Correlation of earthquake intensity measures and spectral displacement demands in building type structures

Seismic damage and its correlation with the earthquake intensity measures (IMs) are important for both record selection and probabilistic seismic risk assessment studies. A lot of studies considering the various structural properties were performed to investigate the correlations of mainly PGA and PGV under different strength reduction (R) and ductility factors (mu). In this study, correlation of many scalar IMs named as PGA, PGV, a(rms), v(rms), d(rms), I-a, CAV, ASI, SI are studied. Building represented by single degree of freedom (SDOF) models were classified according to lateral strength ratios (V-t/W), ratio of strength capacity at yield (V-t) to seismic weight (W), varying from 10% to 50%. Effects of post yield stiffness capacities, hysteretic behavior type and the soil properties on deformation demand of SDOF models are also taken into account. Post yield stiffness ratios of 0%, 5% and 10% considered and assigned to building models. Elastic-perfectly plastic and modified Clough hysteretic models were used in the non-linear dynamic analyses. Strong motion records obtained from firm and soft soil sites were classified according to V-s(30) and inelastic deformation demands obtained from both soil conditions are calculated and compared. Variation of correlation coefficients of different IMs indicates that SI is the best earthquake parameter especially along the period range of 0.5-2 s which can be thought to represent building type structures. Furthermore, it was observed that sensitivity of SI parameter to post yield stiffness, hysteretic behavior type and the soil properties is very limited with respect to considered IMs. Correlation coefficients obtained from SDOF models are compared to that of multi-story buildings and the compatibility of both SDOF and MDOF models are presented.