Civil Engineering Reference
In-Depth Information
flow regions on side walls, values of of 0.6 or greater can occur. Even higher values
can occur at critical points on roofs, with values greater than 1.0 being not uncommon.
Figure 8.8
Corner vortices generated by
quartering winds (from the Texas Tech Field
Experiment).
High instantaneous peak pressures tend to occur at the same locations as high rms
fluctuating pressures. The highest negative peak pressures are associated with the conical
vortices generated at the roof corners of low-pitch buildings, for quartering winds
blowing on to the corner in question (Figures 8.7 and 8.8). Figure 8.9 shows a short
sample of pressure-time history, from a pressure measurement position near the
formation point of one of these vortices, on the Texas Tech building (Mehta
et al.,
1992).
This shows that high pressure peaks occur as 'spikes' over very short time periods.
Values of negative peak pressure coefficients as high as −10 often occur, and magnitudes
of −20 have occasionally been measured.
