MAxwell reciprocal theorem and symmetric stiffness matrix

[svishal03]

As per Maxwell reciprocal theorem, it is valid only for elastic materials and structures indergoing small displacements.That is k12 = k21, kij = kji hence stiffness matrix is symmetric.

Howbver, I just have been going through MY OWN written programs for geometric non linear problems and I observe that stiffness matrix (assembled stiffness matrix) is well symmetric.

How can stiffness matrix be symmmetric for non linear behaviour of structures?

 

[Studiot]

Perhaps if you posted an example?

What elements do you have in your matrix?

k_ij is just a constant and therefore linear.

 

[svishal03]

I have beam elements in my matrix. It is a cantilever beema with end moment.