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Re: UBC97 ASD Sesimic provisions

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Michael,

You are mixing apples and oranges.  Section 2213 is by definition design
using Allowable Stress.  To apply LRFD forces to this would be completely
incorrect.  If the braced frame is designed using LRFD (not adopted in the
CBC for State of California, one of life's great ironies)  you should be
looking at the AISC Seismic Provisions (section 2210 of the UBC)

Paul Feather
----- Original Message -----
From: "Michael Bryson" <MBryson(--nospam--at)mhpse.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Friday, November 09, 2001 10:24 AM
Subject: UBC97 ASD Sesimic provisions


> 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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