Seismosoft | Earthquake Engineering Solutions

Hi,

I will really appreciate if someone could help me to find the problem in my modelling a UCSD blind prediction column. This is also available in Seismo verification manual.

I tried to model the column with a rotation spring at base to check how the link element as a spring works in seismo. However, I could not figure out the problem in my model.

1. I created three nodes (1,2,3, where 1 and 2 are the same coordinate at base.
2. I created rotational spring by linking node 1 and 2 with a zero length element. I used bi-sym model. The spring constant comes from the moment curvature.
3. Then I created a elastic frame element between node 2 and 3 and put the lumped mass on node 3. Properties of this elastic element I considered from the X-sectional geometry of the column.

Then I run static pushover and nothing happen, column is too stiff and not moving. The link element is not working.

I attached my model. Someone please guide me to find the error.
Thanks

http://www.4shared.com/file/tmA_8GFlce/USCD_Column.html

Send me, your full issue as pdf or word to describe more about modeling. I don't know, what is your modeling!

Hi shahnewaz.

Make certain that your spring data is correct. Note that SeismoStruct requires input of moment-rotation values in the link properties, not moment-curvature.

If you'll e-mail your model, I'll take a look at it and respond with any findings along with some simple models I have constructed with link elements. The link you provide raises security concerns from my anti-virus software, hence the request for the e-mail.

Best of luck.

Thank you huffte and Salar. I send my model in your email.

shahnewaz, I have two observations:

1. your linear link spring constants - besides M2, which you have set to your desired values in a nonlinear element - were all very small, and I believe they should be very large. I changed them to large numbers - take caution here and read the Help System regarding the assignment of large artificial stiffness values

2. I had to increase your target displacement in order to get the link to yield. I increased it from 2 to 7.

I'd recommend making sure your properties are the appropriate values.

Best of luck shahnewaz.

Thank you Huffte. Yes, now it works. I restrained my link in other direction (except M2) by giving large spring constant.

how to model beam column joint with rotational spring element for bar slip mechanism can anybody please help me to come out from this problem.