  Every year hurricanes and other extreme wind storms cause billions of dollars
in damage worldwide. For residential construction, such failures are usually
associated with roofs, which see the largest aerodynamic loading. However,
determining aerodynamic loads on different portions of North American houses is
complicated by the lack of clear load paths and non-linear load sharing in wood
frame roofs. This problem of fluid-structure interaction requires both wind
tunnel testing and full-scale structural testing.
  A series of wind tunnel tests have been performed on a house in a simulated
atmospheric boundary layer (ABL), with the resulting wind-induced pressures
applied to the full-scale structure. The ABL was simulated for flow over open
country terrain where both velocity and turbulence intensity profiles, as well
as spectra, were matched with available full scale measurements for this type
of terrain. The first set of measurements was 600 simultaneous surface pressure
measurements over the entire house.
  A key feature of the surface pressure field is the occurrence of large,
highly non-Gaussian, peak uplift (suctions) on the roof. In order to better
understand which flow features cause this, PIV experiments were performed on
the wind tunnel model. These experiments were performed with time-resolved PIV
(sampling rate of 500 Hz) for a duration of 30 seconds. From the fluid dynamics
videos (low- and high-resolution) generated from the PIV data it is clear that
strong circulation is generated at the windward edge of the roof. These
vortices are eventually shed and convect along the roof. It is the presence of
this concentrated circulation which is responsible for the peak loading
observed.
