A new damage index for steel MRFs based on incremental dynamic analysis

摘要

The present study introduced a damage index based on a relationship between two values: the maximum interstory drift ratio and spectral acceleration at the first-mode period of the structure. The proposed damage index was defined so as it equals 0 in the yield point of the structural system, while it equals 1 in the collapse point. The incremental dynamic analysis was used to compute the constituent parameters of the damage index in both yield and collapse points. It was also used to observe the change trend of the index through varying intensities of the earthquake ground motion records. A number of steel models, including single degree of freedom models, stick models and moment resisting frames served as different examples to exhibit the performance of the damage index as well as to compare it with a number of recognized damage indices. Non-linear models were developed in OpenSees. Stiffness and strength deterioration in these models were included using the concentrated plasticity model. The results indicated that unlike the comparative damage indices, the proposed damage index was not influenced by successive hardening and instantaneous softening. In addition, once the intensity of ground motion records increased, the index maintained its ascending trend. Besides, increasing the period as well as the number of floors along with the presence of some levels of inconsistency in structures caused a decline in the correlation between the proposed damage index and the comparative indices. (C) 2019 Published by Elsevier Ltd.