Seismic Capacity Evaluation of Exterior Shear Keys of Highway Bridges

Shear keys as sacrificial components are widely used in cap beams and abutments of highway bridges to limit the transverse displacement of superstructures and avoid damage of substructures. To investigate the seismic capacity of bridge exterior shear keys, six exterior shear key specimens were designed on the basis of current Chinese seismic design guidelines of highway bridges and subsequently tested under monotonic lateral loading. The influence of vertical and horizontal reinforcement ratios on the seismic capacity of the bridge shear keys was studied. Two typical failure modes of the exterior shear key specimens, diagonal tension failure and sliding shear failure, were observed during the tests. The reinforcement ratios of the shear key and cap beam have significant influence on the seismic capacity of exterior shear keys. Moreover, different analytical models corresponding to the two failure modes were developed to predict the seismic capacity of the shear key specimens in this paper. Compared with the experimental results, the two analytical models proposed in this study can better predict the load-carrying capacity of the shear key specimens than the classical analytical models. (C) 2016 American Society of Civil Engineers.