1956 年 6 巻 1 号 p. 15-18
The results of fire-tests on beams, channel-type slabs and plate-like slab members of prestressed concrete for building structural use was shown in this paper.
The behavior of prestressed concrete under fire tests is remarkably different from that of ordinary concrete in the point that the surface of the concrete has begun to spall out explosively in a few minutes after heating.
The test results have shown that prestressed concrete of thin thickness suffers vital damages by a fire and so its fire resistance can be said to be very poor.
The explosive spalling is due to the vapour pressure of the heated water within concrete voids which has no way of escape of water-vapour since the concrete is very dense.
Prestressed concrete slabs provided with non-combustible ceiling or covering, endured Class III fire exposure, specified by Japan industrial standard A 1302, which corresponds to one hour fire in United States and British specifications.