Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

higher loads or better details.

[Subject Prev][Subject Next][Thread Prev][Thread Next]

In comparing the 1997 UBC seismic design with the 1994 seismic design 
requirements, you have to be aware that the 1997 requirements are based on 
"ultimate" load requirements while the 1994 requirements are based on 
allowable stress requirements.  To compare the two, the 1997 loads have to be 
divided by 1.4 (UBC 1612.3.1).  [Rhetorical question:  Why is it that there 
are load factors for all other loads but seismic when designing for ultimate 
loads, and the reverse when designing for allowable stresses?  Consistency, 
where are you?]

Proper loads and details go hand-in-hand with each other.  A "good" detail 
for an inadequate load will have the same result as a bad detail for a proper 
load.  For example, if you are in a Seismic Zone 2 area and you design for 
Seismic Zone 1 forces, but detail in accordance with the requirements for 
Seismic Zone 2, you are still only designing the connections and detailing 
for 50 percent of Seismic Zone 2A forces and 38 percent of Seismic Zone 2B 

Almost everyone who has completed a "Strength of Materials" course should be 
able to do a respectable job of designing a beam or a column.  The material 
design courses should focus on the performance of the different materials.  
The reason that so little time is spent on designing connections in college 
is probably because that is the way most of the professors were taught and 
that they never had to design many connections themselves and it is easier to 
teach what has already been learned in previous courses.

A. Roger Turk, P.E.(Structural)
Tucson, Arizona

P.S.  BTW, what was the final score in the Arizona-Hawaii football game last 
night? <g>

Marlou Rodriguez wrote:

. > My boss, just brought up an interesting idea,
. > 
. > Here in Hawaii, we have just been exposed to the 1997 UBC.  We noticed 
. > that the Base shear has increased by about 30 percent for the 1997 codes.
. > 
. > My boss mentions that it is not the load that will make the building 
. > stand up, you can increase the load as much as you want but if you do not 
. > detail it correctly, larger load is no good.
. > 
. > Making sure that your load flows through your connection correctly is very
. > important, I think a lot of people getting out of school lacks that
. > experience.  Included with the Steel, Concrete, and Timber design, there
. > should be a special class called connections.
. > 
. > I just recently graduated and I think it was sad that we only spent about 
. > a week in connections.
. > 
. > Professional Engineer's opinions welcome.
. > 
. > Marlou B. Rodriguez
. > Robert Englekirk Inc.
. > Honolulu, Hi
. >