Zerolength element

[evgin]

Hi

I'd like to add springs at column top to simulate shear and axial responses as well .

Can I use only one zerolength element but with 2 different materials in the direction of shear and axial forces?

Then I can record the responses separately for axial and shear !

Or should I assign two zerolength elements (i.e. 2 springs ) to simulate the axial and shear responses separately ?

Your help in appreciated !
Evgin.

[nskok]

Yes, you can use only one spring. You can define the spring to have a shear response material in the horizontal direction and an axial response material in the vertical direction.

If you are modeling RC columns, take a look at the shear and axial limit state materials and their examples. http://opensees.berkeley.edu/wiki/index ... e_Material

# Zerolength spring
element zeroLength $eleTag $iNode $jNode -mat $shearMatTag $axialMatTag $slipMatTag -dir 1 2 6

- Nick

[evgin]

Thanks !

I was just wondering why they are assigning material to direct 6 as well?

And I understand that these springs should work in series with column so should I use "uniaxialMaterial Series $matTag $tag1 $tag2 ... ?

Or, use of section aggregator to take into account axial,shear , and flexural interactions would be enough?

Thanks!
Evgin.

[nskok]

Assigning a material in direction 6 will allow the spring to have rotational stiffness. If you want to have a very stiff spring that does not rotate, you can assign an elastic uniaxial material with a large modulus for direction 6, or instead, you can use the equalDOF command to constrain the rotation of the two nodes.

I've only way that I have connected springs in series with a column is the way that it is done in the limit state examples by adding additional zero-length nodes at the ends of the girder or column. The series material will not work with a column element; it can only connect different materials in series.

I'm not sure how the section aggregator would work. I'm pretty certain that if you are planning on using the shear and axial limit state materials, they were not designed in mind for that use.

-Nick

[evgin]

Thanks very much Nick for your clear explanation ! Very Helpful !