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RE: LRFD steel beam bearing plate design

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Title: RE: LRFD steel beam bearing plate design

Andy-

ACI 530(Building Code Requirement for Masonry Structures) - Chapter 2 Allowable Stress Design -  2.1.7.3 "Bearing stresses shall not exceed 0.25 f'm."  This is allowable, not strength or ultimate.

Brian Stanley, P.E.
Baltimore, Md


-----Original Message-----
From: Andy Heigley [mailto:aheigley(--nospam--at)jgaeng.com]
Sent: Thursday, July 17, 2003 9:54 AM
To: Seaint
Subject: LRFD steel beam bearing plate design


List:

I am designing bearing plates for beams bearing on masonry, and would like
to know what others are using as design values.

Using the LRFD 3rd edition, Specification section J9 (pg 16.1-70), it tells
me what bearing strength values I should use for bearing on a concrete
support.  In the 9th edition of the ASD manual, we are provided with an
allowable bearing stress of 250 psi for masonry, but nothing is mentioned in
the LRFD 3rd edition for ultimate bearing strength of masonry.

Here's my question.  I'm not sure of how to get a bearing strength for
masonry, but I'll tell you what my best guess is, and you can direct
me/comment on my procedure.

Turn to the IBC 2000, section 2108 for strength design of masonry, and in
particular the axial strength of plain masonry per section 2108.10.3.  I
would calculate my bearing strength per equations 21-51 and 21-52, leaving
out the 'An' term, and use this value in equations J9-1 and J9-2 of the LRFD
3rd edition in lieu of the (0.85*fc') term.  After all is said and done, I
multiply all of this by phi c = 0.6.

Is this correct?  What are others doing for strength design of beam bearing
plates on masonry?

Thanks in advance,

Andy Heigley






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