Seismic performance of an energy dissipating shear key for highway bridges using butterfly-shaped steel plates

Abstract

Typical small-to-medium-span highway bridges in China are usually equipped with reinforced concrete shear keys in the transverse direction to provide lateral support for the superstructure under design earthquakes. In the 2008 Wenchuan earthquake, a large number of shear keys were severely damaged, resulting in out-of-control consequences of bearing sliding and girder unseating. The deficiency of traditional reinforced concrete shear keys has engendered a sense of urgency in China to develop novel and competent shear keys. As motivated by such a demand, this paper proposes a new kind of energy dissipating shear key (ED shear key) using butterfly-shaped steel plates based on the installation requirements of typical highway bridges in China. Eight full-scale specimens were designed and tested to examine the seismic performance of the ED shear keys under various test parameters. Based on the test results, the failure modes of the ED shear keys were identified and the energy dissipation characteristics were discussed. It was found that the ED shear keys had a stable and considerable capacity of energy dissipation even after buckling occurred to the strips. In addition, the ED shear keys exhibited very good deformation capacity and ductility, with the ultimate drift ratios ranging between 20.4 ∼ 24.3%. According to the identified failure modes of the ED shear keys, an analytical model was finally proposed. The comparison between the experimental and theoretical results demonstrated that the model can well represent the recorded force–displacement skeleton curves. It is expected that the ED shear keys can satisfy the seismic requirements of different highway bridges through adjusting the number of butterfly-shaped steel plates, and the proposed analytical model can be successfully applied to predict the seismic behavior of highway bridges in practical engineering.