Question

The load case centre report shows 'COUPLE' on many occasions instead of the load values. Please help me understand the reason for it.


Answer

What happens is that when we have a couple force that are coming 90 degrees to the applied load direction, if the load direction is along the x-axis, then the Y force will show a COUPLE force. So generally what happens when we have X-direction force, we are supposed to get zero force along the Y-direction. In SACS, sometimes we have magnitude force (small forces) because of solution convergence. 

You will see there are very small forces in either X or Y direction where it will form a couple force locally. It will have a very minor contribution to the overturning moment and it can be ignored.

For example (Sample 02)

From the load case summary, you can see the forces are very small. 



In the load case center we reported the couple forces: 

It will have a very minor contribution to the overturning moment and it can be ignored.