Spin-Lock Concrete Anchor Case Histories:
Tennessee DOT Sign Project

Within the past few years, several states have experienced failures of cantilever highway sign structures. Because of this, Tennessee Department of Transportation began inspections of all structures including cantilever, overhead, and bridge mounted signs. After examining the failed sign structures, it was determined the mode of failure was due to fatigue and/or corrosion of the original cast-in-place anchor bolts. All of the failed structures incorporated a four bolt fastening pattern anchoring the vertical column to the concrete foundation. The design chosen to correct this problem consisted of retrofitting the base to add redundancy to the connection. This was achieved by core drilling the flange and footings to accept two or three, where space would allow, Williams R1H hollow rebar concrete anchors on the opposite side of the cantilever arm. A total of 249 sign structures were retrofitted throughout the state of Tennessee using this method.

MAIN REASON THEY CHOSE WILLIAMS:

This was the anchor of choice because of its ability to generate full anchorage mechanically with the cone and shell, and also, a secondary bond of the grout and deformations in the bar to the walls of the cored hole. The grout also creates a barrier for corrosion protection.