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RE: Horizontal Irregularities

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If that is the case, then how would you deal with stepped diaphragm nailing zones?  At what point away from the boundary edge would you be able to remove the 25% demand load increase? 


Doug Mayer, SE


From: Gerard Madden, SE [mailto:gmse4603(--nospam--at)]
Sent: Monday, November 03, 2008 11:42 AM
To: seaint(--nospam--at)
Subject: Re: Horizontal Irregularities


It applies to the boundary nailing in wood diaphragms, deck welds and shear studs to boundaries in metal deck w/ conc. etc...

Where the diaphragm shear is not at a boundary (i.e. support in your diaphragm shear diagram) it does not apply per this wording.


On Mon, Nov 3, 2008 at 10:54 AM, Doug Mayer <doug.mayer(--nospam--at)> wrote:

Hmm, I worded that poorly.  Yes, the demand should be increased 25% per this section, but does it apply to the diaphragm shear values that you would then compare to the code allowable diaphragm shear? 


Doug Mayer, SE

Structural Engineer





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From: David Topete [mailto:d.topete73(--nospam--at)]
Sent: Monday, November 03, 2008 10:46 AM
To: seaint(--nospam--at)
Subject: Re: Horizontal Irregularities


It appears the demand must be increased 25%, while the "allowable" shear values remain unchanged.

On Mon, Nov 3, 2008 at 10:26 AM, Doug Mayer <doug.mayer(--nospam--at)> wrote:

Section of the ASCE 7-05 states:

"For structures assigned to Seismic Design Categories D, E, or F and having a horizontal structural irregularity…the design forces determined from Section 12.8.1 shall be increased 25 percent for connections of diaphragms to vertical elements and to collectors…"


Does this requirement apply to diaphragm shear values taken from the code tables?  As I read it, it does not, but I would appreciate confirmation. 




Doug Mayer, SE


David Topete, SE