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RE: Question on SAP2K

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I agree - there is no simple way to do this, and IMO it isn't worth it.  I
have done a couple of projects involving single angle struts in trusses, and
I don't recall either RISA nor SAP2K being capable of checking single angle
members in compression.  I just went ahead and used a model with no offset
(axes of both members coincide), then take care of the offset through a
calculation of axial load capacity (works for both LRFD and ASD).  The
offset is a set distance, thus the moment induced for an axial load is also
set (offset*axial load=induced end moment at each end of angle).  So, for
any given axial load, you have the induced end moments, and you can use an
interaction equation for axial load and flexure to calculate the interaction
ratio.  Conversely, you can solve for the axial load for any given length of
the member, and create an axial capacity vs. length diagram for easy
checking (that's the approach I used).  It isn't too much of a pain once you
get beyond the calculation of axial capacity (neglecting flexure) for a
single angle strut, which is a bit of work.

Hope this helps.

T. Eric R. Gillham PE
PO Box 3207 Agana Guam 96932
Ph: (671) 477-9224
Fax: (671) 477-3456


-----Original Message-----
From: Ron Larsen [mailto:rclarsen(--nospam--at)cyseng.com]
Sent: Thursday, July 27, 2000 10:19 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: Question on SAP2K


Ghassem,
There is no easy way to do what your asking such as specifying an offset
perpendicular to the axis of an element.  The only way I can think of doing
what you are suggesting is to create a member whose axis is offset to the
other member's axis, and constrain the adjacent nodes to one another.
However, be careful to make sure your results are correct, and your
constraints are properly identified.

> -----Original Message-----
> From: Khosrownia, Ghassem SPK [mailto:GKhosrownia(--nospam--at)spk.usace.army.mil]
> Sent: Wednesday, July 26, 2000 8:32 AM
> To: 'seaint(--nospam--at)seaint.org'
> Subject: Question on SAP2K
>
>
> I will be calling them in a couple of hours when they open, but
> until then,
> does anyone know how a member should be modeled so its axis is
> off set from
> the joint? Such as a case of a single angle attached to the face
> of the web
> of a T section in a truss situation? I have not found such
> capability in the
> published manuals and help files.
>
> Ghassem Khosrownia
>
> US ARMY CORPS OF ENGINEERS
> Sacramento District
> Military Design Branch
> CESPK-ED-M
> 1325 J Street
> Sacramento, CA 95814
> (916) 557-7347
> (916) 557-7841 (Fax)
> gkhosrownia(--nospam--at)spk.usace.army.mil
>
>
>