×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Risa-3D Moving Loads on a Plates

Risa-3D Moving Loads on a Plates

Risa-3D Moving Loads on a Plates

(OP)
I have a large top slab of a large 75'x15' box that I am trying to apply a HS-25 loading using the moving pattern loads. But apparently it requires a member underneath the pattern to follow. Is there a way to apply them to nodes or plates? or maybe a member have zero (or very little) strength. Tired that but unsure if the forces are getting transfered to the plates since the members still give forces in the results. any advise?

RE: Risa-3D Moving Loads on a Plates

The way I would do it is to include a very (VERY) weak member in the line of the moving load. This could be a physical member attached to joints along its length.
The member stiffness should be set very small along with its modulus of elasticity E. Use a "general" material property that you invent.

After the analysis check to see what the sheas and moments in the beam are - should be small or negligent.

Check out Eng-Tips Forum's Policies here:
FAQ731-376: Eng-Tips.com Forum Policies

RE: Risa-3D Moving Loads on a Plates

The moving load is applied to the member, then the member transmits those shear forces into the plate elements which support it. So, the member carries the shear between plate joints.

You can check to see if the member picks up the internal plate joints by using the Color Coded plot option for the members and setting the basis for the color coding to "phys segment". That means wherever the member picks up an interior joint, you will see a color change.

Note: If the member isn't picking up your plate element joints, then you might have to move some of the joints so that they line up with the member or re-mesh your plates. Whatever you need to do to get those plate joints to fall in-line with the member.

RE: Risa-3D Moving Loads on a Plates

OK - after reading this my statement about the member not taking force is wrong - the member must take force per Josh's post above.

Check out Eng-Tips Forum's Policies here:
FAQ731-376: Eng-Tips.com Forum Policies

RE: Risa-3D Moving Loads on a Plates

(OP)
I re-meshed the slab so the member with no material strength and with the moving load was lined up with the mesh. Still saw forces up to 36k. I tried one long member from end to end and also multiple one plate length members end to end. Relatively the same results between the two.

RE: Risa-3D Moving Loads on a Plates

But if you beef up the member the forces in the FE mesh should reduce, and if you use a "wet noodle" member the forces in the FE mesh should increase.

Check out Eng-Tips Forum's Policies here:
FAQ731-376: Eng-Tips.com Forum Policies

RE: Risa-3D Moving Loads on a Plates

(OP)
Correct and they do, but not enough to be negligent unfortunately. It's hard to over look 30+ kip haha. I just went with doing a lot of different point load cases. Thank you for the help though!

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources