ACADEMICS THIS week clashed with safety officials over claims that current concrete design codes leave flat slab structures vulnerable to progressive collapse triggered by punching shear failure.
The British Cement Association (BCA) has challenged criticism of the requirement for ductilty in floor/column joints made in a recent Health & Safety Executive report.
The report into the 1997 collapse of Pipers Row multi-storey car park in Wolverhampton criticised the requirements set out in the current BS8110 and Eurocode 2 (News last week).
'I don't think these conclusions would be supported by most of the design community, ' said BCA technical director Dr Pal Chana.
Dr Chana has carried out extensive industry-funded research into flat slab systems 'Punching shear was researched intensively all over the world during the 1980s and '90s, and a number of solutions to providing ductility developed, ' he said.
Chana did acknowledge that including over-column bottom steel was a good idea, but added: 'The real lesson from Piper's Row was the need for proper maintenance, inspection and repair.'
But support for the HSE report came from a number of sources.
In a letter to NCE, Dr Nutan Subedi of Dundee University said the recommendations for slab-column connections in the best practice guides published by the BCA 'are based entirely on the cost of construction with no regard to structural efficiency.'
Professor Narayan Swamy of Sheffield University voiced a similar opinion. 'The BCA, like other interest groups who have invested heavily in research, are naturally championing their own solutions, ' he said.
Professor Emeritus Paul Regan of the University of Westminster also supported the report's call for amendments to the design codes regarding over-column bottom steel.
'It would make sense to specify the diameter and length of any such steel, ' he added.
'Provided proper attention is paid to the detailing of the main reinforcement, the result is a much more robust building for very little extra cost.'