# MAxwell reciprocal theorem and symmetric stiffness matrix

1. Dec 14, 2012

### 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?

2. Dec 14, 2012

### Studiot

Perhaps if you posted an example?

What elements do you have in your matrix?

kij is just a constant and therefore linear.

3. Dec 15, 2012

### svishal03

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