DAMPING MATCHED CURVES FOR THE STATIC NONLINEAR PROCEDURE
Nguyen ThuongAnh, Labbe Pierre, Guillaume Hervé-Secourgeon, Semblat JeanFrancois · NCSU Libraries Repository (North Carolina State University Libraries) · 2019
The Static Nonlinear Procedure (SNP), also designated in the literature as Pushover Analysis procedure or Capacity Spectrum Method, mainly developed in ATC 40 (1996), becomes a widely practical engineering method to cope with the seismically induced ductile demand of a structure or equipment without performing nonlinear transient analyses.On its basis consisting in linear equivalent system, many authors have improved this procedure.But the discrepancy between predicted results and references remains quite important.In this paper, the key point of the procedure is discussed.New damping curves matched from a systematic analysis of equivalent linearization are proposed.Various constitutive relationships ranging from purely damaged to elastoplastic, controlled by a hybridity factor 𝜒, are considered for SDOF systems.In particular, the frequency dependence of the damping matched curves is examined through the f0/fc ratio varying from 0.1 to 2.0, where f0 is the SDOF system natural frequency and fc is the dominant frequency of the input signal.Predicted responses using the proposed matched damping are compared with the ones using the damping modification formula of Chopra (1999) and Iwan (1980) as well as the reference results obtained from the nonlinear transient analyses.The main conclusion highlights the strong frequency dependence of the effective damping ratio versus the ductility demand.In terms of performance, the SNP using the proposed damping matched curves can determine with high accuracy the seismically induced ductility demand of SDOF systems.