IDA Curve

[nedved33]

Hi my friends
in my research, I need to perform IDA, but i have a problem with IDA curves. because of increasing of the slope of these curve[ Sa(T)----spectral acceleration in fundamental period Vs Drift max] i can't recognize the dynamic instability on these curve. probably, you know that global instability is equivalent with zero- slope in these curves.but i don't reach to this conclusion at all.
i have 2 questions[:)]:
1) what is my mistake?
2) can i use IDA curve with drift Vs shear force to recognize collapse point? what interpretation is for determination of collapse points in these curves?
thanks a lot
[|)]

[ruipinho]

Dear nedved33,

You have already asked this (http://www.seismosoft.com/forum/topic.asp?TOPIC_ID=1177), and I have already responded, hence why are you reposting the same question?

Rui

[nedved33]

Hi
I have 2 questions.
can i recognize the collapse point with max drift Va max Base shear curve???
I want plot IDA curve and i have to determine collapse point[?]