Brace Buckling

[martinmasanes]

Dear all:
I'm doing some research on braced frames and studing brace buckling, and have a problem trying to capture the displacement of the middle node of the brace. My braces have 10 elements (like Vesna's example) and the main problem is to capture the displacement of the middle node because of 2 reasons:

1) They are in a diagonal direction, so when the bar buckles you loose every posible trigonometric solution to get the displacement of the middle node with respect to the undeformed shape. I'm using Node Disp recorder to capture the disp of that node.

2) Let's say that I can capture the displacemet of the middle node with respect to the undeformed shape (the 'local y displacement'), then I have to 'uncouple' the displacement due to the bar buckling, and the displacement due to the Story floor displacement.

If any can have any idea please help
Thanks

Martin Masanes

[martinmasanes]

In case anyone is doing the same, I found a simple working solution. the Only mputa that you need to know is the length from the beam-columns connection to the middle of the barce, then using the drift command you avoid the Story drift problem and get the deformation (in %) of the node, so you only need to multiply the dift in both directions by the length discribed above and use the 'root of the sum of the squares' then ou got the displacement of the buckled node of the bar.