I would like to calculate the spring constant of a frame structure. I thought that I could do it like this:

  1. I apply a point force on the structure: enter image description here

  2. Then I calculate the displacement at that same point: enter image description here

Finnaly, I asume that the material bends within its elastic limit: $k=\frac{F}{\delta_y}$

Question1: Do you agree with this method ?

Question2: If I have a different type of loading, for instance a distributed load, would the spring constant change ?


Yes it would change.

For example same load if applied at quarter span would cause less deflection and a different curve.

Hence bigger K.

basically for the type of loading you display applying the load at center corrolates to smallest K.

  • $\begingroup$ Thank you for your response. If I apply a continous loading (pressure) how can I find the spring index? Do you know? $\endgroup$ – james Mar 25 '18 at 6:19
  • $\begingroup$ For continius loading say same load as previous one : P if spread over all or part if span, will cause less deflection so the K would be bigger. $\endgroup$ – kamran Mar 25 '18 at 14:18
  • $\begingroup$ I see. How do you calculate k ? Do you use the equivalent force at applied to the centroid of the continius loading ? $\endgroup$ – james Mar 25 '18 at 14:27
  • $\begingroup$ I would use something like Hardy- Cross method to quickly calculate the frames stresses and deflctiins. $\endgroup$ – kamran Mar 25 '18 at 14:30

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.