The base plate anchorage system for major equipment supports is often designed with a combination of shear lugs and anchor bolts to resist equipment support reactions. Shear lugs are designed to transmit the design shear forces from the support base plates to the foundation concrete. The shear lugs are commonly placed inside a pre-formed grout pocket that is eventually filled with non-shrink high strength grout. The pre-formed grout pockets are sometimes left open to a free edge of concrete on one or more sides for ease of equipment installation and alignment before they are filled with grout. Where the equipment loads are applied in the direction of the free edge, the absence of adequate confinement makes it difficult to develop sufficient breakout strength in shear. This paper addresses a few practical issues that an engineer may face while designing non-confined grout pockets encasing equipment anchorage. It will also demonstrate different ways of improving the concrete breakout strength due to shear by means of providing reinforcements across the anticipated failure planes following the recommendations from different US codes and standards.
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