Role of Shear Reinforcement in Large-Deflection Behavior


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Title: Role of Shear Reinforcement in Large-Deflection Behavior

Author(s): Sam A. Kiger, Stanley C. Woodson, and Frank D. Dallriva

Publication: Structural Journal

Volume: 86

Issue: 6

Appears on pages(s): 664-671

Keywords: blast-resistant structures; concrete slabs; deflection; ductility; reinforced concrete; reinforcing steels; shear strength; stirrups; supports; ties (reinforcement); Structural Research

Date: 11/1/1989

Shear reinforcement in the form of lacing or stirrups is required by applicable design manuals for almost all blast-resistant structures. In blast-resistant designs, the primary purpose of this type of reinforcement is not to resist shear forces but rather to improve performance in the large deflection region by tying the two principal reinforcement mats together. The data reviewed in this paper indicate that the requirements of the design manuals for shear reinforcement may be much more restrictive (and expensive) than necessary. Several examples of dynamic and static tests on structures using stirrups demonstrated that support rotations exceeding 20 deg without failure are possible. In one case, for both static and dynamic tests, rotations of over 14 deg were incurred with no shear reinforcement at all. In particular, a widely used manual requiring the use of laced reinforcement for all designs with rotations in excess of 8 deg seems overly restrictive. Additional research should be conducted to quantify the relative advantages of using stirrups versus lacing or possibly no shear reinforcement.