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RE: steel frame with masonry infills

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It is important you to remind that this 1/2" gap, is
a "reference minimum", and according to the codes,
this is to be checked for the amplified elastic deformations.
Regarding this, look at the Blue Book, in the corresponding
chapter ( frames & infills ).

RL

-----Mensaje original-----
De: ijr <issajr(--nospam--at)yahoo.com>
Para: seaint(--nospam--at)seaint.org <seaint(--nospam--at)seaint.org>
Fecha: Sábado, 28 de Abril de 2001 03:19 a.m.
Asunto: Re: steel frame with masonry infills


>Alex
>
>You have the keywords in your post: "Seismic Zone 4" &
>"A school". And it is a school, man.  In US codes your
>are probably forced to do ductile design of such
>frames in such zones.
>
>If I were you I would elect not to attach any  infill
>to the frames, and I would utilize a conservative
>ductile frame design. Infills are terrible and I
>believe your specification is right on suggesting you
>leave a 1/2 "" gap.
>
>I am not sure you can call that "dual". "Dual" may be
>taken to mean "frames sway and shear walls deflect".
>Do you have this basic behavior with infill between
>columns?
>
>For a school I might as well go on add some braces or
>a serious ductile RC shearwall.
>
>Good luck
>IJR
>
>
>
>
>
>
>--- Nacionales Alex <acnacionales(--nospam--at)yahoo.com> wrote:
>> Hello.
>> I am the project engineer for the owner of a four
>> storey steel framed school building with 6" CHB
>> walls.
>>
>> The building is about 12M wide and 62M long and 14 M
>> tall.
>> The frame is a special moment resisting space frame
>> and we are in seismic zone 4. I have little design
>> experience in steel framed buildings but I believe
>> that a dual system would be more economical here
>> where
>> a load bearing 6" CHB wall could act as shear wall.
>>
>> The design specifies that the CHB be laid 1/2" from
>> the steel columns and shall have 1/2" thick styrofor
>> to fill the gap. I find this to be unnecessary. I am
>> aware that masonry infills specially where there are
>> low windows can interfere with the frame action as
>> observed in RC construction in the past earthquakes
>> but RC columns can be designed against this by
>> providing more shear reinforcement above the window
>> level, for steel columns its different because the
>> section is the same for one length so the design for
>> maximum shear at the base of the column should be
>> sufficient.
>>
>> I would appreciate some comments on this. Thanks.
>>
>> Alex C. Nacionales, C.E.
>>
>>
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