Our whistlestop tour of the world of structures starts with an unfolding Olympic arch, then takes in the latest bricks and beams before reaching its destination – the first of a new occasional column, Me and IT
The Hoberman arch
Consulting engineer Buro Happold has collaborated with inventor and toy designer Chuck Hoberman to create the world's largest unfolding arch. It forms the centrepiece of the Medals Plaza at the Winter Olympics, currently being held in Salt Lake City, Utah. It opens to reveal the winners at each medal ceremony and acts as a huge projection screen when closed.

An unusual combination of structure and mechanism, it is 22 m in diameter and features an outer static steel arch into which the moving parts fold. This measures 1.8 m across and can accommodate all the moving elements. The moving part consists of 96 translucent panels made from fibre-reinforced polycarbonate supported on an aluminium box section frame. These are arranged radially and are layered so they overlap each other when retracted. The aluminium box sections are hinged so they can fold up. A series of four cables arranged radially pull the arch open, and it is pulled closed by its own weight. Guide rails hidden under the base of the arch combined with radial slides in the outer static ring locate the panels. Hoberman hopes this is just the first structure of its type, and the expertise gained from the project can be applied to other retractable structures for sports stadiums and theme parks.