Title:
Design of Anchor Reinforcement for Seismic Shear Loads
Author(s):
Derek Petersen and Jian Zhao
Publication:
Structural Journal
Volume:
110
Issue:
1
Appears on pages(s):
53-62
Keywords:
anchor connections; anchor reinforcement; cast-in anchors; composite construction; fastening; headed studs; seismic design
DOI:
10.14359/51684329
Date:
1/1/2013
Abstract:
Existing design codes recommend hairpins and surface reinforcement consisting of hooked bars encasing an edge reinforcement to improve the behavior of anchor connections in shear. Concrete breakout is assumed to occur before anchor reinforcement takes effect in the current design methods. This paper presents an alternative design method for anchor shear reinforcement. The proposed anchor shear reinforcement consists of a group of closed stirrups proportioned to resist the code-specified anchor steel capacity in shear and placed within a distance from the anchor bolt equal to the front-edge distance. Steel fracture was achieved in the tests of twenty 25 mm (1 in.) reinforced anchors with a front-edge distance of 152 mm (6 in.). Meanwhile, the observed anchor capacities were smaller than the code-specified anchor steel capacity in shear because concrete cover spalling caused combined bending and shear action in the anchor bolts. Reinforcing bars are needed along all concrete surfaces to minimize concrete damage in front of reinforced anchors for consistent seismic behavior in shear.