BRITISH STRUCTURAL engineers have reacted with astonishment to official claims that punching failure triggered the collapse of a terminal building at Charles de Gaulle airport in Paris last May.
French government investigators this week claimed that steel struts connected to exterior tubular steel tension members punched through the concrete roof of the airport's Terminal 2E to cause collapse.
Four people died in the resulting disaster (NCE 27 May).
Buro Happold partner Ian Liddell said he was 'astonished' to hear that punching failure was being blamed by the investigators.
'It would be normal practice for there to be continuous reinforcement linking all the strut connections, probably in the form of an embedded tube, ' he commented.
'This would have prevented any punching failure and helped distribute the complex loadings from the struts.'
Atkins head of structural design Mike Otlet also expressed surprise.
'Punching shear failure in concrete that should be under compression is hard to understand. But if it did happen, the concrete would buckle very quickly.'
The struts connected curved precast concrete plates to the steel tension members, forming composite lightweight units that helped create a dramatic long span arched roof effect.
An interim report submitted to the French transport ministry last week says that several of these struts had punched through the 300mm thick concrete, allowing it to buckle and disintegrate.