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Re: Mass realty check...

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So I guess there will be existing unreinforced cmu partition walls left in the building after your renovation. What does the Code require be done for them if anything?

For your situation (changing classification), is there a height limitation to leave these walls without being braced to the structure or minimum reinf. required?



Will Haynes, P.E.




From: Scott Maxwell <smaxwell(--nospam--at)engin.umich.edu>
Reply-To: <seaint(--nospam--at)seaint.org>
To: seaint(--nospam--at)seaint.org
Subject: Re: Mass realty check...
Date: Fri, 14 Jan 2005 10:39:45 -0500 (EST)

David,

First, I would have to say that you need to define "crazy" for me!  <grin>
Everything is relative.

With the limited information that I have to work with, my gut reaction is
that you are not crazy (at least not too crazy).  If it was just an issue
of possible wind for lateral resistance, then it might be tougher to
justify the upgrades, but I "buy" the need for seismic upgrade much more
readily.  Much of the New England area is a moderate seismic zone.  I have
personally worked on a couple of GSA seismic evaluation projects in the
New England area and know that while it is now where near California or
even southern Illinois in terms of the potential for serious seismic
events, it is still a moderately active seismic area that does get an
occasional upper 5 magnitude to very low 6 magnitude quake.

So, I would say that it would certainly not suprise me that the code might
require it.  And if it helped, I had to deal with similar type issues when
working on turning an old office building into a casino in Detroit.  We
determined that the lateral system was inadequate (in this case, there
actually was a system in place) and designed an upgrade.  The casino owner
squawked about the probably less then $10000 worth of bracing upgrades,
all while being more than willing to spend probably more than $300 per
square foot on finishes.

Regards,

Scott
Adrian, MI


On Fri, 14 Jan 2005, David Fisher wrote:

>
>
> Hey gang:
>
>
>
> I am currently working on the conversion of an existing four story heavy
> timber "loft" building
>
> In the Boston suburbs from light manufacturing to residential condominiums.
>
>
>
> The way I read the Mass Building Code, due to the renovation work and change
> of
>
> Use, the existing building must have a seismic/lateral analysis performed on
> it.
>
>
>
> The problem is, there is no existing lateral load resisting system.
>
>
>
> The building is composed of unreinforced masonry (multi-wythe brick) bearing
> walls at the
>
> Perimeter with steel pipe columns supporting heavy timber purlins and wood
> decking.
>
>
>
> The Mass Code, like most others, does not permit the use of unreinforced
> masonry (except that which
>
> Is used as infill for a concrete frame) as a lateral load resisting system.
>
>
>
> Using this logic then, the building must be reinforced to meet the
> provisions of the Code.
>
> Btw, my solution is to install interior steel braced frames which engage a
> new concrete topping to increase
>
> The diaphragm capacity. (I can go into this later.if anyone cares.)
>
> I've taken into account all the Code reduction factors for existing
> construction to reduce the magnitude of
>
> The lateral force (in this case, they let you reduce the force by 60%!); the
> professional ethics of that
>
> Was can debate another time, I guess.
>
>
>
>
>
> The owner, as you might imagine, is having a fit about all the extra steel
> and foundation work he has to do
>
> Because of this.and being "the out of town guy" doesn't help.
>
>
>
> Am I crazy? (I am just referring to this issue, not my various other sm*rt
> *ss list comments over the years)
>
>
>
> Help!
>
>
>
> David L. Fisher SE PE
>
> Senior Principal
>
> Fisher+Partners
>
>
>
> 372 West Ontario
>
> Chicago 60610
>
>
>
> 312.573.1701
>
> 312.573.1726 fax
>
>
>
> 312.622.0409 mobile
>
>
>
> www.fpse.com
>
>
>
>

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