“Toruk: First Flight” Stage Show for Cirque du Soleil
In May 2015 we were asked by Tait Towers Inc to assist them in engineering their design for a stage set, and to act as third party engineer for the whole structure. Tait Towers Inc are a USA based company that operate throughout the world and who design, manufacture, and operate travelling music and event tours. The set is part of a current Cirque du Soleil stage show, one that is based on the Avatar film, and has toured in the USA and Canada throughout 2016, and the Far East in 2017. The specific set that we were involved with is known as the “Home Tree” and comprises a primary framework of inflated tubes, clad by an outer skin that is also inflated and that provides a scenic and climbable surface over the primary frame. The inflated structures are deflated and packed into containers for transport between venues.
The framework comprises a series of A-frames, braced by purlins at two levels, and is designed to be a self supporting structure without assistance from the wrap around skin. The set is constructed in two halves, each 15 metres high and 12 metres wide, and each set has a high level gantry from which performers climb and technicians work. At any one occasion there could be up to seven performers or technicians on each half of the set.
The primary framework comprises tubes of woven and coated fabric with internal inflation pressures of around 90 KN/m2 (KPa). These tubes are configured to create a framework capable of remaining stable should two of the inflated elements fail. An extensive series of load cases were considered, and the connections between the tubes are carefully designs to function should the connecting tubes become deflated. The largest deflections under applied actions were 250 millimetres under the worst load combinations.
One aspect of the design that needed to be given careful consideration, and one not usually associated with inflatable structures, was the buckling stability resistance of the framework as a whole under gravity loading; each structure needed to support its own weight plus an additional three tonnes of equipment and personnel. The analysis suggested that the structure would performed well, largely due to the high internal pressures and stiffness of the primary tubes, and this has been proven in service.
Client Tait Towers Inc
