Retrofit of Slab Column Interior Connections Using Shear Bolts

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Title: Retrofit of Slab Column Interior Connections Using Shear Bolts

Author(s): Bamidele Adetifa and Maria Anna Polak

Publication: Structural Journal

Volume: 102

Issue: 2

Appears on pages(s): 268-274

Keywords: column; concrete; punching shear; shear reinforcement; slab; strength

Date: 3/1/2005

Abstract:
Shear bolts are a new type of reinforcement developed for punching shear strengthening and retrofit of existing slab-column connections. The shear bolt consists of a headed vertical rod threaded at the other end for anchoring using a washer and nut system. The bolts are installed in holes drilled in a slab in concentric perimeters around the column. Previous testing carried out at the University of Waterloo established the feasibility of using shear bolt reinforcement to increase the punching-shear strength and ductility of edge slab column connections. This paper describes an experimental research program in which large-scale models representing interior slab-column connections were tested. Six specimens, 1800 x 1800 x 120 mm, with square columns 150 x 150 mm, were built. Two specimens had openings constructed near the column. These two, and an additional three, specimens were reinforced using the shear bolt system. One slab was without the shear bolts and served as a control specimen. The test results are presented in terms of deflections, strains, and crack width. It was found that the use of shear bolts increased the strength of the connection and significantly improved the ductility.