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Re: URM

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Stephen K. Harris wrote:
> 
> With regard to your questions regarding diaphragm boundary nailing, I
> would like to suggest that you may want see whether it is possible to
> nail your new edge blocking from above.  This commonly done, even in
> historic buildings.  The nails will yield much more effectively than
> the screws, which may break or pull out.  If you really have to use
> screws from below, you should try to put in enough of them that
> you're sure they'll remain elastic.  The diaphagm can still yield, as
> the UCBC intends, along a line parallel to the diaphragm boundary.
> 

Stephen,

My client wishes to refinish the existing hardwood flooring in this
building and for this reason I am working from below. If push came to
shove, my client would likely concede to nailing from above but I
haven't pushed him on the issue significantly thus far. I am using the
same type of A35/screw configuration at tension tie blocking to
diaphragm connection.

The $100 question with regard to your comment is how to establish the
quantity of A35/screw connections that will ensure elastic behavior at
the diaphragm boundary.

Regarding the existing lintel, my concern may be better stated by the
following:

I need to be sure in plane loads will transfer from the masonry above to
the existing steel built up beam buried in the masonry at the head of
the storefront opening. Only then can I feel confident that a new frame
will receive load from the built up steel beam by virtue of a new
connection between the two.

Installing new "shear lugs" on the top flange of existing built up beam
was suggested by a colleague. Chipping out masonry pockets in which the
shear lug could be attached to the top flange and then drypacking the
pockets. This seems like a very good approach and will likely be
pursued.

If my query is now any clearer please feel free to comment.

Regards,

Mark D. Baker
Baker Engineering