moving load in truss 1

[drokapil041]

Dear all,

I have build a truss model in RISA 3D V6. I applied a -1KN moving load along bottom chords and perform the envelop solution.
To my surprise, I found little Bending moment in bottom chords and huge amount of axial force in other members in contrast of just -1KN of applied load. I build this model to get maximum axial force on each member due to unit moving load. please check my model i am attaching here. Please comment if i do something wrong.

Thanks in advance
regards G

 

[drokapil041]

Dear all,

I found that the above error was actually because of some problems in my version. Further i would like to know how we can apply distributed moving load in risa 3d.

thanks in advance
best regards
G

 

[JoshPlumSE]

Wow, version 6 goes back a long way. Something like 2003, 2004. As such, I cannot remember any specific issues / bugs from back then that could have caused the behavior you describe... At least not without going back to the office (I'm at home today) and looking up old documentation. Therefore, I will assume you found some documentation or release notes that describe the issue.

Running it in the current version (14.0.1) the results look like what I would expect. This current version has a number of new features related to moving loads but not a moving distributed load. These new features include:
◦Moving loads can now be included in a Batch + Envelope solution.
◦Added a feature to generate point loads per a specific moving load time step.
◦Envelope member detail reports
◦Moving Loads are now included in the input file, making the transfer of files from one computer to another easier.
◦Added the step location for moving load results to indicate where the moving load is located when it gives the reported results.
◦Updated the moving load animation with play/pause control.
◦Added the ability to view a specific moving load step in the moving load animation.
◦Added the AREMA Chapter 15 Cooper E-80 (Railway loading) to the moving loads database.
•Added the ability to print Response Spectra and Moving Load input data.
*Added the ability to record Moving Load Animations to a video file.

So, if you were to use the newer version of the program, my belief is that things would run a lot easier for you.

 

[jayrod12]

If you have a segment of distributed load that moves you could just model it as a series of moving point loads.

 

[msquared48]

What happened to ILD's?

Mike McCann, PE, SE (WA)