Durability and Behavior of Pretensioned Beams.

To develop data on the factors affecting the durability of pretensioned concrete beams, 28 large beams containing pretensioning strands and 412 small companion specimens without pretensioning strands were fabricated. The concrete in 22 of the beams was air entrained; that in the other six was not. An appendix presents computations used in designing the beams. Some of the beams were subjected to laboratory tests, which indicated that the air-entrained beams showed less average camber and less midspan deflection, but the non-air-entrained beams withstood greater average flexural loads. A number of the auxiliary specimens were also tested in the laboratory to determine the strength, elastic, and plastic properties of the concrete. Some specimens were exposed to natural weathering. A few early results are noted. [ABSTRACT FROM AUTHOR]