Undercut and Grouted Anchors as Post-Installed Shear Reinforcement

Research and experience has shown that given specific loading scenarios and reinforcement configurations, reinforced concrete members may experience nonductile shear failures that can occur in sudden and brittle modes, often leading to structural collapse. It is desirable, therefore, to avoid shear failures and strengthen reinforced concrete elements with potential deficiencies. Candidates for strengthening include concrete elements that ACI 318 permits to be constructed without shear reinforcement (for example, shallow beams, joists, slabs, footings, and others) and concrete in rehabilitated or repurposed structures.

This research investigated the effectiveness of two post-installed reinforcement types (undercut anchors and grout-in-place threaded rods) for strengthening reinforced concrete beams in shear. The results from six full-scale shear tests, compared to design provisions in ACI 318-14 and AASHTO LRFD 2014, indicate that high-strength post-installed reinforcement may be used to strengthen beams in shear and achieve deformation and load capacities similar to traditionally reinforced elements.

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