|主題||SHEAR BEHAVIOR OF PRETENSIONED PRESTRESSED CONCRETE BEAMS|
|連名者1||Sami H. RIZKALLA|
In the last few decades precast concrete structural members have become very popular in the construction field due to the saving of construction time and better quality control. Among such members, pretensioned prestressed concrete members are most economical and prevalent because of easy treatment. However, problems may happen in the stress transfer region of the beam ends when a shear span-to-depth ratio is low and shear behaviour is dominant.
In this paper, the discussion begins with the influence of shear cracks on slippage of prestressing strands for pretentioned T-beams with typical commercialized dimensions. Then, a device for anchorage of strands is introduced, and the discussion is extended to the shear behaviour of beams when the slippage of strands is restricted.
1)The initiation of shear cracks impairs embedment of prestressing strands, and causes slippage of strands. This results in premature failure of pretentioned prestressed concrete beams.
2)Slippage of strands decreases the flexural strength, and may prevent shear failure although it makes shear crack wide.
3)The role of stirrup in pretensioned prestressed concrete beams is not so simple as assumed by the truss analogy. The shear crack initiation load may be predicted by the ACI code equation, but the maximum load or the ultimate shear strength of a beam looks much higher than expected, especially for beams in the third group.
4)There was little difference in effectiveness of various types of stirrup on shear behaviour.