ASCE 7 forces are smaller because they are from a different code. What is
really notable is that the horizontal forces on roofs can be zero with the
simplified method. Also the 2000 IBC 1605.3.2 alternate
load combinations require the wind forces calculated per ASCE 7 or the IBC to be
multiplied by 1.3. This 1.3 factor might give more
should be conservative if you take the reactions you have and design for
them. As an example: '97 UBC, 70 MPH coverts to about 85 MPH in '98
ASCE-7. Your design forces from 110 MPH '97 UBC will be higher than the
pressures from 110 MPH '98 ASCE-7. This is in very general terms,
topographic effects etc. may change the answer. One thing to keep in
mind, the load combinations in ASCE-7 are different than those in the
Salt Lake City, UT
My goal, really, is to see if I can reasonably
conclude that the wind forces computed using UCB '97 for a 110 mph wind are
GENERALLY comparable or (preferably) less than when using ASCE-7
'98. This is for the MWFRS of a non-building structure. The
issue of localized forces on components and cladding will not be an
M. David Finley, P.E.
3810 South First Street - Suite 7
City, FL 32025
----- Original Message -----
Sent: Tuesday, October 08, 2002 1:27
Subject: RE: Wind Loads - UBC 97 vs
They are quite a bit different. ASCE7 has factors for topographic
effects and structure rigidity. The width of the discontinuity zones
to which higher element pressures must be applied are different, and ASCE
uses a bunch of charts to define pressure coefficients rather than the
simpler tables in the UBC. The UBC is, I think, a lot simpler to apply,
but the ASCE methodology is more current.
A client has asked me to design the
footings for a concrete batch plant. The manufacturer has provided
all of the column reactions from the manufacturer, but they are
based upon 110 mph wind per UBC 97. Being an East coast guy, I
have no experience with the UBC.
I will be using ASCE 7 in order to
comply with the Florida Building Code. The design wind speed for
the area is 110 mph.
Can anyone familiar with both codes tell me
what, if any, major differences exist between the wind load provisions
of UBC '97 and ASCE 7?
M. David Finley, P.E.
3810 South First
Street - Suite 7
Lake City, FL