In the Standard Practice for Bracing Masonry Walls Under Construction when determining the loads during construction, per Eq. 5.2.3-1, w=0.00256V^2. Per the notation in section 2.1, V=5-second wind gust velocity. Should the wind speed entered in this equation be 40mph (which is a 3-second wind gust) or is there a different 5-second wind gust speed that I cannot find?
Using 40mph and the equation above, yields a wind load of only 4 psf which seems low. This equation does not take into account exposure, height, or importance factor and states is conservative up to 40 feet height in open areas.
Just want to be sure the wind speed to enter into the equation is truly 40mph and if not, what is the 5-second gust speed?
The 40 mph used in 5.1.3 was chosen to allow a 5 mph cushion above the 35 mph when people are required to evacuate the area. If the wall and bracing apparatus is designed for a w of 5 psf then your wind speed could be up to 44 mph. If you want to be sure you need to get the wind speed at the site of the wall. Again the basis of the included design criteria is 40 mph. even if it is actually less you still use the 40. If you believe the wind speed to be higher through historic data or actual measurement then you design for the higher speed such as a w = 6.4 psf is based on a 50 mph gust. No matter what the people are moved at 35 mph.
I hope this helps, if not give me a call.