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RE: ACI318-99 load combination question

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The Commentary for R9.2.7 says that the intent is to "prevent" the equation
from effectively reducing to U=1.05(D+T). Thus the code side equation is
correct.
 
I agree with your assessment of fluid loads - the code and commentary
wordings are not very clear. 

----Original Message-----
From: Zachary Goswick [mailto:ZachG(--nospam--at)angusyoung.com]
Sent: Wednesday, August 23, 2000 3:57 PM
To: 'seaint(--nospam--at)seaint.org'
Subject: ACI318-99 load combination question



Does anybody know whether equation 9-6 "U=1.4(D+T)" or the commentary on the
same section saying equation 9-6 is "U=1.05(D+T)" is correct?  It appears to
me that they are saying two different things, or am I not seeing this
correctly?

Also, I am looking at section 9.2.5 and reading that 1.4F should be added to
ALL combinations that have live load in them.  The commentary says use just
two equations "U = 1.4D + 1.7L + 1.4F" and "U = 0.9D + 1.4F".  This does not
seem to me to be ALL of the combinations with live load in them.  Wouldn't
this be all of the combinations given in paragraphs 9.2.1 through 9.2.7. as
follows?

U = 1.4D + 1.7L + 1.4F                          - from equation 9-1 
U = 0.75(1.4D + 1.7L + 1.7W) + 1.4F             - from equation 9-2 
U = 0.75(1.4D + 1.7L + 1.7(1.1E)) + 1.4F        - from paragraph 9.2.3 
U = 1.4D + 1.7L + 1.7H + 1.4F                   - from equation 9-4 
U = 0.75(1.4D + 1.7T + 1.7L) + 1.4F             - from equation 9-5 

It appears as if the second equation given by the commentary would not even
be included in what the actual code says.  Am I reading this incorrectly?
Can anybody shed some light on these issues?  

I can figure out what would be the worst cases, but I am just trying to
clarify what the code actually says.  Please help!


Zachary Goswick 
zachg(--nospam--at)angusyoung.com 


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