PCはりの塑性挙動とじん性設計に関する基礎的研究

抄録

This study was carried out for giving the basic data to establish the structural design procedure of prestressed concrete beams based on the toughness as well as to develope the structural members having high ultimate and cracking strength.
Prestressed concrete beams (10×18×170cm), having various amounts of prestressing tendon and compression steel, were loaded up to complete failure. The normal strength concrete, high strength concrete and steel fiber reinforced concrete were included in the study. Also unbonded beams were tested and their test results were compared with those of the corresponding bonded beams.
The principal conclusions derived were: (1) The toughness value of prestressed concrete beams could be roughly estimated by the toughness index γ, which was calculated from the sectional constant and material properties. γ became larger with an increase of the toughness of compression zone. It was noted, however, that sudden failure due to the rupture of prestressing tendon took place when γ became too large. Therefore, the upper limit of γ should be determined so as to avoid the beam failure due to tendon failure. (2) Mechanically high performance prestressed concrete beams can be made by placing a large number of re-bars in both compression and tension sides and by introducing a large amount of prestressing.