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Re: Commercial Construction Standards

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The following are my opinions to your questions:

>1.  Would you recommend welded wire fabric in the slab or a more durable #3
>rebar arrangment. What is the conventional layout of #3 rebar (6" o/c, 12"
>o/c or 18" o/c).

I would use the #3 bars spaced at 16" on center (this is close to the 0.0018
min. reinf. for temp and shrinkage for a 4" slab).

>2. The stores are approximately 15 feet wide, however the owner does not
>want any interior partitions for load bearing. He wants to be able to
>combine stores if wanted. What is the maximum slab area for installation of
>expansion joints? What is the conventional slab thickness (4" or 6")

Convential slab thickness is 4".  We typically space our saw
cut/construction joints at 10 to 12 feet maximum.  However, I have seen this
spacing exceeded by others and there appeared to be no problems.

>3. I intend to use embedded steel in the open front - pendulum type
>columns - which conforms with the clients past conventions. Rather than
>embedding into post foundations, I plan to use the foundation as a grade
>beam with erection pads below (which will be bearing pads as well). I want
>to develop lateral moment in the grade beam. This posses two questions:
>a) should I place the grade beam below and independent of the slab edge? I
>think it is a good idea since the grade beam will be f'c=3000 psi concrete
>with special inspection required and also it will keep the structural
>gradebeam independent of the non-structural slab. Any other thoughts?

I agree with the above.  Keep the grade beam independent of the slab.

>b) Should I follow '94 code and distribute lateral according to an Rw of 6
>or follow the '97 code and take the penalty for the pendulum condition?

Tough question.  I assume there must be a reason why the '97 has made this
change and being somewhat conservative when it comes to engineering design,
I would use the '97 code.  If I had all the information on why the change
was made and believed this was unnecessary, then I would use the '94 code.

>Also, if I follow '97 UBC convention should I use the lateral component for
>the entire building or just the embedded poles?

I would review the code on this issue.
>4. 3(b) leads to this question - Has the SEAOSC code committee taken a
>position yet regarding embedded column lateral design. It was suggested in
>their minutes that they intended to take the position that only the columns
>be loaded with higher shear in order to compensate for story drift. Any
>comments yet?

>5. I have recomended the use of TS (Timber Strand) studs. This is a low
>budget project, but I am under the impression that the labor savings in
>taller walls with dimensionally true and straight lumber will compensate
>the labor cost and scrap necessary to deal with crowned, warped and twisted

You may want to talk to a contractor about this issue.  My experience is
that some contractors only look at the price of material and use the same
labor for both wood products.  However, there are those who have enough
experience to bid the job accurately.
Another option is to use an alternate bid.  This may take a little more time
on your part, but could save the client money in the long run and should
make up the difference if you choose to increase your fees for the
additional time.

I hope this helps.

If there are others who agree or disagree with the above, please respond.  I
am curious to hear what others may have to say.

Mike Brown, P.E.