(следует рассматривать как) статически неопределимые элементы из-за дополнительных связей между ними и стальными пластинами...

Вот пример рассуждений на эту тему:

Consider a bar fixed rigidly at both ends to opposing walls and a force applied in the middle of the bar. The bar is fully constrained, but the reaction forces can't be solved with just the equations of statics, making it statically indeterminate. You could say that the beam in the above example is "overconstrained", and by that I mean that the bar could still be fully constrained without fixing both ends. A cantilever beam is fully constrained in translation and rotation as well, and that problem is statically determinate. I know that's not the exact meaning of "overconstrained", but I'm just trying to illustrate that point.