Space Frame Analysis

I would like to know if space frames can be analysed as a truss. Can
method of sections, or joint equilibrium be used in analyzing space
frames? Thanks.
Reply to
O'neil Coleman
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No, the members in a frame carry moments; truss members do not.
You can try but it's a statically indeterminate.
For a rough approximation, you could treat the members as trusses (carry axial loads only) and analyze the structure. But this could be off a lot, so be warned.
Reply to
Jeff Finlayson
Yes
Brian W
Reply to
Brian Whatcott
Since you got one yes and one no, let me add my two cents. Yes, you can analyze it as a truss if you have pinned joints. If you have rigid joints, then the members carry moments and you may have to use other analysis methods.
Sincerely,
Donald L. Phillips, Jr., P.E. Worthington Engineering, Inc. 145 Greenglade Avenue Worthington, OH 43085-2264
snipped-for-privacy@worthingtonNSengineering.com (remove NS to use the address) 614.937.0463 voice 208.975.1011 fax
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Reply to
Don Phillips
A frame CAN be modeled as a truss.
However it cannot be accurately modeled as a truss since a frame takes axial AND bending loads where a truss ONLY takes axial loads.
What are you trying to do?
cheers Bob
Reply to
Bob K 207
Hmm...three people all sounding helpful, but coming up with different approaches. Pehaps this note from UFlorida mentioning a truss member in two dimensions will help to extend the idea of axial loads only (1D)
A space frame is by definition three dimensional. Each element is desired to take compression and tension forces only. The ensemble is meant to offer a path for loads and torques
Brian W
Reply to
Brian Whatcott
A previous poster (Bob K) had it right. To expand on his comments, a space *frame* is a three-dimensional structure constructed with rigid connections. Thus, deformations under applied loads will induce combined bending and axial loads in the individual members. A space *truss* is a three-dimensional structure constructed with pinned connections. In this case, the members will carry only axial loads.
In years gone by (that is, when computer time was very expensive), structural engineers commonly analyzed frames as trusses and then applied various rules of thumb to estimate the moments in the members. By today's standards of practice, one must analyze a frame as a frame. The means to do so are now readily available to virtually all practicing engineers.
David Duerr, P.E. Houston, Texas
Reply to
David Duerr
I found this note from David Duerr informative
Brian W
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Reply to
Brian Whatcott

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