Investigation into prestress loss and structural performance of prestressed concrete beam with creep promotion at early ages

[出版社版]The authors study the effect of creep promotion by prestressing a prestressed concrete beam at early ages on the inhibition of long-term prestress loss and evaluate the structural performance after the creep promotion. The consistent experimental programs suggest that more progress creep induced by larger prestressing force or elevated temperature at early ages is likely to make the long-term prestress loss smaller. The compressive strength and Young’s modulus of concrete after the creep promotion are larger than those of concrete without creep, while the tensile strength and Young’s modulus are almost the same or decreased when large sustained stress exceeding elastic range is applied. The flexural behavior of the prestressed concrete beam with the creep promotion is not different from that of the beam without the creep at early ages, although the maximum flexural crack width is slightly increased due to the creep promotion. Since it is found that the shear crack propagation is more progressive when the creep is greatly advanced under severe conditions such as at elevated temperature, the appropriate application of the prestressing force to prestressed concrete beam at early ages is indispensible for maintaining the structural performance