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RE: soils pressure

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Thanks Joe,

 

I used a .9 factor for Load Duration since the soil load would be permanent.  Also, I wasn’t looking at the entire joist, but just the top chord.  In that case I wasn’t thinking that it would be a flexural member since the joist as a whole is the flexural member.  I also assumed that in the vertical direction the top chord would be a continually braced compression member and in the perpendicular direction braced at 12” o.c. due to the field nailing from the plywood.  Am I way off base?

 

I have hung the joists from a ledger so we do agree on that one.

 

Some other thoughts would be…if the joists aren’t cut exactly the same length (but assume not huge differences) wouldn’t the longer joist take more compression load from the top of the wall until it shortens from compression, or is that splitting hairs?

 

-----Original Message-----
From: Jnapd(--nospam--at)aol.com [mailto:Jnapd(--nospam--at)aol.com]
Sent: Friday, April 23, 2004 12:08 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: soils pressure

 

Joe:

You might check the joist using the Combined bending and axial loading in the NDS.  I would not use the repetitive increase factor  (Cr) and I would use load duration of of 1.0 (Cd).  I would also hang the joist off the nailer at the top of the wall.  I would strap the bottom of the joist to the CMU wall.  Food for thought.


Joe Venuti
Johnson & Nielsen Associates
Palm Springs,  CA