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Re: Curved Steel Frame

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I might add that if the plan-curve has a single focal point or is of single
curvature it will also act in a tangential-torsional mode about that point.


-----Original Message-----
From: Roger Turk <73527.1356(--nospam--at)>
To: seaint(--nospam--at) <seaint(--nospam--at)>
Date: Tuesday, December 29, 1998 4:40 PM
Subject: Curved Steel Frame

>Speaking only of curved structures subjected to lateral loads in general,
>structure will behave more as a shell than it will behave as a
>framed structure.  A curved retaining wall will not behave as a cantilever
>until it cracks due to circumferential stresses.  Similarly, a curved
>building subject to lateral forces acting *towards* its concave side will
>subject the horizontal circumferential beams to tension and lateral forces
>acting *towards* the convex side will subject those same beams to
>compression.  The radial "frames" will not behave as frames until the
>horizontal circumferential beams (or their connections) fail.
>A. Roger Turk, P.E.(Structural)
>Tucson, Arizona
>. > Ed Gonzalez wrote:
>. >
>. > Greetings:
>. >
>. > Can anyone share their general thoughs or comments, for the design of a
>. > two story, three-bay CURVED ordinary steel frame for lateral seismic
>. > loads in a Zone 4 region.  SAC 95-01, FEMA 267 and FEMA 267a. will be
>. > adhered to as much as possible.  The columns are not equally spaced.
>. >
>. > We plan to orient the columns with the strong axis along the curve, and
>. > have the beams fabricated so as to follow the curve contour as much as
>. > possible. The max. eccentricities are 18", 10" and  6".  Shear studs
>. > be placed along the top beam flange.
>. >
>. > Of particular concern is the best way to model the frame while
>. > for the potential torsional demand on the beams and connections.
>. > of the deck is being considered. We want to start using an elastic
>. > program (RISA3D) and then gravitate into using an inelastic software as
>. > deemed needed.
>. >
>. >
>. > Regards,
>. > ed gonzalez
>. >