• Registered: 2009-11-03
  • Posts: 18

Topic: Monitoring point / External forces

I'm running a pushover analysis of RC frame in ATENA 2D. I have assigned a force as continuous load on the left end of the top beam. Additionaly I've placed a monitoring point in the middle of the height of the same beam very close to the continuous load input (external forces - x direction) and also another point for displacement observation. Since these values (monitoring points/external forces) are in MN, and my load is MN/m, i would like to know what actually am I reading (they are not even close to the input load values - 10 times smaller)? Another problem is that when I use infill in the frame i gett lower values than for the empty frame, and that's not logical. It seems like that lower the value of this monitored force becomes as  the system becomes stiffer. Advantage of this monitoring point is that i gett very realistic shape (softening) of the force displacement curve, but values are not!? Please help! Thank you!

Quote Post 1

  • dpryl
  • CC software developer
  • Offline
  • Registered: 2007-07-13
  • Posts: 1,107

Re: Monitoring point / External forces

You are monitoring the (partial) force applied to the finitel element node nearest to your monitoring point. We plan to include "sum monitors" in some future version od our software, but unfortunately, such a function is not yet available in the current ATENA version (and I am afraid not to be expected in close futore), which means you should:
a) sum the forces outside ATENA (e.g., in a spreadsheed)
b) from the first step, find out the multiplier to get the whole load from the single point value. Do not forget the multiplier has to be updated when you change the mesh
c) add an elastic loading plate and apply the load in a single point of the plate - this is usually the easiest way

Regarding your second question, I would suggest to first check if you are really comparing forces at identical displacements. Also make sure there are no accidental changes in the boundary conditions or materials when introducing the infill. Then, look at the convergence errors.

If you still can't find the explanation, please send both models (without results, ZIPped) to our general support email (cervenka@...).

dpryl's Website

Quote Post 2