NL Link elements - Design/Check

[Techciv]

Hi,

I'm hoping to get SAP to highlight the failing NLLink elements in my structure). I understand that the design function is able to check for and highlight the failing steel and concrete elements.

I made a simple frame, with Linear Link element on diagonal, I also made the same frame with Damper, MultiLinear Plastic and MultiLinear elastic Link element. I assigned the force at top left joint. I think, when I assign a big force, the Link element should break, but program doesn't give me the note that Link element is failed.

I'm just hoping to find out if there is a way of checking for failing Link elements.

I have done it in SAP 2000 version 14.0
Thanks in advance!

 

[jdgengineer]

I don't think the Link Element will outright show you that it has failed. From what I remember (when I did this a few years back in ETABS) you aren't putting "failure" criteria in your link element. I used link elements, similar to as you are describing, to complete a nonlinear time history analysis in ETABS. From what I recall, the element (in ETABS at least) was only capable of bilinear behavior and any checks of adequacy I completed outside of the program by exporting the data to an Excel Spreadsheet.

However, there is an element in SAP that can do what you are talking about, and that's the "hinge" element. With the hinge element (to add go to Insert - Frame - Hinges -- I think) you define the backbone curve similar to how it is described in ASCE 41 (and other FEMA documents). In SAP I believe this is active for both pushover analysis, and time history analysis. In ETABS it was only active for pushover analysis so I had to use the link element.

Not sure if that helps or not...

 

[Techciv]

Thanks for your answer!

I will try with a hinge element.

Are you totaly sure that Link element can't have failure. Because I think when I give him force-displacment dependent i give him maximum force that he can bare. Or there is another way of giving the maximum force?

 

[jdgengineer]

I am not totally sure my only experience is with the plastic (Wenn) element and I don't believe it had the ability for failure. Is the maximum force you are inputting the yield force? I think the best way to do things like th is to do a simple cruciform model that models just one joint of a frame. Then you can troubleshoot the joint to see how the properties work.

 

[Techciv]

Ok. thanks. I will try.

You can see my model in attachment (first message).