Title: Shear Behavior of Exterior Non-Isolated Shear Keys in Bridge Abutments
Author(s): Alexandra Kottari, P. Benson Shing, and Ron Bromenschenkel
Publication: Structural Journal
Appears on pages(s): 225-237
Keywords: bridge abutment; concrete cracks; diagonal cracks; monolithic; non-isolated; shear keys; shear sliding
Exterior shear keys are used in bridge abutments to provide lateral restraints to the bridge superstructure under normal service loads and moderate earthquake forces. They also serve as a structural fuse to protect the abutment piles from damage in the event of a major earthquake. These shear keys are conventionally constructed monolithic with the stem walls in bridge abutments and are referred to as non-isolated shear keys. Past experimental data have shown that the failure of these shear keys under lateral seismic forces tends to be governed by diagonal shear cracks in the stem walls. This type of failure can be sudden, resulting in non-ductile behavior and costly post-earthquake repairs. This paper presents a design method that prevents the diagonal shear failure of the stem wall and allows for a more predictable failure mechanism governed by the horizontal sliding of the shear key. Analytical formulas are presented for design. The design method has been validated by the tests of three shear key-stem wall assemblies.