Damage Potential Prediction of Greek Earthquakes Based on Spectral Sustainability Measures Derived from 3-D Displacement Response Spectra: Part – I

The aim of this work is the investigation of the correlation between seismic damage measures and the sustainability of response displacement peak, deduced from novel 3-D response spectra. These spectra are produced with relatively small additional computational cost compared to their 2-D counterparts and incorporate valuable additional information concerning the sustainability of conventional spectral values to the rest of major response cycles. The utilization of 3-D response spectra leads to the computation of handy sustainability indices, proposed herein, that reflect the sensitivity of standard response spectra values to (i) the number of significant response half-cycles (‘transversal’ sustainability index 1) and (ii) the elongation of fundamental elastic period due to inelastic response (‘horizontal’ sustainability index 2). Based on selected Greek ground motion records, a time domain inelastic dynamic analysis study was performed for elasto-plastic single degree of freedom (sdof) oscillators. The results reveal the strong correlation between the spectral sustainability indices and the damageability of each record and were utilized to produce empirical estimators as functions of the aforementioned sustainability indices, in order to serve as reliable predictors of standard damage indices. The applicability of the findings to a greater sample of ground motion records and more realistic structural systems (such as single and multi-storey plane RC frames) has been confirmed and will be presented in a forthcoming companion publication.