1. Usually, the upper part of the U-shaped ring is reinforced by pressed steel plates. The loosening of cantilever U-ring requires tightening double nuts, and it is forbidden to loosen a single nut.

2. I-beams must pass through the U-shaped ring formed by the anchor bars on the floor. The construction is complicated, the material loss is large, the wooden wedge is easy to loosen, the bearing capacity is low and the reliability is poor.