Proposed Damage Index for Seismic Evaluation of RC Bridge Shear keys

Shear keys are bridge components that support the superstructure in transverse direction and may experience large displacements and extensive damages during earthquakes. Shear keys are designed to limit damage to abutment walls and piles by restraining the transverse movements. The shear force transferred to the abutments is controlled by the design and detailing of the shear keys. Damage to shear keys during earthquakes may affect significantly on seismic behavior of the abutments and consequently the bridge system. In this paper, a damage index is proposed for damage assessment of the bridge shear keys. The proposed damage index is defined based on the friction behavior and the ratio of the energy dissipation capacity to input energy. To evaluate the reliability of the damage index in damage assessment of the shear keys, finite element models of shear keys units, previously tested under cyclic loadings are developed and the proposed damage index is calculated. In addition, seismic response of shear key specimens are obtained under seven earthquake records using incremental dynamic analysis and the damage index is calculated for the shear keys in different PGA values of earthquakes. The results indicate that the proposed damage index can predict the damage progression in shear keys throughout loading histories and can provide reliable values for damage levels of shear keys with respect to the experiment observations.