FOUNDATION CONTRACTORS across Europe will be put under increasing pressure to reuse existing foundations as part of building schemes, an international conference heard in October.
The message came at the two-day Reuse of Foundations for Urban Sites (RuFUS) conference held at the UK's Building Research Establishment (BRE). Delegates heard that as the development cycle of city centre sites is cut to as little as 25 years, the ground underneath is becoming more congested with old foundations. In some cases, installing new ones is becoming impossible or hugely expensive.
'A foundation reuse time bomb will hit every major city in the world in 10 years, ' warned Tim Chapman of UK consultant ARUP.
Last autumn RuFUS published the best practice handbook, written by a cross-European team of foundation and structural engineers. The handbook was produced under the editorship of BRE's Geotechnical Group, which also coordinated the RuFUS project.
It is the principal outcome of the EU-funded scheme, which has been running since 2001 and aims to give con dence to all parties considering foundation reuse.
Geotechnical Group principal consultant and one of the handbook's authors, Tony Butcher, said:
'Many central London buildings are being redeveloped in as little as 25 years. As a result, the ground on a site can become completely congested with old foundations. There is simply no room for installing new piles in the locations required.'
Butcher urged greater reuse of existing piles as a safe option.
'The fact existing piles have already performed satisfactorily under load for decades should give assurance that they are likely to be able to carry the load for the new structure.'
The guide, which has taken ve years to develop and is funded by the European Union, sets out criteria for safe reuse of foundations.
These include: having good records of foundations 'as built' including locations, dimensions, type, materials and pile test data; time for investigation at the desk study stage and on site; a reasonably good match between the existing and new structural layout; a contract allowing the risks of reuse to be fairly assessed and distributed; a collaborative approach by the design and construction team.
The conference heard that on average only 15% to 30% of piles are being reused and that in many cases, a much higher percentage could be used again.