The results are given of a limited programme of fire
tests on prestressed concrete beams of the post-tensioned
type, carried out by the Joint Fire Research Organization
in co-operation with the Building Research Station.
The aim was primarily to obtain data for the design
of beams to be used in buildings of high fire risk, such
as large warehouses, where a fire resistance of 4 hours,
as defined in B.S.476: 1932, would be required for the
structural elements. The limitations of the equipment
precluded testing representative full-size beams, and it
was therefore necessary to extrapolate from the results
of tests on scaled-down specimens. It was shown that
sudden or early failure was unlikely with this form of
construction. Full-scale beams of the types tested
having 2 1/2 in. concrete cover to the cable, should give
a fire-resistance of 2 hours without recourse to special
measures, but for 4 hours fire-resistance extra protection
wouId be necessary for the cable.
