Do structural designers have to do something extra to achieve good vibration performance from composite floors in steel framed hospital buildings?
No, says the Steel Construction Institute (SCI).
Recent research shows that the normal designs used in countless commercial projects over the years have now been proven to produce a vibration performance far superior to National Health Service (NHS) requirements.
The evidence comes from new tests on floors in recently built steel framed hospitals.
The tests followed release of new design guidance from the SCI last year which laid to rest assumptions that uneconomically heavy steel sections would be needed to provide the vibration performance demanded by health professionals in sensitive areas like operating theatres.
SCI carried out tests on five composite floors in four hospitals with overall slab depths of between 175mm-337mm.
The measurements surpassed NHS requirements by a factor of between two and four. On a fifth floor tested it was found that an 80mm screed could have been omitted and the slab reduced theoretically from 325mm to 240mm, and an acceptable response factor would still have been achieved.
Among those tested were the Corus Slimdek floors at the Treatment Centre at St Richard's Hospital, Chichester (NCE 29 January 2004), and the Sunderland Royal Hospital extension now on site.
The test results are said by SCI to conclusively prove that steel framed floors would not need to be significantly deeper than those on concrete framed structures to achieve the NHS required response factor of 1.0 (equivalent to a slab depth of 420mm plus a 50mm screed).
A response factor of only 0.29 was achieved on a floor that was in fact 14% thinner.
SCI's manager for building engineering Dr Stephen Hicks said measurements from five floors have shown that steel framed floors are easily capable of achieving the strict vibration requirements for operating theatres:
'The implications of these test results are that designers can be confident that Slimdek floors in the health sector don't have to be designed any differently from floors in commercial buildings.
There is no need to do anything extra to achieve good vibration response factors, ' he said.
This means hospitals and other healthcare buildings can benefit from the full range of benefits of using steel frames that have brought steel a dominant share of the commercial market, says Corus general manager Alan Todd.
'Hospitals have to be built quickly because there is such a pressing need for them, which brings steel's fast construction time into its own. Health professionals also want flexibility built into hospital designs to accommodate changing needs, which steel, with long, clear spans, can easily offer. '