The effect of spectral shape on damping modification factors
Journal
Earthquake Spectra
ISSN
8755-2930
1944-8201
Date Issued
2020
Author(s)
Type
Resource Types::text::journal::journal article
Abstract
The main objective of this study is to investigate the effect of spectral shape on damping modification factors η used in equivalent static and response spectrum analyses of structures with damping ratios that are different from 5% critical damping. Record-to-record variability of η is also evaluated through a statistical analysis of 5270 ground motions records from 1137 interface earthquakes recorded in Chile. The effect of spectral shape is studied using recently developed spectral shape metrics SaRatio and epsilon [Formula: see text] and evaluating their use as possible predictors for η. Similarly to previous investigations, this article also examines the effect of oscillator period, earthquake magnitude, and earthquake duration for different levels of damping ratio. Results suggest that SaRatio is an effective predictor of η, particularly for highly damped structures. However, results also indicate that for rock and firm sites, earthquake faulting mechanism and site class do not have a significant influence on η. A simple period-independent regression model for η as a function of SaRatio and damping ratio is proposed. A comparison between median η from this study and those in current Chilean seismic codes shows that code factors are unconservative.
Subjects
damping modification factor
;
damping ratios
;
displacement response spectra
;
elastic displacement responses of structures with base isolation
;
elastic displacement responses of structures with high damping
;
elastic response spectra
;
seismic design codes
;
spectral shape metrics
;
chile
;
damping
;
regression analysis
;
spectrum analysis
;
critical damping
;
damped structure
;
earthquake magnitudes
;
ground motions
;
modification factors
;
regression model
;
response spectrum analysis
;
spectral shapes
;
damping
;
displacement
;
earthquake engineering
;
ground motion
;
response analysis
;
seismic design
;
seismic isolation
;
spectral analysis
;
structural response
;
earthquakes