Double Web Plate Girders

[andriver]

Is it possible to model double web plate girders in Risa?

I have been doing some hand calculations to determine my bending capacity in a double web plate girder. I used a structural analysis software used in the offshore industry (SACS) that has the ability to model double web plate girders to confirm my results. The software is giving me a higher capacity than I have computed. I wanted to use RISA to confirm my findings, but do not see an option for double web pate girders. Is it possible to model in Risa 3d?

 

[weab]

You could try using a tube shape. The flanges and webs create a tube but the flanges stick out beyond the webs. I'm not at the office as I write this so if you use a user defined tube, you MIGHT be able to define different wall thicknesses. If so, the top and bottom could be thick enough to equate to the flange areas.

Alternately, you could use a user defined wide flange and use a web equal to double the thickness of one web.

Either way, you will need to manually override the relevant section properties (A, I, r, etc.) to match that of your actual beam.

If you are looking for stresses, this could work. If you are looking for AISC unity checks, I think the user defined wide flange would give you the closest results and be conservative, I believe.

 

[jayrod12]

Or, you can use Risasection to build exact section you are trying to analyze

 

[JoshPlumSE]

RISA cannot do proper code checks on the type of member you describe. Unless modeling it as an HSS tube is good enough. However, you can certainly get reasonable analysis results.... joint deflections and reactions, member forces, and stresses. All you have to do is create a member with the correct properties (A, I and J), or create the member in RISASection to calculate this data directly.