Reliability of results obtained through nonlinear static analyses is strongly dependent on the assessment of the performance point, usually computed by means of the capacity spectrum method. The use of constant ductility spectra as demand spectra, in place of reduced spectra for assigned equivalent viscous damping, can provide better results and a larger stability in the evaluation method of the performance point. In this case, the capacity curve of the SDOF equivalent system has to be transformed in a bilinear curve for computing the available ductility. Such a conversion can be performed according to several criteria that significantly influence results. In this paper, results of analyses carried out in order to assess the dependence of the performance point value on parameters controlling the bilinear relationship and on conversion procedure are shown. Reliability and accuracy of procedures proposed by ATC 40, Eurocode 8 and italian seismic code PCM 3274 as well as of procedures based on the use of constant ductility spectra is assessed by comparing results with the ones from nonlinear dynamic analyses.
[1]
Council
,
1954,
The Aeronautical Journal (1968).
[2]
V E Henderson,et al.
On Standardization.
,
1922,
Canadian Medical Association journal.
[3]
Anil K. Chopra,et al.
Capacity-Demand-Diagram Methods for Estimating Seismic Deformation of Inelastic Structures: SDF Systems
,
1999
.
[4]
Andrei M. Reinhorn,et al.
Inelastic analysis techniques in seismic evaluations
,
2019,
Seismic Design Methodologies for the Next Generation of Codes.
[5]
Sigmund A. Freeman,et al.
Prediction of Response of Concrete Buildings to Severe Earthquake Motion
,
1978
.
[7]
Michael C. Constantinou,et al.
EXPERIMENTAL AND ANALYTICAL INVESTIGATION OF SEISMIC RETROFIT OF STRUCTURES WITH SUPPLEMENTAL DAMPING: PART 1 - FLUID VISCOUS DAMPING DEVICES
,
1995
.
[8]
Peter Fajfar,et al.
Capacity spectrum method based on inelastic demand spectra
,
1999
.