Challenge:
The Black Eyed Peas show at Madison Square Garden in New York City featured a vertical winch system which lifts and rotates a single performer and a “motorbike” set piece above the stage and audience. The winch system was built by the client and required a complete calculation package and stamped drawings by a registered professional engineer in the state of New York before the mechanism could be used in the venue.
Resolution:
For the structural analysis, our engineering team created a RISA-3D model of the main structural support system from the winch cable drum shafts to the aluminum tube support frame to the upper rotating gear up to the two manual “F” type trolleys. These trolleys are supported by and roll along a heavy-duty horizontal truss suspended from the building structural steel above. The model was analyzed for various orientations, dynamic loads, and possible single-point failures. For the mechanical analysis, all data was gathered regarding mechanical components, such as motors, gearboxes, bearings, cables and drums. Then, a series of MathCAD calculations were created in order to verify that all capacities exceeded the proposed static and dynamic loads associated with the winch system by adequate safety factors.
