Performance assessment of moment resisting frames during earthquakes based on the force analogy method

When creating an earthquake hazard map, simplified procedures are needed for structural performance assessment because the number of buildings involved is considerably large. These procedures usually employ damage indices to quantify the level of damages happening to the structure during the earthquake. Based on a force analogy method, this paper proposes a damage index for special moment resisting steel frames considering both maximum deformations and cumulative effects. Assessments on global damage, local damage, and modal damage are performed using the proposed damage index. These assessments are performed using 49 synthetic earthquake time histories and four special moment resisting steel frames. The modal damage indices are correlated with assessments based on full degree of freedom inelastic dynamic analysis. The work of this paper indicates that the modal format of the proposed damage index, up to a certain accuracy, may approximate the global damage index, and therefore it is possible to create spectra of damage indices and spectra of the probability of failure based on the proposed modal index to provide more efficient assessments of the structural performance of special moment resisting frames during earthquakes.