Appearing as the skeleton of a space station, fallen onto an Adelaide beach side park, ‘Skymate’ is an aerial adventure park. Consisting of 54 ‘sky pod’ activity stations over four levels, which form the framework for over one hundred different aerial activities. These include high-ropes obstacles, freefall jumps, suspension bridges, swings and more: some for the extreme, some for the thrill-seekers and merely adventurous, some for the day trippers, and lastly, some pods just for spectators.
In 2015, Partridge was engaged for the structural design of this impressive structure. It is 26 metres high and of the 16 steel columns that support the activity stations, only 6 actually meet the ground. The rest are fully suspended, tied together with platform rings and structural cables, so that the whole appears as if it were still floating in space. This adds to the thrill of the aerial adventures and helping to characterise the structural and architectural philosophy of the structure. This design also allows for flexibility in the arrangement of the activities, as the modular components allow for future versatility.
Creativity and Innovation
The architect’s vision was for the outer ten columns to be suspended 4 metres above the ground, hung from the central structural columns. This gave rise to an architectural study of trying various locations and fixing points of the cables; an analysis of their overall behavioural response, and by an iterative feedback loop discovering the most structurally efficient and architecturally exciting cable arrangement.
To achieve long, slender spans of the pedestrian bridges between the activity pods and to continue the illusion of a floating structure, the simply supported steel beams were stiffened with a tension rod to effectively form a truss.
As no part of the steel structure is hidden from sight, the fine and delicate appearance of the structure greatly depended on the detailing of the steel and bolted connections. Partridge worked closely with both the client and the builders to critically examine each connection point to achieve the desired aesthetic.
Initially we designed the footings as precast concrete ballast blocks for speed of construction and simplicity. However, during the design development process the architect wished for a less visible footing system and as the site consists of a deep profile of loose dune sand, steel screw piles were used to provide an economic foundation structure, with an allowance for construction tolerances built into the connection between the substructure and superstructure.
Modelling and Risk Analysis
A risk analysis showed that redundancy was an important factor in this intricately tied together structure. If one or more of the critical cables were to fail (for whatever reason) was there sufficient robustness so that the whole structure would not fail but would allow the participants’ safe exit? A staged FEA analysis was carried out to confirm an appropriate level of robustness and redundancy.
The modular nature of the structure means that the structure can be continually altered to the client’s need without having to fabricate new elements. At the end of the lease at the site, the structure will be able to be disassembled and recycled and re-built at another site. Further, the use of screw piles as foundations greatly reduced the environmental impact of the footings, as they can simply be screwed out. At the very end of the life of Skymate, it can be dissembled and the sections reused elsewhere, or finally, cut up for scrap.
Structural Excellence on Show
The aerial adventure park promotes the structural engineering profession by allowing participants to closely interact with a raw steel structure in a way they may never have experienced before. They get up close to beams, cables and bolts and they can see (and perhaps feel) how the structure is working and supporting the weight of all the activities taking place around them.
The structural detailing and load paths are on constant show, allowing the public to appreciate how there is ‘simplicity within a complex form’. The overall structural form adds to the adventure and thrill of the experience and will evoke a curiosity from its users, ‘how does this stand up?’