Full-scale fire tests on hollowcore floors

The results from two large-scale fire tests on a hollowcore floor plate, supported on protected steelwork, are presented in this paper. The two tests were identical except for the connection details between the units and supporting steel beams, with Test 2 having a more robust detail to tie the units and beam together. The floor was purposely subjected to a very severe fire created by specifying unrealistically small ventilation openings, compared to modern office construction. The hollowcore floor plate performed very well supporting the full applied static load for the duration of the tests. A beneficial load path mechanism created by lateral thermal restraint to the floor units was highlighted, which has not previously been considered. The tests showed that the small-scale standard fire tests, used to assess fire resistance periods, can be very unrealistic and ignores the beneficial effects of whole building behaviour. The test results presented reinforce the experience gained from real fires that hollowcore floor slabs have good overall inherent fire resistance.

A Passive Fire Protection Federation supplement to
Fire Prevention & Fire Engineers Journal

Passive fire protection is the term applied to the components of a building that ensure it offers adequate fire performance. This may apply to the fire performance of the elements themselves or to the improvement in fire performance gained by the addition of specialised materials, products or systems. The level of fire resistance offered, or the reaction of the materials, to fire may have been known for centuries, or may be the result of the application of modern and novel technology but, as with all complex and dynamic structures, any weak links must be spotted if disaster is to be avoided.

Whole Building Behaviour - Results from a Series of Large Scale Tests
By Tom Lennon, 2003

Structural integrity and stability during and immediately following a fire are traditionally maintained through a reliance on the performance of individual members (beams, columns, walls) subject to idealised loading conditions during a standard fire test. A number of large scale natural fire tests have taken place over the last ten years in a facility purpose built to investigate whole building behaviour. The complex interactions between structural members within a real building subject to a real fire have been investigated using an eight storey steel framed building, a seven storey concrete building building and a six storey timber framed building. The tests have shown the importance of whole building behaviour through identification of modes of failure and support mechanisms that are a function of the building rather than the individual members. The horrific events of September 11th 2001 have stimulated discussion on the performance of real buildings subject to real fires. The results from the full scale tests are presented in an attempt to encourage a holistic approach to the subject of fire safety engineering.

National Building Studies Technical Paper No. 5
Investigation on Building Fires
Part III: Radiation from Building Fires
by Her Majesty's Stationery Office, 1950

This historical report, dealing with the fundamental aspects of the spread of fire from one building to another by direct radiation, is one of a series of Technical Papers describing the results of investigation carried out by the Building Research Station on fire resistance and related problems.