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Re: Cantilever System (Help!)

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I also have used the system as described several times, although always
in residences with a higher plate line at the entry way. The dimensions
and loads are lower, but the system is the same. No moment connect at
the base was used.

Paul Feather wrote:

>     Provided you are adequately tied to the roof diaphragm to transfer
> the required force to the lower roof system, the requirement for a
> moment connection at the base is absurd. I have done similar systems
> in the past.    If the load path is clear and the statics work, the
> deflections are controlled and all details are well defined, I would
> explain how the system works and refuse to change it. Paul
> Feather----- Original Message -----
>
>      From: Alfonso S Quilala
>      To: 'seaint(--nospam--at)seaint.org'
>      Sent: Tuesday, November 07, 2000 10:28 AM
>      Subject: Cantilever System (Help!)
>       I have 2- one story wood buildings to be used as senior
>      citizen center. One is 80ft x 100 ft and the other is 90 ft
>      x 90 ft approximately.  Their roof are almost at the same
>      level (17.5 ft.).  In between these two buildings (30 ft
>      apart) are lounge, lobby, and reception area  and it was
>      covered by a higher roof (at elevation 27 ft.).  There is no
>      shear resistance from the lower diaphragm to the higher
>      diaphragm because it is almost all windows. We decided to
>      use steel columns to cantilever out above the lower
>      diaphragm to resist seismic force. The columns are supported
>      at the lower roof level and at the foundation.  I used R=2.2
>      to get the seismic load at the higher roof.
>
>      The plan checker said that this is not an acceptable system
>      because there is no moment base.  He wants the column to be
>      supported at the base only to be acceptable.  My argument is
>      that the support at the diaphragm level and at the
>      foundation level created a couple moment to serve as a
>      moment base.
>
>      I just need anyone, especially those that are very familiar
>      with the intent of the code could help me.  I am in a
>      situation that if mine is not acceptable that I have spent
>      more hours to finish the project.  But I need to know which
>      way to go to save some time.
>
>      Thanks in advance,
>
>      Alfonso S. Quilala Jr. , P.E.
>