Applicability of damage indices for detection of cracking in steel moment connections

Analytical detection of cracking in connections of steel moment resisting frames using simple damage indices is important since these cracks are not visible unless the connections are uncovered. In this paper, applicability of three cumulative damage indices for detection of cracking in a cover plate welded moment connection is investigated. The damage indices considered in this study are based on the following criteria: energy dissipation, plastic deformation and work index. Cracking of the connection is simulated for different loading histories by incorporating the cyclic void growth model to a finite element method of analysis of the connection. Results of simulation indicate good agreement with test results in terms of prediction of the cracking location and the instant of cracking. Based on the results of the performed simulations, the effects of the damage indices are compared. Overall, the energy dissipation damage index predicts cracking in this connection better than the other indices. Values of this index in the instant of cracking show little scatter for different loading histories.