Capacity Evaluation of Exterior Sacrificial Shear Keys of Bridge Abutments

Shear keys are used in bridge abutments to provide transverse support for the superstructure. The damage observed on bridge abutments in the aftermath of the 1994 Northridge Earthquake prompted the revision of the design of shear keys. As part of this revision, experimental and analytical work was conducted to investigate the seismic behavior of exterior shear keys in bridge abutments designed in accordance with current guidelines and to investigate shear keys designed for damage control. The latter work was aimed at providing guidance for seismic design of shear keys to act as structural fuses that would limit the input force in the abutment piles. Ten shear keys were designed and built at 1:2.5 scale of a prototype abutment design provided by Caltrans. The study concluded that a smooth construction joint should be considered at the interface of the shear key–abutment stem wall to allow sliding shear failure. A mechanism model was developed for capacity evaluation of shear keys with sliding shear failure. The results of the experimental program and development of the simple analytical model for capacity evaluation of exterior shear keys are presented in this paper.