Civil Engineering Reference
In-Depth Information
gives loads for one geometrical shape of arched roof—this has a lower wall height and a
slightly lower rise/span ratio, but is shown in Figure 15.5 for completeness. The zone
system in prEN 1991-1-4.6 and AIJ is the same as AS/NZS1 170.2 and ASCE-7, but the
coefficients are different. The largest magnitude negative pressure coefficients in the
central part of the roof are in the range −0.6 to −1.15.
Note that the reference heights for the pressure coefficients for arched roofs vary
between the various codes: ISO 4354 appears to use the eaves height (but this is not
clearly specified); ASCE-7, AIJ and AS/NZS1 170.2 use the average roof height; and
prEN 1991-1-4.6 uses the top of the roof. No adjustments have been made for this in
Figure 15.5, as these depend on the velocity profile assumed.
Figure 15.3
Comparison of pressure
coefficients for a flat free roof (empty under—
main structural loads),
h/d=
0.2.
