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Re: Masonry wall with epoxy anchors

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Of course you do...I am always right! (Although, I am left politically as
I am sure Bill will attest to).  <grin>

Careful, if you are too nice to me, I might get a big head (even if it is
empty...that could explain the loss of hair...nothing for it to grab
onto)!  <grin>

Scott
Adrian, MI


On Thu, 8 Sep 2005, Daryl Richardson wrote:

> Scott,
>
>         I agree with you completely.
>
> Regards,
>
> H. Daryl Richardson
>
>
> ----- Original Message -----
> From: "Scott Maxwell" <smaxwell(--nospam--at)engin.umich.edu>
> To: <seaint(--nospam--at)seaint.org>
> Sent: Thursday, September 08, 2005 12:52 PM
> Subject: RE: Masonry wall with epoxy anchors
>
>
> > While in a black and white world (i.e. a pure principled view), this
> > approach would make a ton of sense, here in the real world I would argue
> > that it is not such a simple call.  Ideally, the contractor screwed up and
> > should have to remove and replace what he screwed up.
> >
> > But...if you want to advocate such a thing, then you should be prepared to
> > have to pay for a complete tear down and replace of an item that you may
> > have designed incorrectly and later discover your error after it has been
> > built.  After all, why should the owner have to live with a cludged
> > solution due to an engineer's screw up just to save the engineer money?
> >
> > In otherwords, if you want to be completely intolerant of others mistakes
> > (intential or not), then be prepared for people to be completely
> > intolerant of your mistakes.  What comes around goes around.
> >
> > In reality, when a error occurs (no matter why it happened), it is usually
> > best to figure out how the error effects things and then use the most
> > efficient (from time, cost, etc) solution to fix the error.  Sometimes
> > this will be to rip the stuff down and do it over again right.  Sometimes
> > this will be to repair/reinforce it in some manner.
> >
> > Regards,
> >
> > Scott
> > Adrian, MI
> >
> >
> > On Thu, 8 Sep 2005, Eli Grassley wrote:
> >
> >> I would tell them to tear the whole thing down and do it per the plans!
> >> When you give the contractor a "fix" for this kind of a performance, you
> >> are
> >> just feeding the monster.
> >>
> >> ~~ Eli ~~
> >>
> >>
> >> -----Original Message-----
> >> From: Nuttall, Davin J. [mailto:dnuttall(--nospam--at)somervilleinc.com]
> >> Sent: Thursday, September 08, 2005 11:13 AM
> >> To: seaint(--nospam--at)seaint.org
> >> Subject: RE: Masonry wall with epoxy anchors
> >>
> >> Hi Scott,
> >>
> >> We specified a running bond in the original contract documents.  The
> >> contractor took it upon himself to change to a stack bond.  By changing
> >> to
> >> stack bond, he also did not provide enough minimum horizontal
> >> reinforcement
> >> in the wall.  He could have added bond beams not to exceed 4'-0" o.c. or
> >> provided horizontal ladder reinforcement at each course, but he did
> >> neither.
> >>
> >> The bond beams he did provide were spaced at approximately 5'-4" o.c.  I
> >> added the plate and bolts between the in-place bond beams to maintain the
> >> minimum steel and spacing requirements of ACI 530.1 for stack bonded
> >> walls.
> >>
> >> Regards,
> >>
> >> Dave
> >>
> >>
> >>
> >> Dave,
> >>
> >> See comments below:
> >>
> >>
> >> On Thu, 8 Sep 2005, Nuttall, Davin J. wrote:
> >>
> >> > List,
> >> >
> >> >
> >> > Due to contractor error, I had to externally reinforce a 12" CMU stack
> >> > bonded cavity wall after-the-fact.
> >>
> >> If I may ask, why the stacked bond.  If the wall will be furred out, then
> >> it appears that appearance is not the driving factor, so running bond
> >> should have been the better choice.  The exception could be that only one
> >> side will be furred and the exterior a face of the wall will be exposed.
> >> If such is that case, then I have to wonder what the type of load the
> >> wall
> >> must carry is, how was it deemed insufficient as constructed, and what
> >> are
> >> the full details of the repair.  It sounds as if it could be flexure due
> >> to wind pressure and repair could be external steel plates as flexural
> >> reinforcement (all speculation...could be something else).  If so, then
> >> reinforcing one side would not seem to solve the potential problem as the
> >> wind in such as situation could be either positive pressure (resulting in
> >> tension stresses on the inside face) or negative (resulting in tension
> >> stresses on the exterior face).  Just curious.
> >>
> >> >
> >> > My detail included continuous steel plates with epoxy anchors drilled
> >> > into the center of existing solid grouted cores.  The wall will be
> >> > furred out, so the repair will not be visible after the project is
> >> > finished.
> >> >
> >> > I now find out that the contractor ignored portions of the submitted
> >> > fix, and in some cases, located the anchors right in a mortar joint.
> >> >
> >> > Questions:
> >> >
> >> > 1.  Because the wall is grouted solid, would you be concerned with edge
> >> > distance of the bolt relative to the edge of the individual block?
> >>
> >> Generally, I would say no.  It will in general be the edge distance of
> >> the
> >> bolt to the edge of the masonry assembly not the unit.  This would be
> >> largely true even if ungrouted.  This is assuming you are looking at it
> >> from a global point of view.  Where edge distance to a individual block
> >> could be an issue is for local effects that could further weakness in the
> >> "weak points" (i.e. say you use an expansion style anchor in a mortar
> >> joint...could cause the joint to crack/fail due to the expansive force,
> >> which in an ungrouted situation could cause the generally considered
> >> weakest point - the mortar joint - to be even weaker).
> >>
> >> >
> >> > 2.  Are the blocks considered as individual units with respect to the
> >> > new bolts and their capacities, or is the entire cmu wall acting as 1
> >> > monolithic unit?
> >>
> >> Generally considered acting as 1 monolithic unit.  But again, it depends
> >> on what "thing" (i.e. failure mode, behaviour, etc) you are looking at.
> >> Masonry is a "non uniform" material, so some failure modes can be
> >> governed
> >> by the individual components more readily than the overall assembly.  So,
> >> it will require knowledge of how masonry behaves and what the bolts are
> >> "doing" (i.e. how are the bolts loading the masonry) to really make such
> >> a
> >> determination.  And I don't have enough information of the specific
> >> situation to make such an assessment in this situation.
> >>
> >> >
> >> > 3.  How much of a strength reduction would you take because the bolt is
> >> > located in or right next to a mortar joint, and not the published
> >> > distance away from a free edge?
> >>
> >> Again, it depends on what the bolt is "doing" and the configuration of
> >> the
> >> bolts as well as the configuration of the wall as is and what kind of
> >> loads it must carry.  More than likely if the bolts are engaging the
> >> grout
> >> in the cores, it will likely not matter if the bolt is in a mortar joint
> >> or not.
> >>
> >> >
> >> > The worst case scenario would be to remove and relocate the plate and
> >> > bolts to the specified location(s).  As always, time is a major
> >> > concern,
> >> > and they would like to move on with minimal rework.
> >> >
> >> > Thanks
> >> >
> >> > Dave Nuttall, P.E.
> >> > Green Bay, WI
> >> >
> >>
> >>
> >> HTH,
> >>
> >> Scott
> >> Adrian, MI
> >>
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