FAQ >> Flying Strut

Flying Strut

The flying strut is an invention of one of the authors that has been used once. It is mentioned here only to demonstrate that seemingly intractable rigging problems can yield to imaginative thinking. The flying strut was used at a hospital construction site (Figure 7.39) after the framework was in place and the concrete floors had been poured. It was necessary to lower a series of 34-ton (31-t) chiller units and other machinery into a subcellar. Conditions dictated that the lowering be done halfway back into an alley of limited width between an existing building and the new structure. The alley was at subcellar level, and there were beams framed across and a partial deck poured at street level. No existing equipment or procedures could perform the work economically under the given conditions. The flying strut, a compression member suspended horizontally by ropes perpendicular to the building face, was relatively inexpensive to make and install (Figure 7.38). Half inside and half outside the building, the inboard end is held by four positioning ropes attached to columns on either side of the strut at the building face. Stabilizing ropes, or presenters, are run to interior columns as well. At the out-board end of the strut, the upper load block is mounted together with suspension ropes capable of supporting the load and running up several stories to column anchorages. Side preventers are also provided at the outboard end. The load block is not supported by the strut, instead, the strut is a means for positioning the block for the work. By providing take-up devices on the positioning and preventer ropes, the position and attitude of the strut can be controlled. The strut and its suspension system needed to be designed only for the lateral thrust resulting from positioning the load block. At the hospital job, it proved to be a quick and easy means of maneuvering the loads.

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