Fire Safety Science Digital Archive

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.