ETABS nonlinear dynamic analysis

[edgedfire]

Hello, I'm Henry from Philippines

I'm currently working on a project and i have to evaluate the seismic performance of my structures.

I placed nonlinear hinges on my model and run a time history analysis.

my problem is that ETABS does not recognize the nonlinear hinges i placed. the hinges does not appear to have an effect on the result of the displacement due to the earthquake.

does etabs evaluate failure due to dynamic earthquake loading?

 

[stressed]

ETABS cannot consider material nonlinear behavior (plastic hinges) in the time history analysis. SAP2000 can handle material nonlinear behavior using the Direct integration time history analysis option which is not available yet in ETABS. I am told that ETABS will offer this capability within the next few months, but it's not there now. ETABS nonlinear TH analysis currently considers nonlinear boundary conditions like base isolators and gaps.

 

[jdgengineer]

Probably too late to be of any help, but ETABS can in fact "sorta" complete nonlinear dynamic analysis. The nonlinear hinge element you added is only activated when doing pushover analysis in ETABS. It is active for nonlinear dynamic analysis in SAP from what I remember, but has not yet been implemented in ETABS, as far as I know (SAP uses direct integration nonlinear analysis while I believe ETABS uses modal superposition... I could have these backwards).

However, ETABS does activate the "link" element during nonlinear time history analysis. The way I have modeled this in the past is to use the link element to model bilinear nonlinear behavior, meaning you can model a linear region and then a plastic region. I do not believe you can model a failure mechanism using this element as it is limited to bilinear. However, for the retrofit I have done in the past using ETABS we were shooting for immediate occupancy therefore our performance point was well before failure would occur and this element was therefore satisfactory.