Stiffness Matrix and General Question

[ElyasCivil]

Hello everyone, i am getting confused on a rather simple concept any explanations would be very much appreciated. I am trying to use the stiffness method to solve the following problem?
The solution is force in member 5 equals 50 kn but i cannot arrive at this number at all.

In addition if you have a member whose two sides are subjected to unequal axial loads how does that member achieve equilibrium? I have included this in the questi

on as well.

Thank you so much.

 

[Mohanlal0488]

Hi ElyasCivil

I am familiar with finite element formulations, I don't remember much from the stiffness method...

If you are happy to go the route of finite elements I could help.

What type of elements are you dealing with? It is difficult to read what is written on your paper.
There also needs to be load applied to the system somewhere, which I can't see.

Based on what I can read it seems like the elements are springs, I would suggest that you can simplify this into 2 models that deal with the vertical and horizontal separately thus making 2 linear spring models or a single model using a 2 dimensional spring element...

 

[Mohanlal0488]

Additionally if it is infact spring elements I think that the one side needs to have roller supports

 

[r13]

I think you can simplify the spring support at each end, by combining the components of the springs to a single node with springs in the X and Z direction. Yes, I am curios about the nature and magnitude of the applied load that produces the 50 kN force you have mentioned. And what is the nature of the resultant force (tension, compression, shear...)?