geomtransf..

[Elina]

I'm studing example 7 and I'm a little bit confused about vectxz for girders.
Let's say we have the element 1321 with nodeI --> 121 and nodeJ--> 221, so local x-axis has the same direction and sign with global Z-axis. Assuming that local y-axis is vertical, the local z-axis should have the same direction but opposite sign with the global X-axis.
So, the expected vectxz is vectxz [-1 0 0], but at the example it is defined as vectxz [1 0 0].
Can you explane this difference??? Haven't I understood correctly the use of geomtransf???

Thank you!!

[hugo_esquivel]

You say:
x-axis = Z-axis.

Assuming that your global axes were defined as this:
X-axis [crossProduct] Y-axis = Z-axis

You need to understand the difference between case 1 and 2 as follows...

Case 1: vectxz = [1 0 0]:
z-axis = vectxz = X-axis.
y-axis = vectxz [crossProduct] x-axis = -Y-axis.


Case 2: vectxz = [-1 0 0]:
z-axis = vectxz = -X-axis.
y-axis = vectxz [crossProduct] x-axis = Y-axis.

Hope it helps.

[Elina]

Thanks for your reply..

I was confused because I assumed the local y-axis upwards...

Everything is clear now..