Curved Beam

[SR71B]

I have an application (roof truss) that requires a curved beam.

The rest of the structure has been model using beam elements how do I model the curved beam?

 

[GBor]

It would be helpful to understand the rest of the structure, but you can model it with a series of incremental (piecewise linear) beams so that the "true curve" is represented. Basically, your curved beam becomes a series of connected straight beams. Depending on how small you make the beams determines how closely you can approximate the curve.

Another option is to build the curved beam out of plates. Use plate elements to actually draw the web and flanges (if an I-beam). It is even possible to build it out of bricks depending on the configuration of the beam.

Some questions:

I've seen curved beams running the ridge line of large, open auditoriums. They are laminated and curved so that when the load of the trusses lands on it, the weight straightens it out. Is this what we are discussing?

Is this an I-beam? Rectangular? 30 meters? 2 feet? A truss structure of a home or of an indoor arena?

How will the other beam attach to this beam in reality? Again, is it the ridge beam, or a part of the truss?

Is it made of metal? If so, what kind? Wood?

 

[SR71B]

The beam is a round steel tube bent into a "U" shape. It is then welded to a rectangluar section tube that is supported on both ends.

 

[GBor]

What are the overall length and basic cross-sectional dimensions of each tube?

Garland E. Borowski, PE
Borowski Engineering & Analytical Services, Inc.
Lower Alabama SolidWorks Users Group

 

[SR71B]

1.5" OD x .095" wall Attached to a 2" x 1" x .083" rectangluar tube.

U section = 5" centerline radius, 12" from top of bend to bottom.

Span 24"

 

[GBor]

I would go with the piecewise linear beam. You can even draw it using an arc and then divide it in to the number of beams you would like to use to approximate the curve (I would suggest no less than 12 for a 180 degree arc).

Garland E. Borowski, PE
Borowski Engineering & Analytical Services, Inc.
Lower Alabama SolidWorks Users Group

 

[SR71B]

Thank you for your help. I have model the beam with an arc in both Fempro and Superdraw III and divided the arc into sections. At this point I can not select any of the arc to add forces or properties.

What am I missing?

 

[Stringmaker]

Whyme, did you define an element type for the part which the arcs are on?

 

[SR71B]

The software will not allow me to pick the arc to define any properties.

 

[GBor]

When you divided the arc, did you make sure that it created lines from the division, or did you leave as arcs? The processor does not understand curved 1-dimensional elements, only straight ones. When you divide the arc, make sure it "divide(s) to lines". Also, you would apply forces to nodes, not the elements.

I put this problem together after our last exchange. What type of load are you trying to put on the beams and where (I'm assuming you are applying a force at the top of the arch)?

Garland E. Borowski, PE
Borowski Engineering & Analytical Services, Inc.
Lower Alabama SolidWorks Users Group

 

[SR71B]

To the top is correct. Are you modeling this in Fempro or SuperDraw?

I did perform the divide of the curved beam and convert to lines,but I do not remember any command about divide to lines? Where is the command located. When I do the convert to lines it only converts the vertical straight members. So, must not be using the correct command.

Gbor, Thank you for all your help.

 

[SR71B]

I found the divid by lines command. Thank you again, GBor.

 

[SR71B]

All got it to work!!!!

 

[SR71B]

Should be "I got it to work" How do you edit posts?

 

[GBor]

You don't...no edit capability, so you just post the update in the thread. Glad everything is working...

Not that I'm asking for one, but there are three links at the bottom of each post:

"Thank _______ for this valuable post"...this gives stars which count toward the "tipmaster of the week" (which I'll never be because I limit the number of forums to which I belong)

"Inappropriate post? If so, Red Flag it!" This is how some threads are elminated. Things like student posts, posting Algor superiority in the Nastran forum (or vice versa), innappropriate language, marketing products, etc.

And "Check out the FAQ area for this forum"...don't think there's much in this forum, but the site has some interesting FAQ's (frequently asked questions).

Other than that, there's pretty much the ability to post questions, answers, and links to graphics.

Have a great week.

Garland E. Borowski, PE
Borowski Engineering & Analytical Services, Inc.
Lower Alabama SolidWorks Users Group