8/15/2019 Spo2ida Method

1/1

SPO2IDA METHOD

IDA analysis is computationally intensive and hence alternative methods are being developed

to obtain accurate response values without actually performing IDA.

One such approach introduced by Vamvatsikos and Cornell is the SPO2IDA method.

Here the mean\median IDA curve is developed from static pushover analysis and response

spectra curves.

Static pushover analysis (for MDOF 1st mode SPO is found) is conducted for the required

structure and SPO curve is plotted.

Response spectra curve is also plotted.

Vamvatsikos and Cornell suggest an idealized trilinear elastic hardening negative curve for

the SPO curve. Basically they divided the SPO curve into 3 parts i.e elastic region, hardening

region and negative slope region.Each of the above regions is assigned an elastic stiffness (k).

=  (1,5%)

(1,5%) 

= 

  also called ductility

The mean IDA is plotted from K-R-μ tables provided by Vamvatsikos and Cornell. 

Say(T1,5%)=spectral acceleration at yield.

δ=displacement of roof  

δy=displacement at yield.