Steel Arch Truss modeling

[VTAdam]

I need to analyze a steel arch model and check its adequacy. I need to create a model for it. It is a two dimensional, half a circle truss. It is very similar to the one shown in the attachment below. Except mine is half of circle. I have both SAP2000 and Risa 3d, as well as a program called STRAP. Neither one of them has an arch truss. SAP2000 has a Pratt truss. I am aware that I can model it in Autocad. However, I wanted to see if i can do it directly inside the software. Thanks.

 

[JAE]

Neither one of them has an arch truss.

I'm sure that RISA and SAP2000 both allow you to input joint coordinates and build a model of anything.



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[Lomarandil]

Agreed, you can build this in RISA or SAP.

At least in RISA, you could potentially generate your joint coordinates by using the structure generator option and some clever manipulation. That would be "directly in the software". Then you could build the truss from the joints you've generated.

I suspect though that unless your geometry is perfectly semi-circular and uniform, you'd do better to develop a basic model geometry in AutoCAD and import the DXF file with your joint coordinates.

 

[mike20793]

I use a spreadsheet to determine coordinates for circular/elliptical/round objects in RISA. It's pretty easy to do and can be copied directly into the joint coordinates spreadsheet. I use it for domes pretty frequently.

 

[Brad805]

I would model that old truss in CAD and import the CL's as a dxf or dwg. Trying to find a piece of software that has that old profile as a standard feature is unlikely.

 

[IDS]

Assuming that both these packages allow you to generate nodes on an arc and connect them to make beam elements, I would create one segment at the left hand end, then make multiple copies of it using polar coordinates.

Or if the segments were not all the same I would generate the node coordinates and beam connections in a spreadsheet and copy and paste into the analysis program.

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[msquared48]

I would have no problem with this in RISA.

Mike McCann, PE, SE (WA)

 

[SteelPE]

Add me to the excel crowd. I sometimes create a quick spreadsheet in excel that defines the coordinates and then pull the coordinates into the program and play connect the dots.

 

[VTAdam]

I ended up modeling it in AutoCad and importing the DXF file into Risa. It was the easiest way. Thanks for all the advice.