Designers of roofs or facades are faced with a fundamental decision - how best to support the glass? Many modern glass facades are suspended; the earliest and most famous examples being La Villette in Paris, and the Centro de Arte Reina Sofia in Madrid.
At Reina Sofia, a gallery of modern art housed in a former palace in the centre of Madrid, a new 35m high glass tower encloses lifts and stairs. It was designed by Ian Ritchie Architects with structural engineer Ove Arup & Partners and Pilkington Architectural. Each pane of glass in the tower is bored with Planar bolts and carried on its own external central support arm with a balancing downward load carried in the tie-down rod. The loads from the support arms accumulate along the lengths of the rods to maximise at top and bottom. To reduce the effects of temperature the designers anchored the tie-down at the top and provided a flexible spring at the bottom.