Exploring the relationship between earthquake intensity and building damage using single and multi-degree of freedom models

The correlation between intensity and damage measure for generic moment-resisting steel frames (MRSF) that are subjected to earthquake shaking was analysed using optimised nonlinear single degree of freedom (SDOF) models. The parameters for these SDOF models are based on nonlinear quasi-static pushover analyses of the multi-degree of freedom (MDOF) building systems. This intensity-damage relationship was then compared with those obtained from incremental dynamic analysis (IDA), that is a MDOF approach. Results show that the general trend line of intensity-damage measures for nonlinear SDOF model was qualitatively similar to the MDOF model that in this case represents a full nonlinear finite element analysis of the MRSF. While the SDOF model is not a precise match to the MDOF model, results suggests that it can be used in the vital role of ground motion record selection because of its computational efficiency. Furthermore, it is shown that the accuracy of intensity-damage estimates from the SDOF models can be improved if optimal damping, pseudo-yield, and ultimate loads are chosen. The efficacy of various intensity measures on damage are compared and contrasted.