We know the wind calculation can get really complicated really quickly. Our pack of calculators will guide you through the calculation of the different components that go into the wind calculation in accordance with AS/NZS 1170.2.
As per Clause 2.4, the design wind pressure
p
is denoted by
pe,pi
or
pn
.
p=(0.5ρair)[Vdes,θ]2CshpCdyn
Where:
ρair
is the density of air, taken as
1.2kg/m3
Vdes,θ
is the design wind speed
Cshp
is the aerodynamic shape factor, which was denoted as
Cfig
in the the superseded version of AS1170.2
Cdyn
is the dynamic response factor, which is taken as 1.0 except where the structure is dynamically wind sensitive.
The sign of
p
is given by the
Cp
value which is used to evaluate
Cshp
. Additionally, since
Cp,e
takes a different value for each of the wall surfaces (windward, leeward, side) and roof surfaces (upwind, downwind, crosswind), for each wind direction under consideration, there will be many different
pe
values corresponding to each surface. For each surface and wind direction, we need to calculate all combinations to see what gives us the worst-case net pressure.