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UBC97 ASD Sesimic provisions

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Section 2213.8.3.1 Item 2 says to design the connections in a brace for
Omega times the "design seismic force". You then compare this amplified
force to the strength of the connection using 1.7*Fs.
Now for this to make sense, shouldn't the "design seismic force" be the
factored load E and NOT E/1.4? Otherwise ASD would have a 40% advantage over
LRFD in connection design.  
I know that AISC has abandoned this section entirely but technically it is
still the code in California.



-----Original Message-----
From: Gerard Madden [mailto:gmadden(--nospam--at)duquette-eng.com]
Sent: Thursday, November 08, 2001 12:40 PM
To: 'seaint(--nospam--at)seaint.org'
Subject: RE: 1997 NDS Equation Error?


One other thing,

I mistakenly said ...

"My NDS shows the Square Root Symbol Stopping short of the -Re(1+Rt) value
in the
denominator."

I meant Numerator.


When I check NDS Table 8.2A for 7/8" Dia bolts, Doug Fir, 1.5" side plate,
single shear to 3" Main Member for comparison I get these:

Z= 1590 lbs, k1=2.00   (Mode III Governs ; Term included within the Square
Root)
Z= 1387 lbs, k1=0.6794 (Mode II Governs ; Term Excluded from the Square Root
per 8.2.1)
Z= 1390 lbs (Table 8.2A)

This leads me to conclude (provided my calculations are correct) that
Equation 8.2.1 is correct and Table 8.2E is incorrect for mudsill anchor
bolts.

Can anyone else corroborate this.

FYI: Here are my values for the 2x DF Mudsill with 7/8" dia. bolts

D=0.875
SG=0.50
Theta=0
Fyb=45000
ts=1.5
tm=3
Ktheta=1
Fem=6000
Fes=5600
Re=1.07
Rt=2
k1=0.7158  (Using Section 8.2.3)
k2=1.3409
k3=2.0154
Zis=1838#
Zii=1462# (Governs)
Ziiim=3156#
Ziiis=1615#
Ziv=2230#


Thanks again to all,
-gerard
SJ, CA

-----Original Message-----
From: Gerard Madden 
Sent: Thursday, November 08, 2001 9:40 AM
To: 'seaint(--nospam--at)seaint.org'
Subject: RE: 1997 NDS Equation Error?


Hi George,

Here are the values I get for Doug Fir for the case you stated:

Z= 1615 lbs, k1=2.0959 (Mode III Governs ; Term included within the Square
Root)
Z= 1465 lbs, k1=0.7158 (Mode II Governs ; Term Excluded from the Square Root
per 8.2.1)
Z= 1610 lbs (Table 8.2E of NDS)

If you want I can give you all of my variables, but I did consider the Fe
concrete @ 6000 psi (Where do they get that anyway, is it just 3x f'c)


-Gerard
SJ, CA
 


-----Original Message-----
From: George Richards P.E. [mailto:george(--nospam--at)borm.com]
Sent: Wednesday, November 07, 2001 5:13 PM
To: 'seaint(--nospam--at)seaint.org'
Subject: RE: 1997 NDS Equation Error?


Gerard,

For 6" conc, 1.5" side member, .5g wood, Fem 6000 conc, Fes 5600 wood,
Fybolt 45000, Bolt dia, .875, I get 1615lbs mode IIIs failure with the
-Re(1+Rt)outside the radical in the numerator.

Mode II did not govern???

George Richards, P. E.

-----Original Message-----
From: Gerard Madden [mailto:gmadden(--nospam--at)duquette-eng.com]
Sent: Wednesday, November 07, 2001 4:42 PM
To: 'SEAINT(--nospam--at)SEAINT.ORG'
Subject: 1997 NDS Equation Error?


In light of the anchor bolt design values for wood mudsills thread, I
created a spreadsheet to calc the values. When comparing the values with
those of 1997 NDS Table 8.2E, I was noticing that my numbers where not
matching those for 7/8" and 1" Diameter bolts with 2X mudsills.

The problem lies in the equation for k1 in section 8.2.1 (page 53). My NDS
shows the Square Root Symbol Stopping short of the -Re(1+Rt) value in the
denominator. If I include that value within the square root sign, my table
matches Table 8.2E

Is the k1 equation incorrect or is the table wrong? For 3X and 4X members,
the mode Zii does not govern and therefore I cannot compare other values
within the table.

thanks,
-gerard

Gerard Madden, PE
Design Group Manager

Duquette Engineering
10 South Third Street
San Jose, CA 95113
T: 408.494.0944 - ext 102
F: 408.494.0940
E: gmadden(--nospam--at)duquette-eng.com
w: www.duquette-eng.com



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