Intensity Parameters as Damage Potential Descriptors of Earthquakes

This paper provides a methodology to quantify the interrelationship between the seismic intensity parameters and the structural damage. First, a computer-supported elaboration of the accelerograms provides several peak, spectral and energy seismic parameters. After that, nonlinear dynamic analyses are carried out to provide the structural response for a set of seismic excitations. Among the several response characteristics, the overall structure damage indices after Park/Ang and the maximum inter-story drift ratio are selected to represent the structural response. Correlation coefficients are evaluated to express the grade of interrelation between seismic acceleration parameters and the structural damage. The presented methodology is applied to a six-story reinforced concrete frame building. According to the first step of the methodology sixteen seismic parameters are evaluated: PGA, PGV, PGA/PGV, spectral acceleration (SA), spectral velocity (SV), spectral displacement (SD), central period (CP), absolute seismic input energy (Einp), Arias intensity (IA), strong motion duration after Trifunac/Brady (SMDTB), seismic power (P0.90), root mean square acceleration (RMSa), intensity after Fajfar/Vidic/Fischinger (IFVF), spectral intensities after Housner (SIH), after Kappos (SIK) and after Martinez (SIM). The frame structure has been designed according to the rules of the recent Eurocodes. Then, a nonlinear dynamic analysis has been carried out for the evaluation of the seismic response. Among the several response parameters, the focus is on the overall structure damage indices. This is due to the fact, that this parameter summarizes statistically all the existing damages on columns and beams in a single value, which can be easily correlated to single value seismic parameters. As seismic input for the nonlinear dynamic analysis, a set of spectrum-compatible synthetic accelerograms has been used. To emphasize the grade of interrelation between seismic acceleration parameters and the overall structure damage indices, the correlation coefficient after Pearson and the rank correlation coefficient after Spearman have been calculated. As the numerical results have shown, the spectral and energy parameters provide strong correlation to the damage indices. On the opposite, the CP, SMDTB and the term PGA/PGV delivered poor correlation with the damage indices. Due to this reason, spectral and energy related parameters are better qualified to be used for the characterization of the seismic damage potential.