 2012b and the maximum pressure coefficient of 0 8 on the windward roof surface of the flat roof building with frac h w le. When building a structure it is important to calculate wind load to ensure that the structure can withstand high winds especially if the building is located in an area known for inclement weather. The greatest pressures are experienced at the windward corners and edges of the roof where the negative pressure exerted on the roof can be several times that experienced in the central areas.