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Braced Frame Connections

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>>>Chris Palmateer wrote:

I'm curious how others are designing the connections for their
chevron braced frames.  Specifically, with regard to UBC Section
2211.8.3.1, I would be curious at how other engineers interpret item
3.  I have always designed these connections for item 2 and
another engineer in our office is trying to convince me that this is
too conservative.  His position is that per 2211.8.4.1 the brace itself
is only designed for 1.5 times the *seismic* forces (gravity loads
not included), so this is the maximum force that can be transferred
to the system.  Well, how does everyone else read/interpret the
code?

<<<
Your colleague is incorrect in his interpretation.  The intent of item
3 is to account for the amount of force that can get to the frame
from the surrounding structure.  For example, maximum force in
the braced frame may be limited by the capacity of the connections
of the collectors to the braced frame.  The rocking capacity of the
frame as a whole may also limit the force that the brace can take.  
You need to look at where the weak link is in the system.  When
the weak link reaches its capacity (not just yield), then that should
define the maximum force for designing the connections of the
braces.

I hope this clears up the confusion.
------------------->
Brian Kehoe
BEK(--nospam--at)WJE.COM